# First look at LW short stroke piston M4 with Grenadier Precision RAS



## 48thHighlander (10 May 2005)

Hey guys,  just about to deliver to Camp Lejune, 4th MEB (Counter Terrorism).  Our contribution is the unique top opening return to zero RAS.  Not bad for an ex CF Canuck eh? 

Here are some pics of the Grenadier Precision ARM-R (C) rail systems installed on a LW 5.56 CP Upper.  



























Changes that have been made on the production models are:

45 degree chamfer on the front as it is on the back of the rail system.

Reposition the Knights rail notches to the 1st groove from the back of the rail as where they are now, the screw interferes (ooops - some times the simple stuff bites you in the ass because you don't pay attention to it).

Allow more material on the bottom of the clamp.  We left this space thinking their might be some flex when torquing the screws.  There is none.  They will fit flush.

Welds for the flange locating sleeve that also acts works to index the ras will not be visible for a cleaner look.

Teflon impregnated hard coat anodizing instead of standard dye type anodizing will offer rockwell 95 and is the hardest surface available.  This will be harder than a carbide bit.  The only thing harder is diamond.  The teflon offers scratch resistance than standard hard coat does not offer.  It is beyond the Type III Mil. STD.

Rivit steel inserts for the grenade launching holes instead of threaded 6061 or helicoils.











Note the perfectly aligned gas piston clearance as specified by LW.  No contact and symmetrical.
(Patting myself on the back)






Nice view of gas piston.






Another view of the piston through the top vents.  Thumbscrews are in the locked position.





Thumbscrews back out to unlock and take off the cover.  Slide the cover forward the distance you see there and it lifts off.





Topless!





Shameless gun porn.





Our biggest fan.  She told me she likes HK but not their customer service.


http://www.grenadierprecision.com


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## 1feral1 (10 May 2005)

Similar to the AR18 and Uk L85A2 gas systems, and pictured just as I thought. Don't know how far it will go, maybe some LEOs etc, but with millions of M16 FOW in the US, Canada and other countries world wide, I can't vision a change that huge.

I have been around the M16 FOW since 1978, and I have full confidence in the system full stop, and this venture would not be the first time some one tried to go along the road of a gas system change.

Good luck, but I am sceptical. Sorry.

Cheers,

Wes


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## KevinB (10 May 2005)

48th - nice settup, and good luck.

 But like others I remain in the we dont need [or want] it, for the gas piston on the M16FOW.


You seem to have adapted the locking system for the bbl nut from the Troy, ARMS SP SIR, and inverted it - using a Surefire like locking mech for the (in this case) upper handguard portion


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## 48thHighlander (10 May 2005)

You will be surprised.  The advantages are in shorter barrel lengths where cyclic rate problems, premature wear, and unreliability problems are common.  For instance, this will cycle subsonic ammunition reliably in a 10.5 inch barrel.  Can you say that about the M16?

No more heavy buffers, pigtails, fat gas tubes in short barreled carbines.  No more carbon in the receiver.

This system was designed at the request of the US military unhappy with reliability and weapon life of the M4.  The USMC's 4th MEB's interest in this surrounds the 10.3" 5.56 KP.  It will solve all of their problems and allow the use of a QCB M4 styled system just as reliable or more so than a 20" M16.  And if you haven't noticed, the LE community is trending away from subguns toward short barreled carbines.  The added benefit is that in a 10.3" barrel it is day and night more controllable as there is no longer a requirement for a larger tap hole in the barrel and a huge gas volume and short pressure spike as found in current offerings.

The M16 was not engineered to have a 10.3" barrel.

I'm ot here to convince anybody.  Just some gun porn.  The people that are interested are already on the bandwagon.  That said, I will give you a short spiel as you are not likely versed in weapons engineering.

The LW MRS with this gas system was the last rifle to be dropped before the FN SCAR was adopted.  Its mean rounds to failure far exceeded the HK 416.  It was dropped as it did not meet all of the criteria for SCAR which changed continuously.

