Is this a solid AR15 build?


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tsanford405
January 18, 2008, 04:32 PM
I am trying to piece together an AR and wanted people to give me their thoughts on these three components as a build....

LMT lower with SOPMOD stock, ergo grip, ambiselector, and I have a Chip McCormick match trigger to drop in. (#L7C4)

LMT Enhanced bolt carrier group (all pieces "enhanced") (#L7XA3)

GG&G upper (Dominator-1)

Any thoughts? Thank you!

https://www.lewismachine.net/store.php?cid=7&session=6c612dc7c0f6764e49e51a35dd8f1e31
https://www.lewismachine.net/store.php?cid=4&session=6c612dc7c0f6764e49e51a35dd8f1e31
http://www.gggaz.com/index.php?id=35&parents=38,39

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taliv
January 18, 2008, 04:41 PM
skip the match trigger
i can't tell, but from the picture it looks like their bolt is chromed. if it is, skip it. DO NOT get a chromed or otherwise plated firing pin.

tsanford405
January 18, 2008, 04:44 PM
I found this....

New LMT bolt assembly utilizes two extractor springs for postive extraction. Also features locking lug grooves. Includes gas rings.

* Nickle plated
* Magnetic particle tested.

Nickel better?

teombe
January 18, 2008, 04:58 PM
You cannot go wrong with an LMT product. Period.

I'd say you've got a good plan there.

Bartholomew Roberts
January 18, 2008, 05:21 PM
The LMT Enhanced Bolt Carrier has three gas vent holes in the carrier instead of two in order to vent gas pressure faster. It will work well on firearms with a longer dwell time and a short gas tube (16" barrels with carbine gas systems); but you may see problems with rifle or midlength gas systems (or carbine gas with barrels shorter than 14.5").

Personally, I think I would prefer a normal bolt carrier here and use a heavier buffer if I wanted to deal with the longer dwell time. The buffer is cheaper and easier to replace.

arthurcw
January 18, 2008, 05:22 PM
if it is, skip it. DO NOT get a chromed or otherwise plated firing pin.

why?

thanks

taliv
January 18, 2008, 05:26 PM
hmm... i thought i replied, but my post isn't here. gremlins
dunno about nickel. my experience is with chrome and TiN


a) what is the advantage of a chromed pin?
b) after a few hundred rounds, the tip will chip and instead of being rounded, it will be sharp and result in pierced primers, which will start throwing a lot of gas back at you, and can be dangerous.

i have a thread in the reloading section somewhere, i think, showing pics where it happened to me

arthurcw
January 18, 2008, 05:29 PM
thanks.. I did not know that. adding to the list of things to watch for.

Gingerbreadman
January 18, 2008, 05:31 PM
I'm researching the same thing. Is there a reason why a chromed bolt carrier and a regular firing pin would be a bad thing? I'm kind of partial to the chrome bolt look.

Don't Tread On Me
January 18, 2008, 06:21 PM
Everything looks great except for the match trigger. Despite what some people say, NO match trigger made today is "duty" grade and trustworthy by my, or by many others standards.

If this is a range toy. Fine. If this is for business, skip that trigger and stick with a 100% factory trigger (not even a 2-stage national match type). Yes, the pull will be a horrible 5-8lbs, but that's not really a problem for dropping badguys out to 150m. About 5 times further than any realistic engagement max distance.

Bartholomew Roberts
January 19, 2008, 12:07 AM
DO NOT get a chromed or otherwise plated firing pin.

I may be mistaken; but I think the standard GI spec for the firing pin is chrome-plating. The problem with chipping is limited to TiN and Titainum firing pins made to "reduce lock time" as I understood it.

RockyMtnTactical
January 19, 2008, 01:39 AM
LMT makes good stuff. I would skip the enhanced BCG though.

possum
January 19, 2008, 06:21 AM
i agree drop the match trigger, no place on an fighting rifle for a match trigger.

