What would cause a load to do this?

[hill billy]

I have a pet 7wsm load that shoots the lights out. However in new brass, it pops out of the chamber looking perfect and in once fired brass the bolts gets stiff on the extraction part of the upstroke and there are pressure signs on the case head. Shoots about the same either way and at the same speeds, just occasionally it really hangs up in the chamber and I have to smack the bolt up the last 1/4" This gets to be a serious PITA in a match situation. This happens in 1x fired or 10x fired and no matter what amount of case prep I do. I'm sure this is something really simple I am overlooking but just can't figure it out.

Thoughts?

 

[bohem]

Re: What would cause a load to do this?

How do the reloaded cases go into the chamber after the first firing?

 

[bowslngr]

Re: What would cause a load to do this?

and how does the 'headspace' length compare on your new brass compared to the once fired but resized brass?

 

[ChadTRG42]

Re: What would cause a load to do this?

How do you size the cases- neck only, FL?
What do you use to lube the case for sizing, and how do you clean it off?
Do you know, or can you measure how much you size the shoulder back? I aslk this question because I have had to return 2 WSM dies for bumping the shoulder back too far.

 

[hill billy]

Re: What would cause a load to do this?

New brass is just under max length and I trim to min length so I don't think trimming is an issue. The sized cases do not chamber as easy as new brass, obviously, but they also aren't what I would call easy to chamber. I tried neck sizing only, but the the cases were really hard to chamber so I went back to FL sizing.

All of the dimensions of a once fired case and a new case are identical except the base just below the base of the shoulder is .556 and a new case is .549. This is the only dimension I can find that differs.

I use Dillon Lube and tumble it off.

 

[former naval person]

Re: What would cause a load to do this?

Probably die/chamber differences. Send 3 fired cases along with your die to the maker and they will match a die to fit your chamber.

 

[vman]

Re: What would cause a load to do this?

Why do the sized cases not chamber easily? They should as this is why we resize.

Double check the head to datum length on your fired cases. Do the same on your sized cases. Your sized cases should be at least 0.001 to 0.002 shorter.

 

[hill billy]

Re: What would cause a load to do this?

They were feeling like the shoulder wasn't getting bumped enough even with the die cranked way down. I sanded off the headstamp of a case allowing it to get further into the die and had the same chambering results. Then I took a case and sanded around the length of the case from the base of the shoulder to the web removing about 2 thou and then the case chambered like factory. Seems like the FL die is just not sizing enough of the case walls?

 

[The Mechanic]

Re: What would cause a load to do this?

Grinding the headstamp is not changing the sizing. I think you need to machine the die or get a new one.
Here is a thread on it. I had to do this on a die I had about 10 or so years ago.
http://snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1947624

 

[Hummer]

Re: What would cause a load to do this?

I have had to chuck up about 1/4th of my dies (got over 50) and take about .010" off the bottom to allow them to bump shoulder back. You need a MO Gage to determine where you are after firing and after sizing.

As stated above you need to bump shoulder back .001-.002" and you should be good to go.

 

[summitsitter]

Re: What would cause a load to do this?

I had fits with my 270 wsm..Seems the wsm are harder to resize. sounds like they are not completely resized..

 

[hill billy]

Re: What would cause a load to do this?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: The Mechanic</div><div class="ubbcode-body">Grinding the headstamp is not changing the sizing. I think you need to machine the die or get a new one.
Here is a thread on it. I had to do this on a die I had about 10 or so years ago.
http://snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1947624 </div></div>I mis typed. I meant to say the shell holder. After talkign with tech support at Redding, they have suggested a small base die. Going to give that a shot and report back. Seems like my chamber is about 2 thou smaller than SAAMI spec all the way around.

 

[criz123]

Re: What would cause a load to do this?

I had the same problem with a ruger m77 in 30-06, the small base die fixed my problem.

 

[blakheaven]

Re: What would cause a load to do this?

I have a similar issue. In my 308 I have to full length resize (or rather just screw my die set down till it touches the shell holder) just to get the case to bump back .001 and really I want it bumped back a little more cause there is still some tension on the bolt when it is closed. Also I dunno if I am doing something wrong but when I resize it is pretty stiff and I have to use my heavy Lyman press and had to reinforce my bench just for the resizing operation. I don't know that is normal but thinking to myself, that's a lot of force being used just to bump the shoulder one thousandth.

 

[bigwheeler]

Re: What would cause a load to do this?

It sounds like the OP has a pressure problem, ("pressure signs on the case head") what's the load?

 

[blakheaven]

Re: What would cause a load to do this?

No I never got pressure signs on the head and my load use ot be 43 gr of IMR 4064 with a 147gr FMJBT. I am re barreling the 308 (picking it up monday hopefully) and going to a different load, but I never could figure out why that happened. Possibly I had a really tight chamber?

 

[hill billy]

Re: What would cause a load to do this?

Picked up an RCBS small base die as they are the only ones who make one that is priced under $170.

It seems to have fixed the sizing and chambering issues. I'll see tomorrow how it shoots.