Case separation on first firing

There are many ways to measure head-space in the industry. In my quick observation I was referring to this kind of head space. Not belted cartridge which is different. I still think you have oversized chamber space as indicated in below pic as 'headspace'. If your chamber space is within specs then try polishing it to a mirror shine finish.

headspacevideo1602.png
 
propliner said:
The way I see it is a headspace gauge won't detect a problem but a go/no-go might.

Also, if the barrel was ruined due to improper reaming it was junk to begin with and still warrants a refund. Unfortunately it was virtually new yet second-hand so returning it may be impossible, and shipping the barrels back and forth even more so.

I will head to the range with two other different boxes of ammo today (if the weather holds out) and will report back.
Click to expand...

Looking forward to your reply after using different ammo. I still think it is a brass problem and not a headspace problem. Find a smith with a no go standard magnum gauge and you will soon know.
 
SIGP2101 said:
There are many ways to measure head-space in the industry. In my quick observation I was referring to this kind of head space. Not belted cartridge which is different. I still think you have oversized chamber space as indicated in below pic as 'headspace'. If your chamber space is within specs then try polishing it to a mirror shine finish.

headspacevideo1602.png
Click to expand...

This pic is not valid for a belted or rimmed case. Headspace for belted or rimmed cases goes to the forward edge of the belt / rim. As the belt / rim is part of the chamber reamer, the distance from the belt / rim to the shoulder will remain fixed.

Yes, it is possible to size fired cases to "headspace off the shoulder" but that does't work for the first firing, which is where the OP is experiencing difficulties.
 
I took the necessary precautions and fired a single round of different ammo. Here is the result:

n9AC7A3.jpeg


This barrel is garbage.

FWIW, the case stretch from base to shoulder using a comparator is .050"
 
Last edited:
bearhunter said:
How can it be to deep of a ream if the headspace is OK?

The only way it could be to deep, which is doesn't appear to be from the last pics, is if the reamer was purposely ground oversize or to special order. If it's a homemade reamer, it could just have been ground to final dimensions improperly.

I'm with the bad batch of brass on this one.
Click to expand...

Have heard too many issues being had with badly made reamers to discount that. PTG seems to get mentioned a lot...

Have heard of, but not seen first hand, guys using different reamers for the body and the belt. Or guys lopping off various reamers to make an end result they desire (sort of... which is to say, when it works, it works ok, but when it doesn't...).

It's a bit of a guessing game, without a better idea who and how the job was done by, and a chamber cast to see what the whole story on dimensions is.

There is no rule that says there can be only ONE thing wrong... Sadly...
 
propliner said:
I took the necessary precautions and fired a single round of different ammo. Here is the result:

n9AC7A3.jpeg


This barrel is garbage.

FWIW, the case stretch from base to shoulder using a comparator is .050"
Click to expand...

Wow. That sucks. A lot. The barrel may not be garbage, though the chambering job may well be.

Depending upon your means and ambitions, as far as throwing more money at this, I would suggest that starting with a set-back of 1 or 2 threads pitch, and a ream with a good reamer, may clear up the chamber.

Don't send any more work to 'that guy'.
 
It's a Blaser R8 barrel so it has the lug locking ring as an integral part of the barrel. It can't be set back. Maybe it was that ring that was machined incorrectly.

TWMKFMd.jpeg
 
propliner said:
It's a Blaser R8 barrel so it has the lug locking ring as an integral part of the barrel. It can't be set back. Maybe it was that ring that was machined incorrectly.

TWMKFMd.jpeg
Click to expand...

You still can not rule out the brass as a problem.

Until you can have the actual headspace checked with a no go gauge and if it closes on a no go gauge, have the clearance with this gauge measured for an actual excessive head space measurement.

Was this an experienced smith who fit and chambered it? Have you contacted him?
 
trevj said:
Have heard too many issues being had with badly made reamers to discount that. PTG seems to get mentioned a lot...

Have heard of, but not seen first hand, guys using different reamers for the body and the belt. Or guys lopping off various reamers to make an end result they desire (sort of... which is to say, when it works, it works ok, but when it doesn't...).

