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+--- Thread: Most reliable BCG for Grendel pistol? (/showthread.php?tid=21640)
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Most reliable BCG for Grendel pistol? - Disciple - 07-14-2020
I am looking for the most reliable BCG for an AR-15 pistol with a 10.5" 6.5 Grendel barrel, carbine length gas system, and A2 sight gas block. The YFS bolts on the Alexander Arms carrier concern me as I have read that these can be a point of failure. I have also read here of broken extractors so I would like to mitigate that potential. The LMT Enhanced Bolt Carrier sounds like it would help, if I can find one. Is it a good idea?
I want a complete BCG so that I can keep the AA one as a spare. If I get the LMT carrier I'll need to buy a bolt separately. The SixFive Mk136 bolts are out of stock and the JP EnhancedBolt is three times the price. Is the JP actually better?
The LMT/JP combination is the limit of what I can spend but it if will be meaningfully more reliable I am willing.
What do you recommend?
Most reliable BCG for Grendel pistol? - A5BLASTER - 07-14-2020
The bcg you have now will work just fine.
No need to spend more money on parts that won't and can't do any better then what you already have.
If you don't have a adjustable gas block on this gun, then get some tungsten weights for your buffer and adjust the buffer weight till your ejecting at the 3 to 3:30 area and the bcg will lock back after the last round.
Lapp the upper reciver to give a good square bolt lock up for bolt and extractor life.
Most reliable BCG for Grendel pistol? - Disciple - 07-14-2020
The YFS bolts are not worth concern? Are problems from those an urban legend?
I still want a spare BCG. I don't believe I can get another complete BCG from AA. If I get another AA bolt what do you suggest I put it in?
Most reliable BCG for Grendel pistol? - A5BLASTER - 07-14-2020
If by AA you mean Alexander arms, I wouldn't worrie about the gas key bolts at all AA doesn't produce are sell bad products. As too reports of broken bolts on the gas key, I have never experienced that happening and don't know anyone who has. But honestly never went looking for reports of it either. Two of my bcg's are from AA.
As too what to put a spare bolt in, I keep one in my day pack with my truck gun, my house defense gun and my hunting day packs.
If a bolt goes down, just swap it into your bcg and get the rifle back up and going.
Most reliable BCG for Grendel pistol? - Disciple - 07-14-2020
Yes, I meant Alexander Arms. You will find reports of broken YFS gas key bolts if you do go looking, but I don't know how much to trust those. BCM and other make a point of domestically sourced grade 8 bolts. :confused:
Most reliable BCG for Grendel pistol? - Disciple - 07-14-2020
Just one example, YFS bolts being described as "junky fasteners" by someone who seems to know his business.
https://www.youtube.com/watch?v=CrJl3LThLFw
Most reliable BCG for Grendel pistol? - A5BLASTER - 07-15-2020
Disciple Wrote:Just one example, YFS bolts being described as "junky fasteners" by someone who seems to know his business.
https://www.youtube.com/watch?v=CrJl3LThLFw
Don't know. Never had a problem with any of the AA bcg's I have.
To be honest I'm more of a lowmass bcg guy, and run the rightobear lowmass bcg's. But my AA bcg's have a few thousand rounds on them each and no problems. Not anywhere's close to the round counts on my lowmass bcg's.
Most reliable BCG for Grendel pistol? - FLshooter - 07-15-2020
I have several toolcraft BCG.Never given me a problem.
Most reliable BCG for Grendel pistol? - Growler - 07-15-2020
LMT enhanced carrier was designed for an already overgassed rifle running with the additional stress of suppressed operation. Nothing wrong with it but its sure pricey.
JP is known for making top tier bolts for the competition space, but you have to decide if the cost/benefit is right for your use case.
With all the 6mm ARC rifles under construction, there should be an abundance of bolts available in the not too distant future. Id put some rounds on the one you have, inspect it as often as you like, and grow confidence with it. There should be more options soon.
The most reliable bolt may just be the one you have successfully put 1000 rounds on and have good results and wear signs.
Broken bolts are usually a sign of bad heat treat; a bad receiver face; over pressure loads (Im looking at you 8208XBR); or a most excellent round count, as they are cycle limited components.
Most reliable BCG for Grendel pistol? - Disciple - 07-15-2020
Growler, the LMT and JP are expensive but this will be my primary home defense, so if these are actually better and not just fancy marketing I am willing to pay. But since I don't have a suppressor perhaps the LMT is not appropriate? Bravo Company (BCM) and Daniel Defense do not appear to sell bare carriers and one of their complete BCG's would be at least as much as the LMT carrier. The JP carriers are also more expensive. I have seen the LMT carriers listed for $149 (but out of stock). Is there a less expensive "first tier" carrier to put a Grendel bolt into?
Perhaps I should wait for other options to appear as you said.
Most reliable BCG for Grendel pistol? - Growler - 07-15-2020
Home defense is important, but a decently simple use case. Unless you keep sand in your safe or leave the heater off and live in the arctic circle, your gun will likely run well.
