Should I get the enhanced LMT bolt group?

[Newaza]

I just bought an LMT lower and am about to buy the LMT upper. Do you guys think it is worht the extra money to get the LMT enhanced bolt group? Any advice would be greatly appreciated. Thanks.

[Sid Post]

Why do they say to use it only on 14.5" and longer barrels? Is the Enhanced BCG a good choice for a 10.5" upper?

[KevinB]

Why do they say to use it only on 14.5" and longer barrels? Is the Enhanced BCG a good choice for a 10.5" upper?

Unless you want it to work - its great ;) - I've never had worse problems with my Shorties than a brief experience with those bolts.

FYI even in the M4 and Middy Recce rifles an O Ring Colt bolt has more positive extraction. I've used them - and my reliability in both guns went down - and replacing the Colt bolt in - they worked a lot better... I beleive the extractor in the LMT "Enhanced Bolt" does not produce enough tension for that...

[Robb Jensen]

Why do they say to use it only on 14.5" and longer barrels? Is the Enhanced BCG a good choice for a 10.5" upper?

The 'enhanced' carrier vents off a larger volume of gas when compared to a regular carrier. I would only use one on a 14.5" registered machinegun (Colt/LMT).

I had a customer with one in a midlength and it short stroked badly. When I put a regular M16 carrier in it, it ran 100%. He later returned the whole upper for a refund. Hint - midlengths don't need upgrades, why this manufacturer sold him a LMT enhanced carrier for a midlength barrel I don't know. Shame on them.

Interestingly enough just yesterday I worked on a 18" stainless SPR midlength for a different customer of mine (factory upper from the same manufacturer of the one my previous customer) I did a 'shave' job on the FSB and installed a YHM rifle length rail. For sh*** and giggles I measured the gas port, it wasn't perfectly round more like egg shaped and now their gas ports on midlengths are .090" :( WTF?

[AR15barrels]

Hint - midlengths don't need upgrades

I'll drink to that. :cool:

[Newaza]

Thank you very much for all the replies. I'll go with a standard set-up. If it ain't broke, don't fix it. ;)

[AR15barrels]

For sh*** and giggles I measured the gas port, it wasn't perfectly round more like egg shaped and now their gas ports on midlengths are .090" :( WTF?

Was this a high round-count barrel?
Egg shape could happen with some erosion on a well used barrel.
Not so common on mid-lengths though.

[Robb Jensen]

Was this a high round-count barrel?
Egg shape could happen with some erosion on a well used barrel.
Not so common on mid-lengths though.

Brand new unfired upper.

[Newaza]

When people refer to mid-lengths, do they mean carbines with 16" barrels?

[SuicideHz]

No, midlength refers to the gas tube length basically- it's 2" farther forward than a carbine length gas system.

Don't confuse "carbine" and "carbine length gas system." They are two different animals.

I'd still consider a 16" midlength a carbine.

Midlengths require longer handguards and therefore a different rail system- the KAC RAS etc. are 7" for carbine gas systems, 9" handguards like the DD and Larue 9.0s are for midlength gas systems.

[Newaza]

Thanks.

[AR15barrels]

Gas systems.

http://www.ar15barrels.com/gfx/gas-block-seats.gif

Picture is easier to view here (http://www.ar15barrels.com/prod/gas-systems.shtml)