If this fades off into the sunset, then you can say I told you so.  All I have to say is if you shoot one, or you shot the 10.3" KP I shot that had 50,000 rounds through it with lube only, no cleaning, you would say "why not?"  If you saw who was looking at it and why, you would no longer be skeptical from the armchair.  Of course that KP had to have springs replaced not related to the gas system like the extractor, ejector, hammer springs replaced.  That is with a standard M16 bolt.  The since have adopted the advanced combat bolt that has a larger extractor, 2 extractor springs, decreased bolt locking lug mass to eliminate bounce.

This is not a sales call.  None will likely see civillian ownership in Canada, and the 2 agencies in Canada that have requested demo models are likely the only 2 that have a serious need and will not likely pick it up unless they buy conversions for their existing carbines.


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## KevinB (10 May 2005)

48th,

 Colt first went with the 10" in the XM-177E1's - so dont tell me it was not engineered.  LMT makes 10.3" for Crane that dont seem to have reliability problems.

 All shorties have bolt wear issues - but the bolt is an expendable part when you are doing that sort of round count.  I have friends down south that are in that sort of field and I know the piston systems do have a following.  However even with a 560 rd load how many times do you think you'd go thru 20 mags (28rds per) w/o cleaning.

 I 've seen a  KAC SR16E3 10" do a lot more than 11k w/o breakage - and with minimal cleaning.  KAC's 3rd gen bolt solves most of the short barrel issues (from ther bolt persepctive) 

As far as you set up goes.
Its not that I am skeptical that it works - my question is IS IT WORTH IT.  The minimal improvment in performance...

I'm not trying to slag you - I just have experience with a few piston systems - and I have been underwhelmed.


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## 48thHighlander (10 May 2005)

Minimal increase in performance?  You have never shot it so how would you know?

PM HipFiredGun on AR15.com and ask him.  He was part of the SCAR trials.

BTW, my 10.5 inch upper is LMT.  It was converted to the LW system.  There is no comparison before and after.  I see you have bought into the LMT hype and bullshite.  I bought the LMT as I couldn't find a complete upper in 10.5 anywhere else.  Read this.  It is the WORST piece of crap AR upper I have ever seen.

You are welcome to come to Texas and see for yourself.  I am a Class7 sot and we will shoot some post samples and you can see the difference.  LW doesn't even bother selling the attributes of the system.  They just give you one and let you figure it out on your own.

Again, I don't really care if you buy into it or not.  It is annoying that you have so much "experience" with gas piston uppers, yet NONE with this one, yet you claim to be an expert.

Anyone that gleens tech data from arfcom is playing with fire.  AR 15's are like purses over there.  What is written on the side is more important than just about anything else.

I don't want to slag it out with anybody, but please talk about what you actually know.  Get a hold of the picatinny arsenal high speed films and look at the difference in a standard 10.5 and an LW.


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## KevinB (10 May 2005)

48th I know others involved in the SCAR trial, MD/NS and the accompanying RISII.  

 You have picqued my interest however - since I admit I have shot the M416 and a few G36 variants but not the LW, I made a brush stroke on my thoughts on piston uppers.   I have a few friends in TX I might just come down  

I will say one thing about LMT - KAC was usign their forgings and now does their own in house...  AND (okay two things) there have been some questions if their a lot of their civilian/LE sale stuff is in fact reject QC from Crane...


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## Britney Spears (10 May 2005)

I thought what he meant by "minimal improvement in performance" was that there was no practical value in 10k rounds between cleanings versus 5k rounds between cleaning. I mean, really, that IS a minimal improvement, since it serves no purpose. At that point you better be careful about cooking off M203 rounds in the launcher too......


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## MG34 (10 May 2005)

Britney Spears said:
			
		

> At that point you better be careful about cooking off M203 rounds in the launcher too......



Not if you have the Diemaco wonder mount... : what a piece of sh*t. I would love to see where they got the M203 round cook off information from,seems to me it isn't a problem.

I have to say that I am skeptical of the actual improvement that a piston upper would make,but am keeping an open mind.


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## 1feral1 (11 May 2005)

Took this pic of a L85A2's gas system in Nov 03.


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