Summary of results with different powders and bullets for two Savage LE .308s.

Since many of you have shown interest in the data for my .223 and 6.5mm CM rifles, I thought I might also amass some data for my two .308 Savages Model 10 LE rifles, as well.

I apologize, in advance, for the long post, but I wanted to give you all the similarities and commonalities of the two rifles so you can make conclusions on how my results might apply to your rifles.
If felt that posting the data for each rifle separately would make it more difficult to compare the results considering these rifles are both .308s.

PLEASE NOTE: The data presented is for two particular rifles with 24-inch Savage barrels and the results show that barrels have preferences.
Any other rifle barrel may or may not produce similar results.
However, the data provides information on powder and bullet performance that might be of help and provide some ideas for .308 reloaders.

Background:

My two .308 Savages are both Law Enforcement models.
The 10 FP .308 is a 2008 model with 24-inch 1:10 twist barrel with an Accu-trigger, and a hidden magazine stock, similar to the one that comes on the 12 FVs. The stock has no strengthening element and is subject to flexing.
I shot 6,500 rounds through the 10 FP rifle as I was learning to reload and finding out what the rifle liked,
Eventually the erosion of the lands and the subsequent seating out to keep the jump around 0.020 caused a drop in group averages around 6,200 rounds, probably due to inconsistent neck tension with less and less bullet body in the neck. My groups grew by about 0.2 inches on average.
I was somewhat inexperienced with chamber erosion and took about 300 more rounds to realize that it was not me but the rifle losing accuracy and it wasn’t getting any better.

I bought a 10 FCP-K .308 as a replacement when I was deciding whether to replace the barrel the 10 FP.
The 10 FCP-K came with a fluted, 24-inch 1:10 twist barrel fitted with a muzzle brake mounted in an Accu-stock with a detachable mag.

I had the 10 FP rebarreled by Savage in 2013 with a 24-inch fluted, 1:10 twist target Savage barrel. After it was rebarreled, I replaced the original stock with a Bell & Carlson adjustable stock because I had become aware that the original stock was a bit too short for me.
The adjustable B&C stock had an aluminum strengthener so, as an added advantage, it also eliminated flex in the factory stock.

Both rifles have their Varmint/Target Accu-triggers set at 2 lbs.
Both rifles now have NightForce 8-32x56mm Benchrest scopes mounted on Burris Signature Zee rings.
The 10 FCP-K has a Mil Dot reticle and the 10 FP has a NP2-DD reticle.

When I got my rebarreled 10 FV back from Savage, I wound up with two .308 rifles with new barrels but I also had about 5 years of reloading data for .308s based upon the lessons learned shooting my original 10 FP barrel.
One thing I quickly determined is that the two new barrels were slightly different when it came to bullet weight preferences.

You also will probably note looking at the data below that the best load velocities for the 10 FP are slightly faster than the 10 FCP-K.
The 10 FCP-K has a 2.125-inch muzzle brake (from the factory) which changes the reflection time for the barrel & muzzle brake and, therefore, increases the exit time for the bullet in order to match the point when the reflection is at the chamber (keeps the crown tight and minimizes harmonics). I reduce the charges in the 10 FCP-K to slow the exit time to account for the added reflection through the muzzle brake (except for the last pass down the barrel to the muzzle since there is no rifling in the muzzle brake and the added muzzle brake reflection doesn’t matter).

I have found that each rifle’s best performance occurs when the bullet exits within +/- 0.003 msec of the calculated exit time for its barrel, and in the case of the 10 FCP-K, its muzzle brake (+/- 0.003 msec. of exit time equates to about 0.1 grains of powder).

Results for Powder-Bullet Combinations

The following tables show the average performance for each Powder-Bullet combination shot with each rifle and also shows the best load average and the best load velocity.
All the data summarized below is for 5-round groups shot at 100 yards at a range that is 250 ft above sea level in Northern Virginia.

The data for each combination is an average for all seating depths and powder charges for the groups shot with each particular combination.
I have found that the combination average gives a very useable representation of what powders and bullets work best for my rifles.
The best loads show what might be achieved by tuning for a particular powder bullet combination in a specific barrel.

