Excessive Shoulder Bump

[Young_Engineer_89]

All,
I messed up, I measured the shoulder on some fired cases in my new 7mm SAUM. Well long story short, I screwed up and transposed some numbers and when I was setting up my body die, I set it up to bump the shoulders back, 25 thousandths of an inch, instead of 3 thou. I learned this because I loaded all the cases and went to shoot them, but they wouldnt chamber, well they will if I really beat on the bolt to get it closed. I couldnt figure out why and measured the shoulder. I found my mistake, but it doesnt make any sense why that would make it so the rounds wouldnt chamber.

I guess my question is, can bumping the shoulder back excessively cause a round to not fit in the chamber?

Thanks in advance for the help
YE out

 

[Drifter™]

Take a measurement near the case head to see if the excessive setback bulged the case further down just below where a full-length die reaches. I reckon the brass has to get pushed somewhere...

 

[Young_Engineer_89]

would it even be safe to fire these rounds with the excessive headspace? I will measure the cases.

 

[Fuzzball]

Measure your case length before you fire any of it.

All that shoulder brass did have to go somewhere and that's into the neck. If you're driving excess neck length into the end of your chamber that "jammed" ammo is pinching the bullets in place, hard, and chamber pressure will sky rocket.

 

[former naval person]

Get a K&M neck expander mandrel in .308 or .313. Expand the necks (lube inside the necks) and then resize with your FL die to the proper bump. That will give you a false shoulder to seat against in the chamber. When fired they will be okay. Might want to anneal after two loadings or so. JMHO

 

[Young_Engineer_89]

okay I measured the body of the case, at the largest point it is 0.549". New brass pieces that I have measure 0.535", but this is remington vs nosler brass. I measured the case length. It is all right at the trim to length, I did trim it before I loaded the rounds, but I remember very little brass being taken off. I tried just for shits and giggles to chamber an unloaded piece of brass. It chambered flawlessly.

The only thing I can think of now is that maybe the bullets are hitting on something but I cant see anything when looking through the bore. Also this brass was shot yesterday with the same OAL to ogive. I made a dummy round and it wouldnt chamber, i kept seating the bullet deeper and deeper. eventually the dummy round chambered, but aprox 0.200" shorter than what I measure my length with my hornday OAL gauge.

I am so confused... I hope i didnt eff up my new rifle

 

[Young_Engineer_89]

so Marc Soulie called me and had the fix. I had tumbled the brass in STM and there was a small lip on the end of the neck that i didnt trim off. Usually I trim before tumbling. Anyway I pulled the bullets, trimed that lip off and bam, it works perfect.

Thanks a million Marc, now I know why I buy rifles from you