Help me build a 300 blk upper

[jnitti1014]

I just bought a 10.3 inch 300 blk upper from delta arms http://www.deltacompanyarms.com/product ... 52d15.html.

Now I need to order the rest of the parts. I was thinking a flat top upper. Mostly run suppressed with some super thrown in. I'm learning to reload my own ammo, and I want this gun to be able to cycle subsonic. Ammo. Any suggestions/tips? Can an adams arms retrofit piston system be used on a 300 blk upper, would you have to drill out the gas port? Also what buffers and springs are recommended.

Thanks in advance

[txwin70]

Great info can be found here.
http://www.silencertests.com/forum/view ... 28&t=73274

[stmcelroy]

So you bought a barrel, not an upper?

[jnitti1014]

Yes just a barrel. I saw the FAQ but did not see any info on pistons or buffer springs.

[JasonM]

Yes just a barrel. I saw the FAQ but did not see any info on pistons or buffer springs.

my personal opinions based on my experience-

- "Regular" GI buffer spring

- Start with an H buffer, with suppressor might be better with an H2. Basically, you want to run the heaviest buffer that will allow your gun to lock back on an empty mag with the ammo you use.

- Piston systems on ARs are not worth it in any way. No real benefits, extra weight, proprietary parts.

[jnitti1014]

Thanks, thats the kind of info I was looking for. Not sure I agree with the assessment of the piston system if your shooting suppressed. I will try out a cheap piston system from Centerfire and see if it works, if not I'll just put it on one of my 5.56 pistols. Which is the heavier buffer, an H or H2?

[stmcelroy]

Thanks, thats the kind of info I was looking for. Not sure I agree with the assessment of the piston system if your shooting suppressed. I will try out a cheap piston system from Centerfire and see if it works, if not I'll just put it on one of my 5.56 pistols. Which is the heavier buffer, an H or H2?

H2 is heavier.

[BretJ]

Piston vs Gas Impingement = Chevy vs Ford.....

I know some serious operators who favor one or the other and will argue the benefits of the respective flavors pretty convincingly. I am primarily an AK guy so I know what I prefer but I have heard (but cannot verify because I have not personally experienced it) that the piston systems are louder when suppressed than the gi systems. Try both if you can and see which you prefer.

[Dogtired]

Did they have the barrel in stock? I have my name on a list...

[dtom29]

Piston vs Gas Impingement = Chevy vs Ford.....

I know some serious operators who favor one or the other and will argue the benefits of the respective flavors pretty convincingly. I am primarily an AK guy so I know what I prefer but I have heard (but cannot verify because I have not personally experienced it) that the piston systems are louder when suppressed than the gi systems. Try both if you can and see which you prefer.

My experience with a SIG 556 (piston) and S&W AR (DI) is the SIG is noticeably louder.

[Recoil737]

Piston vs Gas Impingement = Chevy vs Ford.....

I know some serious operators who favor one or the other and will argue the benefits of the respective flavors pretty convincingly. I am primarily an AK guy so I know what I prefer but I have heard (but cannot verify because I have not personally experienced it) that the piston systems are louder when suppressed than the gi systems. Try both if you can and see which you prefer.

Pistons put a little less carbon in the bolt area when they are suppressed compared to DI. That is about their only advantage over DI.

The pistons have the disadvantage of using proprietary parts even between piston manufactures. They also add moving mass above the center line of the rifle causing a slight increase in muzzle rise. They add weight and complexity (springs/moving parts that can get bent/jammed/stuck) to the rifle. They add stress to the upper via carrier tilt by hitting the bolt at the carriers highest point. It will always be louder since you are expelling the hot and higher pressure gas less than an inch from the gas port directly into the atmosphere instead of through a gas tube then through the carrier into the bolt and finally being released out of the ejection port of your rifle.

Here is the kicker for all the drawbacks with very little advantages they charge you A LOT more for it.

P.S. I also own an AK and could not see hardly any advantage to putting a DI system on it. It just works with its simple bolt/carrier/piston all in one.

P.S.S. Spikes tactical makes an excellent H2 carbine buffer filled with tungsten powder vs blocks giving it a little less rattle noise. http://www.spikestactical.com/new/z/low ... p-201.html

[BretJ]

Piston vs Gas Impingement = Chevy vs Ford.....

I know some serious operators who favor one or the other and will argue the benefits of the respective flavors pretty convincingly. I am primarily an AK guy so I know what I prefer but I have heard (but cannot verify because I have not personally experienced it) that the piston systems are louder when suppressed than the gi systems. Try both if you can and see which you prefer.

Pistons put a little less carbon in the bolt area when they are suppressed compared to DI. That is about their only advantage over DI.

