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View Full Version : LMT 10.5'' which buffer to use??



WILDBILL
03-04-07, 06:42
I am building a LMT 10.5'' MK18 MOD0 Clone and don't know which buffer to use in it, should I use the H2 or the H3 Buffer? I would like to tame a lot of that short barrel recoil and try to get it like the 14.5'' or the 16.0'' if that is possible .

Robb Jensen
03-04-07, 07:02
I'd recommend a H2 with a standard power spring. But I would check to make sure it's cycling well and locking the bolt back everytime by only loading 1 round per mag. If it's not locking back reliably go to an H buffer with the same spring and it should work fine, if not use the standard CAR buffer. Later as the gas port erodes and the cyclic rate increases you can use an H2 or H3 and a heavier rate spring like an ISMI, David Tubb(a more expensive ISMI), or Wolff +10%.

What I find that's working best in my 10.3" LMT right now is a H2 with a standard rate chrome silicon spring. This barrel has about 4K rounds through it now. It was a factory 14.5" LMT and I had it cut to 10.3" and had gas port work.

http://img.photobucket.com/albums/v408/gotm4/gunpics/newpics002.jpg

C4IGrant
03-04-07, 07:07
Since LMT's tend to have smaller gas ports, I think you need to pay attention to what type of ammo your shooting. Like Gotm4, I like H2 buffers, but they don't always work in the LMT uppers.

With mil-spec ball, I can use an H2 and a IMSI springs in most LMT 10.5.



C4

WILDBILL
03-09-07, 18:18
Grant, I was thinking, have you ever tried a H3 in a LMT 10.5'' Upper?

LukeMacGillie
03-09-07, 19:32
Im quite happy with my Mk18, but im only about 4 grand round count into it at the moment. It works fine with or without a supressor and contrary to what I expected has no problems with a standard carbine action spring and H buffer, No O ring on the extractor.

Thats shooting M855 and Mk262.

QuietShootr
03-09-07, 20:30
I have a Colt 9mm buffer and a Brownells standard-weight CS buffer spring in mine. The gun has <checks gun book> 2270 rounds through it of mixed XM193, M855, 5.56 TAP, and a little el cheapo shit just to see if it would run. I have had NO malfunctions to date with this setup. That's right, zero.

However, I also have a KX3, a 5-coil Wolff XP extractor spring with a black Colt insert, and a D-Fender installed. YMMV, but I don't think that stuff hurts.

grinch
03-09-07, 20:51
I think you can get away with the H2 no problem but FYI the military uses the H buffer and I've got 20K rounds with no issues thruogh mine.

Robb Jensen
03-13-07, 07:05
I did some playing with my digital scale this morning and found this out :

buffers
CAR buffer 2.96oz
Bushmaster H buffer 3.75oz
CMT H2 buffer 4.57oz
CMT H3 buffer 5.43oz
Enidine hydraulic CAR buffer 4.34oz (newest type, softer spring rate)
Enidine hydraulic rifle length buffer 5.84oz

bolt carriers (w/o bolts in them)
Colt non shrouded 1/2 circle carrier 8.63oz
Colt shrouded 1/2 circle carrier 8.87oz
Bushmaster non shrouded AR15 carrier 8.92oz.
Bushmaster shrouded AR15 carrier 9.26oz.
CMT M16 carrier 9.46oz
ARES G35 M16 carrier 10.54oz.
Bushmaster gas piston AR15 carrier 10.10oz (w/screwed on solid carrier key like older POF, newest POF ones use integral key like ARES).

WILDBILL
03-13-07, 07:21
GotM4, have you weighted a LMT FA BCG? And Grants, FN Fullauto BCG? I plan on making my LMT MK18 MOD0 all LMT Parts and later building a Stag F-top upper Rec. and a Colt M4 14.5'' barrel and Grants FN FA BCG.

Robb Jensen
03-13-07, 07:24
GotM4, have you weighted a LMT FA BCG? And Grants, FN Fullauto BCG? I plan on making my LMT MK18 MOD0 all LMT Parts and later building a Stag F-top upper Rec. and a Colt M4 14.5'' barrel and Grants FN FA BCG.

There shouldn't be much difference at all in weight between a CMT/LMT/Colt & FN M16 bolt carrier weights. Same with bolts, should be really close to each other in weight.

For your factory LMT 10.5" I'd just use an H buffer for about the first 5-10K rounds and after that then try an H2, by that time the gas port should be eroded enough to where it warrants the use of an H2 or H3 buffer.

twl
03-13-07, 08:43
The 10.5" carbines have a very short dwell, and they have relatively large gas ports to get a quick burst of gas to operate the system, instead of getting a longer gas charge from normal dwell.

As a result, this can get things into motion more quickly and perhaps violently, and that's why the heavier buffers are preferred in these 10.5" applications.

