Mike S is who I dealt with.
Below are excerpts from my correspondence with them in reverse order.
As you can see I stressed they had a heat treat problem with the Tin coated extensions.
I did receive the replacement, but only have 40 rounds on it.
Mike,
Following up on this. Called last week on the 13th & spoke to someone. He said he’d been trying to head space a new barrel to the old bolt
. Told him to give up as that bolt was just sent so you would have the full picture. He said A new barrel would ship Tuesday the 14th? Haven’t received any email or tracking. Has this shipped?
Thanks
Mike,
Thank you for the reply.
I would prefer you just replace the barrel. If the replacement barrel extension can easily be verified for heat treat by your shop that would be fantastic.
The barrel was shipped today using your label. You should receive it Tuesday 3/7. Tracking #
I did include the Maxim bolt that was run with the barrel. If possible I'd like the bolt returned with the new barrel. Ejector + spring & extractor were tuned and I'd like to recycle them for spares.
Not sure if your shop has the ability to perform a Rockwell test on the extension, but I would suggest doing so. It's a very high probability this was the result of improper heat treat by your extension or heat treat vendor.
Build specs below for ref.
VLTOR Fusion F-15 monolithic upper, receiver face trued, extension thermal fitted with 1 full wrap of SS .001 shim stock
Odin works adj gas block & + 2" gas tube.
Rubber City light weight bolt carrier, FP, Cam pin
Maxim type 2 6.5 Grendel bolt
JP silent capture buffer system std weight + standard spring
Magpul PRS gen 3 stock + spacer for silent capture.
JL billet ambi lower
Trigger Tech single stage & ambi selector
Gas block was running pretty close to the center of adjustment range.
The ejection pattern was 4:00
BCG over travel was checked and good.
Attn: Mike
Total round count on barrel is 446. FWIW the receiver face was trued and the barrel was installed with 1 full wrap of .001 shim stock. Lug contact was even & I always run lube on carrier and lugs. When new head space with new Maxim bolt was Go plus at most .001. Now it's go plus .0013
Per our conversation please see attached pictures of the barrel extension. The pictures are in the following counter clockwise order looking from the back.
3, 1:30 (extractor lug), 12, 10:30, 9, 7:30 (might have to stare at this one for a minute), 6, 4:30.
1 picture of 12 oclock lug on Bartlein with 100 rounds on it for reference.
Pictures of the bolt lugs & top.
Back of extension showing metal displaced back on bottom 3 lugs
I think the extension was either improperly heat treated or Tin coated without heat treat. Hopefully you didn't get a big batch of the same. I have a lot of AR's and have never seen this happen before.It was gaining almost .003 HS per 100 rounds. I do not trust this to continue running it. I spoke with one gentleman who's broken 3 bolts each @ about 1000 rounds. Each time a new bolt head spaced to the barrel i.e. no extension wear. He was also running Varget which IMO is too fast a powder for ARC so I'm not that surprised.
1 pic of shoulder area in chamber. Not relevant to this issue nor accuracy but still it's disappointing & hopefully not the norm.
Pictures of the go gauge used when this was assembled, might have been go +.001 at most. And a pic of where it is head spaced now No Go + .004 via 2 pieces of scotch tape.
Pictures of 1 x fired Hornady 108 in Bartlein barrel compared to 1 x fired Lapua in Rainier barrel in Headspace comparator. Both are deprimed.
Let me know your thoughts?
Thanks
On Mon, Jan 31, 2022 at 2:46 PM Rainier Arms <
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Rainier Arms
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Items Qty Subtotal
Rainier Arms UltraMatch MOD2 6mm ARC Rifle Barrel - 22"
SKU: RAB-UM2-6ARC-22-R2-FF-SAT
Color
Satin
1 $400.00
UN12 Magazine - Issue 7 (NO PATCH)
SKU: UN12-7-PROMO
1 $0.00
Subtotal $400.00
Shipping & Handling $16.31
Tax $24.00
Grand Total $440.31
Thank you
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