It's a bit of a guessing game, without a better idea who and how the job was done by, and a chamber cast to see what the whole story on dimensions is.

There is no rule that says there can be only ONE thing wrong... Sadly...
Click to expand...

If you read a previous post, I wrote the same thing that it may be an improperly ground reamer. I've had that happen and it wasn't PTG.
 
A test you can do while waiting... Pull a bullet, dump the powder and fire one case with the primer only... the primer will back up the amount of clearance there is...
A magnum case is supposed to measure exactly .220 from rear of the case to the front of the belt. A go gauge measure exactly that... but they do not manufacture brass accurately enough... the vast amjority are less than .218" with some as low as .215"... so most case have an excessive clearance built into them...

so how much does the primer back up with a primed only case?
 
Tokay444 said:
Just plop a comparator on the shoulder of a fired and unfired case. You'll be able to tell quite quickly what's going on. Continuing to shoot it before doing that sounds like Darwinism.
Click to expand...

Doing this would work wonderfully for a rimless case that headspaces on the shoulder. It won't work for a rimmed case, or a belted case, as they use a different surface to hold the case head tight to the breech face.
This is the same reason why fireforming a belted or rimmed case to a blown out wildcat is so much simpler than with a rimless case. Moving the shoulder forward is entirely possible and totally safe. To do that with a rimless case you need to neck up, then back down to create a partial shoulder to headspace on.
 
It looks to me like a headspace problem with factory ammo. If you are reloading you might try jamming the bullets hard into the rifleing to fireform to your chamber . I think some Weatherby chambers have a lot of free bore so that may be a problem with that scenario. Another plan might be to try forming brass from a larger case like 300 Weatherby and fireformming when they are still tight. You are likely not keen about the commotion in getting it back to your US smith-barrel maker, but that is what should be done.
 
Jonnyofalltrades said:
Doing this would work wonderfully for a rimless case that headspaces on the shoulder. It won't work for a rimmed case, or a belted case, as they use a different surface to hold the case head tight to the breech face.
This is the same reason why fireforming a belted or rimmed case to a blown out wildcat is so much simpler than with a rimless case. Moving the shoulder forward is entirely possible and totally safe. To do that with a rimless case you need to neck up, then back down to create a partial shoulder to headspace on.
Click to expand...

Except, belt stretch isn’t where incipient case head separation happens. His brass is growing .050” at the shoulder. That’s way too much, and my prescribed method proved it. /
 
Tokay444 said:
Except, belt stretch isn’t where incipient case head separation happens. His brass is growing .050” at the shoulder. That’s way too much, and my prescribed method proved it. /
Click to expand...

If the problem is excess headspace, the firing pin will jam the round forward against the front edge of the belt rim. The case body then expands and grips the chamber walls. Then pressure stretches the case body back until it meets the bolt face. This is what can cause the head-body separation.
 
Tokay444 said:
Except, belt stretch isn’t where incipient case head separation happens. His brass is growing .050” at the shoulder. That’s way too much, and my prescribed method proved it. /
Click to expand...

Except for the fact that it could be blowing the shoulder forward .100", and although that wouldn't be a good thing, if the headspace is correct on the belt, there will be no case head separation.
Shoulder location on a belted case is a very loosely toleranced dimension.
 
Last edited:
Jonnyofalltrades said:
Except for the fact that it could be blowing the shoulder forward .100", and although that wouldn't be a good thing, if the headspace is correct on the belt, there will be no case head separation.
Shoulder location on a belted case is a very loosely toleranced dimension.
Click to expand...

No, if it moves enough separation will happen. - dan
 
Jonnyofalltrades said:
Except for the fact that it could be blowing the shoulder forward .100", and although that wouldn't be a good thing, if the headspace is correct on the belt, there will be no case head separation.
Shoulder location on a belted case is a very loosely toleranced dimension.
Click to expand...

Lol. Not .050” loose, but please, keep going. SAAMI is +.01”/-.00”…
 
You must log in or register to reply here.
Back
Top Bottom