Having Problems with .338 Lapua Brass?????

[Shadow_Warrior]

Ok I have two different lots of Lapua brass for my Surgeon .338 LM.
Both lots have been fired formed with 300 SMK at 2750fps with no overpressure.
1 out of 10 will not chamber (bolt will not close)
1 out of 4 will chamber with medium/heavy force
So far I have used a Redding Match Full length and a Body resizer full adjusted all the way down with a heavy bump.
I have completly cleaned the bolt and chamber.
All cases are Giruid trimmed to 2.710"

Any ideas??

 

[USFTR]

Re: Having Problems with .338 Lapua Brass?????

headspace?? Do you have any measurements from before and after sizing? At one point, I think I remember the shoulder moving a little forward after FL sizing if I didn't size all the way. If this is the problem, you might need to take 0.001 - 0.002" off the bottom of the shell holder (cheaper if you mess up) or 0.001 - 0.002" off the bottom of the die (expensive if you mess up).

Just to be sure, you did fire form in the same rifle you are currently using and we are talking about brass only, not loaded?

 

[Shadow_Warrior]

Re: Having Problems with .338 Lapua Brass?????

The sizer dies are making contact with the shoulder.
Is there a good way to measure the setback?
What is the best way to trim .001 off the bottom of the sizer die?

One lot of brass has been fired through other rifles and one lot has only been fires through the Surgeon.

 

[USFTR]

Re: Having Problems with .338 Lapua Brass?????

You still may want to check the shoulder to rule it out. Even 0.001 - 0.002" is noticable if it is close to matching the rifle chamber. I've seen a drop in headspace gauge. I think Pacific Tool and Gauge made the one I saw. I use the RCBS precision mic set for .308 and .270, but I don't think they make one for .338 that I saw. I'm in the middle of a build as well for .338LM and checked recently.

To reduce the size of the shellholder 0.001 - 0.002", I just used a little sandpaper. The sandpaper was flat on a hard surface and I moved the shellholder over it a minute or two measuring along the way. I had to use this on one of my body dies a few years back. My gunsmith took a little off the body die on this lathe.

Is there a relationship between the brass fired in another rifle and the brass fired in your rifle. What about fired brass in your rifle before sizing? Any left?

 

[Shadow_Warrior]

Re: Having Problems with .338 Lapua Brass?????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: usftr</div><div class="ubbcode-body">
Is there a relationship between the brass fired in another rifle and the brass fired in your rifle. What about fired brass in your rifle before sizing? Any left?</div></div>

Yes I have a few left that are not sized.
I took .002 of the bottom of the shell holder and resized the brass that is giving me problems but this did not seem to help??

 

[Augustus]

Re: Having Problems with .338 Lapua Brass?????

You should not be having tight cases after fireforming with low pressure loads. Try to rechamber before re-sizing, they should bolt up nice. If they bolt up w/o resistance go ahead and resize. If they are tight at this point you are inducing the problem with your die. The most common cause is you are not screwing the die in the press far enough. Some die --chamber combinations require the press to be lifted all the way up, the die should then be screwed snug against the shell holder. Now lower the press and screw the die down 1/4 to 1/2 turn. This should cause the press to cam over when cycled. Try that and see if it helps. If not you may have to reduce your die or shellholder. I have found custom chambers and stock dies to be a pain. Usually you can get by tweaking the die or shellholder. If you are having problems with once fired brass you are almost certian to have chambering issues when the brass becomes less resiliant with repeated firings.

 

[USFTR]

Re: Having Problems with .338 Lapua Brass?????

I was referring to the top of the shellholder so the brass is able to enter the die a little further and thus push the shoulder back more.