The heavier buffers will tend to help delay your extraction slightly and to make the cycling slower. This is good.

However, the actual energy imparted to the system from the gas is the same, and even if the heavier buffer takes a little longer to get going, and goes slower, the energy being transmitted rearward is roughly the same as with a lighter buffer, except slower.
Sort of like light and fast, vs heavy and slow. Different ways to transfer the same energy.
When it hits the back end of the buffer tube(and consequently your shoulder) it will transmit that same amount of energy(roughly) as the lighter buffer would have. Slightly less sharp perhaps, but more inertia and more "shove" to it. Just as it didn't really want to get into motion right away, it doesn't really want to stop right away either.

So, if you want to help with the recoil reduction and muzzle-rise, then you're going to need a buffer with a recoil-reduction function built into it.

The MGI RRB (RateReducing/RecoilReducing Buffer) is made for these types of applications, and consists of a heavy(7.1 oz.) buffer with a mechanical tungsten weight and spring system which is activated at the back end of the recoil stroke by a very short plunger in the buffer tail. This sends the tungsten weights into forward motion inside the buffer body, to strike the rearward moving parts just prior to bottoming out at the back of the buffer tube, and cancels a large portion of the recoil, and spreads-out the impulse of whatever recoil might be left.
And it has the delayed extraction and slower cycling benefits of the 9mm type buffers too.
And the tungsten weight system also performs to eliminate any bolt bounce.

It will provide better cycling characteristics, less recoil, less muzzle rise, and overall better controllability of the weapon, especially during rapid fire sequences. Works equally well in semi-auto or full-auto.

Cincinnatus
05-10-11, 10:08
Sorry for the necro post here, but can anyone verify the info in the last post by TWL? It has been my understanding that pneumatic buffers, etc. are all "voodoo" and "snakeoil."

floyd
05-10-11, 14:02
MGI buffers do slow down cyclic rate and felt recoil. Its all physics. They do as advertised. The problem is that they can be more ammo sensitive. Lower pressure ammo may not function as well.

dudshep31
05-11-11, 14:37
I've been running an H buffer in a 10.5 mrp. Runs great both suppressed/unsuppressed. Using 855 ammo. recoil is almost unnoticeable.

99HMC4
05-29-11, 00:30
I've been really happy with the spikes buffer in my LMT 10.5 so far. Eats any type of ammo I throw on it.....

armakraut
05-29-11, 00:33
Does the stock buffer on these really need to be replaced or is it good to go from the box?

mikeahe
05-29-11, 11:42
Use LMT Enhanced BCG, that's what it's made for.

hatidua
05-29-11, 12:23
I have an H2 in my 10.5" LMT and it runs perfectly regardless of what I have the Switchblock set at (factory LMT 10.5" barrel, Switchblock installed after-the-fact), or whether it has a suppressor on it or not.....with any ammo.

99HMC4
05-29-11, 14:21
Use LMT Enhanced BCG, that's what it's made for.

I was told by LMT not to use that group in the 10.5 upper...

usmcvet
05-29-11, 16:38
I was told by LMT not to use that group in the 10.5 upper...

I think their web site says not to use it on anything shorter than 14.5"

usmcvet
05-29-11, 18:59
http://www.lewismachine.net/product.php?p=52&cid=7&session=744d6492b33b2ecebbbc8043b037b5f7

NOTE: Full-Auto Enhanced (to be used with a 14.5" barrel or longer)

99HMC4
05-29-11, 23:43
They told me why when I set up dealer account with them and ordered my personal 10.5 upper. Don't remember why now but he told me DO NOT use it with the short MK18 type uppers. So I got their normal spec BCG and it runs perfect....

ccosby
06-02-11, 23:39
I am building a LMT 10.5'' MK18 MOD0 Clone and don't know which buffer to use in it, should I use the H2 or the H3 Buffer? I would like to tame a lot of that short barrel recoil and try to get it like the 14.5'' or the 16.0'' if that is possible .

Best option would be to try a few different ones and see what happens. I want to say LMT use to provide a carbine buffer in some of their 10.5 factory sbr's but I'm sure someone can chime in.

When I built mine(10.5 lmt on an lmt lower I did a form 1 on) I started with an h buffer but had a carbine and h2 buffer with me. Gun hasn't given me any problems related to the buffer both unsuppressed and suppressed so I've left it as is. I do have the h2 buffer in its bag in case it needs it down the road when the gas hole opens up some from wear.

usmcvet
06-03-11, 01:26
My factory LMT 10.5" SBR came with a carbine buffer and it ran fine for 1,000 rounds. I changed to an H buffer in hope of less bolt bounce and pounding on the bolt its been good to go for 1200+ rounds. I just got an H2 in from BCM but haven't tried it yet.