Is there a repository of Bolt information here?
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3,086 Posts
I've use the LMT Enhanced, CMT/STAG, and CMMG and they all worked fine. If you really plan on pushing your loads, get the LMT.
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5,565 Posts
Harrison and Tim will be good sources of bolt tech for you. They've spent months looking at components for their Xtreme upper builds.
Stag/CMT and LMT are very common in builds for 6.8's. RRA if you found one would work well also. With the parts shortage any of the major brands would be nice to find, except for maybe DPMS.
Like 5.56 bolts, there are better extractor springs available to upgrade the 6.8 bolts.
The LMT enhanced bolt receives lots of accolades, but you have to decide if you really need that heavy duty of a bolt. It's the same discussion you've seen in other forums with the LMT enhanced 5.56 bolt. If you run hot loads and high round counts then it makes sense. Harrison is manufacturing a heavy duty 6.8 bolt for his Mk68 uppers that hopefully will be out soon.
We just do not see that many bolt failures in this forum to really have a consensus as to which brand has the highest failure rate. Well, I take that back, DPMS bolts do come up in that discussion.
One thing to watch out for is 5.56 bolts that have been opened up to 6.8 bolts. Early on this was the source for 6.8 bolts, but now there are dedicated 6.8 bolts. Why bother with conversions? Model 1 Sales has sold some of these recently.
viewtopic.php?f=25&t=6630
Stag/CMT and LMT are very common in builds for 6.8's. RRA if you found one would work well also. With the parts shortage any of the major brands would be nice to find, except for maybe DPMS.
Like 5.56 bolts, there are better extractor springs available to upgrade the 6.8 bolts.
The LMT enhanced bolt receives lots of accolades, but you have to decide if you really need that heavy duty of a bolt. It's the same discussion you've seen in other forums with the LMT enhanced 5.56 bolt. If you run hot loads and high round counts then it makes sense. Harrison is manufacturing a heavy duty 6.8 bolt for his Mk68 uppers that hopefully will be out soon.
We just do not see that many bolt failures in this forum to really have a consensus as to which brand has the highest failure rate. Well, I take that back, DPMS bolts do come up in that discussion.
One thing to watch out for is 5.56 bolts that have been opened up to 6.8 bolts. Early on this was the source for 6.8 bolts, but now there are dedicated 6.8 bolts. Why bother with conversions? Model 1 Sales has sold some of these recently.
viewtopic.php?f=25&t=6630
CMT/STAG bolts are the norm. The MP testing on any bolts not Colt of FN everyone makes such a big to do over is nothing but an extra charge of $3 to have a person engrave the MP on the bolt. Unless the bolt is first used to fire a proof load before MP testing the test is nothing but window dressing and not done they are only at the very most batch tested which could be one out of every 1K or 10K.
The best bolt currently out is the LMT Enhanced bolt. It is made of a stronger alloy, chromed, and has other design improvements on the lugs and used the lobster tail extractor. If the 6.8 had extraction issues the lobster tail would be a big plus but personally at a replacement cost of $50 each its steep. This is the bolt I currently run in all my own ARs.
ARP / Constructor is coming out with a bolt that has many design changes that increase lug engagement area and strength by a significant amount. It is made of a stronger alloy and uses standard AR extractors, springs, etc.. They are currently being made and hopefully should have testing done in the near future.
If I had to pick the ideal setup of what is currently out there: Young NM M16 carrier, LMT Enhanced Bolt all sent out to be ion bonded. You would then have a BCG with min slop more weight and a surface that is the hardest available and has self lube properties and carbon does not adhere to it. Add in upgraded key screws, side and top counter staking, a couple of drops of red loctite, replace the cotter pin with the original style retaining pin, and its as close to bomb proof as you can currently get.
If you need detailed specs on the different bolts I can post or PM it to you.
The best bolt currently out is the LMT Enhanced bolt. It is made of a stronger alloy, chromed, and has other design improvements on the lugs and used the lobster tail extractor. If the 6.8 had extraction issues the lobster tail would be a big plus but personally at a replacement cost of $50 each its steep. This is the bolt I currently run in all my own ARs.
ARP / Constructor is coming out with a bolt that has many design changes that increase lug engagement area and strength by a significant amount. It is made of a stronger alloy and uses standard AR extractors, springs, etc.. They are currently being made and hopefully should have testing done in the near future.
If I had to pick the ideal setup of what is currently out there: Young NM M16 carrier, LMT Enhanced Bolt all sent out to be ion bonded. You would then have a BCG with min slop more weight and a surface that is the hardest available and has self lube properties and carbon does not adhere to it. Add in upgraded key screws, side and top counter staking, a couple of drops of red loctite, replace the cotter pin with the original style retaining pin, and its as close to bomb proof as you can currently get.
If you need detailed specs on the different bolts I can post or PM it to you.
