8.6 Blackout RemAge Barrel on .308 R700 – Brass Coming Out Fire-Formed? Need Help Understanding

[zekecurvin]

Hey everyone, this is my first gun build, so sorry in advance if I’m missing something obvious. I recently picked up a RemAge barrel in 8.6 Blackout to put on my .308 Remington 700. I used a GO gauge and then a GO gauge with one piece of Scotch tape to double-check headspace. Everything seemed completely normal during setup.

But when I shoot the rifle, the brass comes out looking like it’s being fire-formed into a totally different round. The shoulder is blown forward by at least .1 inches, which definitely doesn’t look right to me. Also the primer gets pushed out slightly on each fired case.

I’m going to attach a picture of the GO gauge, an unfired round, a fired round from my setup, and another fired round from a different 8.6 Blackout for comparison.These are lined up from right to left in picture

If anyone can help me understand what’s going on—or point out what I messed up—I’d really appreciate it. Again, sorry if this is something simple.
Thanks.

 

[paperpuncher]

Headspace looks wrong. Did you strip the bolt when you set it up? Take some diameter measurements on the headspace gauge make sure its not oversized at shoulder body junction. Make sure the headspace gauge fits into the bolt nose properly and seats against the boltface. Recheck headspace

 

[Jsaum]

If its not clicking over the extractor when you set the headspace that is likely causing the extra long headspace. I find this particularly true with savages. You have to pop the bolt down a little to get the headspace gage to click over the extractor and seat to the boltface properly

 

[J_Hensley]

Yeah, your headspace is not correct.

Maybe remove the extractor from your bolt face and then redo the headspace.

 

[tobnpr]

Check headspace the right way.
Strip the bolt.
No fp assembly. No extractor. No ejector.
Removes any resistance that would cloud the "feel" which is required to accurately set headspace.

You can't let a bolt handle fall under just it's own weight- which is the correct way to do this- when you've got tension from the firing pin spring and ejector fighting you.

 

[zekecurvin]

Thank you I will strip the bolt tn and try again thanks!

 

[dellet]

Unless you also loaded long enough for the bullet to jam the lands, it’s not likely that a cartridge would have fired with that much headspace.

It’s possible that the gauge and brass is contacting the chamber somewhere else than the shoulder, or the barrel is stopping before contacting the gauge.

For the bolt to close on the gauge, and not close with a piece of tape on the case head, sounds more like a diameter problem somewhere other than the shoulder. You might want to compare fires case diameters to SAAMI chamber diameters. Pat attention to body diameter at the neck/shoulder junction and the base up to the 200 line and another .100”. A case that long base to shoulder should not have been completely chambered and I would expect the base to be bulged for lack of support.

Start with correctly checking the headspace if you haven’t already, but cartridges routinely fail to fire with only +.010” case head clearance.

 

[zekecurvin]

Unless you also loaded long enough for the bullet to jam the lands, it’s not likely that a cartridge would have fired with that much headspace.

It’s possible that the gauge and brass is contacting the chamber somewhere else than the shoulder, or the barrel is stopping before contacting the gauge.

For the bolt to close on the gauge, and not close with a piece of tape on the case head, sounds more like a diameter problem somewhere other than the shoulder. You might want to compare fires case diameters to SAAMI chamber diameters. Pat attention to body diameter at the neck/shoulder junction and the base up to the 200 line and another .100”. A case that long base to shoulder should not have been completely chambered and I would expect the base to be bulged for lack of support.

Start with correctly checking the headspace if you haven’t already, but cartridges routinely fail to fire with only +.010” case head clearance.

I did see that the fired cases do seem to have a recessed part before the shoulder if you zoom in on the picture you can see it. I don't know if this could be something that it was catching on or just wear it was fire formed but I didn't think that would be the problem because I believe that would mean the manufacturer of the barrel had messed something up and it is a faxon barrel which is mass produced I believe.