10 FP (New Barrel) .308 (Law Enforcement Model) - 5-round Groups

By Weight
# Grps -- Powder ---------Bullet --------- Wgt. – Avg. -- Best Load – Vel. – Weight Avg.
---17-------IMR4064—Sierra TMK #7755----155---- 0.373 ------ 0.306------2598
---16-------IMR4166—Sierra TMK #7755----155---- 0.392 ------ 0.338------2560 ---- 0.403 - 155 grs
---28------- H4895 --- Sierra TMK #7755----155---- 0.430 ------ 0.429------2633
---16------- N140 ---- Sierra TMK #7755----155---- 0.415 ------ 0.345------2604
---4------- IMR4166— Sierra SMK #2000----168---- 0.327 ------ 0.327------2544
---4 ------- N140 ---- Sierra SMK #2000----168---- 0.348 ------ 0.348------2568
---47----- IMR4064— Sierra TMK #7768----168---- 0.455 ------ 0.413------2546 ------ 0.412 - 168 grs.
---24----- IMR4166— Sierra TMK #7768----168---- 0.443 ------ 0.399------2522
---22---- H4895 ----- Sierra TMK #7768----168---- 0.462 ------ 0.363------2599
---9------ N140 ------ Sierra TMK #7768----168---- 0.436 ------ 0.387------2547
---7 ----- IMR4064 — Sierra TMK #7775----175---- 0.455 ------ 0.403------2546
---2 ---- IMR4166 -— Sierra TMK #7775----175---- 0.475 ------ 0.475------2509 ------- 0.469 – 175 grs.
---5 ----- H4895 ----- Sierra TMK #7775----175---- 0.477 ------ 0.477------2583
-207 –Total Grps. -------------------------- Average –0.431

By bullet weight average, the 10 FP (New barrel) seems to perform slightly better with 155 grain bullets than 168 grain bullets and significantly better than 175 grain bullets.

By Average
# Grps -- Powder ---------Bullet --------- Wgt. – Avg. -- Best Load – Vel. --Rank
---4------- IMR4166—Sierra SMK #2000----168---- 0.327 ------ 0.327------2544 -- 1
---4 ------- N140 ---- Sierra SMK #2000----168---- 0.348 ------ 0.348------2568 -- 2
---17-------IMR4064—Sierra TMK #7755----155---- 0.373 ------ 0.306------2598-- 3
---16------IMR4166 —Sierra TMK #7755----155---- 0.392 ------ 0.338------2560-- 4
---16------- N140 ---- Sierra TMK #7755----155---- 0.415 ------ 0.345------2604-- 5
---28------ H4895 --- Sierra TMK #7755----155---- 0.430 ------ 0.429------2633-- 6
-----9------ N140 ---- Sierra TMK #7768----168---- 0.436 ------ 0.387------2547-- 7
---24---- IMR4166 -—Sierra TMK #7768----168---- 0.443 ------ 0.399------2522-- 8
---7 ----- IMR4064 -—Sierra TMK #7775----175---- 0.455 ------ 0.403------2546-- 9
---47---- IMR4064 -—Sierra TMK #7768----168---- 0.455 ------ 0.413------2546-- 10
---22---- H4895 ----- Sierra TMK #7768----168---- 0.462 ------ 0.363------2599-- 11
---2 ---- IMR4166 -— Sierra TMK #7775----175---- 0.475 ------ 0.475------2509-- 12
---5 ----- H4895 ----- Sierra TMK #7775----175---- 0.477 ------ 0.477------ 2583-- 13
-207 –Total Grps. -------------------------- Average –0.431

Looking at rankings by average, the 10 FP (New Barrel) rifle seems to prefer the 168 grain bullets with IMR4166 and N140 powder (averages of 0.327 and 0.348 ranking #1 & #2 but the # groups is a small sample). The analysis of the top 25 loads, listed below, gives a slightly different perspective.
But the H4895 and IMR 4064 powders (rank #10 & #11) did not perform as well with the 168 grain bullets (averages of 0.436 and 0.443).
However, the 155 grain TMK bullets hold the #3 through #7 rankings with 4 different powders and much more statistically significant samples.
The 155 grain TMK bullets performed better (averages from 0.392 to 0.430) with all powders compared to the 175 grain TMK bullets (averages from 0.455 to 0.477).

