7 mm RM problems

Neck sizing for a belted mag , not a good idea.
The case becomes unsupported in front of the belt at the time of firing.

The unsupported part will bulge, keeping rounds from chambering.

More here https://www.longrangehunting.com/th...ss-photos-included.196986/page-2#post-1390811
LOL. No.That bulge is caused by an oversize chamber or from full length sizing and the brass being pushed down there. Or a combination of both. With so much confusion about belted mags, it's no wonder so many people hate them.
 
LOL. No.That bulge is caused by an oversize chamber or from full length sizing and the brass being pushed down there. Or a combination of both. With so much confusion about belted mags, it's no wonder so many people hate them.

Lol it's funny. You won't see oversized chambers as much as you think. You see headspace wrong more than anything.
 
Neck sizing for a belted mag , not a good idea.
The case becomes unsupported in front of the belt at the time of firing.

The unsupported part will bulge, keeping rounds from chambering.

More here https://www.longrangehunting.com/th...ss-photos-included.196986/page-2#post-1390811
Funny...I've never had a problem in years of neck-sizing my belted magnum cases...Ranging from .257 Weatherby all the way up to .300 Ackley...

And actually, you're wrong, neck-sizing resizes JUST the case neck, and leaves the rest of the case formed to your chamber. And if the chamber was properly cut with a good reamer, the case is supported in MORE places including just in front of the belt, and at the shoulder/neck junction, which is just as critical for consistent accuracy.
 
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Neck sizing will produce zero head clearance.

A maximum chamber and minimum cartridge can produce as much as .015" of unsupported case body. Simple math.

Not all chamber have this amount of slop.

Will a bulge happen in front of the belt? Depends on the PSI of the reloads and amount of slop.
7mm Mag.jpg UNSUPPORTED.jpg
 
Neck sizing will produce zero head clearance.

A maximum chamber and minimum cartridge can produce as much as .015" of unsupported case body. Simple math.

Not all chamber have this amount of slop.

Will a bulge happen in front of the belt? Depends on the PSI of the reloads and amount of slop.
View attachment 88817
What you have marked there is where the belt is. Not the area on front of the belt. And after fire forming and neck sizing, my cases are fully supported, except for the actual belt and have .001-.002" of clearance in the chamber.
 
Neck sizing will produce zero head clearance.

A maximum chamber and minimum cartridge can produce as much as .015" of unsupported case body. Simple math.

Not all chamber have this amount of slop.

Will a bulge happen in front of the belt? Depends on the PSI of the reloads and amount of slop.
View attachment 88817

It has nothing to do "reloads and slop". Once you start full length sizing brass, it is pushing part of your case downwards. Shooting excess pressure has limited effect on it. What's amazing is you say my loads are " to hot" yet I can take a once fired brass and full length size it and be ok. My brass fails because of primer pockets after 3xish firings.

Honestly you seem like an old school reloader trying to prove science and experience wrong. Old school ways are in the past. Move on.
 
Once you start full length sizing brass, it is pushing part of your case downwards.

Not sure this is correct. I believe that the mechanics of "full length sizing" actually pushes the brass upward towards the neck. This is a primary reason for necks getting longer and also what causes donuts in side the case, at the neck shoulder junction, on cartridges with sharp shoulders.
 
Not sure this is correct. I believe that the mechanics of "full length sizing" actually pushes the brass upward towards the neck. This is a primary reason for necks getting longer and also what causes donuts in side the case, at the neck shoulder junction, on cartridges with sharp shoulders.
Regardless of which way it's moved, with a belted magnum it stops at the belt. It just seems you have excess "brass" right above the belt than normal full length sized non belted brass.
Some reasons are:
1. High pressure.
2.oval chamber.
3.bolt face not square to the chamber.

His reason has already be fixed yet you continue to post about things that aren't correct with his rifle.

I have been trying to be nice but it's obvious you don't have a **** clue about what's going on other than the ****** personal experience you have with belted magnums. If I was you I would go back to running a 7RM 168s at 2800fps saying it runs with the best.
 
Guess I am not following this close enough. I thought he was giving generic reasons why a case may not chamber.

Guess my pain pills are working.o_O

Steve
 
Guess I am not following this close enough. I thought he was giving generic reasons why a case may not chamber.

Guess my pain pills are working.o_O

Steve

There was many generic reasons as why the case wouldn't chamber after being "neck sized". After talking to the OP and finding out hat original once fired brass wouldn't chamber unless being FL sized brought me to the headspace issue. I had him headspace off the shoulder and now everything is golden. He had a tad of excess headspace which was causing everything to blow forward.
 
There was many generic reasons as why the case wouldn't chamber after being "neck sized". After talking to the OP and finding out hat original once fired brass wouldn't chamber unless being FL sized brought me to the headspace issue. I had him headspace off the shoulder and now everything is golden. He had a tad of excess headspace which was causing everything to blow forward.
Don't want to read it all again. Is his chamber bad or was the belt poorly located on his batch of brass? Surprised that there is no issue with shallow primer strikes if head space is excessive.

Steve
 
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