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+--- Thread: Help!! Broken bolts! (/showthread.php?tid=5735)
Help!! Broken bolts! - Keep The Change - 06-12-2013
OK drifter and bwaites made comments about things being square. Drifter more specifically asked about the upper.
This is a LB product so I would continue to send it back to LB and ask about the upper and barrel extension being square and whatever else we can suggest. I'm thinking there is something between the bolt and BE that is off.
If the BE is not square to the upper, could this not angle the BE and barrel just a touch so that one side of the upper flange is flush with the barrel nut flange while leaving a gap on the other side. Remember if it is off a tad at the upper receiver and barrel nut mating surface, it is magnified at the Bolt to BE mating surfaces because of the length of the BE.
Maybe the threads and or face on the upper are not square and causing some added interference in the bolt to BE lock up.
This would give you varying interference between the bolt and BE lugs from one side to the other. You may not see it or feel it when you charge or release bolt catch, but it could be there.
Then couple in the possibility of barrel whip being able to move that BE inside the upper just a bit as the bolt comes forward.
I would suggest that LB check for squareness of receiver to BE. Check squareness of upper rec threads with the barrel axis.
I might be way off but after my experience last week with my BE and Bolt interfering, it doesn't take but 0.002"" to cause issues.
Help!! Broken bolts! - Tedward - 06-12-2013
I had talked to LBC a few weeks ago and the .134 is correct for there Type 2 Bolt. So everything everyone said sounds correct but is it possible the barrel nut is loose allowing flex or movement and it is causing the binding? Simple check and worth looking into.
Also LBC only has bolts right now and no extractors. I need a couple because I have been using them on Beowulfs and they work great. A few of my friends just had me build them a couple and that is the only piece of the pie I need to finish them up, Type 2 bolts and none around.
Help!! Broken bolts! - Nimrod - 06-12-2013
LB is sending me a new bolt, I am going to run a couple boxes of factory ammo through and I do expect it to fail at that point I am sending the whole mess back it LB to let them figure it out. LB insist that the rifle is perfect and that my loads are producing the problem, I don't feel this is right because I have trimmed my loads back so far. 27.5grns of 8208 behind a 123 gr Amax is not a still load. I believe something is off, but as long as I am breaking a bolt with a reload instead of a factory load I don't think I am going to get my rifle fixed. I will update when I have more info.
Help!! Broken bolts! - Nukes - 06-12-2013
bwaites Wrote:Most significant difference is that the hard use bolt has a cutout in the lug opposite the extractor to allow more even distribution of thrust on the bolt.
Interesting and counter-intuitive. You'd think that "cutting out" metal would weaken the bolt. From that description, do I correctly infer that there is no headspace difference between those bolts? That they are freely interchangeable?
Thank God for engineers!
Help!! Broken bolts! - bwaites - 06-12-2013
Nukes Wrote:Interesting and counter-intuitive. You'd think that "cutting out" metal would weaken the bolt. From that description, do I correctly infer that there is no headspace difference between those bolts? That they are freely interchangeable?
Thank God for engineers!
Bolts are the same otherwise. The failure point on AR bolts is almost always the lugs next to the extractor, because they take excessive pressure at unlocking because of the imbalance due to there not being a lug at that spot. This is exacerbated by improper timing, hot loads, or anything else that increases gas pressure. It also is exacerbated by stretched threads, improper or loose tolerances, and simple stacking of manufacturing tolerances.
Help!! Broken bolts! - wrsteve - 06-13-2013
That load is not hot. I use 28.2 grains of 8208 with the 123 amax as my most accurate load. In my rifle it is shows no signs of pressure.
Help!! Broken bolts! - SHORT-N-SASSY - 06-13-2013
Reviewing the input of this particular incident of Bolt failures, I would agree with those who've suggested that there's something wrong with this particular rifle. That said, and having researched the 6.5 Grendel Forum Archives, [B]The Big Bolt (6.5 Grendel ARs and other semi-autos, April, 2011) and Sheared Bolt Lugs (6.5 Grendel Troubleshooting, June, 2011), I believe the viable corrective suggestions offered in those previous Threads should be strongly considered, at this time.
1, The AR15Performance Big Bolt w/ matching Barrel Extension (http://68forums.com/forums/showthread.php?13626-New-Bolt-for-the-264-LBC) --- Sheared Bolt Lugs, 6-18-2011 Reply, "Gents, This is the one area where we really need a dedicated bolt and barrel extension for the Grendel, with increased mass around the bolt lugs to support the cartridge head, as well as balance out the load on the lugs. . . ."; 6-18-2011 Reply, "I really wish AR performance would have the 'Big Bolts' available. They look like a great idea, as not only is the bolt beefed up, but the system includes a specially made barrel extension to accommodate the beefed up bolt. I really doubt that anyone who is even close to the listed max loads would blow bolt lugs off the 'Big Bolt' system."
