The Third Way: How to improve DI

[Heavy Metal]

Everybody seems to be stuck in this binary choice that we either must accept the current DI systems or switch to a Piston.

Why limit yourself? What about a third choice? How about improving the DI system itself.

Two improvements to DI I can think of are:

The LMT Enhance Bolt and Carrier for the 14.5-16 inch Carbine gas rifles.

http://img190.imageshack.us/img190/9901/2wftgs2.jpg

The Knight Industries SR-25.

http://www.knightarmco.com/images/sr15_last_01.jpg

[Spot]

What exactly does the LMT enhanced BCG accomplish (assuming your gun is running well)?

I did read somewhere that it is kinder to the brass if you intend to reload, so that seems like a plus though.

[Heavy Metal]

Correct the timing issues generated by the Carbine gas system.


I would love to see LMT make a standard carrier with the less agressive cam track. Every AR could benefit from that singular feature regardless of gas system.

[ICANHITHIMMAN]

What exactly does the LMT enhanced BCG accomplish?

Good question I heard its only needed if your running a suppressor.

[usmc45]

Yea, supressor for sure. I ran one on a 14.5 with a Noveske Pig and it ran great. Then i put a standard 18" SS on it and the dam thing wont make it past 100 rounds without jamming up sticking and ****ing up your day. Dont use it unless you are running suppressed all the time. jusy my 0.02. Happy shooting

[sinlessorrow]

Everybody seems to be stuck in this binary choice that we either must accept the current DI systems or switch to a Piston.

Why limit yourself? What about a third choice? How about improving the DI system itself.

Two improvements to DI I can think of are:

The LMT Enhance Bolt and Carrier for the 14.5-16 inch Carbine gas rifles.

http://img190.imageshack.us/img190/9901/2wftgs2.jpg

The Knight Industries SR-25.

http://www.knightarmco.com/images/sr15_last_01.jpg

i wish they made a nicer BCG for a MK18 type rifles

[VIP3R 237]

Imo I think the sr15 is the epitome of all designs right now. After I shot one for the first time I thought why the hell do we need a piston when you have perfection already. If you can combine the lmt mrp with the kac innovations you may have the perfect ar.

[sinlessorrow]

Imo I think the sr15 is the epitome of all designs right now. After I shot one for the first time I thought why the hell do we need a piston when you have perfection already. If you can combine the lmt mrp with the kac innovations you may have the perfect ar.

you have to give it to stoner, his final designs are amazing.

he designed the 7.62 version of this rifle

[ABNAK]

What exactly does the SR-15 do to "tweek" a DI system?

What about a DI system similar to the MAS-49? Has a gas tube that blows into a dead-end hole in the carrier. No crap blown into the carrier/bolt, just into a deadspace that forces the carrier to the rear.

[E-man930]

Heavy Metal I agree with you.
I have a KAC Block III SBR upper on order from Knights and plan on dropping in my LMT enhanced carrier and then wring her out a few thousand rounds.

[Sry0fcr]

I'll admit to doing some brainstorming on this in the past but before we go about suggesting solutions, shouldn't we identify problems with the legacy system first? I'm curious to see if there's anything currently on the market that would be pretty close to what we could come up with.

[MikeCLeonard]

My tweaked DI rifles are going to consist of the following:

-LMT MRP
-LMT Enhanced Carrier
-LMT Standard Bolt
-Small Gas Port (14.5" barrel cut to 11.5")
-Vltor A5 buffer system

We'll see how she runs...fingers crossed! :D

[Clint]

Are you talking improving the AR platform or just the gas system?

[QuietShootr]

My tweaked DI rifles are going to consist of the following:

-LMT MRP
-LMT Enhanced Carrier
-LMT Standard Bolt
-Small Gas Port (14.5" barrel cut to 11.5")
-Vltor A5 buffer system

We'll see how she runs...fingers crossed! :D

I have a $20 that says that gun won't go 100 rounds without a malfunction.

