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maschronic
02-12-2007, 7:28 AM
i was check out 10% website and noticed enhanced bolt assembly. the enhanced bolt assembly is about twice the price.

what is the difference between standard bolt assembly and enhanced bolt assembly.

bu-bye
02-12-2007, 8:08 AM
Well, I would suggest you contact Wes at 10% and ask him. I have my opinion on the two but Wes is a good man and can answer that question better then I.

wildcard
02-12-2007, 8:11 AM
Given the cost, I'd suggest just buying a LMT M16 (full auto) bolt carrier group and be done with it.

!@#$
02-12-2007, 8:11 AM
LMT enhanced bcg has dual extractor springs. many problems have been reported with these unless you stick to m855 ammo. the standard lmt f/a bcg is just as good with none of the enhanced groups problems. the cmt bcg with mpi bolts and restaked carriers are nice too.

Technical Ted
02-12-2007, 9:39 AM
All answers wrong so far.

ETA: except !@#$. The enhanced bolt was designed for sustained full auto fire of M855.

For most of you guys it's nothing more than a penis extension: the ability to say you have an "enhanced" bolt.

There are two types of enhanced bolt carriers and one kind of enhanced bolt on the market.

The first bolt carrier is the enhanced bolt carrier as patented by Lewis Machine and Tool. During SOCOM development of the full auto M4A1 for special forces uses, several problems were found with the M4A1 during sustained full auto fire. One of those problems was increased stress on the rifle bolt and extractor due to higher cyclic rates and operating pressures experienced with the shorter gas system.

Note: the M4 is 3 round burst fire.

The LMT enhanced bolt carrier is reinforced at the forward end to keep it from cracking around the cam groove. It has more mass (i.e. more material) in order to slow down the cyclic rate. It has a third gas port--instead of two--to relieve gas pressure in a faster period of time and thereby reduce stress.

Under sustained full auto fire, the M4A1 also experienced cracking at the locking lugs and failures to extract. LMT redesigned the the bolt to incorporate a dual spring reinforced extractor and stress relief notches in the locking lugs for extended bolt life.

One area where enhanced bolt might have justifcation in a semi-auto rifle is in 6.8 chambered rifles. The face of a 6.8 bolt has to be opened up and the extractor groove has to be widened in order to accomodate the larger diameter and thickness of the cartridge head.

Anyone can manufacture a standard M16/AR15 bolt. The LMT enhanced bolt was designed in house and is patented to an LMT employee.

The other enhanced bolt sold by some vendors is nothing more than an M16 bolt carrier.

AJAX22
02-12-2007, 9:49 AM
Thanks Ted, I'm going to have to check my AR bolts when I get home, I didn't know there was a difference, I run M16 bolts and carriers for the added mass, but I never thought to look for 'enhanced' features on them.

Sydwaiz
02-12-2007, 9:51 AM
Some have a shrouded firing pin but that's about all I know. YMMV

Technical Ted
02-12-2007, 10:09 AM
Some have a shrouded firing pin but that's about all I know. YMMV
The firing pin shroud is not an enhancement per se. When Colt wanted to sell the AR15 as a semi-automatic civilian commercial rifle, the removal of the firing pin shroud was one of several modifications they made to full auto parts to make conversion difficult.

bwiese
02-12-2007, 10:16 AM
Ted has the straight poop.

I'd generally advise folks, esp newbiews w/1st AR, to avoid 'special case' parts like this.

Most all folks can be well-served by standard AR bolts and carriers, with some folks liking the heavier M16 carriers (which are legal to have/use, btw - as long as no other M16 fire control parts installed or in possession).

You start having problems with marginal ammo (in combination, perhaps, with a bit of a gas leak) and heavy carrier and heavy buffer, etc.

I'd advise noobs to get best quality 'regular' stuff they can get and stay away from special-case stuff until they have a real need for it or a second or third AR they can play with while leaving the other ones in a reliable configuration.