By Powder
# Grps -- Powder ---------Bullet --------- Wgt. – Avg. -- Best Load – Vel.- Pwdr. Avg.
---28------- H4895 --- Sierra TMK #7755----155---- 0.430 ------ 0.429------2633
---22----- H4895 ----- Sierra TMK #7768----168---- 0.462 ------ 0.363------2599 --- 0.447 - H4895
---5 ------ H4895 ----- Sierra TMK #7775----175---- 0.477 ------ 0.477------2583
---17-------IMR4064—Sierra TMK #7755----155---- 0.373 ------ 0.306------2598
---47------ IMR4064— Sierra TMK #7768----168---- 0.455 ------ 0.413------2546 -- 0.429 – IMR4064
---7 ------- IMR4064 — Sierra TMK #7775----175---- 0.455 ------ 0.403------2546
---4------- IMR4166— Sierra SMK #2000----168---- 0.327 ------ 0.327------2544
---16-------IMR4166—Sierra TMK #7755----155---- 0.392 ------ 0.338------2560 – 0.417 – IMR4166
---24----- IMR4166— Sierra TMK #7768----168---- 0.443 ------ 0.399------2522
---2 ---- IMR4166 -— Sierra TMK #7775----175---- 0.475 ------ 0.475------2509
---4 -------- N140 ---- Sierra SMK #2000----168---- 0.348 ------ 0.348------2568
---16------- N140 ---- Sierra TMK #7755----155---- 0.415 ------ 0.345------2604 – 0.412 – N140
---9------ N140 ------ Sierra TMK #7768----168---- 0.436 ------ 0.387------2547
-207 –Total Grps. -------------------------- Average –0.431

Note: For H4895 and IMR4064 powders, the averages are sorted by weight from 155 to 175.
IMR4166, with the second-best overall average, follows that weighting order sorting with the exception of the small sample of 168 SMK bullets.
N140 powder, with the best overall average, follows the IMR4166 sequencing except that there were no groups shot with 175 grain bullets.
However, it should be noted that no 175 grain bullets were shot with N140, so the average is slightly skewed to the low side.

10 FP – Best 25 Loads

By Weight
# Grps -- Bullet ----------------- Wgt. – Avg. -- Median - St Dev
----39 ----- Sierra TMK #7755 – 155 – 0.349 – 0.337 ---- 0.044
---- 8 ----- Sierra SMK #2000 – 168 – 0.337 – 0.344 ---- 0.047
--- 21 ----- Sierra TMK #7768 – 168 – 0.378 – 0.385 ---- 0.039
--- 66 ------------------------------ 0.360 – 0.357 ---- 0.044

By Average
# Grps -- Bullet ----------------- Wgt. – Avg. -- Median – St Dev
---- 8 ----- Sierra SMK #2000 – 168 – 0.337 – 0.344 ---- 0.047
---39 ----- Sierra TMK #7755 – 155 – 0.349 – 0.337 ---- 0.044
--- 21 ----- Sierra TMK #7768 – 168 – 0.378 – 0.385 ---- 0.039
--- 66 ------------------------------ 0.360 – 0.357 ---- 0.044

Note that the accuracy for the 8 groups of 168 SMK bullets is about 0.012 smaller than the 39 groups of the 155 TMK bullets.
However, the best three loads are with 155 TMK bullets and average 0.311 followed by a load of 168 SMKs at 0.327.
Also, 8 of the top 10 loads were shot with 155 TMK bullets and average 0.334 overall with a total of 23 groups.
The other two loads were 168 SMKs (the only two shot with 168 SMKs to date) with an overall average of 0.337 with a total of 8 groups.

Since the Top 25 loads contain 6 additional loads (#s 11,12, 14, 18, 19, and 21), the top 25 average tends to mask the best performance of 155 grain TMKs.
The best 175 grain load was ranked #67 overall.

10 FCP-K .308 (Law Enforcement model) – 5-round Groups
Note that the number of 155 grain bullet samples is quite small primarily because I abandoned the 155 grain bullets pretty quickly after I confirmed the performance was lacking compared to the heavier weight bullets.
I had shot a lot of 150 and 155 grain bullets prior to switching to exit time reloading so I didn’t waste time and money hoping for miracles once I had established that this barrel prefers bullets from 168 to 175 grains.

