Ruger No. 1 headspace

[myfriendis410]

I have a 1976 vintage No. 1 in 7mm rem mag that has, I think, a headspace issue. I was wondering if anybody else here has had similar issues and what I can do about it. The darn thing eats brass--I get maybe two loads out of it before incipient case head separation. My A-Bolt in the same caliber exhibits NO signs of case separation after five or six loadings. Any thoughts?

[Moondawg]

What Excess 650 said. Adjust your sizing die so you headspace off the shoulder. What you are describing is a not uncommon problem with belted magnums.

[Tatume]

Go/No-go headspace gauge sets are not terribly expensive:

http://www.brownells.com/.aspx/cid=0...arch=headspace

If the rifle has excessive headspace Ruger will fix it.

[leadman]

Ignore the belt on the 7 mag and headspace it off the shoulder. I had the same problem with my Encore in 7 mag and did alot of investigating and measuring.

After talking with many techs at the powder companies and some gunsmiths I determined the problem is not so much with the headspace as the fact that almost all of the brass made for the 7 mag is short in the body.
This creates the same effect as an excessive headspace issue in a bottlenecked case like the 30-06.
What I do to correct the problem is prime the new cases, add 20grs of Unique, fill the remainder of the case with Cream of Wheat cereal and make a wax plug to keep everything in the case.
After firing the case fits the chamber so do not push the shoulder back. I went from 2 or 3 loadings to over 5 now. and these are close to max load with jacketed bullets.

[montana_charlie]

I have a 1976 vintage No. 1 in 7mm rem mag that has, I think, a headspace issue.

If you put a small piece of Scotch tape on the head of a new case, will the breechblock close on it?

How many layers of tape will it accept?

CM

[Lloyd Smale]

My #1 in 2506 is the same way. If you full lenght size brass will last 2 or if your lucky 3 firingings using dies set up for any other 2506. What ive come to do is just neck size for that gun.

[myfriendis410]

I really did not want to have to load specifically for that rifle. My other rifle takes an F/L sized case beautifully and won't accept one lengthened for the Ruger. I suppose that's my only realistic approach though......

[leadman]

Since the headspace is the distance from the rim to the rim recess in the barrel having the headspace corrected probably won't fix your problem.
I read where some are chambering for a 7mm mag without the belt.
This is more of the cases not being made long enough from belt to shoulder.

If you could find a gunsmith with a reamer ground shorter from belt to shoulder it would probably work good.

Another option is to use a different belted case like a 300 Win Mag and sized it to fit the chamber. It would be easy to tell these from cases for your other guns and if one did find its way into a 300 WM probably no damage would occur.

[myfriendis410]

I fired three rounds this a.m. and all three developed near case head separation. To the point that it dented the case below the shoulder from blow-by. Cases fell out of the gun and when a caliper was put on 'em they were at 2.507" which started at a trim-to length of 2.493". That's a LOT of stretch.

[Tatume]

Service inquires for Shotguns, Revolvers, 22 Charger Pistols
and all Rifles except PC4/PC9 Carbines.

Sturm, Ruger & Co., Inc.
Customer Service Department
411 Sunapee Street
Newport, NH 03773

Telephone: 603-865-2442 / Fax: 603-863-6165
(Monday through Friday 8:00am - 5:00pm EST)

[Lloyd Smale]

id usually agree with you but this particular #1 is a real shooter. So much so that id be afraid to send it to ruger and take a chance on getting it back with a different barrel (crappy one) i guess in this case its worth the extra to me.

I really did not want to have to load specifically for that rifle. My other rifle takes an F/L sized case beautifully and won't accept one lengthened for the Ruger. I suppose that's my only realistic approach though......

[Rico1950]

"What you are describing is a not uncommon problem with belted magnums".

+1 on that. I've had a Rem 700 BDL 350 mag since about 1975. Always set the dies to headspace off the shoulder. Brass will last alot longer.

[Clark]

The SAAMI drawing for 7mmRemMag is much like the drawings for other belted magnums.


