Reply With QuoteNext time I head out to the 800 yard range I will take my 9 twist .223 and try some 77 TMK's at distance. I was stopping at 69 thinking it would be a waste going heavier...
Some of you have been following my published results with the 12 FV .223 on the “Ammunition & Reloading” forum in the “First results with new 12 FV .223” with the factory plastic stock and on the “110-Series Bolt Action Rifles” forum with the Oryx chassis in the “Documented results from replacing the 12 FV factory stock with an Oryx Chassis” thread.
While I was reporting the results on both threads, I got a note from another shooter who told me that he shot 77 gr SMKs in his 1:9 twist .223 and had good results.
He claimed that the bullet shape overcame the stabilization problem.
I have had great results with 77 grain SMKs and TMKs in my 1:8 twist Les Baer .223 but I have always read that a 1:9 twist wouldn't stabilize bullets over 73 gr bullets, so I never tried them in my two 1:9 twist rifles. In fact, both Sierra 77 grain bullets have a warning not to use the 77 grain bullets in barrels with twist slower than 1:8.
Always curious to try something I haven’t tried yet, I disregarded the long-held belief that a 1:9 twist can’t stabilize 77-grain bullets, and experimented with 77-grain Sierra SMK and TMK bullets in my Savage 12 FV 1:9 twist barrel. Surprisingly, the 77 grain bullets have been consistently more accurate than even the 69 grain bullets that the 12 FV really shot well.
Here is a summary of the results of 5 round groups sorted by bullet weight and by average.
By Weight By Average
Wgt. Avg. Median St Dev # Grps. Rank ----Wgt. Avg. Median St Dev # Grps. Rank
50 0.390 0.392 0.064 --- 3------ 6 ------- 77 0.285 0.271 - 0.066 - 94 ----- 1
52 0.366 0.382 0.079 --- 11 ---- 4 ------- 69 0.313 0.286 - 0.083 - 39 ----- 2
53 0.376 0.366 0.082 --- 8 ------ 5 ------ 55 0.343 0.305 - 0.094 -- 4 ------ 3
55 0.343 0.305 0.094 --- 4 ------ 3 ------ 52 0.366 0.382 - 0.079 - 11------ 4
60 0.487 0.487 ------- --- 1 ------ 7 ----- 53 0.376 0.366 - 0.082 -- 8 ------ 5
68 0.653 0.653 0.001 --- 2 ------ 9 ----- 50 0.390 0.392 - 0.064 -- 3 ------ 6
69 0.313 0.286 0.083 --- 39 ----- 2 ------ 60 0.487 0.487 - --------- 1 ------ 7
70 0.619 0.670 0.189 --- 4 ------ 8 -------70 0.619 0.670 - 0.189 -- 4 ------ 8
77 0.285 0.271 0.066 --- 94 ----- 1 ------ 68 0.653 0.653 - 0.001 -- 2 ------ 9
All 0.319 0.288 0.102 --166 ---------------All 0.319 0.288 - 0.102 -166
Note: I tend to shoot bullets that shoot the most accurately, but I have only been shooting the 77 grain bullets since June 19th, so I have really been impressed by the accuracy the 77 grain bullets produce and the group counts show it.
The difference in performance in the 69 and 77 grain bullets needs to be explored in a number of ways since both bullet weights were shot in two different stocks and with two different primers.
I had been shooting CCI BR-4 primers with Lapua brass (made to use small rifle primers) and after a member reported that he was having problems with loose primer pockets with Remington 7 ½ BR primers I offered to try those primers because I had over 5,000 lying around. I tried the Remington 7 ½ BR primers and found that they performed slightly better than the CCI BR-4s so I shot more loads using them to see if the results would hold up with a larger statistical sample. I also reported that they were slightly smaller in diameter and were easier to fit in to the primer pockets in Lapua brass that had been reloaded more than 11 times, but weren’t especially loose. The results showed that Remington primers were performing well.