By Weight
# Grps -- Powder ---------Bullet --------- Wgt. – Avg. -- Best Load – Vel. – Weight Avg.
---- 3------- H4895 ----Sierra TMK #7755----155---- 0.466 ------ 0.400------2498
---- 4-------IMR4064—Sierra TMK #7755----155---- 0.430 ------ 0.430------2467 ---- 0.455 - 155 grs
---- 4------- H4895 --- Sierra SMK #2000----168---- 0.394 ------ 0.394------2468
---29------ IMR4064 -- Sierra TMK #7768----168---- 0.428 ------ 0.349------2385
---- 5------ IMR4166 -- Sierra SMK #7768----168---- 0.398 ------ 0.378------2385------ 0.428 - 168 grs.
---- 1------- H4895 ----Sierra TMK #7768----168---- 0.446 ------ 0.446------2453
--- 33-------- N140 ---- Sierra SMK #7768----168---- 0.471 ------ 0.283------2413
--- 4------- H4895 ----Sierra SMK #2275----175---- 0.324 ------ 0.324------2445
---11------ IMR4064— Sierra SMK #2275----175---- 0.372 ------ 0.347------2434
-----5----- IMR4166— Sierra SMK #2275----175---- 0.361 ------ 0.361------2380
-----4----- N140 ------ Sierra SMK #2275----175---- 0.370 ------ 0.363------2404
---81 --- IMR4064 ---- Sierra TMK #7775----175---- 0.428 ------ 0.295------2417
---22 --- IMR4166 --— Sierra TMK #7775----175---- 0.413 ------ 0.336------2356 ------- 0.394 – 175 grs.
---42 ------ H4895 ---- Sierra TMK #7775----175---- 0.453 ------ 0.316------2429
---34 ------ N140 ------ Sierra TMK #7775----175---- 0.428 ------ 0.322------2391
---17 ------ H4895 ---- Sierra TMK #7795----195---- 0.446 ------ 0.367------2382
-----3 --- IMR4166 -— Sierra TMK #7795----195---- 0.421 ------ 0.421------2331------- 0.430 – 195 grs.
-----3 ------ N140 ----- Sierra TMK #7795----195---- 0.423 ------ 0.423------2344
-298 –Total Grps. -------------------------- Average –0.431

From the overall average by bullet weights, the 175 grain bullets, particularly the 175 gr SMKs, seem to perform the best in this rifle.
The 195 TMKs have a very slight edge over the 168 grain TMKs. The small sample of 168 SMKs out-perform both.

By Average
# Grps -- Powder ---------Bullet --------- Wgt. – Avg. -- Best Load – Vel. – Rank
--- 4------- H4895 ----Sierra SMK #2275----175---- 0.324 ------ 0.324------2445 ----- 1
-----5----- IMR4166— Sierra SMK #2275----175---- 0.361 ------ 0.361------2380 ---- 2
---22------ N140 ------ Sierra SMK #2275----175---- 0.370 ------ 0.363------2404 ---- 3
---11----- IMR4064 — Sierra SMK #2275----175---- 0.372 ------ 0.347------2434 ---- 4
----- 4------ H4895 --- Sierra SMK #2000----168---- 0.394 ------ 0.394------2468 ---- 5
---- 5----- IMR4166 -- Sierra SMK #7768----168---- 0.398 ------ 0.378------2385 ---- 6
---22 ---- IMR4166 -— Sierra TMK #7775----175---- 0.413 ------ 0.336------2356 ---- 7
-----3 ---- IMR4166 — Sierra TMK #7795----195---- 0.421 ------ 0.421------2331 ---- 8
-----3 ----- N140 ----- Sierra TMK #7795----195---- 0.423 ------ 0.423------2344 ---- 9
---34 ----- N140 ------ Sierra TMK #7775----175---- 0.428 ------ 0.322------2391 --- 10
---81 --- IMR4064 ---- Sierra TMK #7775----175---- 0.428 ------ 0.295------2417 --- 11
---29------ IMR4064 -- Sierra TMK #7768----168---- 0.428 ------ 0.349------2385 --- 12
---- 4------IMR4064-- Sierra TMK #7755----155---- 0.430 ------ 0.430------2467 --- 13
---- 1------- H4895 ----Sierra TMK #7768----168---- 0.446 ------ 0.446------2453 --- 14
---17 ------ H4895 ---- Sierra TMK #7795----195---- 0.446 ------ 0.367------2382 --- 15
---42 ------ H4895 ---- Sierra TMK #7775----175---- 0.453 ------ 0.316------2429 --- 16
--- 3-------- H4895 ----Sierra TMK #7755----155---- 0.466 ------ 0.400------2498 --- 17
--- 33------- N140 ---- Sierra SMK #7768----168---- 0.471 ------ 0.283------2413 --- 18
-298 –Total Grps. -------------------------- Average –0.431

The 10 FCP-K rifle prefers 175 grain SMK bullets (holding the top 4 places in the table with 4 different powders with averages between 0.324 and 0.370)
The next two places go to 168 grain bullets (1 SMK with H48985 and 1 TMK with IMR4166) with averages of 0.394 and 0.398.
The 175 grain TMK bullets averaged from 0.413 to 0.466.
The 195 grain TMKs averaged from 0.421 to 0.446.



