Acceptable headspace tolerance for belted magnums?

[Redonthehead]

I posted my troubleshooting quest in another forum:

https://www.snipershide.com/shooting/threads/my-bolt-is-getting-tighter-or.6992692/#post-8399004

and have gotten to thinking I have a tolerance issue with ammo, so this forum is more appropriate.

I have a basic setup for handloading my 7mm Rem Mag but have been buying cheap factory ammo. Lately my bolt won't close on a few Federal and almost all Winchester. Headspace for 7RM is 0.2200". My bolt closes smoothly on cases up to 0.2220".

Even if I start handloading again, I will need to buy brass. Is it reasonable to expect it to be 0.2200 plus or minus two thousandths?

Thanks!

 

[Redonthehead]

Up

 

[Huskydriver]

If your just buying empty brass why does it matter what it comes in at? Size it to your chamber and rock n roll

 

[Redonthehead]

Not sure I can re-size for headspace on a belted mag. Do people trim the belt back?

 

[Huskydriver]

Maybe I am misunderstanding where your size issue is happening.

How are you measuring your .2220" for HS?

The belt only sets the hs on the first firing. After that, belted mags hs just like a normal case off the shoulder.

 

[Redonthehead]

I'm buying factory ammo to shoot until I have enough brass to reload. Can't close my bolt on way too many new cartridges.

 

[Huskydriver]

I'm buying factory ammo to shoot until I have enough brass to reload. Can't close my bolt on way too many new cartridges.

Got it. So how do you know where the tight fit is? You could have a short cut chamber and the shoulder is hitting before the belt seats in the chamber.

Your best bet is to buy empty brass

 

[onetopgun]

Have you tried inspecting and cleaning your chamber? Bolt? Extractor? Ejector? Have you inspected your throat? Years ago, I had a buddy that complained of hard chambering on a Colt Sauer in 300 Weatherby Mag. Turned out to be rust and carbon in the neck and throat... Cleaning and polishing fixed the issue.

 

[buffybuster]

What rifle is this? Factory barrel?

As previously stated, headspace is set by the belt on the first firing. Afterward it's recommended to use the shoulder for headspace. Since the belt sets the headspace the shoulder dimension for many belted cartridges is held looser than non-belted cartridges. If this is a factory rifle, I would inspect and clean the chamber including the belt area. Check for a short throat.

 

[Redonthehead]

Yep, all of that. Started with a inked up cartridge to see if tight spots leave marks. Nothing. Polished it anyway. Then bought a borescope to confirm no carbon ring, etc.. Then bought higher resolution caliper to measure casings versus spec.

 

[Redonthehead]

It's a stock Weatherby Vanguard (Howa 1500) approx 25 yrs old and has functioned properly until these recent two boxes of ammo. I am outfitting with new chassis, etc... to convert from hunting to ELR.

 

[Tchitcherine]

Why not just buy a box of quality brass and see if they chamber? I have had excellent results with Norma, but there are others ... search function is your friend.

 

[supercorndogs]

.220 min .227 max. IF the belt on your brass is .23 the brass is likely out off spec. It working for twenty five years points to the same.

7mm Rem Mag Chamber Print

When the 7mm Remington Magnum was originally released, it was met with overwhelming demand. Every r...

precisionrifleblog.com

 

[FatBoy]

I'm curious is your getting into the lands with modern bullets. As several have mentioned, but a box of brass and to or pull a bukket off one that won't chamber now and recheck it.

 

[Redonthehead]

I pulled a bullet from a no go. Belt to face was 0.2225". I inked it, chambered it and cranked hard enough to close the bolt. The edge of the belt was the headspace limiter as expected.

I then rubbed the butt face of the casing on a flat sharpening stone to flatten it and take a little off. Now the bolt closes smoothly at 0.2220", which appears to be my limit.

I'm going to buy some Hornady SST or Norma and see if they fit.

Thanks Gents.

 

[Redonthehead]

Spoke with a tech guy at Hornady. He assured me Hornady 7RM belt to face will be 0.216" + tolerance of 0.003" for a max of 0.219".
We'll see...