2, The R-15 And The .30 RAR (http://www.shootingtimes.com/2010/09/23/longgun_reviews_st_r15andthe30rar_200905/) --- ". . . the .30 RAR bolt shares the body of the .223 bolt with the head of the .308 bolt."
I submit that there's a whole new experience in store for 6.5 Grendel Enthusiasts hooked on gas guns. And, for those who have been considering the cartridge for military applications, "If only it had a little more velocity with the heavier bullets," this could be the bridge to that vision! [/B]
Help!! Broken bolts! - Tedward - 06-13-2013
I think Item 1 would be a great idea, bigger bolt and smaller barrel extension just for the bigger bores. Very simple fix across the board but would leave Type 1 and 2 behind and now have a Type 3. Beefier bolt and Barrel Extension to match. Great fix.
Help!! Broken bolts! - Nukes - 06-13-2013
Isn't that called an AR-10, SR-25, etc.?
Help!! Broken bolts! - Drifter - 06-13-2013
As inconvenient as a broken bolt can be, a beefed-up design would potentially mask a problem with the rifle and / or ammo. In the role of precision target shooting and / or hunting of non-dangerous game, the existing bolt design seems appropriate. It might also be appropriate in other roles if the weapon components are in spec and properly assembled, and only factory ammo is used. Blaming and / or changing the bolt design seems more like addressing a symptom rather than the underlying cause of an issue. If good ammo is used in a good weapon, a bolt of existing design will likely outlive the barrel. But eventual bolt changes wouldn't be surprising due to the perceived need by the consumer, and the desire to reduce headaches after the sale from a manufacturer / builder standpoint.
Help!! Broken bolts! - SHORT-N-SASSY - 06-14-2013
A more in-depth search of the 6.5 Grendel Forum Archives netted a rather extensive Discussion, as to why the 50,000 psi limit was established for the strong 6.5 Grendel cartridge case, when used in the standard AR-15 platform, [B]Is anyone currently selling a 60K psi bolt? (http://www.65grendel.com/forum/archive/index.php/t-3549.html).
And, from an upbeat Discussion on the .30 RAR necked down to 6-7mm, on another Forum, ". . . I think the RAR could be a family of cartridges in the [R-15] that would serve target shooters and hunters alike, who are looking for longer-range or heavier pill performance, in addition to varminters. There is no need to do all the High Pressure Testing and MPI on the AR10 bolt because it has so much mass, and was designed around the cartridge it was meant for, namely the 7.62x51 NATO. The AR15 bolt, receiver set, and extension was NOT designed around the 5.56 NATO, but the 50,000 psi limited .222 Remington. They never changed the geometry of the stress components when they blew the shoulder forward and ramped up pressures to well over 50,000 psi for the .222 Remington Special, since the dimensions would have grown maybe .100", so they just left it as is, but then started realizing the need for Carpenter 158 versus 8620 on the bolt, and the whole HPT/MPI process to QC the bolts. I like that the RAR uses an AR10 bolt lug & face geometry, with an AR15 bolt body, enlarged outer diameter just behind the lugs to support them, and a larger extension to handle the hoop stress. . . ."
All of which begs the question, What if Remington necked-down their .30 RAR to 6.5mm? The approx. 44 grain (water) capacity of the cartridge is within 4 grains of the superb 6.5x47mm Lapua, which requires an AR10-length action.
Oh, the painfully slow evolution of American sporting arms and ammunition! [/B]
Help!! Broken bolts! - LRRPF52 - 06-14-2013
I'm getting a nice balance in performance from my 6.5 Grendel right now, and have been for the past 4 years. I have never mass-loaded any loads that showed signs of excessive pressure, and have been able to match factory velocities with 123gr pills.
A larger bolt would allow higher pressures, but at what performance gains? 100fps...200fps? It might make a difference for some of the guys running 6mm on the extreme end of performance requirements, but still won't get the Grendel up to speeds of the .260 Rem class guns, although it would be close IF you could squeeze out 200fps.
The .30 RAR is a whole different class of case, because it makes the AR15 a single-stack magazine, which would be fine for hunters.