.220 - .008" for cartridge belt
.220 + .007" for chamber belt clearance
---------------------
Belt specified to have between .000" and .015" clearance

2.2700 - .0070" for cartridge shoulder clearance
2.2791 + .0100" for chamber shoulder clearance
---------------------
Shoulder specified to have between .0091" and .0261" clearance


The brass I measure of many samples of many brands looks like .210" to .215".
So when I cut threads and the cut chamber on a 7mmRemMag rifle, I headspace the rifle at .215".

But the factory rifles are all more than .220"
I have a Ruger #1 7mmRemMag.

So what to do with a factory rifle?
The first time brass is fired, the belt will stop the forward movement of the cartridge when the firing pin pushes.

Partial neck size, neck size, or FL size and push the shoulder back .001".
Then on the next firing, the shoulder will be what stops the cartridge forward movement in reaction to the firing pin.

[Gtek]

+1 on what the others have said on creating false shoulder. 50/100 new and start is the way I go and serialized batch to individual weapon. I have even done quick anneal after first size and before first firing. You may also notice your groups will shrink a little, also paying attention to jump at about .010"-.020". Problem has been around since they made them, but being in the crowd that takes your brass home, welcome to the madness! Gtek

[leadman]

I chased this problem with my Encore for awhile and at some expense. I bought bag of different brands of popular brass and measured them. They were all short from the front of the belt to the shoulder.
Fireforming them as posted above has solved the problem for me. As mentioned the accuracy does get better with the fireformed brass. I investgate if my groups go over 2" at 200 yards as it will usually keep a group size about 1.5" at that range.
You may want to do a chamber cast so you can see the various dimensions of your chamber and then fireform your brass to fit. Pushing the shoulder back with the die screwed down to touch the shellholder will recreate your original problem.

[myfriendis410]

I have loaded three rounds, mid-range, with the false shoulder. I will try to get them through the gun Monday. I will post results. The one good thing is I have a boatload of 7mm r.m. brass so sorting and identifying for one gun should not be a big deal. I just hate to do it.

[Crusty Deary Ol'Coot]

Because of manufacturing tolerences that we all live with, using one set of full length dies for a number of firearms is very likely false economy. It may work or it simply may not.

Back toward the start of this topic it was said that a belted case should be head spaced on the belt. Simply WRONG!!!!!!!!!!!!! most of the time.

That may work and work well in some cases, but far better results will, and this goes for all bottle neck cartridges including the belted kind, be had if you always size the case just enough to allow for a cartridge fired in your chamber to again chamber in your chamber.

Size all bottle neck cartridges the minimum amount possible for best brass life and consistancy.

In most cases, head spacing a belted cartridge on the shoulder will give far better results and MUCH longer case life.

Been there and done that years back with my first belted cartridge rifle, also a 7mm mag.

AND ----------- for most of us and in most of our reloading, a set of properly adjusted full lengthy dies is all you need and the purchase of a neck sizing die is only taking money from your pocket and moving it into someone else's.

Keep em coming!

Crusty Deary Ol'Coot

[myfriendis410]

So I finally got to the range and ran 6 rounds through. Two loads: a mid-range load with a 140 gr. Sierra and a hotter 150 gr. Barnes TSX. Both were tight in the gun with the false shoulder and when fired dropped out of the gun with no sign of case failure. I put a tool into the cases and no sign of a ring forming either. Interestingly; the cases only stretched .003" in overall length. The loaded rounds that were giving me trouble measured .018" larger after firing.

Thanks for the help, guys!

[Ed in North Texas]

[QUOTE=leadman;1745377
snip
I read where some are chambering for a 7mm mag without the belt.
This is more of the cases not being made long enough from belt to shoulder.
snip
[/QUOTE]

Help me out here. Some folks are cutting a 7mm Remington Magnum chamber without a recess for the belt. How does a case with a belt chamber in that rifle? I just can't wrap my mind around a 7mm Rem Mag chamber without a cut for the belt. I must be missing something.

Ed

[myfriendis410]

A case with a belt wouldn't be able to chamber if the belt cut is not present. They would have to rely on custom ammunition.