Doublestar barrel/bolt issues

[chrisfly1]

I just built a 6.5g carbine using a Doublestar chrome lined barrel with carbine length FSP. I am also running a Doublestar star bolt. I am having 1pm ejection, numerous double feeds and FTEs per magazine. I am currently using C-products 28rd magazines and 10 rd magazines. Same issue with both mags. Currently running an H1 buffer with standard spring. Would it be beneficial to try an H3 to fight the over gassing or could it be a magazine issue? I am new to the 6.5 Grendel.

[GregP42]

That sounds more like mag issues to me. But without knowing the barrel length and stock configuration I can't say about the buffer. Have you tried just a normal buffer in it?

[chrisfly1]

Sorry, it's a 16" carbine length gas system. Standard m4 stock. Standard weight buffer spring. Is there a better brand of magazines?

[rabiddawg]

Sounds under gassed to me. One of my 16? started to eject at 1 o?clock and would occasionally not feed the next round causing a bolt over base situation.

I changed the gas block to an adjustable type and cured the problem. The original block was leaking.

After the last round is fired, does the bolt lock back on the catch or the lip of the mag? If the mag doesn?t drop when you press the release could be a sign it?s not traveling far enough to the rear

[Shooterrex]

If you put 1round in the magazine and load and shoot the rifle does the bolt lock open? If it does you might not be under gassed. A heavier buffer might help but not if it's under gassed.

[VASCAR2]

I suggest you load 1 round in the mag, chamber then fire the round. If it cycles and locks the bolt back try two rounds. Make sure the BCG is well lubed. If you experience cycling issues try factory ammo like Hornady 123 grain ELD-M, SST or 123 BTHP. If the rifle will not function with four or five rounds in the magazine sounds like there might be an issue. Inspect the brass and look at the brass and see if the extractor is leaving marks on the case rim. Is the rifle failing to eject or only failing to feed the top round in the mag?

I have the same basic upper but with the heavy profile CMV barrel. Mine functions with a supplied carbine buffer and spring. The symptoms of over gassed and under gassed can be the same. More information and pictures will help if you continue to have problems.

[LRRPF52]

Tune your extractor lip corners.

Try a heavier buffer starting with an H2.

What ammo are you using?

[chrisfly1]

It does lock back with one round. I was shooting both Wolf and Hornady Black. It happened with both brands. I just wondered if the bolt is outrunning the magazine. The barrel extension and upper both have rifle feedramps. Not M4.

[chrisfly1]

This one is also the heavy profile. CMV chrome lined.

[chrisfly1]

I pulled the bolt apart and found it had no O-ring under the extractor. Added that. Also, the bolt has faint marking that say "RGS" or "BGS". Does that make any sense?

[chrisfly1]

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[worthen86ford]

Sounds overgassed to me. I use an H2 on my grendels. Both are AA 16? lite mlgs. With a 16? clgs and bolt hold open working, i?d start with an H3 and you could play around with weights from your other buffer to make it lighter (H2) if needed.

[rabiddawg]

It does lock back with one round. I was shooting both Wolf and Hornady Black. It happened with both brands. I just wondered if the bolt is outrunning the magazine. The barrel extension and upper both have rifle feedramps. Not M4.

But did the mag drop free when pressing the release? If not, it locked back on the mags lip and didn’t go far enough back to catch the bolt catch.

[LRRPF52]

I pulled the bolt apart and found it had no O-ring under the extractor. Added that. Also, the bolt has faint marking that say "RGS" or "BGS". Does that make any sense?

O rings are the first thing I remove from my extractors.

They were a band-aid for the M4A1 shooting suppressed and high volume, where port pressure and back pressure was causing early extraction and resulting FTExtract malfs.

Instead of addressing the underlying issues, the added power extractor O ring increased extractor tension, which also fights chambering with extractor snap-over.

I prefer a balanced operating system vs trying to treat symptoms, so a well-behaved cyclic rate with a relaxed extractor is where the AR15 likes to be.

Without knowing what the gas port size is, it's hard to diagnose.

Your symptoms are common for a large gas port though, especially if it's doing it with Wolf and still locks back on a single round.

If you know the difference between a bolt over base and a double-feed, that would help.

If the carrier is getting a full stroke, I'm leaning on excess gas.

You can do several things to fight that amount of gas.

Step up the buffer weight and use it as a rate reducer.

Step up the action spring weight.

Use adjustable gas.

[DeanD]

Similar problems here with a J&T Distributing (Doublestar) 16" chrome lined barrel, ejecting at 1:00, only ejecting short distance, stovepipe on empty. Pulled the FSB off this morning and the gas port is .0935! I believe it should be .0625. Probably going to plug the hole and drill it .062.

[Lastrites]

Similar problems here with a J&T Distributing (Doublestar) 16" chrome lined barrel, ejecting at 1:00, only ejecting short distance, stovepipe on empty. Pulled the FSB off this morning and the gas port is .0935! I believe it should be .0625. Probably going to plug the hole and drill it .062.

I wouldn't go through that hassle, there is a company that makes a plugs that are drilled to the appropriate size.
Found it. https://blackrivertactical.ecwid.com/BRT...-p76704128

[Shooterrex]

Just use an adjustable gas block.

[DeanD]

Drilling & tapping a hole, screwing in a plug and drilling a 1/16" hole isn't a hassle for me. Old tool & die maker here. Piece of cake and free.

As far as using an adjustable gas block: I prefer to keep my A2 front sight, I don't want to spend money when I can avoid it, but mainly I would rather get the gas system regulated correctly and fixed permanently. I don't see adjustable gas blocks on military M4's and other weapons. They are made right for the ammo they use in the first place. I see an adjustable gas block (for other than using a suppressor, etc.) as a "work around" solution instead of getting to the root cause.