By Powder by Average
# Grps -- Powder ---------Bullet --------- Wgt. – Avg. -- Best Load – Vel. – Powder Avg.
---- 4-------- H4895 --- Sierra SMK #2000----168---- 0.394 ------ 0.394------2468
--- 4-------- H4895 ----Sierra SMK #2275----175---- 0.324 ------ 0.324------2445
---17 ------ H4895 ---- Sierra TMK #7795----195---- 0.446 ------ 0.367------2382---- 0.441 – H4895
---- 1------- H4895 ----Sierra TMK #7768----168---- 0.446 ------ 0.446------2453
---42 ------ H4895 ---- Sierra TMK #7775----175---- 0.453 ------ 0.316------2429
---- 3------- H4895 ----Sierra TMK #7755----155---- 0.466 ------ 0.400------2498
---- 4-------IMR4064—Sierra TMK #7755----155---- 0.430 ------ 0.430------2467
---29------ IMR4064 -- Sierra TMK #7768----168---- 0.428 ------ 0.349------2385
---11------ IMR4064— Sierra SMK #2275----175---- 0.372 ------ 0.347------2434------ 0.423 – IMR4064
---81 ----- IMR4064 --- Sierra TMK #7775----175---- 0.428 ------ 0.295------2417
-----4----- IMR4166— Sierra SMK #2275----175---- 0.361 ------ 0.361------2380
---- 5----- IMR4166 -- Sierra SMK #7768----168---- 0.398 ------ 0.378------2385 ------- 0.406 – IMR4166
---22 --- IMR4166 -— Sierra TMK #7775----175---- 0.413 ------ 0.336------2356
-----3 --- IMR4166 — Sierra TMK #7795----195---- 0.421 ------ 0.421------2331
---- 4------ N140 ----- Sierra SMK #2275----175---- 0.370 ------ 0.363------2404
-----3 ----- N140 ----- Sierra TMK #7795----195---- 0.423 ------ 0.423------2344------- 0.430 – N140
---34 ----- N140 ------ Sierra TMK #7775----175---- 0.428 ------ 0.322------2391
--- 33------N140 ------ Sierra SMK #7768----168---- 0.471 ------ 0.283------2413
-298 –Total Grps. -------------------------- Average –0.431

The 10 FCP-K rifle also seems to prefer IMR4166 powder followed by IMR4064 powder based upon the average ranks.
Also note that N140 powder didn’t perform well with the 168 grain bullets (rank #17) although it did produce a best load under .300 inches.

10 FCP-K – Best 25 Loads

By Weight
# Grps -- Bullet ----------------- Wgt. – Avg. -- Median – St Dev
--- 13 ---- Sierra TMK #7768 – 168 – 0.336 – 0.335 ---- 0.035
--- 15 ---- Sierra SMK #2275 – 175 – 0.351 – 0.350 ---- 0.052
--- 32 ---- Sierra TMK #7775 – 175 – 0.337 – 0.337 ---- 0.049
---- 1 ---- Sierra TMK #7795 – 195 – 0.367 – 0.367 ---- ----
--- 65 ----------------------------- 0.342 – 0.346 ---- 0.049

By Average
# Grps -- Bullet ----------------- Wgt. – Avg. -- Median – St Dev
--- 13 ---- Sierra TMK #7768 – 168 – 0.336 – 0.335 ---- 0.035
--- 32 ---- Sierra TMK #7775 – 175 – 0.337 – 0.337 ---- 0.049
--- 15 ---- Sierra SMK #2275 – 175 – 0.351 – 0.350 ---- 0.052
---- 1 ---- Sierra TMK #7795 – 195 – 0.367 – 0.367 ---- ----
--- 65 ------------------------------ 0.342 – 0.346 ---- 0.049

Note that the difference between the accuracy of the 168 TMK and 175 TMK loads, accounting for 45 of 65 groups, are within 0.001 inches.
That would tend to indicate that there is very little difference in the rifle’s preference for the two bullets but averages can be deceiving.

The top 10 loads include 175 TMK bullet loads in position # 2,3,5, 7, 8 & 10 with a total of 13 groups and an average of 0.312.
168 grain TMK bullet loads average 0.295 and occupy position #s 1 & 4 but with a very small sample of groups (2), and 175 grain SMK bullets occupy position # 9 with 4 groups (0.324).

Summary:

The overall 5-round group averages for the two rifles are within 0.0007 inches for 207 and 298 groups for the 10 FP and 10 FCP-K respectively making the results just about dead even when all recorded rounds are considered.

The 10 FCP-K rifle has two best loads that are under 0.300 inches while the 10 FP has its smallest best load average at 0.306.

The averages for the 25 best groups show a slight advantage (0.018) for the 10 FCP-K for about the same number of groups.
The Medians for the 25 best groups have a smaller advantage (0.011) for the 10 FCP-K.
The standard deviation is slightly larger by 0.0011 for the 10 FCP-K but that difference is also inconsequential.
The two rifles are incredibly similar in accuracy but their best accuracy occurs with different weight bullets.

