338 Lapua Help

[dustingaunder]

I have been reloading 338 LM for a long time but I always had 250gr Bullets and 88gr of H4831sc. Load shot great in my 12 twist TRG

I sold that rifle a while back and replaced it with a 10 twist TRG 42 and started working on a load with 300 Bergers and H1000. Seems like a lot of people were getting them between 90 and 92 gr. I started at 83gr, 84.5gr, 86gr for starting loads to safety check for pressure. Those 3 loads had flat primers and faint ejector marks. No swipe. Decided to keep pushing forward. I got through 89gr with flattened primers and heavy ejector mark (still no swipe) Should have stopped here but I tried 1 more. 89.5 gr almost separated the case head.

Ok that’s enough. I know dumb ass but I was morbidly curious and in sort of disbelief.

Looking at the brass I think it’s all ruined...no biggie I still have all 10 digits.

1x fired Lapua from another rifle. FL sized (bumped shoulder .010) .002 neck tension.
Federal GM215M Primers
Berger 300gr Hybrid
COL was 3.723 to fit in magazines
CBTO is 2.846
Lands are at a CBTO of 2.966 and COL of 3.842
Jump is .120

I’m assuming the bullet crammed into the case to fit in mags is causing my pressure. I’m gonna try some loaded out to .020 off to see if that is the issue. I usually single feed anyway. Any other ideas? I really don’t want to blow my face up. I’ve been loading for a long time and have never had any pressure surprises before.

Factory 250gr lapua ammo shoots fine. Brass looks perfect.

 

[dustingaunder]

measured the brass with my Giraud comparator.
2.250 before firing.
Factory lapua fired 2.266
86gr handloads 2.268
Highest handload fired 2.270.

 

[dustingaunder]

Pics of the highest hand loaded case.

 

[Peterpan]

You say your bumping your shoulder back 10 hundreths. Why so much?

 

[dustingaunder]

10 thou. I just resized back to SAAMI (the die caming over) since it was fired from a different rifle. That resulted in about .010 of bump.

 

[Gbyleveldt]

Any chance you chronied the shots? Not to state the obvious, but ‘seeing how far it’ll go’, without Chrono data is asking for trouble.

As a matter of interest, I shoot a TRG-M10 and found that my speeds are almost 100fps faster than what others are getting with similar barrel lengths and similar components. I get 2710fps using 88gr Retumbo, 285gr ELD-M on my 27” barrel. Hornady max for this combo is 93gr Retumbo with their test TRG getting 2750fps if memory serves, quite a massive difference. I wouldn’t go nearly as much propellant in my rifle; thank goodness I chronied my shots.

 

[spife7980]

10 thou. I just resized back to SAAMI (the die caming over) since it was fired from a different rifle. That resulted in about .010 of bump.

It’s also leading to your case head separation.

 

[dustingaunder]

It’s also leading to your case head separation.

I understand if I did that every time it’d severely decrease brass life but doing it once ever shouldn’t lead to case head separation unless I’ve got an excess of headspace. If a person follows the instructions on the die it shouldn’t cause a KB.

 

[OLD308]

So both my 338LMs like H1000 (standard and improved). Both are stupid simple to load for the 250 class bullets. Lapua brass only, FL sized shoulder bumped back 2-3 thousands. I don’t ever use a chronograph for load development. I look at the brass, groups at distance and vertical spread. I would suggest a box of factory Lapua or Berger ammo for a control.

It’s highly unlikely in a TRG that you received a short chamber causing the pressure issue your showing. But, those Berger’s are some long slugs. So maybe a combination of the two is the issue? The factory ammo should tell you what’s up as they are way under max. Worse case you at least walk away with new brass. Hope this helps.

 

[spife7980]

I understand if I did that every time it’d severely decrease brass life but doing it once ever shouldn’t lead to case head separation unless I’ve got an excess of headspace. If a person follows the instructions on the die it shouldn’t cause a KB.

 

[dustingaunder]

I did some more measuring this morning. New lapua brass measures about 2.265 on my comparator. Somehow putting my body die on the shell holder is way over sizing the brass. I’m gonna try again with my new brass. I’ve got about 400 pieces of this once fired brass sized like this. About half of it is 8 thou longer so maybe salvageable after fire forming with some light loads

 

[dustingaunder]

View attachment 7108895

You I guess...

[hangs head in shame]

 

[spife7980]

You I guess...

[hangs head in shame]

Ha, we've all been there before.

Those 400 that you have sized like that will have the comparably short life etc but you could hopefully still get a couple firings. I wouldnt load them all up at once, I would test some more at the lower end just to make sure that you dont end up with a pile of junk that you then have to pull bullets on. Maybe the same 25 or so pieces fired and sized 3-4 times if they will allow it. If they go fine at the low end then I would feel more confident about the rest.

 

[dustingaunder]

I was thinking about loading them light with a little jam on the lands to keep the case head firmly against the bolt to get most of the forming in the shoulder and hopefully keep from thinning the web.

 

[Dai Bando]

False shoulders is the only move there man.

 

[dustingaunder]

They’re a buck or so each. I’m gonna crush them and start over. No sense in burning a dollar fifty worth of components to have shitty usable brass that I could replace for less.

 

[OLD308]

Lapua 338 brass for less than $1.50? Did I miss read this? If not send me the link, google could not find it. $2.50 is sale prices last time I bought some.

 

[GIXXER2000]

For what it worth this is my load in my AI-PSR 27 inch barrel
Lapua brass bump the shoulder .002
primer 215M
Bullets Berger 300 hy
Powder Retumbo 90.1
COAL 3.765 (fits in the mag )
AVG FPS 2770
I am on my 4th firing on this brass. I do anneal every firing and have had zero case issue so far.

 

[Huskydriver]

With 300 grain bullets all 3 of my 338 lms topped out between 87.8-88.7 of h1k grains FYI.

 

[dustingaunder]

Lapua 338 brass for less than $1.50? Did I miss read this? If not send me the link, google could not find it. $2.50 is sale prices last time I bought some.

1x fired yes.

 

[dustingaunder]

I sectioned the highest and lowest load. No sign that I can see or feel of incipient case head separation on the light loads. I’ll load some more up to test. If that goes well I’ll have a few hundred rounds of trigger time if nothing else.