6MM Arc AR15 Platform FTE/Stuck-Case

[d0nkey]

Images and video of issue: Imgur

Details:
Faxon Match Barrel 20"
Centurion 6.5G/6Arc Bolt
AR-15 Platform

Load:
Nosler RDG 105
25.4 8208 XBR (leftovers)
Mix of 2.245 and 2.25 COAL

Issue:
more often than not, I get a FTE/Stuck Case, I then have to use a cleaning rod to push the cartridge out by entering the muzzle. Pushing it out takes 0 force so I think it could be boltface/extractor issue.

Any thoughts? Thanks

 

[CStroud]

Is the barrel/chamber clean?

 

[d0nkey]

It’s a brand new build, barrel was wiped down with cleaner prior to first shots taken

 

[vmpglenn]

Does your extractor have both a donut and an insert? That combination in 6.5 Grendel can cause extractor failure to engage the case rim.

 

[TonyAngel]

Images and video of issue: Imgur

Details:
Faxon Match Barrel 20"
Centurion 6.5G/6Arc Bolt
AR-15 Platform

Load:
Nosler RDG 105
25.4 8208 XBR (leftovers)
Mix of 2.245 and 2.25 COAL

Issue:
more often than not, I get a FTE/Stuck Case, I then have to use a cleaning rod to push the cartridge out by entering the muzzle. Pushing it out takes 0 force so I think it could be boltface/extractor issue.

Any thoughts? Thanks

I have very limited experience with any sort of ARC round, so I'm speaking generally.

Assuming that all is good with the chamber, not meaning that it's clean, but that the chamber is cut properly, a stuck case can be caused by either an over pressure round or insufficient closed bolt lock time.

Either will usually require knocking the casing out with a cleaning rod or, at least, having to mortar the rifle to unstick the case.

If you are able to push the case out with zero effort, I'm thinking that you're having more of a failure to extract than a stuck case.

When this happens, have you tried dropping the bolt on the case that's in the chamber and then re-racking the bolt to get the case out? If so, what happened? Is it stuck, such that you can't rack the bolt or does the bolt just come back without grabbing the casing? Once you get the casing out, is the rim torn from where the extractor tried to pull the casing out?

If you can pull the charging handle back on the casing in the chamber and it fails to extract and there is little to no damage to the casing from the extractor, I'd say replace the extractor, spring and insert.

If there is damage to the casing, from the extractor trying to pull it out, to the extent that the extractor can no longer grab onto it, you either have a pressure problem or a gas problem. If there are no over pressure signs on the fired casings, try a heavier buffer to increase the closed bolt lock time.

 

[d0nkey]

Does your extractor have both a donut and an insert? That combination in 6.5 Grendel can cause extractor failure to engage the case rim.

No donut, just an insert and spring. I’m headed to bass pro to get a box of 6arc factory ammo. I’m using nosler brass and found out the case rim on nosler leaves a lot to be desired and sometimes claws can’t grasp it.

 

[d0nkey]

I have very limited experience with any sort of ARC round, so I'm speaking generally.

Assuming that all is good with the chamber, not meaning that it's clean, but that the chamber is cut properly, a stuck case can be caused by either an over pressure round or insufficient closed bolt lock time.

Either will usually require knocking the casing out with a cleaning rod or, at least, having to mortar the rifle to unstick the case.

If you are able to push the case out with zero effort, I'm thinking that you're having more of a failure to extract than a stuck case.

When this happens, have you tried dropping the bolt on the case that's in the chamber and then re-racking the bolt to get the case out? If so, what happened? Is it stuck, such that you can't rack the bolt or does the bolt just come back without grabbing the casing? Once you get the casing out, is the rim torn from where the extractor tried to pull the casing out?

If you can pull the charging handle back on the casing in the chamber and it fails to extract and there is little to no damage to the casing from the extractor, I'd say replace the extractor, spring and insert.

If there is damage to the casing, from the extractor trying to pull it out, to the extent that the extractor can no longer grab onto it, you either have a pressure problem or a gas problem. If there are no over pressure signs on the fired casings, try a heavier buffer to increase the closed bolt lock time.

I tried pulling the charging handle and i am able to, but case remains in chamber, i dont think the extractor is engaging the case rim. I’ll be buying factory ammo Hornady, supposedly case rim on Hornady is a bit more beefier versus the nosler brass I’m using. Thanks for your input, I’ll report back

 

[d0nkey]

Turned out to be the nosler brass. I bought Hornady factory loads and starline brass at bass pro today. Loaded starline with same charge and projectile as i did the nosler. No issues. Really really strange though. So i got my buddy’s 6arc ar15 and he had the same issue with the nosler brass. Thanks everyone for the input. Gonna contact the supplier to see if I can get a refund.

 

[WeR0206]

Turned out to be the nosler brass. I bought Hornady factory loads and starline brass at bass pro today. Loaded starline with same charge and projectile as i did the nosler. No issues. Really really strange though. So i got my buddy’s 6arc ar15 and he had the same issue with the nosler brass. Thanks everyone for the input. Gonna contact the supplier to see if I can get a refund.

I had a similar issue with 6 ARC Alpha brass in my AR build. If not using factory loads I'd always check the new (unsized) brass in your chamber first to see if it sticks (the shoulder might need bumped back a few thou). In my case the headspace of the new brass was slightly bigger than the headspace in my chamber (using a headspaced bolt it closed very tight on a Go gauge and it didn’t close on new alpha brass). To fix the issue I ran the new brass through my FL sizing die to bump the shoulders back about 3 thou.

In comparison the headspace on new hornady brass was about a few thou shorter than the alpha brass so I didn't have to bump it at all, I can chamfer/deburr, just load it up, and use it.

In summary, always the check the headspace in your chamber with go/field gauges and always check new brass to see if it needs its shoulder bumped before heading to the range. I've had to pull bullets from cases and redo/mortar rounds out b/c of failing to do this check.

Below are my shoulder bump gauge measurements if that helps to explain:

• 1.1901 go gauge: 1.1735” (stripped bolt closes very tight)
• New brass:
  • Alpha: 1.174” (stripped bolt won’t close)
  • Hornady: 1.1725” (bolt closes tight)
• 1.2001 field gauge: 1.183” (stripped bolt won’t close)
• Brass at 1.1725” seems to feel as tight on bolt close as the 1.1735” steel go gauge
• To open/close bolt easily: 1.171” (max of 1.172”)

 

[d0nkey]

Thanks, I decided not to stop using them and will bump back around 3 thou. I'm hoping by doing so, it willl make a difference. Luckily I haven't had to mortar at this point. I'll post results soon

 

[LRRPF52]

Do you have a Hornady headspace comparator set?

If so, what is the datum to the Nosler brass shoulders?

 

[d0nkey]

yes, i have comparator kit, i'll be home soon and provide the data for hornady and nosler fired brass and out of the box brass for starline and nosler

 

[d0nkey]

Fired hornady - 1.1900

Fired nosler - 1.1855

Unfired empty nosler - 1.1770

Unfired empty starline - 1.1790


I think it's me. i'm new to long range and single press loading. i've reloaded 50k+ rounds of straight wall and tapered on progressive so this is a new chapter of reloading for me. tbh i didn't even think of resizing new rifle brass out the box, appears may have been my fault. going to try 1.172 and report back. i'm probably the donkey in this matter and the nosler brass is probably fine. will let you guys know, thanks everyone for the great feedback.

that being said, after the rounds has been fired and the shoulder length between the hornady and nosler seem to be fairly close (after firing), i wonder why the hornady had 0 issues extracting and the nosler failed to extract 50% of the time.