Interestingly, I recently began shooting each of these again because I have lots of .308 powders, large rifle primers, and .30 caliber bullets so I decided to shoot the two old .308s rather than my newer .223 and 6.5mm CMs so I could save some of the reloading supplies for the rifles I have been shooting a lot because their reloading supplies were in shorter supply in my stash.

Both of these .308 rifles have been well used.
The 10 FP has shot over 3900 rounds through its replacement barrel and the 10 FCP-K has shot over 4400 rounds through its original barrel.
Just about all of the loads have been tuned to optimum exit time, so they are not even close to Pmax pressures.
You can tell that from the muzzle velocities of the best loads.

For those who would presume that these two well used barrels are shot out, here is something to consider.
The average group size for the last 4 loads for the 10 FP, using 155 TMK bullets and IMR4064 powder, averaged 0.355 with the best load averaging 0.306, the smallest load average it has ever shot.
The 10 FCP-K shot its last 4 loads with 175 TMK bullets and IMR4064 powder to an average of 0.334 with its best load averaging 0.295, the second-best load it has ever shot.
For everything that I see, they both seem to be shooting as good as they have ever shot.

Other potential sources of inaccuracy:
It is probable that the accuracy of each rifle is limited by the shooter’s capabilities as well.
Those familiar with the performance of my 12 FV rifles in .223 and 6.5mm Creedmoor calibers have probably noted that I performed best with the lowest caliber rifle and that these two .308s with a higher caliber have the largest average but almost identical group sizes.
The heavier recoil may be the factor expanding group size as caliber increases.

It would be interesting to find out whether other shooters note the same average group size growth.
If they don’t, it probably is a reflection of my problems with maintaining accuracy with increasing recoil.

Thanks for this. A wealth of information for us who are not as good and helps shorten development efforts. More than 90% of my shooting has been with Varget, the other powders being 4895, RL15 and BLC2.

On the other hand, lol.
When my grandson who is now 21 and a 3rd year college student was 14 we bought him a 308 FCP model and put a Nikon Buckmaster scope on it. i mean we really went all out on the scope. lol
I picked the gun up from a dealer in Pa and took it to our camp there.
I just cleaned the barrel and did nothing else, didnt even remove it from the stock or touch the trigger.
I loaded up some 150 gr SMKs i had laying around with 4320 powder which i like because it meters so precisely there is no need to weigh them.
First group after bore sighting and 100 yd zero was one of the best i had ever shot, just a ragged hole.
Load workup finished.
When a gun shoots, it will let you know right away, no need for long load workup sessions.
Later that fall when my grandson arrived from Florida he began shooting it at rocks and other things on the sidehills across from our camp.
He took a Porkupine out of a tree with it at 900+ yards the first day he used it.
We dont use that gun or the other 308s for actual l/r hunting, just practice shooting.
But fact is it is an awsome cartridge that can make someone a better shooter when used with those type rifles.

Good write up with a lot of groups shot, it will help guys save bullets, TIME and powders. i have never shot 4166 but it is supposed to be identical to Varget.
RL15, IMR4895, Varget , IMR4064 ,CFE223 with 168smk/175 have been giving me .3's in three 308(including an AR10) ,i can't honestly tell what's better and came to the conclusion that 308 with Sierra MK just rock. I also found the CCI BR2 to perform slightly better than the Fed210 in my guns. The 178 ELD-M and ELD-X on the other hand have outperformed the SMK ONLY with Varget.
I don't believe recoil affects accuracy in my testing; when i am shooting ,i usually switch between 3 guns(barrels cooling down) with one being 300WM or 450 Bushmaster AR and it has never affected my groups. What affects me personally is a shoulder/chest workout 24 hour before the range .
Good shooting and thanks for sharing.

IMR4166 is advertised as a temp insensitive version of IMR4064. Varget is a little slower.

I started with Varget cause I started with the heavier bullets, 168SMK, 175SMK and 178ELD Match. Groups were OK but not great. Went to 155gn and things got better. Just forgot to try the faster powders with the 155's. So, going to 4166 seems to be my next step since I have a bit of it laying around.

Quote:

---

Originally Posted by charlie b

IMR4166 is advertised as a temp insensitive version of IMR4064. Varget is a little slower.

I started with Varget cause I started with the heavier bullets, 168SMK, 175SMK and 178ELD Match. Groups were OK but not great. Went to 155gn and things got better. Just forgot to try the faster powders with the 155's. So, going to 4166 seems to be my next step since I have a bit of it laying around.