[chadbag]

My rifle has a 16" mid-length barrel from Centurion Arms. It has a UBR with standard spring and carbine buffer. It has the LMT enhanced BCG (both bolt and carrier). (I believe it is an M16 one not a S/A one but would have to check)

(It also has a BAD on it but the problem I mention below happened before the BAD was added too IIRC)

The only "issue" I have seen in a year and a half of shooting it (not that much but both in 15deg weather and 90 deg weather and overall between 1500-2000 rounds probably [need to get out more]) is that in cold weather, down in the 30s or below, it won't always reliably lock back on the last round. Sometimes will and sometimes won't. Otherwise it has been rock solid. This is with mid-level 223 type ammo. Not 5.56 but not super weak 223. (Have not tried those last two -- mainly my own loads and a small amount of S.A. PMP 223 and a few various very small amounts of Norinco 223 and old 1990s PMC 223 and other random boxes I found in my ammo storage). This lock back issue only happens in colder temperatures.

When I was using a plain DD M16 BCG group I did not have the lock back issues in cold weather.



---

[MikeCLeonard]

I have a $20 that says that gun won't go 100 rounds without a malfunction.

HAHA, QS, you very well could be right on that!

I'm basically running along the same lines as Grant's small gas-port SBR though. With the enhanced carrier and H2, he was able to get that rifle running really well for high round-counts, and with an even smaller gas-port than I will be using.

With a tad-bit larger gas port, and the supposed consistency of the A5, I feel like I'm running on the safer side of operation with more gas than he did...So I'm hopeful it will work well...though if it doesn't, all I really have to do is open up the port to 11.5" barrel specs and all will be normal.

[Sry0fcr]

I have a $20 that says that gun won't go 100 rounds without a malfunction.

I say it won't get through 1 magazine before it short strokes.



HAHA, QS, you very well could be right on that.

I'm basically running along the same lines as Grant's small gas-port SBR though. With the enhanced carrier and H2, he was able to get that rifle running really well with an even smaller gas-port than I will be using.

With a tad-bit larger gas port, and the supposed consistency of the A5, I feel like I'm running on the safer side of operation with more gas than he did...So I'm hopeful it will work well...though if it doesn't, all I really have to do is open up the port to 11.5" barrel specs and all will be normal.

Except Grant's gun was built to run specifically with a suppressor. Unless you accidentally left that tidbit out...

[MikeCLeonard]

I say it won't get through 1 magazine before it short strokes.




Except Grant's gun was built to run specifically with a suppressor. Unless you accidentally left that tidbit out...

His rifle functioned just fine unsuppressed too though, if you didn't see that mentioned in his thread.

Mine will be run suppressed also, which I didn't mention...But if it doesn't run reliably unsuppressed, I'm going to open the port.

[MistWolf]

First thing I'd do is re-design the upper & lower to eliminate the accuracy killing slop between them!:dance3::jester:

Only two ways come immediately to mind on how to improve the AR design.

One would be to change the charging handle to a FAL style folding charging handle. It would make it easier to manipulate while slung up, especially when performing a "rack rack rack" to clear the action. It would also make the rifle easier to charge during dry firing (won't have to break cheek weld) and would make press checks easier, if using that method of verifying a loaded chamber.

The other change I would make is to the controls so it's easier to lock the slide back. I haven't tried one yet, but the button that lets you lock the slide back while depressing the mag release looks like it would work nicely.

A third change not as important to me as the first two would be to change the safety to a 45 degree throw ambidextrous style.

The only reliability/durability change I can think of using current technology would be to use a heavier barrel for better heat control. This would only be useful during the very rare, extremely harsh firing schedules, however

[sinlessorrow]

First thing I'd do is re-design the upper & lower to eliminate the accuracy killing slop between them!:dance3::jester:

Only two ways come immediately to mind on how to improve the AR design.