Just a few weeks after trying the Remington primers, I purchased an Oryx stock for the 12 FV .223 to get a detachable magazine. That added another potential variation in the results so I analyzed the data to see if the results were consistent under both the primer change and the plastic factory stock to aluminum chassis change.
Comparison of 12 FV .223 Factory Stock with Oryx Chassis
------------------------------------------ Savage Factory Plastic ------------ Oryx Chassis
------------------- Bullets ----------------- Avg. Median St Dev # Grps. --- Avg. Median St Dev # Grps. Delta %Impr
Sierra Match King # 1380 - 69 gr -------0.329 0.303 0.087 --- 10 ------ 0.307 0.295 0.098 ---- 7 ---- 0.022 6.7%
Sierra Tipped Match King #7169 - 69 gr 0.304 0.288 0.061 --- 12 ------ 0.258 0.272 0.038 ---- 7 ---- 0.046 15.2%
Sierra Match King # 9377 - 77 gr ------ 0.344 0.327 0.118 --- 11 ------- 0.250 0.245 0.016 --- 11 ---- 0.094 27.3%
Sierra Tipped Match King #7177 -77 gr 0.272 0.266 0.039 --- 20 ------- 0.286 0.286 0.059 --- 51 ---- 0.014 -5.0%
----------------------Overall ---------- 0.296 0.282 0.078 --- 53 ------- 0.280 0.272 0.059 --- 76 ---- 0.016 5.4%
The Oryx chassis provided some improvement but it wasn’t as consistent as I would have expected. The biggest improvement came with the 77 SMK bullets and the 77 TMK bullets actually performed better in the factory stock. That was a surprise and there is no apparent reason for the difference that I can determine.
Comparison of 12 FV .223 with CCI BR-4 versus Remington 7 1/2 Primers - equivalent Jump
------------------------------------------ CCI BR-4 primers ----------Remington 7 1/2 BR Primers
----------------------Bullets--------------- Avg. Median St Dev # Grps. Avg. Median St Dev # Grps. Delta %Impr
Sierra Match King # 1380 - 69 gr ------- 0.399 0.422 0.078 --- 3 --- 0.303 0.287 0.084 -- 14 ---- 0.096 24.2%
Sierra Tipped Match King #7169 - 69 gr- 0.354 0.339 0.065 --- 5 --- 0.264 0.272 0.030 -- 14 --- 0.090 25.5%
Sierra Match King # 9377 - 77 gr ------- 0.352 0.287 0.140 --- 8 ---- 0.265 0.250 0.038 -- 15 --- 0.087 24.7%
Sierra Tipped Match King #7177 -77 gr 0.269 0.282 0.051 -- 24 ---- 0.289 0.277 0.055 -- 47---- 0.020 -7.4%
-------------------------Overall -------- 0.306 0.291 0.090 -- 40 ---- 0.283 0.272 0.056 -- 90 --- 0.023 7.4%
The performance with the different primers shows just about the same kind of results, even down to the better performance for the CCI primers over the Remington primers for the 77 TMK bullets when all the other bullets performed better with the Remington primers. Again, there doesn’t seem to be an apparent reason for the difference that I can determine from looking at the data.
Confirmation using other 1:9 twist rifles
I then asked two range buddies who had 1:9 twist .223 bolt actions to test how their rifles shot with 77 grain bullets.
Two tried 77 gr Federal Gold Medal Match with SMK bullets in their rifles.
One shot a 12 FV .223 and the other shot a CZ 527 Varmint .223, both with 1:9 twists.
The Savage 12 FV shot factory Federal Premium Gold Medal Match SMK 77 gr ammo to a 16.1% larger average than his factory average for all bullet weights.
The same 12 FV shot factory Nosler Custom Competition 77 gr ammo to a 15.6% smaller average than his factory average for all bullet weights.
At a later session, the Savage 12 FV owner tried hand loads using 77 TMK bullets and shot the hand loads to a 11.2% smaller average than his hand load average for all bullet weights.
