Adams Arms AR-15 Conversion to 6.5 AR Grendel Carbine

[gunner69]

I don't like the "direct gas" system on my AR it is too damn finicky with some ammo.

Every piston powered rifle I have tried shoots everything you feed it.

Anybody ever try one of these conversions??? Thanks.....

[z06man]

That's odd. I've never had a failure with my AR using numerous brands and bullets, but to answer your question, I've known quite a few people that have used the Adams piston. Almost all eventually go back to DI. They aren't a bad unit from what I understand. They just don't add anything but some weight to the system. You do have to worry the carrier tilt problem with piston systems also.

[MrSurgicalPrecision]

I've seen a lot of piston system failures. Even the Adam's Arms system. I've seen some that looked like a little grenade went off inside of them. I would think that the extra pressure of the 6.5G might not be good. Just my thoughts on the subject, not hard facts by a long shot.

[LRRPF52]

Everyone I know so far that has attempted to make an op-rod system work in the AR for shooting high-volume has been disappointed, to say the least. If you read all the gun rags, you'd think that op-rods in the AR were the cat's meow.

The real beauty of the AR design is that it is lightweight and has an in-line recoiling system, along with the mass of the rifle being balanced right above your firing hand. An op-rod negates these benefits, and steps backwards in achievement in my opinion, and the experiences of almost everyone I have seen with the op-rod AR's.

The op-rod driven AR does help reduce the carbon blast in your face when using a suppressor on the AR with a DI system, but that's about it. You can mitigate that with a simple PRI Gas Buster Charge Handle if you need to, versus changing the whole operating system. There's another thread on here where this was discussed in more length, but I can't find it right now. I suspect there are a lot of manufacturers who saw an opportunity to sell a new accessory for the AR, since there was a perceived solution to a problem created in the pages of gun writers looking for something to fix/print at $5.99-$8.99 a copy.

I've seen so many crazy piston systems at SHOT Show, with blatantly unreliable designs with small springs in piston valves and conversion kits for only "$299!!!", I lost track of them. As we have seen these kits eventually show up to high-volume carbine courses lasting at least 2 days and spending no less than 600 rounds per day, most of the piston guns have gone tits up within the first few mags, including damage that required the use of a backup gun, which is always DI.

There may be some designs out there that are holding up, but I would rather rock on with a known system that has been trucking along for decades. As I have said before, the Army looked into the op-rod AR back in the late 1960's, and they rejected it because it was less reliable than the standard DI M16, was more front-heavy, and cost more to produce on top of that. Here are some pics of that failed venture, from way back then.

Colt703-L.jpg
Colt703-R.jpg

LRRPF52

P.S.: I do like the sling loop hole on the buttstock of the Colt 703 though.

[sneaky one]

Wow, thanks lrrp52 . I was planning on changing to a piston sys. Yet I wondered why spend 300.00 on unknown reliability. I'll just keep wipin the soot off every once in a while on my rifle. Pick a clean powder, and there's no reason to waste coin on COOL new stuff... more time at the range, at less cost !

[LRRPF52]

When I see at least 3 prolific designers of op-rod driven AR's or members of those design teams, who also run high-volume courses using DI guns in their courses, I have to ask myself: Why are they voting with their weapon selection for their daily bread-and-butter with a DI gun, when they have been central to the development of op-rod driven systems?

Examples:

LAV and the HK416
Magpul and the Masada/now Bushmaster/Remington ACR
Some others I will not name, but they fall under the same phenomena

What you do see these guys shooting thousands and thousands of rounds through are DI AR's with particular attention to;
1) Quality barrels made to meet or exceed certain specs, with 5.56 chambers
2) Quality bolts/carriers with good extractors and proper springs, as well as secure gas keys
3) Balanced recoil and gas systems for the cartridges they are shooting (gas port diameter, gas system length, carrier weight, buffer weight/configuration, recoil spring type)

There have been way too many op-rod driven AR's that have shown up to classes, where time is critical and can't be wasted or diverted from the schedule to do armorer-level maintenance on a broken gun. One of the companies in particular has some pretty straightforward claims about 100% reliability (not even hammers achieve this in some people's hands), and their guns have been labeled POS (versus the actual name...hint hint) after breaking within 90 rounds downrange in rapid succession.

