260 Rem case problems

[Jim Tisdale]

Long time lurker, first time poster. Ive got a few issues I need help/advice with regarding a few observations I've had loading for my new Savage LRP 260.
I'm getting some stretch marks on the bottom of the case (Lapua) from my apparent sloppy Saami chamber. So bad that one came apart (case head separation). Ive read other people having the same issue with a Saami chamber and Lapua brass in the 260. I had a gunsmith check the headspace and its gtg. But the back of the chamber seems too sloppy.
I fired factory Federal ammo and don't have the stretch marks. It flowed out further than the Lapua when fired.
I can't use the Lapua brass with this chamber. Is their another "match" brass like Norma or Nosler that will work without this issue?
Thx

 

[ballison]

Is this virgin Lapua brass or has it been fired before? If it is virgin brass, it is usually really short out of the box, but will expand to fit your chamber after just a firing or two. I've never had a separation with virgin brass, so if this is the case, maybe someone else has an answer. If it's been fired, the die probably needs to be reset to just bump the shoulder .001" to .003" (depending on the rifle's purpose). You will need a headspace gauge and some calipers to properly set your die. Either way, I doubt it's the SAAMI chamber unless the it was miscut and is really long.

 

[Jim Tisdale]

Virgin Brass. I'm neck sizing. The Lapua doesn't expand as much at the base as the Federal did. The separation occurred after several firings. Some pieces showed heavier markings sooner than others.

 

[jlow]

Virgin Brass. I'm neck sizing. The Lapua doesn't expand as much at the base as the Federal did. The separation occurred after several firings. Some pieces showed heavier markings sooner than others.

Most people will tell you that if you have case head separation, it is always caused by the reloader sizing the brass too short. Your gun’s headspace sound like it is OK but have you check the headspace of a fired round and one that has been bumped back after sizing? As FTRinPA have said, It should be about 2 thousands shorter.

 

[22BRGUY]

I had a similar problem with Winchester brass in a 260AI. I found that by annealing the neck shoulder junction area before fire forming it pretty much solved the issue. I did get about 10 firings though before the case head separation was a serious issue. It's very important to me to always check that before reloading now and as you said, some pieces showed more signs than others and had to be culled.
Lapua brass did not have the issue for me and it was visibly well annealed when new and fire formed nicely with no issues. Maybe a bit more annealing before initial firing/fire forming could help or be worth a try. Good luck.

 

[Milo 2.0]

Measure a fired case starting 1/4" above the rim, then as you go down to the rim edge, what does it measure?

 

[Laurie]

As others have said, it'll be down to your sizer die setting pushing ('bumping') the shoulder back too much. Hornady comparator body plus the appropriate 'headspace' gauge (actually, it's properly a case gauge), which in this case is 'headspace' insert # D. (also does 308 Win and other 308 Win based cases).

http://www.hornady.com/store/Headspace-Gauge-Kits/

http://www.hornady.com/store/Headspace-Gauge-Bushings/

Many precision die-makers such as Whidden and Harrells now include a little collar with their sizer dies that does the same job, ie measure the shoulder datum line position on a fired case and to allow you to set the die up to 'bump' the shoulder back by a thou'.

Just remember to deprime before measuring a fired case as the fired primer may not be flush with case-head or below it and will therefore give a false reading.

 

['Freak]

Try a full length die backed an eighth to a quarter turn (~ .009” to .018”) away from contacting the shellholder, so leaving room inside the die for the case shoulder to be squirted forward whilst the full length die is squeezing in on the side of the case body, sorta like a reverse shoulder bump.

 

[jlow]

Try a full length die backed an eighth to a quarter turn (~ .009” to .018”) away from contacting the shellholder, so leaving room inside the die for the case shoulder to be squirted forward whilst the full length die is squeezing in on the side of the case body, sorta like a reverse shoulder bump.

The reality is since this is brass after several firing and you are getting case head separation in some, most likely all of them has been bumped down too far and stretched when firing over and over again and they are all ready for case head separation and there is no going back.

About the only thing you can do is to test the old brass with the "paper clip test" (do a Google search - there is a lot of good description of this on the web) and see if you have any salvable brass left. I would actually start new and make sure you don't over bump your shoulders.

