Load development 101

[Texas10]

My load development hasn't been going as well as expected since installing a new Criterion 26", 8 twist in 223 match barrel, and it occurs to me that maybe I'm just doing it wrong.:o

So I am hoping that I can beg some help from you guys with the "gray haired" load development skills, as plainly, mine suck!

I tried out the 77 TMK at the range yesterday with very good results. I'd decided to use IMR8208 for my loads because it was was near the top of the velocity list in my Lee loading manual, and experience tells me 8208 is fairly temperature stable.

Using the Lee manual, my loads started at 20.5 gr and 2535 fps (SG of 1.46) and topped out at 23.5 gr (a tad over book) for 2830 fps (calculated) and SG of 1.50, and were set to touching lands.

I shot 3 shot groups in round robin fashion at 200 yds, in conditions as follows: 100 F, winds 220 relative, 6 to 12 mph with gusts to 15. The range is fairly protected, but winds still matter. SG's were above as calculated due to extreme temps.

Groups were measured in MOA with calipers, (someday I'll get OnTarget for measuring results) with best at lowest velocity, and next best at max, although there was a big jump in elevation on the target at max load, much more than I'd expect with only a .5 grain increase.

Groups were: .316' at 20.5 gr., .665' at 21.5 gr., .557' at 22.5 gr., .563' at 23.0 gr., .234' at 23.5 gr.

All groups moved up the target with increased load, but the possibility exists that I skipped over a node around 22.0 grains. I'd loaded up 5 rounds in 22.0 grains to use as sighters, and after several scope adjustments, the last shot hit right on point of aim, so I may go back and explore that a bit.

The load at 22.5 gr. also fell right on POI, like the sighter at 22.0 gr., and shots 1 & 2 were at POI and spaced .577" (.288 moa) apart with shot #3 slightly higher, but barrel heating may have played into the results. Again, these were shot round robin.

So here's my question: Where to start refining the load? Do I go with the smallest group, the highest velocity ( second smallest group) or the two more consistent groups in the middle of the sequence?

I appreciate any and all help you guys can give. This 77 TMK looks to be a winner.

[darkker]

What distance were you shooting to for groups?
You need to test your speed on these as well, as calculated never works the way you wish it did. Lee's newest manual is quite old, and lots can vary greatly, so don't expect X-number of grains to corrolate with reality.

[Texas10]

All shot at 200 yds. No magneto speed yet....but you'll be happy to know that its on my X-mas list ;)

BTW: Using the same manual for 69 TMK load, I got significantly higher measured velocities.

[cowtownup]

If your largest group was .665" @ 200 yards that is just over 1/4 MOA.. It sounds like that barrel likes any thing you throw at it.. One big consideration regarding load development is the intended purpose of the rifle. If its a F-class long range gun or just a plinking gun may help you decide if you want to push it hard or just go easy on the brass and run it slow..

Personally, I like to run the same test at least twice to see if the results are consistent. Regardless, with the group sizes you mentioned at that range, you have got a nice shooting rifle on your hands...

[rjtfroggy]

Start with the 22.5gr load and get it OFF the lands. Move it back 0.003 at a time all the way back to 0.018 off, or just go to 0.015 off and move back a couple times, and try 5 shot groups.
I personally have never had luck jammed or just touching most times I am anywhere from 0.018-0.022 off and in that span is the sweet spot. I also never go much above the mid point of the load range.

[darkker]

All shot at 200 yds. No magneto speed yet....but you'll be happy to know that its on my X-mas list ;)

BTW: Using the same manual for 69 TMK load, I got significantly higher measured velocities.


If you don't have a chrono of sorts yet, how did you measure this?

[Onewolf]

I would use smaller load increments (0.3 gr) when load testing and I would shoot 5 shot groups rather than 3.

[Texas10]

If you don't have a chrono of sorts yet, how did you measure this?

Another shooters chrono. I let him shoot it in case things went south. IIRC it was a Caldwell Chrono.

[Texas10]

I would use smaller load increments (0.3 gr) when load testing and I would shoot 5 shot groups rather than 3.

Thanks, but where to start? I'm thinking around 22 grs. What's your take?

[Texas10]

If your largest group was .665" @ 200 yards that is just over 1/4 MOA.

Personally, I like to run the same test at least twice to see if the results are consistent. Regardless, with the group sizes you mentioned at that range, you have got a nice shooting rifle on your hands...