One would be to change the charging handle to a FAL style folding charging handle. It would make it easier to manipulate while slung up, especially when performing a "rack rack rack" to clear the action. It would also make the rifle easier to charge during dry firing (won't have to break cheek weld) and would make press checks easier, if using that method of verifying a loaded chamber.

The other change I would make is to the controls so it's easier to lock the slide back. I haven't tried one yet, but the button that lets you lock the slide back while depressing the mag release looks like it would work nicely.

A third change not as important to me as the first two would be to change the safety to a 45 degree throw ambidextrous style.

The only reliability/durability change I can think of using current technology would be to use a heavier barrel for better heat control. This would only be useful during the very rare, extremely harsh firing schedules, however

I actually like ADCORS attempt at the forward CH.

I am not a believe in we need a piston tapet system but adcor does make a DI version

http://www.adcorindustries.com/wordpress/wp-content/uploads/2011/06/product-image-bear-gi-elite-main.jpg

On that same note imagine a upper/HG combo that has a forward CH, but eliminates the rear. This would be, IMO a good upgrade. Suppressed shootig wouldnt blow stuff in your face anymore and you would have a better CH.

[justin_247]

Here's my ideal AR system, which I would use to standardize the system:

- Upper receiver:
-- LMT slick MRP upper in CQB and Rifle length
-- ADCOR BEAR-style forward charging handle
-- KAC E3 bolt
-- internal rails like on the Colt 6940P to accommodate piston-mods
-- Barrel lengths from 9" (like for 300BLK and 5.45) to 18"

- Lower receiver:
-- Shorter and wider magwell to accommodate the wider 5.45, 6.8, and 7.62 caliber magazines
-- Magwell blocks to ensure proper fit of the various magazines
-- Full-ambi controls like on the AXTS and LWRC lowers
-- VLTOR A5 receiver extension

Of course, most of this is already accomplished on the Colt CM901.

[rob_s]

One would be to change the charging handle to a FAL style folding charging handle. It would make it easier to manipulate while slung up, especially when performing a "rack rack rack" to clear the action. It would also make the rifle easier to charge during dry firing (won't have to break cheek weld) and would make press checks easier, if using that method of verifying a loaded chamber.

There ain't no free lunch. The Masada had a charging handle further rearward and operating it was obstructed by optics. So the ACR moved it forward, and not it obstructs certain rail-mounted devices.

I have no major objections to the location of the AR charging handle, and I think that the location is part of it's attraction as it leaves all of the rest of the gun free to mount accessories as well as place one's hand.

[TMS951]

I have a SR-15 upper, and a upper I built it is a 14.5" chf lw DD barrel with a carbine gas system, and the LMT enhanced BCG.

Shooting both uppers on the same lower with a Vltor A5 and using the same M885 clone ammo, They both shoot as soft as each other, with maybe a slight nod in softness to the LMT/DD set up.

I personally think the 14.5" carbine gas system, and LMT enhanced group is awesome. It has been totally flawless for me, and a real pleasure to shoot.

[Sry0fcr]

I think the platform could benefit greatly from a reduced cyclic rate & an adjustable gas system to allow for suppressed use, a wider range of ammunition and it might be able to mitigate gas port erosion and gas block placement to some degree as well. It seems that most of the function issues attributed to the M4 platform stem from the high cyclic rate caused by the guns being arguably "overgassed" even with TDP sized gas ports. Also from my home brew analysis there's some design issues with the standard bolt evidenced by the fact that it tends to fail in 1 of two modes: sheared bolt lugs opposite the extractor. Personally, I like Armalite's approach to the bolt lug issue. By relieving the offending lug it distributes the load more evenly among the other 6 lugs instead of the 1 taking the brunt of the impact. KAC's solution was to effectively strengthen all of the lugs, but it requires a new barrel extension. Perhaps use a lubricious plating or surface treatment (NiB or nitrocarburization?) to help keep the gun running when it gets hot and dry. Outside of that I think everything else is just a preferential thing.