 

[CTK]

Do you have a small shoulder forming in front of the web area? Measured the diameter in this area on fired case vs. unfired? Been there done that with a sloppy 280ai chamber.

 

[savagedasher]

Your probably going to find . Difference in case capaicy .Lapua has 2 GR less capacity so the are
Loaded hot Larry

 

[jlow]

Your probably going to find . Difference in case capaicy .Lapua has 2 GR less capacity so the are
Loaded hot Larry

Case capacity may be different and so Lapua is indeed going to run hotter on the same load, but case head separation is not caused by the round being too hot.

 

[Jim Tisdale]

Do you have a small shoulder forming in front of the web area? Measured the diameter in this area on fired case vs. unfired? Been there done that with a sloppy 280ai chamber.

Yes a bump near the base is forming. Also, I've used the paper clip method to find the ridge on the inside as well.

 

[Jim Tisdale]

I took some measurements today. The Lapua is definitely smaller dimensionally at the base and base to datum.
Also, when fired, the Federal expands less in both dimensions.
I'm looking for a brass that is sized like, and behaves like the Federal, but is more uniform and consistent like the Lapua.

 

[mikecr]

Might as well rake what you've fired into a trash can.
Prep your next batch with the intent of producing correct cases with fire-forming.
Bullet jamming, false shoulders, whatever it takes to get a stiff fit on chambering, so that you can form good cases without stretching them. Done right, your case OALs will shorten on fire-forming instead of lengthening.

 

[Scott Harris]

You need tools to troubleshoot your problem:

1. GO/NO-GO Gauge. Have a gunsmith determine the headspacing...how far past GO your chamber is. Ideally, your chamber will be .004 or less over GO, but anything less than +.007 is acceptable. It is highly unlikely that your chamber head-space is out of spec, but that's how you check. If you think other chamber dimensions are out of spec (like base diameter), then you'll need to get a chamber cast; a gunsmith or Savage can perform that service.

2. Shoulder bump gauges allow you measure case head-space changes. Measure brand new brass, fired brass, and resized brass. The results will identify where your problem lies. Here are some bump gauges along with directions on how to use them: http://www.sinclairintl.com/reloadi...tors/sinclair-bump-gage-insert-prod35265.aspx

Use directions:

The most common cause of case head separations is overzealous sizing of fired brass....bumping the shoulder too much. Most of the time, you don't need to bump the shoulder more than .003. Anything more than .005 is going to lead to case head separations at some point. There is little difference between "enough" and "too much" shoulder bump...that's why you need tools. Let us know what you find out.

PS. There is nothing wrong whatsoever with using SAAMI chambers and Lapua brass works great with any SAAMI chamber that is in-spec. Lapua is not going to make 260 REM brass that doesn't work in a 260 REM chamber. The whole point of the SAAMI spec is to guarantee that brass and chambers interoperate. It's the resizing that causes most of the problems. So-called "match" chambers that are smaller than SAAMI cause their own set of headaches. Stick with in-spec SAAMI chambers, get the shoulder bump correct and you should be good to go.

 

[Jim Tisdale]

Thanks for the replys. I've already thrown out the Lapua. I have a bump gauge and have been using it.
The headspace has been checked several times and is fine.

 

[savagedasher]

Thanks for the replys. I've already thrown out the Lapua. I have a bump gauge and have been using it.
The headspace has been checked several times and is fine.

You don't have to throw out the brass just adjust the powder drop . Larry

 

[Scott Harris]

... I have a bump gauge and have been using it.
....

So, how much were you bumping the shoulders on your fired brass???

 

[Jim Tisdale]

I've been using it to see how much the brass grows.
I wish I could post a pic. It would be SO much easier to show my problem.
The Lapua grows from 1.553 (virgin) to 1.566 after one (1) firing of 39 gr of H4350 and the base gets a very pronounced crack in it. Velocity is about 2760.
Same charge, bullet, seating; everything..the Federal grew from 1.159 to 1.562 with no visible problem on the base.
I understand 39 is too much for the Lapua. I'll start over with a lower charge.