---

Midway and the Hodgdon website advertise it as a substitute for Varget. What’s “OK group”(.4?)? How far off the land were you with the 178 Eld ? Will PM you my loads , don’t want to Hijack the OP thread .
https://shop.hodgdon.com/imr/imr-enduron-4166

A wealth of information and we all appreciate your efforts Junkie.

I was probably .020" off the lands. OK was less than MOA. For me, good is .5MOA cause that's about as good as I can hold these days.

great article,you have shot a ton of rounds.thanks for writeup

charlie b,

I'm not sure that I would classify 155gr .308s as light bullets, but it is possible that they might perform better with a slightly faster powder.
My data shows 155 grain bullets perform well with the same powders as the heavier bullets but accuracy seems to be impacted more by the particular barrel than the powder choice.

I certainly would consider a faster powder if I tried .308 varmint bullets 125 grains or below but I have never tried anything that light so I have no data to justify that assumption.

The different powders are interesting when it comes to performance. And, yes, the 155's are not true light bullets for the .308, more like middle range.

I just kinda got 'stuck' on Varget because it became my go to powder for the .223 with the 77gn bullets so I bought it by the barrel. Two cartridges, one powder. But, it is the first powder to disappear from shelves even before COVID.

I kinda 'stumbled' into the 4166 when I could not get Varget. It did not do as well for me in the .223. I use it in the .30-06 and it does really well, even with cast bullets. It will be the next powder I use in the .308.

Quote:

---

Originally Posted by Robinhood

A wealth of information and we all appreciate your efforts Junkie.

---

Add a solid yes from me as well!

Interesting that IMR4166 didn't shoot well in your .223 but every barrel (either bore or length or both) seems to create its own preference.

With my 12FV .223 with a 26-inch barrel, IMR4166 has #1 position out of 22 combinations on my Powder Bullet list with 77 TMKs (0.279 for 205 groups) and and the #5 position with 69 TMKs (0.287 for 96 groups).
It also holds the # 8 position with 69 SMKs (0.292 with 89 groups) and and #9 position with 77 grain SMKs (0.297 with 77 groups).
With those group sample sizes, these results are statistically significant.

The #2 position is with N140 and 77 TMKs (0.280 for 40 groups) and #3 position is held by N140 and 77 TMKs (0.283 for 40 groups) so the 77 grain bullet preference seems to hold for this barrel - 4 out of the top 10. But 5 out of the top 10 positions are also held by 69 grain bullets.
Position #4 is held by H4895 with Berger 70 grain VLDs (0.286 for 11 groups) - I finally figured out what jump the Bergers liked.

But IMR4166 also holds # 17 position with Nosler CC 69s (0.403) and position #20 with 60 TMKs (0.487), and position #21 with 70 Berger VLDs (0.509 - but one of the loads averaged 0.291) and Position #22 with 68 Hornady 68s (0.653).
I have never gotten the Hornady 68s to shoot well in any of my .223s.
Also I haven't shot many groups for the combinations that sort of 'bring up the rear'.
I don't like wasting my time and money on combinations that don't work well.

That is a pretty varied result history for IMR4166 with the .223 12 FV - either really good or really bad. But I think the bullets (and a sub-optimum jump in the case of one Berger 70 VLD load) were the reason for the bad performance of the 4 combinations near the bottom of the list.

Quote:

---

When a gun shoots, it will let you know right away, no need for long load workup sessions.

---

+1

Quote:

---

Originally Posted by CFJunkie

charlie b,


My data shows 155 grain bullets perform well with the same powders as the heavier bullets but accuracy seems to be impacted more by the particular barrel than the powder choice.
.

---

Bingo, that one statement says it all as for how well a gun will shoot, or not shoot.
Lets be perfectly honest here, much of what we do as for load work up is strictly for the entertainment value of the individual shooter.
Not saying that a load cant be tweeked in order to make it better to at least some degree in a particular gun.
But average Joe shooter who might be reading all this neednt be feeling guilty about the way he loads for his factory built rifles either.
Finding ways to improve ones shooting will pay bigger dividends than shaving a small amount from our groups.
Especially at the longer distances.
Which is why my grandson was able to hit that porkupine at 900 yds with a factory built Savage.

I agree.

Most people, especially hunters, would be more than happy with 90% of the loads I have fired, even the ones I consider 'bad'.

I also like the challenge of getting cast bullets to shoot well.

All of this depends on what each of us likes to do. Some have gone deep down the rabbit hole, while some like me just kinda hover around the entrance :)

Quote:

---

Originally Posted by CFJunkie

Interesting that IMR4166 didn't shoot well in your .223 but every barrel (either bore or length or both) seems to create its own preference.
.....
That is a pretty varied result history for IMR4166 with the .223 12 FV - either really good or really bad. But I think the bullets (and a sub-optimum jump in the case of one Berger 70 VLD load) were the reason for the bad performance of the 4 combinations near the bottom of the list.

