260 lrp Lapua brass pressures

[Zero333]

Since you already established the chamber with go and no-go gauges that it's withing spec...
This should be very easy to diagnose with a headspace comparator by checking the unfired Lapua brass and comparing it to a go-gauge.

Or with Masking tape on the head of the unfired brass.

I only know of one way this can happen. If the brass has excessive working headspace. If there is another way this can happen I would like to know.
I'm just going of off the pictures tizzy provided. Looks like a typical excessive working headspace issue. In this case due to the brass and not the chamber, since it's been checked to be good.

I would also cut a unfired case lengthwise with a dremel to see if the brass above the head is thin to begin with, causing this problem.

[LoneWolf]

The thread you reference has not been locked. Not sure what gave you that idea. I do not see the post as trolling either. Just an issue that is believed to require someone with the proper knowledge to inspect the rifle. If this is happening with new Lapua brass not once fired ect. like stated in the other post I would also check any other brass I've fired in the rifle by taking a paper clip straightening it out leaving a hook on the bottom and run it inside the case scraping against the side wall near the case head to see if it catches on the wall. This would tell you that the case is getting ready to fail near the head due to excessive case stretch.

Old antique rifles like the 303 British you've posted can show what may be occurring, but the Savage should not be having this issue plain and simple. It needs to be inspected for safety of the shooter/OP and anyone who may be around him. Not because he does not know what he is doing at the bench, but because there appears to be a true issue with the chambering of the rifle in question.

[tizzy]

The comparator I am using (Sinclair body and insert 20A) locates on the shoulder where it meets the case body, not on a datum line partially up the shoulder. Those measurements I listed earlier in this post don't seem to add up. My fired brass is longer than the no-go gauge. I'm not sure how that's possible unless it has to do with the design of the insert I'm using. I have a #26 insert that would locate farther up the shoulder and for all intents and purposes for this specific comparison, might work better. Otherwise I'll have to get the Hornady body and insert this weekend. I'll cut a few cases and try to get them posted today.

[tizzy]

After a quick google check it appears as both comparators are equally fine. Here, though, is a new case and a once fired virgin cross-sectioned.

https://instagram.com/p/BVkAnRRAD6-/

[LoneWolf]

You've got a lot of brass moving there!

[tizzy]

Velocity averages were measured using a ProChrono 5 shots
34.5 Varget 139 Scenar virgin=2450/1 fired=2584
39.5 H4350 same bullet virgin=2767

[LoneWolf]

Remove the barrel from the action. and drop an unfired case in the chamber. See how much is hanging out. I'm wondering if you have a properly headspaced barrel to action with a short chamber that wasn't reamed to the proper depth.

[rjtfroggy]

Lonewolf yesterday after your noon hour post the thread was locked. Now it isn't.

[LoneWolf]

Lonewolf yesterday after your noon hour post the thread was locked. Now it isn't.

:confused: Wasn't me...... If I had locked it I would have noted a reason why!

[bigedp51]

The OP stated he checked the rifle with a GO and NO-GO gauges, and the bolt would not close on the NO-GO gauge. This eliminates rifle headspace issues and leaves the new Lapua brass. The OP also shot some Federal Fusion ammunition and that brass did not have a case head separation.

If you look at the SAAMI cartridge and chamber drawings it lists headspace as min and max with .010 in between. The GO and NO-GO gauges have .003 between them and are for setting up new or re-barreled rifles. And a Field gauge represents the maximum of .010 more than the GO gauge and max allowable headspace.

Bottom line, according to the OP only one brand of case had a case head separation and that was his Lapua cases. And from all the posts by the OP this tells me its not a rifle problem and points to a Lapua case problem.

And my "antique" Enfield rifles have a removable bolt head to adjust the headspace. And to study the effects of headspace on the cases I set the headspace to different amounts.

And I then checked the cases for stretching and thinning.

http://www.larrywillis.com/RCBS%20casemaster3.jpg

So forgive me LoneWolf for having "antique" rifles with adjustable headspace that allowed me to play with my bolt heads until I nearly went blind.

P.S. And LoneWolf Savage made more No.4 Enfield rifles during WWII than any other country. (antiques my gluteus maximus)

And the "antique" Enfield rifle below was made in 1950 and then was custom bedded by the military for competitive shooting.

http://i.imgur.com/v1GFvaK.jpg

[bigedp51]

tizzy

You stated you had no problem with the Federal fusion factory ammunition the first firing and after reloading the Federal cases once. So do not start working on your rifle and taking it apart and do some more checking of the fired cases.

1. Section a few of the Federal cases and see if you had any stretching and thinning. If you have no problems with the Federal cases then the new Lapua brass was defective or extremely short in cartridge headspace length.