Friends of mine who make High-end Titanium suppressors bought 2 of these op-rod driven AR's to see how they performed with cans, and they broke straight away. I've never seen this or experienced it when running a suppressor when running any DI gun, and I've run DI AR's with cans in extreme cold weather scenarios under high-volume sessions, where the grease in my selector detent started to freeze.

You don't have to keep wiping the carbon soot off your AR, just make sure it's lubed with a good lube and keep shooting. I would suggest looking back at the importance of the 3 things on the list I mentioned for a reliability formula, without overlooking the ammunition factor as well.

If you believe in white-glove cleaning like we were forced to do in most military units, you still will have to disassemble a new set of small parts on an op-rod gun, and clean that piston and gas block...which is way more susceptible to foreign debris like large granule sand particles, since the gas block is exposed, as are the operating parts related to it...unlike the DI AR system.

LRRPF52

[montana]

I have to say I own both a DI and ADAM ARMS 6,5 gas systems . If I had to pick one I would go with the Adam Arms gas system. The DI system works fine and have it on a lite weight carbine. The Adam arms gas system is on a 18 inch heavy barrel and it shoots great. The difference is the fact that the Adam arms is self regulating and doesn't over gas like some DI systems can if the gas port is too big. I can also regulate the system when I put a suppressor on. I have shot allot of ammo without any problems with either of them . The DI system does require more lube like slick 2000 to keep it running good.But I wouldn't concern myself with either system You choose.

[warped]

When I see at least 3 prolific designers of op-rod driven AR's or members of those design teams, who also run high-volume courses using DI guns in their courses, I have to ask myself: Why are they voting with their weapon selection for their daily bread-and-butter with a DI gun, when they have been central to the development of op-rod driven systems?

Examples:

LAV and the HK416
Magpul and the Masada/now Bushmaster/Remington ACR
Some others I will not name, but they fall under the same phenomena

What you do see these guys shooting thousands and thousands of rounds through are DI AR's with particular attention to;
1) Quality barrels made to meet or exceed certain specs, with 5.56 chambers
2) Quality bolts/carriers with good extractors and proper springs, as well as secure gas keys
3) Balanced recoil and gas systems for the cartridges they are shooting (gas port diameter, gas system length, carrier weight, buffer weight/configuration, recoil spring type)

There have been way too many op-rod driven AR's that have shown up to classes, where time is critical and can't be wasted or diverted from the schedule to do armorer-level maintenance on a broken gun. One of the companies in particular has some pretty straightforward claims about 100% reliability (not even hammers achieve this in some people's hands), and their guns have been labeled POS (versus the actual name...hint hint) after breaking within 90 rounds downrange in rapid succession.

Friends of mine who make High-end Titanium suppressors bought 2 of these op-rod driven AR's to see how they performed with cans, and they broke straight away. I've never seen this or experienced it when running a suppressor when running any DI gun, and I've run DI AR's with cans in extreme cold weather scenarios under high-volume sessions, where the grease in my selector detent started to freeze.

You don't have to keep wiping the carbon soot off your AR, just make sure it's lubed with a good lube and keep shooting. I would suggest looking back at the importance of the 3 things on the list I mentioned for a reliability formula, without overlooking the ammunition factor as well.

If you believe in white-glove cleaning like we were forced to do in most military units, you still will have to disassemble a new set of small parts on an op-rod gun, and clean that piston and gas block...which is way more susceptible to foreign debris like large granule sand particles, since the gas block is exposed, as are the operating parts related to it...unlike the DI AR system.

LRRPF52

What I see is that people will read what you, Gene, Bob Reynolds, Bill Alexander and a few others write or have built and will yet second guess all that knowledge and somehow think that a piston operating system is superior.

We saw with our own eyes rifles with DI run suppressed 4k rounds without a hiccup, what this means is that if a rifle is assembled properly, with everything in proper balance and lubed correctly it will run like a Swiss watch.