The .665 is a MOA measurement. Still...not bad but they were only 3 shot groups. It's tuning out those fliers that is so pesky. For instance, the first two rounds into target one, shot round robin style, were touching. The third shot was higher and gave the group a .316 moa overall. Round 3 in all the groups was a bit out compared to the first two. Barrel heat, or perhaps I need to swab the barrel? It's a Criterion barrel with about 200 rounds down it.

[Texas10]

Start with the 22.5gr load and get it OFF the lands. Move it back 0.003 at a time all the way back to 0.018 off, or just go to 0.015 off and move back a couple times, and try 5 shot groups.
I personally have never had luck jammed or just touching most times I am anywhere from 0.018-0.022 off and in that span is the sweet spot. I also never go much above the mid point of the load range.

This has always been the hardest part for me, sorting out what is jump induced fliers vs other factors. I started this load on the lands thinking I would work my way back once I had some idea of what charge I wanted. So what's next, change the jump or refine the charge? Or will there be some back and forth?

For me, it's not so much a question of what I should do, as it is WHEN I should do it. What are the steps, and the best order of steps to refine a load?

Sorry, just noticed you answered an important part, to start with 22.5. Thanks, Froggy.

[Onewolf]

From Hodgdon website for 223 with 77gr bullet:

IMR IMR 8208 XBR .224" 2.260" 20.5 2,535 41,800 PSI 23.2 2,792 55,000 PSI

I would start at 22gr and go up in 0.3gr increment: 22.0, 22.3, 22.6, 22.9, 23.2. Five rd groups for each.

[darkker]

So what's next, change the jump or refine the charge? Or will there be some back and forth?



I can't remember who I was talking to now, it's been too long.... Someone in the bullet community. Said "I've never met a bullet that didn't shoot well, with a 1/16th jump".
Berger's VLD's can be an exception if you are in the top few percentage of shooters, but otherwise that has always held true for me. Jump is ALWAYS the last thing I fool with.

Unless you can tell what your BR variance is, don't waste your time with tenths of a grain differences. Nominal variations will have you chasing ghosts. 1/2 grain jumps are the smallest, until you get things really dialed in. There was a gent I believe on this board, that I was discussing volume loading with. Who did some testing in his endeavors, who found this to be the case as well. When he was loading by weight, he thought it was important. Once testing began, he found it to not be the case.

[Cmgoff]

Since you did have chrono data from this shoot what did you get for SD and ES of each group? Also take note of the shape of your group. Assuming you do your part, horizontal spread is either wind or a horizontal mode, vertical shift is either large SD or a vertical mode.

I use to tune my loads ignoring velocity, but recently I have shifted to targeting the lowest SD I can find then adjusting jump to get smaller groups. This way I can manage my vertical group size with powder charge, then shrinking the rest with jump.

This technique also works best with test groups of 5 or more. I usually do two 5 round groups of each charge weight when testing.

Regardless, less then 1 MOA is a great shooting rifle, and you could be chasing ghosts (trigger pull, bipod hop, parallax adjustment...)


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[Cmgoff]

I forgot to add, I agree with froggy, I would not start with touching the lands.


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[Texas10]

[QUOTE=Cmgoff;375590]I forgot to add, I agree with froggy, I would not start with touching the lands.

I'm starting to see the wisdom in that technique, and am beginning to see a pattern in this Criterion barrel, it seem to like a small jump. Maybe with more experience I'll know about where to start with my jump.

I plan to only load bullets between 69 and 77 grains with this 8 twist barrel. That only leaves me with...what....a thousand choices of bullets to try out? Should have a good one about the time the barrel is shot out....LOL

[Texas10]

Hey, wait a minute, when did I rate a Team Savage Logo?

[Texas10]

From Hodgdon website for 223 with 77gr bullet:

IMR IMR 8208 XBR .224" 2.260" 20.5 2,535 41,800 PSI 23.2 2,792 55,000 PSI

I would start at 22gr and go up in 0.3gr increment: 22.0, 22.3, 22.6, 22.9, 23.2. Five rd groups for each.

Thanks, I think that's exactly what I'm going to do, starting at .020 off the lands. And once I have the load better defined, I'll adjust the jump a bit, again, and see how it goes. Maybe another charge adjustment after that to tweak it in.

Any other suggestions or tips?

[mike21]

Hey, wait a minute, when did I rate a Team Savage Logo?

http://www.savageshooters.com/showthread.php?52386-A-Few-Changes-amp-Announcements