The 77 grain TMK hand load average was 40.3% smaller than the 77-grain factory SMK average and 28.0% smaller than the Nosler CC average.
The 77 grain TMK hand load average was also 9.6% smaller than the rifle’s 69-grain SMK hand load average.
The owner of the CZ 527 shot factory Federal Premium Gold Medal Match SMK 77 gr ammo to a 13.2% smaller than his factory ammo average for all bullet weights.
Conclusion:
The historical concerns that a 1:9 twist barrel will not stabilize a 77-grain bullet appears to be a myth, at least for Sierra SMK and TMK bullets and Nosler Custom Competition bullets, even though both the Sierra boxes and Nosler CC boxes clearly advised that their bullets were only recommended for 1:8 twist barrels or faster.
Next time I head out to the 800 yard range I will take my 9 twist .223 and try some 77 TMK's at distance. I was stopping at 69 thinking it would be a waste going heavier...
Gosh, celltech, that was a quick response.
You must have read my mind as I was typing the post.
I also was convinced that 69s were about the limit when the 70s didn't perform well.
I am so pleased with the performance of the 77 SMKs and 77 TMKs that I just bought another 500 of each.
I am loading for the 12 FV and my CZ 527 Varmint this evening for a Friday morning session.
Good luck at 800 yards with your 77 TMKs.
Load them out for a 0.020 jump so they can really shine.
it is all about LENGTH, not weight.
9 will stabilize some not all
plastic tips can cause issues,( hornady 75 match vs 75 amax)
all guns are different, change altitude, temp, humidity.
bbl lenght limits velocity.
problems show up quicker in shorter bbls
One of the things that surprised me is that CFJunkie is nearer to sea level (and high humidity) and I am closer to 5000ft elevation (and low humidity) and we both see better groups with the 77gn bullets.
Sierra specifically states that their bullets should be used with faster twist barrels. 1:10 or faster for 69gn and 1:8 or faster for 77gn. I am assuming that Sierra is playing it a bit safe in case someone wanders out of the 'envelope', such as a high air density environment and marginal velocity.
FWIW, the 75gn Hornady ELD's also work with my 1/9 twist barrel, but, I have not tried them at 600yds, only 400yds.
PS it is not all about length. That refers to the simplified formulas for stability that assume a football shaped bullet at Mach 2.5. For actual calculations you need bullet shape details, as well as mass, to calculate things like polar and transverse moments.
The only reason I started playing with the 77gn smk mk262 mod 1 was because of the bulk supply I could get my hands on.
I read and read on they wouldn’t work.
My seal buddy said shut up and spend some time on the range with them.
My rifle is a 2007-9 predator 10.
A truck gun it was. Barrel rode on the floor board and very rarely cleaned.
Basic 3x9-40 leupold scope.
It shot that load with no mods to the rifle at 1.5 or so MOA.
That wasn’t good enough for me as it would shoot the little blitz king into tiny groups.
I almost gave up on the 77gn smk.
So I kept reading and wanted to improve the rifle. I should have used process of elimination before changing things to see what worked and what didn’t.
All at once I bedded the plastic stock and stiffened it up and shaved forearm away from the barrel. A lot.
Cut the barrel an inch and recrowned it.
Disclaimer I took the gun to a smith to evaluate the gun and give advice.
He said there is heavy pitting at the crown lets cut a new one and there was light pitting down the tube the whole way. Again a truck gun. After the new crown he scrubbed the bore clean clean.
Torqued the action to my backyard shop bedding job to 65# in the front and 25# in the back. He’s a long range bench guy.
I put a fixed 12x swfa scope on it. The recital has that little dot in the cross hair. So.. now I can hold inside a 1” dot at 100yds. The basic Leupold the reticle almost covered the dot..
Any way back to the range 100yd range at the time. After about 10 fowl shots I started to shoot some groups. Well dang on. Back to the tiny groups I expect with a .223
What made the difference? I don’t know.