Id spend your money on enjoyable high quality training and buckets of ammo. Run a few training courses with your AA BCG, then inspect it. If it looks good, set it aside as your reserve, now that its proven. Between now and then, there should be more options available. Id look for a Geissele 6mm ARC BCG, or wait for the next group buy Grendel bolt and put it in this:
https://www.primaryarms.com/geissele-automatics-m4a1-bolt-carrier-group
Really, the only wrong answer is any BCG you shoot one box through and then assume its good.
For example, my first LMT carrier had an unfinished bolt tail, and wouldnt fit the JP bolt I wanted to put in it. I returned the carrier and ended up buying a complete LMT enhanced BCG. Its a fine BCG, but now I wish I had made that investment in more ammo.
Most reliable BCG for Grendel pistol? - Disciple - 07-15-2020
Growler, thank you for the advice. Now rather than upgrading I would like a second BCG as a backup, even if it's the same type. I will wait to see if the SixFive Mk136 bolts come back in stock as $55 is a great price. You seem to have had a mixed experience with LMT; would you still recommend them? With more searching I found a non-enhanced LMT carrier for $120; completed it would be about the same as the Geissele.
Most reliable BCG for Grendel pistol? - Kswhitetails - 07-16-2020
Any true Mil spec BCG, and a Group buy 65arms bolt. This doesn't need to be rocket science. Grendel works with the M4 pattern system. It takes a new barrel and bolt, and mags. Otherwise, leave it alone. It's not hard. Save yourself the troubles, and don't make it so.
Most reliable BCG for Grendel pistol? - Disciple - 07-16-2020
Yes, I'll wait for the SixFive Mk136 bolts to be restocked. Thank you.
Most reliable BCG for Grendel pistol? - 82HALO - 07-20-2020
I also use right to bear arms light BC with never a problem with the group buy bolts!
Most reliable BCG for Grendel pistol? - Growler - 07-20-2020
Disciple Wrote:You seem to have had a mixed experience with LMT; would you still recommend them? With more searching I found a non-enhanced LMT carrier for $120; completed it would be about the same as the Geissele.
Still dont have enough rounds on my LMT enhanced BCG to give an opinion. So far, its fine. My build philosophy changed after I put it together and that is the reason for the low rounds count on it. Originally, I planned to use a fixed gas block on a shorter barrelthats the gas management issue it was designed to band-aid. Im now running adjustable gas blocks and tuning for specific loads. This approach is a trade-off. Not as reliable for temperature extremes or light loads, but it runs much smoother.
I originally bought an unusual version, carrier only (no bolt). I got a one-off result. Cant judge LMT or any other manufacturer for that, as Murphy plays in one-off situations. When I returned it for a complete BCG, I got a smooth finished, tight little gem. Customer service was great.
Most reliable BCG for Grendel pistol? - montana - 07-20-2020
Not all bolt carrier groups are made the same. I have many different types of BCG from back to the 70's. I pin gauge all of them, test the straightness of the gas keys, and check the finish with a bore scope.. Four of my favorite were quite cheep when purchased many years ago. The machining, internal finish were perfect. That said, I use only BCM BCG's in all of my new builds. BCM has been very consistent with their manufacturing. JP is top of the line and is the Cadillac of AR manufactured products.. I have an older Olympic bolt carrier that had the gas key channel milled crooked..If you are concerned with the YFS fastners, then it is quite easy to replace the screws with a new BCM key and fastners...https://bravocompanyusa.com/bcm-gas-key-with-fasteners/ You can seal around the gas key port with Permatex aviation form a gasket https://www.permatex.com/products/gasketing/gasket-sealants/permatex-aviation-form-a-gasket-no-3-sealant-liquid/ or use green loctite. Torgue to 58-60 inch lbs...
Most reliable BCG for Grendel pistol? - Disciple - 07-21-2020
montana Wrote:If you are concerned with the YFS fastners, then it is quite easy to replace the screws with a new BCM key and fastners...https://bravocompanyusa.com/bcm-gas-key-with-fasteners/ You can seal around the gas key port with Permatex aviation form a gasket https://www.permatex.com/products/gasketing/gasket-sealants/permatex-aviation-form-a-gasket-no-3-sealant-liquid/ or use green loctite. Torgue to 58-60 inch lbs...
Thank you, I will do that or have it done.
Most reliable BCG for Grendel pistol? - montana - 07-22-2020
Disciple Wrote:Thank you, I will do that or have it done.
If you are the do it yourselfer kind of person, the best gas key fasteners and counter staking tools are from Michiguns LTD. http://www.m-guns.com/tools.php
Most reliable BCG for Grendel pistol? - am4966 - 07-22-2020
If your worried about the bolts on your gas key on the carrier then just replace them. Its not hard and its a lot cheaper than buying a new carrier.
But Im gonna say youll probably never shoot enough ammo through your Grendel to stress the bolts on the gas key.