7mm Rem Mag Won't Chamber After Resizing

coxa2

New member
I have a 7mm Rem Mag that will chamber factory loaded ammo just fine. Any resized brass will not chamber in the rifle. The bolt will travel fully foward but will not lock down. I have tumbled/cleaned the brass, ran it through a FL resizing die, trimmed to propper length, then seated the bullet just off the barrel rifling. At first I thought it was the bullet causing the problem so I tried to chamber a resized and trimmed case without a bullet and it still won't chamber. Thinking it might be some kind of dirt build up in the rifle itself I throughly cleaned the chamber and I still get the same results. Any advise would be greatly appriciated!

Andy
 
Run the die right down to the top of the shell holder, touching the die right to it...measure and trim to length and see if that fits...if it doesn't check and compare the various points on the sized and trimmed case to the chart measurements found in the reloading booklets..the case must be larger than those numbers not to fit and maybe your die just was not cut right..hard to believe but there's no other explanation other than the expander but on the decapping pin is to large and the case is hitting the throat in the barrel...
 
Could be a couple things...but I'd say you werent getting enough shoulder bump.

Or it could be case bulge in front of the belt and your die isnt sizing far enough down.

I've only "heard" of the second issue and have never delt with that after owning several belted magnums.
 
The die was sitting on top of the shell holder when resized. All the measurements I took were within +-.001 of reloading specs. The only measurable difference I can see is right above the base/belt of the case and it's about .05-.06 difference from factory ammo.

P.S. I borrowed the dies (RCBS) from my neighbor who loads 7mm quite often with no problem.
 
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Try borrowing his shell holder and see if that makes a difference.Or you can take a couple thou off the top of yours as a last resort.
 
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I have a 7mm-08 that is the same way. What I have come up with is that full length die is at the long end of SAAMI specs and my chamber is on the short end. Even with the shell holder touching the die you can't get bolt to close. To fix it I cut a piece of pop can to fit in the bottom of the shell holder so it gets that extra couple of thousandths of shoulder bump. After doing that the bolt closes like butter!!! When you deprime the case the spent primer will make a perfect hole through the pop can!!!


 
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Originally Posted By: BeluebowTry borrowing his shell holder and see if that makes a difference.Or you can take a couple thou off the top of yours as a last resort.

Yes, I used his shell holder when I was reloading.
 
Originally Posted By: Jabey9210I have a 7mm-08 that is the same way. What I have come up with is that full length die is at the long end of SAAMI specs and my chamber is on the short end. Even with the shell holder touching the die you can't get bolt to close. To fix it I cut a piece of pop can to fit in the bottom of the shell holder so it gets that extra couple of thousandths of shoulder bump. After doing that the bolt closes like butter!!!

I'll have to try that and see if that makes a difference.
 
If your die is touching the shell holder at its highest point lower the ram slightly and give the die an 1/8th of a turn down. Try and chamber an empty casing. If you still can't chamber it then lower the ram again and give the die another 1/8th of a turn. Repeat until you get it to chamber. Make a dumbie round and try to chamber. If it chambers you are good to go. The press needs to slightly cam over at the top of the stroke.
 
Originally Posted By: deaddogwalkinIf your die is touching the shell holder at its highest point lower the ram slightly and give the die an 1/8th of a turn down. Try and chamber an empty casing. If you still can't chamber it then lower the ram again and give the die another 1/8th of a turn. Repeat until you get it to chamber. Make a dumbie round and try to chamber. If it chambers you are good to go. The press needs to slightly cam over at the top of the stroke.

Thank you! I did that along with adding a couple shims under the case itself. I can get the bolt closed now but is a little "sticky"
 
Originally Posted By: deaddogwalkinIf your die is touching the shell holder at its highest point lower the ram slightly and give the die an 1/8th of a turn down. Try and chamber an empty casing. If you still can't chamber it then lower the ram again and give the die another 1/8th of a turn. Repeat until you get it to chamber. Make a dumbie round and try to chamber. If it chambers you are good to go. The press needs to slightly cam over at the top of the stroke.