This is my verified dope to 600yds. 3-5” groups pretty consistent.
Cheers all. You all are a wealth of knowledge.
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Stability is a product of twist AND velocity. Low on velocity? Add more twist. Low on twist? Add more velocity. It is not lost on me that I distilled that down to the simplest variables and that other things like atmospherics play a role as well. Readily available calculators like this one: https://bergerbullets.com/twist-rate-calculator/ are available online.
The bold red text on the end of the box tells you something. And the Sierra reloading manual tells you what twist rate the .223/5.56 bullets will stabilize at.
That's nothing more than their bottom line disclaimer.....better to err on the side of caution. When you're on the fence, it better to go faster instead of slower. I've got 90 gr match kings to stabilize with a 1-8" twist, not the 1- 6.5" you absolutely have to have they claim.
"As long as there's lead in the air....there's still hope.."
That is why it took me two years before I decided to try them. I stuck with 69gn because I believed Sierra. I am glad I tried the 77's as they shoot so well with my 1/9 twist.Originally Posted by bigedp51
The bold red text on the end of the box tells you something. And the Sierra reloading manual tells you what twist rate the .223/5.56 bullets will stabilize at.
I do believe they put that disclaimer on there simply because of all the slower twist AR's out there with shorter barrels.
at the 600-1000 yards they were intended for ?
i own a very nice krieger 1/7 that was used to test 90's.
27" long and did not work with 90's.
the good news is i got the "used" bbl for all of 75 delivered!
The barrels that don't shoot them are probably a true 1-9 twist. The ones that do shoot them are probably a little faster twist. On button rifled barrels you will always get a little drift on the true twist. Very few makers can actually keep the stated twist on button rifled barrels. That is why most use a cut rifled barrel because the twist stated is what it says it is.
I agree that machining has a built in error factor. The question is whether it could be large enough to make a 'marginally stable' bullet stable.
I have no doubt that it is difficult to get an exact twist on barrel rifling, but I doubt if a 1:9 twist turning is going to be off by another 1/2 inch or more out of 9 inches.
I wouldn’t argue that the error could be 2.5% (or less than ¼ inch out of 9 inches) but I would think that more than that would be a major screw up in setting up the rifling lathe.
Maybe Dave or some qualified machinist could give us some idea of how much error would be the norm.
Just to see if the premise that the barrel twist was cut faster than specified, I did the twist test with a cleaning rod and the barrel was very, very close to 1 twist in 9 inches. It wasn't off by anything close to 1/2 inch.
So I went back to the Berger calculator that I had used before but abandoned because all my best shooting bullets were being classified as 'marginally stable'. Somehow I just didn't believe that.
I entered the temperature, velocity and altitude that I was shooting at, and the BC and bullet length of the 77 gr SMK and 77 gr TMK bullets gave the following results:
77 SMK -- bullet stability rating = 1.36 – twist to stabilize = 8.50. Rated as 'Marginally Stable'.
No way a “little faster twist” is going to be ½ inch faster (5%). That lathe would have to really be humming to be that far off.
77 TMK – bullet stability rating = 1.12 – twist to stabilize = 7.75. Rated as 'Marginally Stable'.
That ‘little faster twist’ would have to be a 'whole lot faster' by 1.25 inches or almost 14 %. A 1:8 twist would only be 11.1% faster than a 1:9 twist.
To test the sensitivity of the stability calculator to altitude, temperature and velocity for the 77 gr TMK bullets:
I changed altitude from 250 feet to 2500 ft (900% change) and stability rating changed from 1.12 to 1.22. (0.010 or 8.9%) That is 1% for each 250 feet in altitude.
I changed temperature from 70 to 100 degrees (42.5%) and stability rating changed from 1.12 to 1.18. (0.06 or 5.3%). That is 1% for every 7.5 degrees of temperature change.
I changed velocity from 2540 fps to 2700 fps close to Pmax (6.2%) and stability rating changed from 1.12 to 1.14 (0.02 or 1.7% change). That’s 1% for every 100 fps.
