.308 load Chrono Data

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FitchHall

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THR,

I've been shooting for 12 years in the Marine Corps, but only recently have gotten serious about studying ballistics. After reading the outstanding book "Understanding Firearm Ballistics" by Robert Rinker, I found a very useful source of information and further study.

I have been able to shoot some outstanding 100 yard groups with my Remington 700 PSS in .308 and recently put these loads to the Chrono Test. The purpose of this post is to share some of these results and also ask more experienced shooters if these results are either typical or desirable.

Loading Equipment
RCBS RockChucker
Lee Neck-Sizing Die on once-fired brass in the test weapon
RCBS Seating Die
Lee Factory Crimp Die

Cartridge Data
Federal Match Brass once fired in the test weapon
Winchester Large Rifle Primers
Powder individually measured on a Lyman dispenser/scale combo.

Conditions:
Outdoors, 78degrees, 84 percent humidity.

Equipment
Shooting Chrony, shaded from direct sunlight with plenty of ambient light using the diffuser screens for a consistent photoreceptor backdrop.

OAL - 0.030 offset from the lands determined by using a Stoney Point OAL gauge.

Load 1 - Speer 168gr HPBT with 41.4gr of 4064 OAL 2.958
4 shots - 2438 / 2389 / 2452 / 2438
AVG - 2429.25 StDev - 27.633

Load 2 - Speer 168gr HPBT with 41.4 gr of AA 2520 OAL 2.958
4 shots - 2505 / 2527 / 2522 / 2527
AVG - 2520.25 StDev - 10.44

Load 3 - Hornady A-Max with 41.4gr of AA 2520 OAL 2.900
4 shots - 2591 / 2591 / 2584 / 2577
AVG - 2585.75 StDev - 6.70

During the test, Load 1 produced the best groups in spite of the largest StDev.

Comments or suggestions? Thank you for your time.
 
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my best grouping loads @ 100 yrds or less are rarely the best Std dev.

however, 4 shots isn't enough to tell you much. i'd recommend at least twenty of each before your Std dev starts to mean something.
 
taliv said:
however, 4 shots isn't enough to tell you much. i'd recommend at least twenty of each before your Std dev starts to mean something.
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I agree with that. Also, if you plan to use the loads past 100yds, then you should be testing at a longer range.
 
Thanks

30Cal said:
I agree with that. Also, if you plan to use the loads past 100yds, then you should be testing at a longer range.
Click to expand...

Thanks for the feedback. I'll definitely try it again with more shots per string for data collection.

There is an interesting "science" to both the internal and external ballistics involved in shooting.
 
.308 loads

I was wondering how you get small rifle primers to work in .308 brass? I use Federal large Magnum Primers #215. Was that a typo or can I get by using them?
Just wondering?
Jerry
 
Major,

Them Remmies sure got long throats, huh?;) With an OAL as long as what you're using, your loads are EXTREMELY conservative. I'd bump up your charge weight for the 4064 powder by atleast 1 full grain. Absolutely no reason you can't run your 168gr bullets at 2650-2750fps and find an accurate load. I think your ES and SD numbers will go down as well.

Don
 
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