If the shell holder is touching the die firmly what does it matter what position the press is in? To me it seems that once the shellholder hits the bottom of the die, that's as far as you're going to get it to go no matter if the press is at 1/4 stroke or 3/4 stroke? Not arguing just asking!!!
 
Originally Posted By: Jabey9210

If the shell holder is touching the die firmly what does it matter what position the press is in? To me it seems that once the shellholder hits the bottom of the die, that's as far as you're going to get it to go no matter if the press is at 1/4 stroke or 3/4 stroke? Not arguing just asking!!!



Cuz...

... when you screw the die down to "touch" the shellholder, the press is not being stressed.

When you run a case into an FL die, it is under a lot of force, so the top of the press starts to be pushed up - it "flexes".

When it flexes, the die is no longer touching the shellholder, so the case does not go in the die for the last 4 to 7 thou... so the shoulder does not get pushed back in place. This is important, because when you partially size a case, the shoulder gets pushed forward, and now is too long.

When you partially FL a case, (like 98% of the way) it is worse than when you started - which is why the original poster (Coxa2) could not chamber cases that came out of the rifle, fitting the chamber, with no problems of tightness... they fit the chamber of the rifle when they were extracted, but now they don't.

What happens is, the FL die starts squeezing the body fairly soon and that squeezing causes the case to GROW longer - so now the headspace of the case is longer than the chamber that it was just shot in - and will not go back in.

So when you set up an FL die, you MUST make sure that the die is still in contact when the ram is all the way up, and the press handle is all the way down... even AFTER the press has stretched/flexed.

That is why it is necessary to adjust an FL die so it is screwed past the point that it hits the shell holder.

The easy way to do it is to screw the FL die down to the shell holder when the ram is all the way up. Then let the ram down and screw the die down an additional 1/2 turn. It should hard to finish the ram stroke, even when there is no case in the press - that is called "camming over".

It is not necessary to do with neck sizing dies.

 
Proper sizing is very important if you trim based on the shoulder. If you trim based on OAL, it is not as important. However, you will can get into situations where the case is trimmed to the proper length but wont chamber. This is usually a tale tell sign that your dies are not set quite deep enough.

With a new die setup, i usually test the first 5 cases to make sure they will chamber and then i test 1 out of every 5 through the next 50.

A easier way to check this is to buy a head space guage similar to this

http://www.lewilson.com/casegage.html
 
Originally Posted By: captninsanoProper sizing is very important if you trim based on the shoulder. If you trim based on OAL, it is not as important. However, you will can get into situations where the case is trimmed to the proper length but wont chamber. This is usually a tale tell sign that your dies are not set quite deep enough.

With a new die setup, i usually test the first 5 cases to make sure they will chamber and then i test 1 out of every 5 through the next 50.

A easier way to check this is to buy a head space guage similar to this

http://www.lewilson.com/casegage.html

Gauges like that will NOT solve the OP's problem.
 
Originally Posted By: captninsanoWhy do you say that, cat?

Because it is true!
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Originally Posted By: captninsanoWhy do you say that, cat?

First off, those little $20 drop-in gauges are close to worthless...

... but in this case, they do nothing, and here's why.

There is a large variation in allowable chamber size.

With the 7mm Remington Magnum, the allowable chamber headspace length is from 2.1253" to 2.1353"... that's a 10 thou allowable variation in headspace length of the chamber.

The allowable case length is from 2.1092" to 2.1162"... that's an allowable variation of 7 thou in case headspace length of the case.

So... we can have a 2.1092 case and a 2.1353, for a whoppin' total of 17 thou difference between a min case and a max chamber.

So the $20 gauge must have 17 thou of acceptability (that silly little step).

Now... if Coxa2 has a rifle with a middle of the road chamber (2.1303") and he partially sizes a case, and the case grows 5 thou in length, the case is now 2.1353... it is STILL INSIDE OF SAAMI specs and will pass the cheap drop-in gauge test, but it will NOT allow the bolt to close.

OK???

Do you understand this?

 
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