None of those rates of change are incredible and could account for the accuracy that these bullets are showing.
I then tried to determine the effect of bullet length or BC changes on the stability rating:
Then I adjusted only the length of the bullet from 1.069 for the 77 gr TMK to the same length as the 77 gr SMK (1.000) and the stability rating as the 77 SMK changed to the stability rating of the 77 SMK 1.36.
I then adjusted only the BC of the bullet from the 0.420 of the 77 gr TMK to the same BC as the 77 gr SMK (0.372) and the stability rating didn’t change at all.
The Berger Calculator makes Length the only really significant driver in the stability calculation - but contrary to general belief that long thin high BC bullets are better – the calculator says that shorter is better and according to the calculator, BC makes no difference.
Somehow, to me, that is counterintuitive, especially since all my long, high BC bullets shoot more accurately than the stubby low BC bullets, regardless of caliber.
How can the more accurate bullets be less stable?
That is because the simplified equations do not really take into account bullet shape. They assume the bullet is shaped like a football. Aerodynamically that is a bad assumption, especially for supersonic bullets that are designed to have shock waves at specific locations relative to the moments of inertia and the center of gravity. The nose length/ogives and boat tail location, angles and lengths are VERY critical to the bullet performance.
The equations are good for basic questions, but, are NOT good if you are looking at the edges of performance envelopes. As an example, with my front stuffer shooting 550gn paper patch bullets the simplified calculators say they should be stable when they are not. Those bullets have no boat tail so the CG is further back than a football shape.
Good work CF,
I don’t have a chronograph but to get my dope chart correct online I have to plug in close to 2800fps. Then when I go back to the Berger page and punch in the high velocity. I get way closer to stable. I wonder what CB said about they assume bullet shape. I wonder if they are calculating bergers shape, the shape of a football, or? I’m not sure. I wonder if a 90gn bullet made with a heavier material in the same shape and size as serria 69-77gn match bullet would shoot?
As I don’t have two to compare what are the dimensions of he 69 vs 77gn smk? Or bergers 75gn bullet vs serrias 77gn.
Environmental factors are super hard to predict much less calculate besides wind and that’s challenging enough. Snipers use a spotter. I’m at 400ft in the thickest air in the US. Maybe not but downeast NC in the summer is a wall of humidity. The thickness of the mosquitos should be calculated to bullet travel.
Again I wonder what CF and CBs velocity is.
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I think what Fred failed to note there is that he's pushing them at much higher velocities than can be had from a .223. Think 22-250AI, 22-243, 22 BR, 22 Dasher, 22-284 Super Hotrod, etc. With the higher velocity offered by these cartridges you can easily get by with the 1-8" twist.
For all intensive purposes, if you can't push the 90's faster than 3100fps you're better off shooting the 80's.
"Life' is tough. It's even tougher if you're stupid." ~ John Wayne
“Under certain circumstances, urgent circumstances, desperate circumstances, profanity provides a relief denied even to prayer.” —Mark Twain
what is your results at 600 yards ?
as competition bullets, it is where they would be shot.
I do not measure velocity since I got rid of my chronograph years ago. Based on Sierra's tables I estimate to be in the neighborhood of 2700fps (23.5gn Varget). Sorry I don't have a recorded group size at 600yd but I do have a few ~4" groups (8 round groups) at 400yd and I have many 5rd groups at 300yd that are in the 1.5-2.5" range.Good work CF,
I don’t have a chronograph but to get my dope chart correct online I have to plug in close to 2800fps. Then when I go back to the Berger page and punch in the high velocity. I get way closer to stable. I wonder what CB said about they assume bullet shape. I wonder if they are calculating bergers shape, the shape of a football, or? I’m not sure. I wonder if a 90gn bullet made with a heavier material in the same shape and size as serria 69-77gn match bullet would shoot?
As I don’t have two to compare what are the dimensions of he 69 vs 77gn smk? Or bergers 75gn bullet vs serrias 77gn.