Joined
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11,788 Posts
I still don't think LMT is a stronger alloy, this is a quote from their site.
If it was 9310 they would say it, I mean they go as far as saying something as small as heat treat is better.
I think it is the true DOD carpenter 158, not the lessor C158 or 8620 commercial bolts like most are.
"Our enhanced bolts have a more resilient coating and stronger heat treat, as well as the cartridge case being fully supported by the bolt face."
On the other hand, I don't know of anyone breaking a 6.8 bolt.
If it was 9310 they would say it, I mean they go as far as saying something as small as heat treat is better.
I think it is the true DOD carpenter 158, not the lessor C158 or 8620 commercial bolts like most are.
"Our enhanced bolts have a more resilient coating and stronger heat treat, as well as the cartridge case being fully supported by the bolt face."
On the other hand, I don't know of anyone breaking a 6.8 bolt.
Joined
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7,772 Posts
I am going to run a LMT bolt in both my 556 and my 6.8 carbines to use in courses and such until H comes out with the ITS bolt, then the LMT's will get put into the my precision rigs... All i know so far about the LMT's is that the wait was forever.....
Joined
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272 Posts
Thanks for the info fellas.
On the subject of the LMT...
A couple of you mentioned hotter loads, and this has also been an issue for a lot of shooters with the Enhanced bolts in 5.56 as well when the shooter over compensates and puts an enhanced bolt with an H2/3 buffer, stronger spring, heavier carrier, and o-ring on the extractor spring, and then shoots Wolf.
My intention with the 6.8 is to find a load I like (or the rifle likes) and then buy 500-1000 rounds and be done. For the amount I intend to shoot this rifle/upper that should cover me for quite some time. Not really planning on reloading. Given that, is there a potential for issues with the LMT Enhanced bolt and, say, a typical factory 6.8 loading in a 16" midlength?
On the subject of the LMT...
A couple of you mentioned hotter loads, and this has also been an issue for a lot of shooters with the Enhanced bolts in 5.56 as well when the shooter over compensates and puts an enhanced bolt with an H2/3 buffer, stronger spring, heavier carrier, and o-ring on the extractor spring, and then shoots Wolf.
My intention with the 6.8 is to find a load I like (or the rifle likes) and then buy 500-1000 rounds and be done. For the amount I intend to shoot this rifle/upper that should cover me for quite some time. Not really planning on reloading. Given that, is there a potential for issues with the LMT Enhanced bolt and, say, a typical factory 6.8 loading in a 16" midlength?
Joined
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7,772 Posts
Rob-
With the good configuration even the tactical loadings from SSA only run you at 52-54K which is where the .mil wants the pressure for repeated fast firing... I think if you buy any decent upper with the correct specs and get 1K of the SSA OTM (for anti personal) or say the pro hunters for hunting or even the 110 or the newer 100 grain accubonds (for both) you will never have an issue with your bolt...
H has used the same bolt for all of his testing and pressure loads and hasnt had an issue... and we all know H runs his loads very hot....
With the good configuration even the tactical loadings from SSA only run you at 52-54K which is where the .mil wants the pressure for repeated fast firing... I think if you buy any decent upper with the correct specs and get 1K of the SSA OTM (for anti personal) or say the pro hunters for hunting or even the 110 or the newer 100 grain accubonds (for both) you will never have an issue with your bolt...
H has used the same bolt for all of his testing and pressure loads and hasnt had an issue... and we all know H runs his loads very hot....
Rob
For your purpose you can go with either the STAG/CMT bolt or the LMT Enhanced. Both will last longer than most 5.56 carbine bolts last. The benefits of the LMT are better extraction and its stronger and easier to clean. TI uses the lobster tail extractor so you have to go to them for those parts where the STAG used standard mil spec 5.56 parts. You will be fine with either you choose. I prefer the LMT.
C,
You could very well be correct on the alloy. It may be they are nitrided and then chromed. The lugs and bolt face extractor are def improvements.
For your purpose you can go with either the STAG/CMT bolt or the LMT Enhanced. Both will last longer than most 5.56 carbine bolts last. The benefits of the LMT are better extraction and its stronger and easier to clean. TI uses the lobster tail extractor so you have to go to them for those parts where the STAG used standard mil spec 5.56 parts. You will be fine with either you choose. I prefer the LMT.
C,
You could very well be correct on the alloy. It may be they are nitrided and then chromed. The lugs and bolt face extractor are def improvements.
Joined
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1,581 Posts
I spoke to the owner of a company who is coming online as a sponsor when the new board goes live.... they are looking at making there own 6.8 bolts since right now , no one can get them.
The 6.8 market share will get a bit larger if they indeed take this step.
The 6.8 market share will get a bit larger if they indeed take this step.
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11,788 Posts
If it's PWS, they were or maybe still are thinking of making them but they asked if I was and if they could buy them from me.Cold said:
I think this shortage will make several companies produce their own stuff.
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