Chris Rhines
January 19, 2008, 10:16 AM
Solid, yes. I don't like the LMT Enhanced BCG for all the reasons Bartholomew Roberts explains. I would suggest one of the excellent Mil-Spec BCGs from Bravo Company (http://www.bravocompanyusa.com/BCM-Bolt-Carrier-Group-MPI-Auto-M16-p/bcm%20bolt%20carrier%20group%20auto%20mp.htm).

It's amazing the amount of wailing and kvetching the word match produces. I swear, you could sell stock USGI AR trigger groups with the word "MATCH" written on the package, and some people would tell you to avoid them.

I have three JP match trigger assemblies in three different rifles, with a total round count between them somewhere north of 15,000 rounds over four years. Total number of trigger-related malfunctions has been zero.

Keep the match trigger if you prefer it. It will make it significantly easier for you to shoot fast and accurately.

- Chris

Outlaws
January 19, 2008, 01:39 PM
i can't tell, but from the picture it looks like their bolt is chromed. if it is, skip it. DO NOT get a chromed or otherwise plated firing pin.

I don't think LMT does much wrong with their builds.... Where you are getting this information.

taliv
January 19, 2008, 06:57 PM
bart, you are probably correct. for some reason, I seem to be plagued with non-standard firing pins. i will try to verify that shortly.

outlaws, i'm not knocking LMT at all. love their stuff, just not their "enhanced" stuff. my opinions are purely from personal experience and worth what you paid for them.

for instance, my experience with match triggers in AR15s:

two jewell triggers - fantastically crisp, but two failures, one a major safety issue, which happened to me just prior to the President's 100 at Camp Perry 3 yrs ago. was a major bummer. first had 1255 rnds fired in matches plus unknown number of practice rounds (and God only knows how much dry firing), second has 939 rnds fired in matches.

two rock river 2-stage - not as nice as the jewells, but not bad. no problems. one has 11,413 rnds on it (including carbine classes and tactical matches) the other was unfired. lack of problems here is not an endorsement, just luck.

two JP single-stage match - unbelievably great feel. absolutely in love with this trigger. was recalled due to very soft metal after bad heat treat. i sent it back with a large gouge in the face of the hammer where it impacts the firing pin, after only 100 rnds or so. I have 682 rnds on the two combined.

KAC match trigger - unfired, but can't wait to try it!

mccormick - no experience
geiselle - no experience

much as i love match triggers, the wailing and kvetching comes because most are chock full of tiny little screws and springs that can and will adjust themselves at the worst possible moment.

chipperi
January 19, 2008, 07:03 PM
IIRC in the past there were problems with "slam fire" discharges with titanium pins But I am not certain about chromed. Slam fire being the pin in an AR is free floating, hence on occasion upon dropping the bolt onto a live round the inertia would cause the firing pin to bounce forward hard enough to unintentionally fire the round. You have me wondering so I will try to find more info.



Ok I found this same general noe all over the place...
All AR-15 and M16 rifles were designed to fire military spec ammo. Military ammo contains thicker, less sensitive primers than commercial or reloaded ammo. All AR15/M16s are manufactured with an inertia type non-spring loaded firing pin, which can cause premature firing of reloaded commercially primed ammo! Anytime you chamber a cartridge you will notice a dent on the primer caused by the firing pin. This unsafe condition is easily remedied with the installation of our MATCH GRADE quality surgical titanium firing pin, which is 40% lighter than the stock firing pin. Our firing pin is much stronger and gives you the benefits of reducing vibration and lock time, which increases accuracy!


Aparently the heavier the pin is the problem. So I think it would be safe to assume that a chrome coated steel pin would be heavy and potentilly dangerous. After all they just found a guy guilty of having an illegal firearm when all it was was an ar 15 slam fire malfunction that made it go auto.

Bartholomew Roberts
January 21, 2008, 08:27 PM
So I think it would be safe to assume that a chrome coated steel pin would be heavy and potentilly dangerous.

I think a safer assumption would be that somebody has a lot of titanium firing pins they need to sell.

lamazza
January 21, 2008, 08:36 PM
I've heard from more than a few people that a titanium firing pin is a pretty bad idea. My understanding is that if you should pierce a soft primer that titanium pin can easily fuse your chamber closed forever.

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