How to load development for a 338????

[brianlangeliers]

So I got my GAP built 338 LM, I have been reloading for a few years for smaller calibers like .308 and 30-06 so I am far from a expert but have the basics down for sure. I decided it was time to step up to the big leagues and make the jump to a large magnum caliber to really reach out and touch things. The problem is I dont know how to load develop for such a large caliber. I am shooting 300 gr bergers, lapua brass, H1000 and Retumbo powder to test. Do I do a ladder test? If so How far do I need to do that out too? I can get to 500 yards at phoenix rod and gun club. I am familiar with the OCW test (thats where I got my loads for my 308 and that got me sub 1/4 moa load) but if I do the OCW test how far do I do it at with a 338? That test requires there to be as little as wind deflection as possible to get good results. Any advice or past experience with guys who have done load development with a 338 LM would be awesome. Thanks in advance for the help.

 

[ChrisGarrett]

Re: How to load development for a 338????

I just slapped some shit together and went out over the first year and fired away, mostly at 100 yds.

I don't know if the OCW method is one of the 100-200 yd deals, unlike the ladder method, which requires 300 yds and farther, even out to 600 yds.

Remember, the longer you go, the harder it is to shoot consistently and we're really interested in minute differences with these tests.

Remember, we're all Bob Lee Swaggers on the internets.

Chris

 

[SONIC SAAMI]

Re: How to load development for a 338????

Have you read this?
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2867663&page=1

 

[Aimsmall55]

Re: How to load development for a 338????

If you call GAP they will likely know what's going to work best.

 

[MitchAlsup]

Re: How to load development for a 338????

Stage 1: objective to find pressure signs
Stage 2: objective to find a good group
Stage 3: objective to find the best group
Stage 4: objective to dial in the load

In stage 1 you load up one case with sequentially increasing powder charges (1% step size should work fine). You shoot these simply to find where pressure rears its dangerously ugly head. The last case that fails to display pressure signs is used at a peak charge.

In stage 2 you drop back 5% and load up 3 cases at each charge weight with a step size of 0.4%-to-0.5%. Here you are shooting groups, so be at your best behind the gun. Choose the best group's charge weight.

In stage 3 you survey the window of charge weights bewteen the lower group not chosen and the higher group not chosen in as fine a step size as you can accurately measure (typically 0.1 gr). Here, you want at least 5 shots per charge weight. When you shoot these for groups, be at your best behind the gun. What you are looking for is the range over which the load delivers good groups. Take the average of the lowest group that shot well and the highest group that shot well as you optimal charge weight.

In stage 4 you do bullet seating experiments (OAL), neck tension experiments with the charge weight determined in stage 3.

 

[Paladin2147]

Re: How to load development for a 338????

Get out your wallet.

 

[Layton]

Re: How to load development for a 338????

Lead sled for stage 3?

 

[THUNDERBOLT68]

Re: How to load development for a 338????

do not even waste your time at 100 yards. The bullet diameter is large and you will not really be able to see much. Start at 200 yards..

 

[pmuniz10920]

Re: How to load development for a 338????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: THUNDERBOLT68</div><div class="ubbcode-body">do not even waste your time at 100 yards. The bullet diameter is large and you will not really be able to see much. Start at 200 yards..</div></div>

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