UPDATE - New Alpha Dasher brass grew a lot - problem?

[Jackanapes]

UPDATE 3/14/24 - I just spoke with someone at Proof Research. Apparently their chambers are intentionally cut with a radius at the shoulder/neck area, so it's not concerning that the shape of the 1x brass looks the way it does. Also not concerning that I was able to close the bolt on the no-go gauge (just arrived yesterday). He suggested that I try the scotch tape trick and it probably wouldn't close...which I did, and he was right. Thanks everybody for your input on this.

Just ran 50 rounds through a new rifle and found that the brass grew to the tune of 0.020, which seems like way too much and the shape of the shoulder/neck junction doesn't look right to me.

Virgin Alpha brass
Impact 737
Proof prefit barrel
N140 29.6-32.4 grains (2620-2850 fps)
CCI 450
A couple of heavy bolt lifts and light ejector marks, but no other pressure signs
Ran the brass straight out of the box - no sizing, no neck turning.

What sort of problem could this be - pressure, headspace, other?

Thanks.

 

[Cfshooter]

What bullet? Who cut chamber? Have you looked in barrel to see how much room is left for brass to grow in chamber (OAL).

 

[Jackanapes]

What bullet? Who cut chamber? Have you looked in barrel to see how much room is left for brass to grow in chamber (OAL).

Berger 109, seated at jam minus .030. I assume Proof themselves...bought from Altus. No, what do you suggest that I look for?

 

[AlNyhus]

It looks like the shoulder may have been blown forward. How was the barrel headspaced when installed? What does the case head to datum measure on new versus fired brass?

 

[LVLAaron]

Get a set of gauges before you go any further.

 

[Jackanapes]

It looks like the shoulder may have been blown forward. How was the barrel headspaced when installed? What does the case head to datum measure on new versus fired brass?

I torqued it on to 90 ft-lbs and that was it. Didn't verify with go/no-go because I assumed that everything was so uniform with Impact. Perhaps a mistake. I use the LE Wilson case gauge as opposed to measuring head to datum, and that shows about .020 longer with the once-fired brass.

 

[Pres100]

Yeah, The neck lengths don't look the same and no definition at the neck shoulder junction. The shoulder to body junction looks good.
Do you have a bore scope that you could look at the chamber? Iwould also like to better understand what the headspace is and the before and after fired dimensions.

 

[Jackanapes]

Get a set of gauges before you go any further.

I have some on the way from PTG.

 

[Pres100]

Aaron's correct ... definitely start with some gauges.

 

[Sheldon N]

No harm in getting a set of go/no-go gauges if you want to verify the chamber headspace is within spec. However, I would argue it's far more beneficial to have a set of headspace comparators like Hornady or similar. You want to measure the base to shoulder datum of virgin brass and then of fired brass to see what the difference is, that will give you a rough idea of how much headspace there is when you're fireforming the brass.

It also appears that you may be measuring the brass incorrectly with your case gauge. You say that the brass has "grown" 0.020" but I think what you mean is that the brass now sticks out of the case gauge by 0.020". If you measure the brass OAL itself (deprimed) I would guess that it has NOT grown by 0.020, since brass length doesn't usually increase until you size the brass and squeeze it forward. Additionally, 0.020 of brass growth is a lot, it would take many firing sizing cycles to achieve that. I think what's happened is the shoulder angle or neck shoulder junction has changed slightly and now it fits in the case gauge differently.

 

[Eagle Six]

In addition to checking the headspace with gauges, I sure would be questioning that chamber especially in the neck to should junction as you are already suspicious.

 

[LVLAaron]

If you’re getting barrels regardless if they’re prefit, shouldered, nutted, or from a gunsmith… you should own gauges and check yourself.

Same principle as “the gun is loaded until you check it yourself”.

 

[Coyotefurharvester]

I doubt even once fired brass will drop into the Wilson case gage, unsized. How much headspace with the new brass?

 

[AM_ARixon]

Looks like a larger than normal radius at the shouler neck junction than standard, should be around .075. with the blown out radius it could be contacting the wilson die and not providing a true measurement of the shoulder growth. I'd recommend the area 419 gauge or standard hornady to measure the growth of the shoulder on a .350 diameter datum. If this is still looking suspicious please reach out to us at 844.412.5742x704

 

[RSchatz]

Shoulder angle looks incorrect
Looks like a BRX case to me.
Possibly a mislabeled prefit????

 

[LVLAaron]

Shoulder angle looks incorrect
Looks like a BRX case to me.
Possibly a mislabeled prefit????

I looked at that picture for a few minutes yesterday... I'm tending to lean towards something is wrong... more so than headspace. The concave shoulder on the fire case is suspicious.

 

[mikecockcroft]

Weatherby Dasher

 

[LVLAaron]

UPDATE 3/14/24 - I just spoke with someone at Proof Research. Apparently their chambers are intentionally cut with a radius at the shoulder/neck area, so it's not concerning that the shape of the 1x brass looks the way it does. Also not concerning that I was able to close the bolt on the no-go gauge (just arrived yesterday). He suggested that I try the scotch tape trick and it probably wouldn't close...which I did, and he was right. Thanks everybody for your input on this.

WHAT?

 

[Eagle Six]

WHAT?

I'll double that, WHAT? WHAT?

 

[Jackanapes]

I'll double that, WHAT? WHAT?

He said that their chambers are slightly rounded (i.e., not as angular as the shape of virgin brass) at the neck/shoulder area, so it's no surprise that the brass would take on that shape. That made sense to me, but it seems that you and Aaron aren't buying it.