 

[linebaugh]

Nor 100% sure but it almost looks like the cases you made have an exaduraded neck length to me. I would consult a print but I think the neck length is .3something. Will look in a minute. I dont know how you formed the cases but if its possible to over form and set the shoulder back farther than needed this could be the issue. Compare measurements off a print vs what you have... and dont shoot any more until you fivure out where the problem lies.

 

[linebaugh]

Looks like neck length should be .318. Hard to tell from a picture but your loaded round "looks" l8ke the neck is longer than that.

 

[zekecurvin]

These are Callaway ballistics 300gn smk subs I have some dies otw for 8.6

 

[dellet]

I did see that the fired cases do seem to have a recessed part before the shoulder if you zoom in on the picture you can see it. I don't know if this could be something that it was catching on or just wear it was fire formed but I didn't think that would be the problem because I believe that would mean the manufacturer of the barrel had messed something up and it is a faxon barrel which is mass produced I believe.

If could not close the bolt on a go gauge with a piece of tape on it, and a fired case measures .100” longer at the shoulder, you either have a gauge problem or a barrel problem.

Based on the photo, I think it’s the barrel.

If the shiny mark on the brass is where the diameter is smaller, compare that with the end of the body on the gauge. Then take a sharpie and color the gauge and insert that into the chamber with finger pressure. If there is a rubber spot there instead of on the shoulder, it would confirm a diameter problem.

The big red flag is not being able to close the bolt by adding .002” to the length of the case base to shoulder datum length. Yet the fired case is .100” longer base to datum.

If the brass was not sized correctly, it’s hard to imagine a die off by .100”, but anything is possible.

This is likely more than not stripping the bolt.

 

[tobnpr]

This is likely more than not stripping the bolt.

Concur. I failed to consider that the cartridge fired- which as pointed out shouldn't have happened if the chamber were reamed far too deep, but I suppose it might be "possible" with enough force and slight sticking to the chamber wall that the FP could detonate the primer without the shoulder bottoming out in the chamber as normally would happen.

I shoulder all my barrels but far as I know Remage prefits are flat-breeched without the counterbore.
OP should unscrew the barrel and drop the go gauge into the chamber. Should be something around .125 protrusion from the breech. That should clarify whether the barrel is the problem or if there was something else going on. Definitely an odd one...esp that the case could "grow" by over 100 thou without a casehead separation. OP is a lucky man...

 

[LVLAaron]

OP should unscrew the barrel and drop the go gauge into the chamber. Should be something around .125 protrusion from the breech.

^^^^

 

[dfrosch]

Did the headspace gauge extract and eject when you were setting the headspace?

 

[zekecurvin]

Thanks

Did the headspace gauge extract and eject when you were setting the headspace?

yes, but every three or so times chambered it would fail to extract

 

[zekecurvin]

Concur. I failed to consider that the cartridge fired- which as pointed out shouldn't have happened if the chamber were reamed far too deep, but I suppose it might be "possible" with enough force and slight sticking to the chamber wall that the FP could detonate the primer without the shoulder bottoming out in the chamber as normally would happen.

I shoulder all my barrels but far as I know Remage prefits are flat-breeched without the counterbore.
OP should unscrew the barrel and drop the go gauge into the chamber. Should be something around .125 protrusion from the breech. That should clarify whether the barrel is the problem or if there was something else going on. Definitely an odd one...esp that the case could "grow" by over 100 thou without a casehead separation. OP is a lucky man...

Here is 2 pictures with the go gauge in the barrel

 

[dellet]

Here is 2 pictures with the go gauge in the barrel

Measure that protrusion
Insert the fired case and measure. Then compare.

 

[zekecurvin]

Here is 2 pictures with the go gauge in the barrel

Measure that protrusion
Insert the fired case and measure. Then compare.

The protrusion is 25 thou and the fired case is flush

 

[zekecurvin]

The case expanded .08 in length
Where the case expanded the diameter is .4480
And where the case was not expanded is
.4620