Once fired 7mm RM case preparation question

theiss

theiss

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Hi Folks,

I have Remington 700 Sendero in 7mm RM.
I've shot 105 rounds of factory ammo (mostly Federal Premium line, ie: trophy bonded tip & sierra game king, and a box or two Remington's).
I also have a bag of Winchester brass.

When I tried to put a new bullet into the once fired brass, it will not go in even with a slight push.
I reload for .308, and I can put a bullet into the once fired brass without any effort.
I have not done anything to the 7mm brass other than stainless tumble it.

When measuring the once fired brass (10 cases) at the mouth, I found the following reading:
Outside dia: 0.3155
Inside dia: 0.2815 - 0.2825
Case thick: 0.0155 - 0.0150

Those measurement are very close to the new Winchester brass:
Outside dia: 0.3070
Inside dia: 0.2715
Case thick: 0.0180


Is this normal? or should I worry that the barrel maybe underbored(?) ?
I have not measured the length with a caliper, but they don't look any longer (eye inspection) than the Winchester brass. So, it is not too long that it would stretch into the lands and causing a "crimp" to itself.

Thanks for your inputs.

Regards,
Trev.
 
The dimensions seem OK except for your .2715 measurement, this seems very tight!
The fired ID also seems very tight. Did you deburr the cases? Sometimes this throws the dims off.
Since you have fired some factory ammo in this gun without any ill effects
it doesn't sound like anything is wrong. Even though your dim's are off.
If you are uncertain have someone do a chamber cast.
bb
 
This is just between you and me, but I often do not even use an expander plug when reloading, if I deburr the cartridge after sizing, it will usually take a bullet just fine.
 
The reason that the bullet will not go back into your once fired brass is more than likely due to the reminants of the factory crimp. Deburr the inside of the case mouth and try to insert the bullet. More than likely it will go in.
 
Thank you everyone!

I deburred the inside of the case - and voila! the bullet will go in with no effort.
I guess I was freaking out too early.

Thanks for the help on this.

Trev.
 
Deburring is one of the things once fired factory brass needs anyway. You should have checked 'em for length first though. Most cartridges will stretch the most on the first firing. Doing it isn't hard, but doing 105 can be a bit time consuming. The fix, if you don't have a case length gauge, is to lock your vernier calipers to the max case length given in your manual(it's 2.5") and check 'em that way. Trimming isn't needed if they're no longer than that length.
 
Thanks, Sunray!
I have a case length gauge on order to make life easier.
I have a lyman trim pilot for the caliber, but I think I will use the caliper method in the mean time.

Trev.
 
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