7 mm RM problems
- Thread starter Buckreed
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It ended up being a headspace issue. The full length sized brass would chamber and fire but once fired brass that wasn't sized wouldn't chamber.
I don't doubt you but I am confused why brass that came out of your chamber won't go back in?
Wild Bill G
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- May 13, 2016
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I am wondering what he calls hard to chamber. Does he just mean harder then factory or hard like you can hardly get the bolt closed. He mentioned his 308 has no problem neck sizing but 7 mag does are both rifles the same make. The 308 may have a little extra leverage in the bolt. I neck size everiy thing I load exept my pistol and even then I only size enough to hold bullets tight. The only gun that chambers rounds harder is my 270 WSM Sako 85. I neck size to save money on brass as brass is not cheap and I want to get all I can out of it. Rich is right he could have a chamber issue It would not hurt if he took his gun smith and got it checked out completely. Was the rifle bought brand new or did he get someone elses problem.
Exactly. I just had the same problem with a 6.5 McGowen barrel. Sent it back & they found the rear of the chamber was out of spec by 4 thou. Made me a new barrel.
BW
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
I believe he had excessive headspace. I would have to go back into the messages and check. As some of you know a belted mag is headspaced off the belt. Belt width varies from one piece of brass to another. It's best to set headspace off the belt then reset the headspace off the shoulder once you have a couple pieces of fired brass. As far as the neck sizing, it has nothing to do with anything from the neck shoulder junction down. It sizes the neck and the neck only. The bulge you are referring to is done after full length sizing. A full lengh die does not size the whole piece of brass. The part directly above the belt isn't sized.
From my link above. Belted magnums- seen a 7mm Rem mag that was neck sized only, till a fl sizing was needed to close the bolt. 
When the head clearance/cartridge headspace is set by the shoulder, the case body in front of the belt becomes unsupported, in the chamber on firing. So i feel its best to fl size every loading. Bumping the shoulder back about .005" Many fl dies will do this using a single stage press, with the shell holder making contact with the bottom of the fl die. Not so on some progressive units.
Just my opinion. Others may be different.http://www.larrywillis.com see collet die. I never needed one for 7 & 300 mags.
When the head clearance/cartridge headspace is set by the shoulder, the case body in front of the belt becomes unsupported, in the chamber on firing. So i feel its best to fl size every loading. Bumping the shoulder back about .005" Many fl dies will do this using a single stage press, with the shell holder making contact with the bottom of the fl die. Not so on some progressive units.
Just my opinion. Others may be different.http://www.larrywillis.com see collet die. I never needed one for 7 & 300 mags.
From my link above. Belted magnums- seen a 7mm Rem mag that was neck sized only, till a fl sizing was needed to close the bolt.
When the head clearance/cartridge headspace is set by the shoulder, the case body in front of the belt becomes unsupported, in the chamber on firing. So i feel its best to fl size every loading. Bumping the shoulder back about .005" Many fl dies will do this using a single stage press, with the shell holder making contact with the bottom of the fl die. Not so on some progressive units.
Just my opinion. Others may be different.http://www.larrywillis.com see collet die. I never needed one for 7 & 300 mags.
After x amount of sizing you will receive that bulge regardless of where your headspace is set. Neck sizing gives you a little longer brass life in a belted magnum. It's science. When you size a piece of brass, it gets longer. Unfortunately when you size a belted magnum, it only pushes so much toward to the neck the rest goes to the belt and stops above the belt. That creates the bulge. It's going to happen regardless eventually if you full length size your brass. I don't run into it much due to neck sizing and primer pockets being shot out after 3-4 firings depending on what brand brass I am using. Neck sizing gives you extra firings on belted magnum brass
Sigh the load is to HOT. Helps make bulge. Good luck.
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Rich Coyle
Well-Known Member
This reminds me of a guy I worked with. He often bragged about having seventeen years of experience. What I observed was a guy with six months experience repeated thirty-four times. If a full length sized case has support, and it is sized away from the chamber wall, where does the non-support happen with a neck sized case?
Wild Bill G
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Exactly when you fire a brass case in a chamber it expznds to the dimensions of that chamber. That is partly why you can not neck size some one elses brass and expect it to fit your chamber.
I neck size all of my magnum rifles and I don't think I have ever had to FL resize them before cases wore out. Tlhe less you reshape and force the brass to another shape the longer it will last. Look at it this way what happens if you continually bens a piece of tin it breaks so will your brass. As I said before the only magnum I had to FL resize was may short mag guess what no belt. Only neck size my 300 Weatherby and some of those cases have been reloaded 6 times and look like new.
I neck size all of my magnum rifles and I don't think I have ever had to FL resize them before cases wore out. Tlhe less you reshape and force the brass to another shape the longer it will last. Look at it this way what happens if you continually bens a piece of tin it breaks so will your brass. As I said before the only magnum I had to FL resize was may short mag guess what no belt. Only neck size my 300 Weatherby and some of those cases have been reloaded 6 times and look like new.