I have seen $3k rifles shoot like crap and I have also seen low budget high quality builds run perfectly, I have seen rifles shit the bed in a modest carbine course.

I am not deriding anyone for their personal choice, but why is it that even COLT Defense with all their money can turn out the best piston weapon anyone has ever seen and yet it gets beat hands down by a DI IAR (6940)????

This is because nothing else runs as well and is as inherently accurate, we need to remind people that DI guns are the only thing that approached and have beaten bolt rifles in competition (not anecdotal evidence)

I know for a fact Ricky Harris beat all others in sniper competition with a DI 5.56mm weapon built by Templar Consulting, he ALLOWED the rifle to shoot as it should.

In fact he will be running a Grendel next time out due to its ability to buck the wind and allow for less drift.

We always read about people wanting something that shoots better, yet we can take nearly any quality rifle and put it into a machine rest and it will outshoot any of us.

We are the problem, if your rifle does not run and it is built well, then I suggest look at your maintenance, lube choice and choice of optics.

If it won't group then look at optics and mounts. If it won't run well suppressed then maybe you need to evaluate the buffer, gas block and buffer spring.

I know for a FACT that an oversized gas port was addressed with a simple mod to a gas block (not meant to be adjustable) and it ran perfect both suppressed and unsuppressed.

Chris Rance will be running a Grendel in his upcoming sniper competition, I feel he will come out exceptionally well, he is mentally prepared and trains hard.

He is capable of living up to his rifles potential.

He is only running a 16" chrome lined bbl and I am honored he is using the WCI brake as well.

Christian Eidsmoe shoots extremely well in 3gun, he runs a Grendel and WCI, he knows his rifle will run and how to ensure it is lubed and tuned properly.

My last point to make is that people often will shoot and blame themselves or the rifle, when the problem was the ammo used.

Even seasoned shooters have made mistakes with reloads and different environmental changes, like a race car we can only guaranty how something will run in a certain situation until all possible variables have been addressed, find another set of circumstances and that all goes out the door.

[Drifter]

I know for a FACT that an oversized gas port was addressed with a simple mod to a gas block (not meant to be adjustable) and it ran perfect both suppressed and unsuppressed.

Please share details regarding the simple gas block modification. -Thanks

[warped]

It got drilled from the top, a blunt tip, allen head, stainless, machine screw was put in and it was adjusted until the brass only flew about three feet.

Then it was left alone.

They made the screw fit inside the gas tube, it worked as a plunger type of valve.

It kept from wasting a very expensive bbl.

What happened was that during the drilling a bit broke, then it got buggered trying to get it out.

Things happen.

This was all under a FF tube so it did not matter.

[gunner69]

Thanks for all the inputs so far..... Montana, my concern with the Adams Conversion was that the 6.5 Grendel would cause the bolt wear that some piston conversions experience.

Warp, my experience with the AR is military related from the 60s & 70s. I kept my weapon clean and the damned thing still jammed a couple times. I must say it's a bitch to break out the cleaning rod, in the middle of a firefight, to clear your weapon. When I worked with the 1st Royal Austrailian Regiment (1st RAR) I carried their model of the FAL (L1A1) and that rifle WORKED 100%, but was heavy as hell to carry. Another plus for the FAL was that when your shot the little dinks, the 7.62 Nato put them down for good with one round. I guess I still don't completely trust the AR, but will admit it is accurate in the hands of a good marksman. I always shot expert, with the AR, but never liked the mouse caliber 5.56 (Bigger is Better).

When the Grendel round came out I bought three Alexander Arms Uppers and love them all. However, I have had several problems with two of those uppers. One seems to be overgassed, and the other is a f**kin' mystery at times. The Grendel caliber is a God Sent to the AR shooter. It is more than capable for most game, it is VERY accurate, and it is easy on the shooter.

[warped]

I love my FAL, it ain't heavy.

I carried the pig....wanna do cqc with a pig?

I will promise that you will have your heart pumping running up stairs with that.

Maybe I was not always the fastest runner, usually second, but that thing had me at next to last.