2. Always measure new cases, fired cases and resized cases for shoulder location. This way with your measuring your cases you will have a good idea of your chambers actual headspace.

3. Below the cheap bastards headspace/head clearance gauge

Measure the length of the new case before firing and write down this measurement.

http://i.imgur.com/SgwqgaU.jpg

Next take a fired spent primer and start it into the primer pocket just using your fingers.

http://i.imgur.com/oNIvIiX.jpg

http://i.imgur.com/zQxlYGp.jpg

Now chamber this test case and slowly close the bolt and let the bolt face seat the primer. Then extract the case and measure the case from the base of the primer to the case mouth and write it down.

Now subtract the first case measurement from the second and this is your head clearance and how far the case has to stretch to meet the bolt face. You can do this same test with a Hornady cartridge case headspace gauge using the primer method.

So again if the Lapua brass was too short in cartridge case headspace length or if the case was too "soft" in the base you can have a case head separation.

I buy bulk once fired Lake City 5.56 and 7.62 cases because this military brass is harder in the base than commercial brass. These cases are then checked with my RCBS case mastering gauge for stretching and thinning. And I have yet to find one of these military cases that have stretched and thinned.

Just one of the early jamming problems with the M16 rifle was soft brass which was brought to light in the 1968 Congressional Hearings.

http://i.imgur.com/OujD1z7.jpg

Below my buddy CatShooter did a Rockwell hardness test of various .223/5.56 cases and the Lake City brass had the hardest brass in the base.

How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests
http://bulletin.accurateshooter.com/2014/05/how-hard-is-your-brass-5-56-and-223-rem-base-hardness-tests/

[tizzy]

https://instagram.com/p/BVk76VTAOm5/

https://instagram.com/p/BVk78Frgq0V/

https://instagram.com/p/BVk7_tTgR7b/

https://instagram.com/p/BVk8DpagMAp/

This is the Federal Fusion case shot initially with the factory load, then necksized 4 times and fired with the 39gr. H4350 load. The difference in length is .002 between no primer and seating the primer with the bolt. The bolt head currently only has the extractor claw installed.
The virgin Lapua brass base to shoulder is .006 shorter than a new Federal. Case length of the Federal is .005 longer than a new Lapua.

[J.Baker]

I have merged this and the second thread Ed started together so all the posts and info are in this one. Next time you have a question about something a moderator does Ed, ask in PM so as to avoid duplication such as this.

[Robinhood]

I am curious if the case protrusion is correct. I realize that failure to extract might/should be an issue, however if the firing pin is hitting hard enough it may be growing enough to facilitate extraction.

Are there any circular marks on the face of the bolt? If you can see the breech are there any rub marks on the face?

Being a new rifle and if that is in fact the problem, Savage is the only one that should touch it. I can think of a couple of Savage smith ways to verify...... naw. Call Savage



EDIT: I just noticed and I think this is the same or similar to what LW was saying in post 27.

[tizzy]

No unusual marks on the bolt face.
I really appreciate everyones patience and help.

[bigedp51]

Tizzy

Your Federal brass did not stretch and thin and has nothing wrong with it, and the Lapua brass stretched, thinned and separated.

If you had a problem with your rifle both cases would have separated, and the actual problem is bad Lapua brass.

[tizzy]

Should Lapua brass work fine in a SAAMI chamber, or is it more suited for "match" custom reamed chambers? The million $ question is, will another box of Lapua net the same results or did I just get a bad batch?
Thanks again.

[schnyd112]

I have 300 pieces of .260 lapua brass from different lots and I can't tell a measurable difference worth a bother. I turn the necks for a match chamber but I haven't ever heard of a problem with SAAMI chambers. The one picture of fired vs unfired lapua brass looks off. LoneWolf already said, that is a lot of brass to move just above the web. It looks like the case is not chambered fully and unsupported where it is failing.

Gonna have to agree with the above and refer it to a gunsmith. With a full separation like that you may have scarred the chamber and it's just getting worse.

[Zero333]

I think the same thing as Bigedp51.

The Lapua brass is the problem. It's very obvious after farther evidence provided by tizzy.

A very good example tizzy posted is the big gap in velocity from virgin to once fired.

The reason why the Virgin brass made so much less velocity than the once fired is because when the brass stretches this much during firing it delays the pressure buildup / peak pressure.

You can still save the Virgin brass by either making a false shoulder on the neck or jamming bullets hard in the rifling. The false shoulder on the neck is the best solution, but you'll need a bigger expender or bushing in the sizing die. Research "false shoulder reloading brass" on google and you'll save the rest of the good virgin brass.

On the other hand... I would first call Lapua and let them know what's happening. I'm sure they would want to know.

[tizzy]

I'm on it. Thanks again!