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What is this?

Nomad47 said:
If bolts were swapped and that caused excessive headspace in one rifle, then the other rifle should have too little headspace and should be difficult to chamber a round.

Not necessarily, per saami specs, the 7mm08 is .040" longer from case base to neck shoulder junction. And OAL is longer also, but doesn't matter here.

There's a lot of talk of headspace causing separation, while I totally agree, even bumping shoulders back too far creates headspace issues, but if you figure it out after the first firing, and by NOT oversizing your brass, you can get decent service life out of the brass. Just bump the shoulders enough to chamber the case and don't overwork it.
If you gain a little more case capacity because of the oversize chamber, run with it!
 
Nomad47 said:
If bolts were swapped and that caused excessive headspace in one rifle, then the other rifle should have too little headspace and should be difficult to chamber a round.
Especially one of the ones with the ring. Mark one bolt with the rifle it is in and swap to the other as Nomad says it should be difficult to chamber. Just keep track of the bolt now. This is before you resize.
 
To be absolutely sure rent a set of G0/No-G0 headspace gauges from 4-D Products (www.4-dproducts.com) for the .308 family of cartridges. Will cost $8 or so and you can keep them for a week. Check your headspace on both rifles and both bolts until the bolts will not close on No-Go and will close on Go gauges. I found it was worth it to buy a set as they are not horrendously expensive.
 
Buy the Hornady tool that measures base to shoulder on the brass and measure brass fired from each gun and keep them separate. Set up for the shortest headspace and buy the die shim set and use them under the die for the longer HS gun.
 
Erik Cortina said:
Buy the Hornady tool that measures base to shoulder on the brass and measure brass fired from each gun and keep them separate. Set up for the shortest headspace and buy the die shim set and use them under the die for the longer HS gun.

One is a 7mm08, the other a .308 ::)
 
milo-2 said:
Erik Cortina said:
Buy the Hornady tool that measures base to shoulder on the brass and measure brass fired from each gun and keep them separate. Set up for the shortest headspace and buy the die shim set and use them under the die for the longer HS gun.

One is a 7mm08, the other a .308 ::)

I missed that. So, easier to do what I said then. ;)
 
M-61 said:
Nomad47 said:
If bolts were swapped and that caused excessive headspace in one rifle, then the other rifle should have too little headspace and should be difficult to chamber a round.
Especially one of the ones with the ring. Mark one bolt with the rifle it is in and swap to the other as Nomad says it should be difficult to chamber. Just keep track of the bolt now. This is before you resize.

I guess I should have said "assuming both rifles' dies were set up to bump shoulders the proper amount". Then if a bolt swap caused excessive headspace in one rifle, it would definitely cause too little in the other.
 
The OP JDBraddy needs to find out if he inadvertently swapped bolts on his .308 and 7mm-08 and if this is causing the problem.

Excessive head clearance is what causes case head separations.

HEADCLEARANCE-a_zps1a9a1011.jpg


Cheap bastards headspace gauges.................

Take a new unfired case or a full length resized case and measure its length and write it down.

303gauge_zpsb1e333a7.jpg


Next take a fired spent primer and start this primer into the primer pocket with just finger pressure.

303primer_zpsae8fdb45.jpg


303primera_zps612343f9.jpg


Now take this test cartridge and chamber it in the rifle, slowly closing the bolt. The bolt face as the bolt closes will seat the primer. Remove the case and measure the case length again, the case is going to tell you a story.

The amount the primer is protruding from this test cartridge is head clearance or the "air space" between the rear of the case and the bolt face. Subtract the first case measurement from the second case measurement and this is your head clearance in thousandths of an inch.

hedspace-b_zpsce06e3e4.gif


enfieldHS_zps99b67ad8.jpg


The primer trick will work with any rifle and type cartridge, forgive me I collected Enfield rifles and most of my illustrations are for the British .303 Enfield rifle. I have headspace gauges for most of my rifles but you you do not need head space gauges to figure out your head clearance.

The only difference between cartridge designs is the distance from the bolt face to the datum line.

Headspace_2_lg_zps3fea821e.jpg

Headspace_1_lg_zpsdd7501b6.jpg
 
Took the rifles to a gunsmith today, each rifle did have the correct bolt, and headspace is within spec on both, so back to the dies, started to measure the cases using RCBS Precision Mic, and found as much as eight thousanths of an inch difference from one case to the other, this is in the fired cases that have been deprimed but not resized. I find this extremely odd, because all of them have been fired from the same gun, several times. I'm not sure which ones to use to set the dies.
 
JDBraddy said:
Took the rifles to a gunsmith today, each rifle did have the correct bolt, and headspace is within spec on both, so back to the dies, started to measure the cases using RCBS Precision Mic, and found as much as eight thousanths of an inch difference from one case to the other, this is in the fired cases that have been deprimed but not resized. I find this extremely odd, because all of them have been fired from the same gun, several times. I'm not sure which ones to use to set the dies.

If you can close the bolt without resistance, then neck size then and wait until the cases are tight enough so you can adjust a FL die - you cannot adjust it on cases that already are loose in the chamber - or you will continue to have headspace problems and head separations.
 
I measured each, and chose five of the longest cases, each chambered in the rifle without resistance, so I set the sizing die so that it touches but does not bump the shoulder at all, in fact a couple of these cases actually grew a thousanth longer when sized, I assume because of the neck expantion ball pulling upward on the inside of the neck/shoulder junction as the case was extracted from the die. I then resized all the cases and they are in the tumbler removing the lube now. Unfortunately, I work all weekend, so will have to wait till next week to load an fire them again.
 
JDBraddy said:
I measured each, and chose five of the longest cases, each chambered in the rifle without resistance, so I set the sizing die so that it touches but does not bump the shoulder at all, in fact a couple of these cases actually grew a thousanth longer when sized, I assume because of the neck expantion ball pulling upward on the inside of the neck/shoulder junction as the case was extracted from the die. I then resized all the cases and they are in the tumbler removing the lube now. Unfortunately, I work all weekend, so will have to wait till next week to load an fire them again.

It is not because of the expander "pulling" on the case.

When the die squeezes the case body smaller, the shoulder portion is forced forward. If you take the expander out, you will find that the case still gets longer when you partially FL size it.
 

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