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+--- Thread: Keep breaking extractors on PLGS BCA 10.5" (/showthread.php?tid=21024)
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Keep breaking extractors on PLGS BCA 10.5" - rabiddawg - 04-18-2020
rabiddawg Wrote:3 2 1 goI was betting the bca lovers would be here defending them.
Keep breaking extractors on PLGS BCA 10.5" - Oldbev - 04-19-2020
First of all not trying to be rude here but generally you get what you pay for. And my time is better spent doing constructive things then chasing poor quality parts trying to make chicken soup from chicken sh:t.You don't have to go to top money vendors to build a decent 6.5 grendal but I would think with that kind of horsepower in your face you'd want to build with parts a little better the bca. And free advise is worth what you pay
Keep breaking extractors on PLGS BCA 10.5" - worthen86ford - 04-19-2020
Lemonaid Wrote:Those shorty Grendels to me look way cool. I'd like one someday but they have their shortcomings so to speak. From what I've read the shorter gas length system is the harder it is on parts. If the bolt is trying to extract before the gas pressure has gone down enough that the brass contracts then it will be very hard on the extractor. An adjustable gas block may be a must have.My money is on this.
With plgs i would think the round is being extracted before pressure drops enough for the case to contract in chamber. Need to figure out how to keep the chamber closed as long as possible. Might not be solvable by typical means but Id start with the heaviest buffer and strongest buffer spring i could get. You already have a way to regulate gas.
Keep breaking extractors on PLGS BCA 10.5" - slappyhooper - 04-20-2020
I wasn't running an O ring until the last extractor. I ran one that time just to see if it made any difference.
Chamber doesn't seem rough, although I suppose I could get out the drill and some fine steel wool.
Keep breaking extractors on PLGS BCA 10.5" - slappyhooper - 04-21-2020
That is my assumption as well. I'm telling you guys though, .046" restricted gas port right now.
If you compare area of a circle, my gas is choked off to about 16% of what it was.
I'm telling you guys it BARELY locks back on an empty mag, and it shoots very softly now.
Keep breaking extractors on PLGS BCA 10.5" - worthen86ford - 04-21-2020
Even with it choked, Gas is still acting on the bolt sooner than a longer gas system.
Maybe get one of those pigtail gas tubes? Make one out of a rlgs tube? Just tinkering right?
https://www.deltateamtactical.com/Omega-Manufacturing-AR-15-Pistol-Length-Spiral-Pigtail-Gas-Tube-USA-MADE_p_4420.html
I always thought these were a gimmick but maybe a solution.
Keep breaking extractors on PLGS BCA 10.5" - slappyhooper - 04-21-2020
Heavy profile barrel. Doubt it fits.
Keep breaking extractors on PLGS BCA 10.5" - Klem - 04-21-2020
What about dwell time. How much barrel length is in front of the gas port? You need to keep the pressure up for the system to work and that means having enough barrel in front of the port to maintain pressure until the bullet exits and the pressure drops. It's a balancing act.
Keep breaking extractors on PLGS BCA 10.5" - slappyhooper - 04-21-2020
I think it would be fine.
There's 6.5" of barrel ahead of the port currently.
Keep breaking extractors on PLGS BCA 10.5" - Old Bob - 04-22-2020
worthen86ford Wrote:Even with it choked, Gas is still acting on the bolt sooner than a longer gas system.
Maybe get one of those pigtail gas tubes? Make one out of a rlgs tube? Just tinkering right?
https://www.deltateamtactical.com/Omega-Manufacturing-AR-15-Pistol-Length-Spiral-Pigtail-Gas-Tube-USA-MADE_p_4420.html
I always thought these were a gimmick but maybe a solution.
A few years ago at one of our club 3 gun matches a feller showed up to give a demonstration of his pig-tail gas tube installed on a SBR. I think some of our club members bought some but I didn't 'cause I was shooting a 20" barreled AR & had no intention to shoot anything with a shorter barrel at that time. I did get his business card but lost it a long time ago. Guys from our group who shot his SBR said it did seem to smooth out its operation. He also had pig-tail tubes that mimic rifle length systems in carbine ARs. I don't recall if he had a tube for mid-length systems.
Keep breaking extractors on PLGS BCA 10.5" - LRRPF52 - 04-22-2020
The only thing I would use a Pistol-Length Gas System with 6.5 Grendel would be subsonic loads shooting 140-160gr bullets.
Supersonic loads are hitting a Pistol Gas port location with insane amounts of pressure, that has to go somewhere.
The torsional loads being placed on the extractor are beyond the design window of the AR15 if you have a ~30gr case volume at 45,000-50,000psi chamber pressure pushing long, high SD projectiles through a tight 6.5mm bore.
When the case is obturated, not only are the case walls firmly attached to the chamber walls, but the case head is firmly seated against the bolt face, and extractor shelf with pressure.
As the gas flows into the Stoner expansion chamber inside the carrier/bolt combination and forces the carrier rearward before the case is able to rebound off the chamber walls, the bolt starts rotating in this condition of everything pressured up against the bolt and extractor.
The extractor is being asked to do a job it was never meant to do, with torsional loads (rotational axis) being placed on it, in addition to excessive longitudinal loads as it tries to rip the obturated case from the chamber.
This is worse than a large-ported 18" MLGS because of the Pistol gas port location.
Keep breaking extractors on PLGS BCA 10.5" - slappyhooper - 04-24-2020
Replacement BCG just arrived. I'll probably wind up just returning the barrel.
The replacement BCG seems like it's pretty decent though, so I've got to try once more.......Worst case, I send it all back.