Help!! Broken bolts! - Sputnik - 07-17-2013
Nimrod Wrote:LB is sending me a new bolt, I am going to run a couple boxes of factory ammo through and I do expect it to fail at that point I am sending the whole mess back it LB to let them figure it out. LB insist that the rifle is perfect and that my loads are producing the problem, I don't feel this is right because I have trimmed my loads back so far. 27.5grns of 8208 behind a 123 gr Amax is not a still load. I believe something is off, but as long as I am breaking a bolt with a reload instead of a factory load I don't think I am going to get my rifle fixed. I will update when I have more info.
Nimrod, anything new to report at all? How fast did they ship you your new bolt?
Help!! Broken bolts! - oklahomaman - 07-17-2013
Have you used a dental mirror to look into the barrel extension--back at the locking lug surfaces? Could one have chipped, broke, got peened down, etc.?
Help!! Broken bolts! - woohoo - 07-17-2013
LRRPF52 Wrote:I'm getting a nice balance in performance from my 6.5 Grendel right now, and have been for the past 4 years. I have never mass-loaded any loads that showed signs of excessive pressure, and have been able to match factory velocities with 123gr pills.
A larger bolt would allow higher pressures, but at what performance gains? 100fps...200fps? It might make a difference for some of the guys running 6mm on the extreme end of performance requirements, but still won't get the Grendel up to speeds of the .260 Rem class guns, although it would be close IF you could squeeze out 200fps.
The .30 RAR is a whole different class of case, because it makes the AR15 a single-stack magazine, which would be fine for hunters.
I agree, a bigger bolt behind the PPC case is not the answer. You may gain 50fps if you are willing to push the performance. If you are worried about a flat primer or crater you wont load hotter anyway. If you want more performance like 200fps stepping up to a 6.5BRX would be the next move or buy an AR10 in 6.5x47 or Creedmoor.
I told the OP the receiver could be out of square, that is the only time I have seen an issue with newer bolts. One of the extension lugs could be damaged on the back side but I have never seen one.
ETA-If a receiver that has a tight bore like Vltor or Mega is used the extension is aligned by the diameter of the barrel extension, the front does not need to be squared. If the extension is sloppy in the bore like most receivers, squaring the front of the receiver doesn't hurt.
Help!! Broken bolts! - LRRPF52 - 07-18-2013
woohoo Wrote:I agree, a bigger bolt behind the PPC case is not the answer. You may gain 50fps if you are willing to push the performance. If you are worried about a flat primer or crater you wont load hotter anyway. If you want more performance like 200fps stepping up to a 6.5BRX would be the next move or buy an AR10 in 6.5x47 or Creedmoor.
I told the OP the receiver could be out of square, that is the only time I have seen an issue with newer bolts. One of the extension lugs could be damaged on the back side but I have never seen one.
I remember that conversation I had with you where the guy kept breaking bolts, and you finally asked him to send you his upper, which was significantly out of square enough to place uneven loads on one side of the bolt lugs.
Help!! Broken bolts! - Nimrod - 07-20-2013
Update: After talking with Les more he decided to have a further look at the whole upper as he feels there is an issue other than my loads. So it sent off the upper and am just waiting to hear back from them.
Help!! Broken bolts! - Nimrod - 08-18-2013
Incorrectly head spaced bolts, that is all it was. Les gave me a new correctly head spaced bolt and sold ma an extra one.
Help!! Broken bolts! - Tedward - 08-18-2013
Nimrod Wrote:I don't know how to check to see it is square or not, I would hope it is since it is a Les Baer custom, I think I will order some of his ammo and run it to see if I have trouble, I agree that the factory ammo is hotter than 2350, but he said they are using different powders that produce less pressure. I don't understand that though as it would seem to me that pressure is what pushes the bullet down the barrel, more pressure more velocity it would seem to me. My original bolt had over 1,000 rnds of significantly hotter loads then 2350. Every since then it is bolt after bolt even while I continue to step back on my loads. As I said before I sent the rifle in last time to be checked out and Les cleared it and sent it back. I am at a loss and at 2350 out of my 20" barrel I can't very well take advantage of what the Grendel has to offer.
Once the first bolt broke it may have damaged the barrel extension maybe? If the issue started after a hot load broke something, then it may have caused another issue. Send ti to LBC and let them use the correct equipment to test it rather than try with new bolts and lower pressure bullets. Just the upper and your bolt. sounds cheapest way and less than a bolt in shipping.
Help!! Broken bolts! - cst - 02-11-2014
Nimrod Wrote:Incorrectly head spaced bolts, that is all it was. Les gave me a new correctly head spaced bolt and sold ma an extra one.
In know its been a while since this has been resolved...but can you clarify what you mean that the bolt was incorrectly headspaced? Does that mean you were shooting the type1s all that time and he just got you a type2? Or were all the ones you broke incorrectly made? Have you had any issues since?