---

Might be the gun. My .223 is an Axis with a 22" heavy barrel. And really bad is not how I'd describe it. Just not as good as I experienced with the Varget. Difference was probably less than 1/4MOA, ie, 1.0" groups vs 1.5" groups at 200yd.

Quote:

---

When a gun shoots, it will let you know right away, no need for long load workup sessions.

---

Quote:

---

but accuracy seems to be impacted more by the particular barrel than the powder choice.

---

yobuck, wbm & charlie b,

I think we all agree that good rifles shoot well and a good shooter quickly determines that when he fires one.
Obviously, yobuck, you and his father trained your grandson well and he is obviously a good shooter.
You three, also, have probably have forgotten more about shooting than I have ever learned.

Just turning 78, I also realize that my best days are behind me, but interestingly, my group sizes are just about as good as ever.
I'll admit that my best groups are not as small as they were a few years ago, but my worst groups are a lot smaller also.
The standard deviation of my groups is actually slightly smaller than ever.
What I have lost in ability, I seem to have made up with improving my consistency.

I would put a caveat on all of our statements - they are true if the shooter is good enough to see the difference.

Case in point, I have a good friend that bought a 10 FCP .308 in 2013 because my original 10 FP shot well.
He put the gun away in 2016 after several years of trying to get it to shoot accurately (averaging over 0.7 inch groups) stating "this gun won't shoot worth a crap".

I knew he was suffering from inconsistent set-up positioning because, with his great eyes, he shot some of the smallest groups of any of our group.
But he also, within the same loads shot some of the largest groups.
In fact, his average standard deviation was well over 1-inch for his loads.
He just wouldn't accept that he was the cause and blamed it on the rifle, the powder, the primers, etc.
A fellow range officer told him one day that his set up was creating inconsistency, something I tried to suggest nicely many times before.
He dabbled a bit with trying to fix things but he still didn't really believe.

He eventually paid almost $3,500 for a .308 that came with two 100 yard 5-round test targets with factory ammo shot from a fixture that averaged just under 0.1 inches.
As much as he tried, he could never get it to shoot under 0.5 inches.

Finally, he listened and began to work on his set up.
He managed, after a year or so, to get his average groups under 0.4 inches with his expensive rifle.

I suggested he get out his old Savage 10 FCP .308 and see how it did with his new technique.
He found it shot really well with his old loads and, after his last few sessions, his group average was 0.325 for about 30 groups.

His rifle was always a good shooter. Unfortunately, the shooter just didn't perform well enough to see it until he became a better shooter.

Quote:

---

Finding ways to improve ones shooting will pay bigger dividends than shaving a small amount from our groups.

---

yobuck, you are so right. But I believe that one can't learn to shave a small amount from one's groups unless one improves one's shooting.

I hope some of our forum readers realize that just buying rifles, replacing stocks and barrels, trying new bullets or ammo, and buying new scopes will not replace learning to become more consistent.

I hope I didn't give the impression that I am trying to shame anyone.
I just intended to provide this information for those who reload who might be able to make use of it.
I know that, years ago, I would have saved lots of time, effort and money if someone had provided this kind of information for me.

As a Range Officer for many years I have seen lots of 'good' shooters and lots of 'not so good' shooters.
I've even had the good fortune to meet some 'really great' shooters who have taught me a lot.

If a shooter is willing, I am happy to share what I know, or think I know, and there are actually some members at our range that know my schedule and come to my sessions to get advice and share their experiences. To see them become better shooters and get great results makes it all worthwhile.

As you know I went through this same discovery a few years ago. I had stopped shooting rifles many years ago. Shot pistols a lot. Then a few years ago I decided to get back into rifle shooting.

Saw a Savage .223 HB with one of the cheap 4-12 scopes on the shelf at a Walmart, on sale for just over $300. I figured I could shoot it cheaply without needing to hand load. Bought it and started shooting. First groups with bulk ammo were a bit disappointing, 2" or so. Got a box of Federal GMM and it shot 10 into less than an inch at 100yd and less than 2" at 200yd. I was hooked :)

Still could not get consistently less than MOA. Then discovered, almost by accident, that my setup was lacking a lot. Got a better bench rest and concentrated more on the setup. Now I get consistent 1/2MOA groups. Not great, but, I am still hopeful of doing better :)

And, yes, it was much easier to shoot at that level with a .223 instead of the .308. The .308 taught me more about follow through :)

I don't remember having these kinds of problems when I was younger. :)