Oh - I'd also add that it behooves most folks to stay away from chromed bolt carriers too (that is, hard chroming on outside). These just wear the inside of the upper receiver more.

mltrading
02-12-2007, 10:46 AM
Yes, I always suggest my customers to stick with high-quality "standard" BGs unless they are real weapon experts.:)

meangreen
02-12-2007, 11:46 AM
save the money on the "enhanced" LMT BCG assembly and get a "MP" tested CMT BCG with some extra upgraded features-

-Crane "O" ring
-Black insert
-Professional staked carrier

www.gandrtactical.com

Technical Ted
02-12-2007, 12:21 PM
save the money on the "enhanced" LMT BCG assembly and get a "MP" tested CMT BCG with some extra upgraded features- MP tested is good. Proof fired is better (but as yet no one offers those outside of preassembled and test fired uppers). MP just indicates flaws prior to firing.

-Crane "O" ring
-Black insert Again, adaptations for reliable sustained full auto fire of an M4A1 SOCOM in the hands of special operations. Blue inserts and standard extractor springs work fine in a semi-auto only rifles.

-Professional staked carrier
Good idea. I ordered a pair of CMT carriers from a well known vendor (Before they offered MP tested). One of them had the carrier key installed at an angle and wouldn't fit in any upper receiver. One call and I had a replacement, a t-shirt and a 10% discount letter a day later.

meangreen
02-12-2007, 12:30 PM
I should have added on my above post that you can get the complete CMT BCG with the extras I listed for $135 through www.gandrtactical.com

that is not much more than a standard carrier group.

if you're just a plinker then it won't matter much if you have a BCG with a blue insert and standard extractor.

the extra parts are just cheap insurance...

maschronic
02-12-2007, 3:06 PM
thanks guys. i'll stick with the standard.

SemiAutoSam
02-12-2007, 3:45 PM
Ted

How many MP's does the army have testing these things ? :rolleyes:

Maybe the NAVY shore patrol would volunteer to help with the monumental task ?



MP tested is good. Proof fired is better (but as yet no one offers those outside of preassembled and test fired uppers). MP just indicates flaws prior to firing.

Again, adaptations for reliable sustained full auto fire of an M4A1 SOCOM in the hands of special operations. Blue inserts and standard extractor springs work fine in a semi-auto only rifles.

Good idea. I ordered a pair of CMT carriers from a well known vendor (Before they offered MP tested). One of them had the carrier key installed at an angle and wouldn't fit in any upper receiver. One call and I had a replacement, a t-shirt and a 10% discount letter a day later.

maxicon
02-12-2007, 4:14 PM
The firing pin shroud is not an enhancement per se. When Colt wanted to sell the AR15 as a semi-automatic civilian commercial rifle, the removal of the firing pin shroud was one of several modifications they made to full auto parts to make conversion difficult.

Is this the firing pin shroud difference?

http://www.maxicon.com/guns/ar15_bolts.jpg

SemiAutoSam
02-12-2007, 4:18 PM
And how did this keep the conversion from semi to full from working ?
The bolt carrier also does not have the lower dimension as the top of the rear section. so wasn't that enough modification ?

Is this the firing pin shroud difference?

http://www.maxicon.com/guns/ar15_bolts.jpg

AJAX22
02-12-2007, 4:33 PM
by milling the firing pin shroud it prevents you from being able to alter your rifle to FA function through having the hammer ride the bolt down, the hammer catches in the notch of the firing pin instead of keeping pressure on the back end. (at least thats what I've been told)
don't know if its true or not.

SemiAutoSam
02-12-2007, 4:37 PM
This may make some sense as a lot of the hammers did have notches in the area where it could catch. I'm really surprised colt went that far however I suppose its the liability aspect of it for them.

by milling the firing pin shroud it prevents you from being able to alter your rifle to FA function through having the hammer ride the bolt down, the hammer catches in the notch of the firing pin instead of keeping pressure on the back end. (at least thats what I've been told)
don't know if its true or not.

Technical Ted
02-12-2007, 4:39 PM
Ted

How many MP's does the army have testing these things ? :rolleyes:

Maybe the NAVY shore patrol would volunteer to help with the monumental task ? Everybody knows MP stands for Minister of Parliament. The uppers are sent to England for testing.

Is this the firing pin shroud difference?

http://www.maxicon.com/guns/ar15_bolts.jpg Yes.

And how did this keep the conversion from semi to full from working ?
The bolt carrier also does not have the lower dimension as the top of the rear section. so wasn't that enough modification ? "Announcement fourteen: This question has been addressed in the last three weeks. Please use the search function if you require more information."

Hint: "AR notched hammer" thread.

Yes the sear trip surface on semi-auto only bolt carriers has been trimmed back. Both bolt carriers shown are semi-auto only.