Environmental factors are super hard to predict much less calculate besides wind and that’s challenging enough. Snipers use a spotter. I’m at 400ft in the thickest air in the US. Maybe not but downeast NC in the summer is a wall of humidity. The thickness of the mosquitos should be calculated to bullet travel.
Again I wonder what CF and CBs velocity is.
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The 77 SMK's are 0.97" long. Don't have any 69gn on hand.
Just to be clear here. This is all just a notice that some of us have had good luck with the 77gn SMK's in the Savage 1:9 barrels. If you want to try it with your rifle, feel free. If not then don't.
In the future I plan on trying to shoot a few groups at 1000yd just to see what happens. According to my ballistic tables the 77gn will still be supersonic at that point so will be an interesting experiment. The problem will be is that my wind dope skills are not very good so.....
it is why i asked the question.
if you are at 1 moa at 400...life at 1000 will pretty much suck.
high power guys go for 1/2 moa
Maybe. Or maybe it is just my shooting ability :)
I shoot a lot of the 75 gr Hornady Match,and Sierra 77 gr SMK's out of my old 12 FLVSS with a 1-9 twist,they shoot great. But,I have never been able to push the 75 gr Hornady A-Max or the newer ELD's fast enough to stabilize for good groups,so I just built a 22 Creedmoor to shoot those bullets.
Have you shot them at distance to see if they are still stable ?
My question would be what’s the point to all this?
I can understand where rules would require a certain caliber or cartridge be used, but otherwise?
The very best 1000 yd benchrest shooters aren’t all using 6mm cartridges for example.
And some who do don’t always use them, depending on conditions.
But if 75% are, does it not make sense that that caliber should win?
So why doesn’t it? At least always?
And as for conditions, go to a match and see how the best of them deal with that, regardless of cartridge.
For the average guy who only cares about reaching out to touch something, say a prairie dog, its best to take about 3 different guns along
and forget about the heavy bullets for the 223.
As I stated, the point is that some of us are having better results with the 77gn SMK bullets (rather than 69gn SMKs) in our Savage barrels, at the distances and velocities we shoot at. Nothing more.
The only reason this has come up is because Sierra says they should not work, so the posts are more of an FYI to others who might not otherwise try them.
There is no claim of anything else. And they are not hunting bullets, just for paper. And no one is claiming they are a good choice out to 1000yd. I will be trying them at that range just for grins, but, I do not expect much.
And, yes, there was at least one person using these for 600yd informal competitiom shooting and doing well with it.
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Well fact is i shoot 69 gr SMK bullets in a factory Savage 9 twist barrel also.
But in a 22x250 AI, not a 223, and they shoot as well as i can shoot them.
Would it be worth my time seeing if 77 gr might shoot as well or better?
Well too each his own, but not in my opinion.
I can see myself using the real heavy 22 caliber bullets in a hot rod wildcat like a 22x243, but without the powder what’s the point?
As for SMKs not being a hunting bullet, don’t be betting anything you cant afford to lose on that, because you for sure will lose it.
Same goes for most if not all the other so called match bullets.
Another little secret as it pertains to (ahem) precision reloading, and factory guns like Savage.
All my SMK (match) bullets come to me in jars, like rinsed out empty large peanut butter jars.
Reason is they are all seconds, sold by the pound at the Sierra store.
Would you like to know what the Sierra employee shooters use?
I mean if they are seconds, are they still SMKs? Why not just trash them and start over?
So lets be sure we get the powder charge to the exact 1/10 of a grain here folks, and the velocity
cant vary by even 5 FPS if we want real accuracy. Lol
Much has to do with mind over matter, and it only matters to those of us who mind.
The main reason I make myself unpopular for saying these things other than it being what i think, is that it would be very easy for the new shooters who haven’t the experience level as yet to be convinced that all this is normal and necessary in the name of accuracy.
Fact is it isn’t, and far from it, at least for the vast majority of us.
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