The pistons have the disadvantage of using proprietary parts even between piston manufactures. They also add moving mass above the center line of the rifle causing a slight increase in muzzle rise. They add weight and complexity (springs/moving parts that can get bent/jammed/stuck) to the rifle. They add stress to the upper via carrier tilt by hitting the bolt at the carriers highest point. It will always be louder since you are expelling the hot and higher pressure gas less than an inch from the gas port directly into the atmosphere instead of through a gas tube then through the carrier into the bolt and finally being released out of the ejection port of your rifle.

Here is the kicker for all the drawbacks with very little advantages they charge you A LOT more for it.

P.S. I also own an AK and could not see hardly any advantage to putting a DI system on it. It just works with its simple bolt/carrier/piston all in one.

P.S.S. Spikes tactical makes an excellent H2 carbine buffer filled with tungsten powder vs blocks giving it a little less rattle noise. http://www.spikestactical.com/new/z/low ... p-201.html

That's my point. I have other guys telling me their piston driven AR's recover much faster due to the mass of the piston system. One other selling point seems to be that the piston systems run much cooler. Probably due to the fact , as you stated, the high temp gasses are released to the atmosphere vice shot directly into the upper. Chevy's and Fords.

[jnitti1014]

I think I'm on the same waiting list, I ordered it two weeks ago, still has not arrived. No worries though, I need time to figure out what other components to use.

As far as the piston kit goes, does anyone foresee any problems using an Adams arms retrofit piston on a 300 blk barrel? Things like barrel diameter or gas port sizing?

[Recoil737]

Piston vs Gas Impingement = Chevy vs Ford.....

I know some serious operators who favor one or the other and will argue the benefits of the respective flavors pretty convincingly. I am primarily an AK guy so I know what I prefer but I have heard (but cannot verify because I have not personally experienced it) that the piston systems are louder when suppressed than the gi systems. Try both if you can and see which you prefer.

Pistons put a little less carbon in the bolt area when they are suppressed compared to DI. That is about their only advantage over DI.

The pistons have the disadvantage of using proprietary parts even between piston manufactures. They also add moving mass above the center line of the rifle causing a slight increase in muzzle rise. They add weight and complexity (springs/moving parts that can get bent/jammed/stuck) to the rifle. They add stress to the upper via carrier tilt by hitting the bolt at the carriers highest point. It will always be louder since you are expelling the hot and higher pressure gas less than an inch from the gas port directly into the atmosphere instead of through a gas tube then through the carrier into the bolt and finally being released out of the ejection port of your rifle.

Here is the kicker for all the drawbacks with very little advantages they charge you A LOT more for it.

P.S. I also own an AK and could not see hardly any advantage to putting a DI system on it. It just works with its simple bolt/carrier/piston all in one.

P.S.S. Spikes tactical makes an excellent H2 carbine buffer filled with tungsten powder vs blocks giving it a little less rattle noise. http://www.spikestactical.com/new/z/low ... p-201.html

That's my point. I have other guys telling me their piston driven AR's recover much faster due to the mass of the piston system. One other selling point seems to be that the piston systems run much cooler. Probably due to the fact , as you stated, the high temp gasses are released to the atmosphere vice shot directly into the upper. Chevy's and Fords.

Actually the piston driven uppers are harder to get back on target as they tend to INCREASE muzzle rise. This is partly why on full auto a DI m16 is much more controllable as all the reciprocating mass is centered along the horizontal axis of the rifle and not above it like the pistons are.

Try doing a full auto magazine dump on the AK and the rifle will rise up and to the left in a manner that makes any type of accuracy uncontrollable. This is due in large part to the mass centered above the horizontal axis of the AK and this is why they have funky compensators to try to minimize this effect.

You are right about the bolt running cooler but I have yet to see a good reason that I need my bolt to run cooler. To my knowledge no one has had a bolt melt or jam because it was too hot. By the time the bolt is even close to having problems with temperature your barrel would already be glowing white hot and about to fall apart.

To keep your chevy vs. ford argument you would have to have a gun that is on par as the one it is being compared too with close to the same price range and a piston driven AR is not.

A piston AR adds price, complexity, weight, non-uniformity all without any appreciable gains for it.

P.S. Since this is a blackout forum and a good number of the people on here want to suppress their rifle the second you put a suppressor on the rifle with a piston upper just about every little gain the piston gave disappears as the suppressor will send the heat and soot from the cartridge right back into the bolt area.

[BretJ]

Hehehehe...I am absolutely not disagreeing with you. Great point about suppressed. But you are proving my point. I have seen/heard/read many, many arguments on the DI vs Piston AR argument. I know operators who would tell you that you are as full of it as you would tell them they are full of it. I just read a rightup on a piston driven AR in a recent popular gun rag. They say just the opposite about muzzle rise at least as far as the AR they were reviewing. That is the point I was trying to make. I have found over time that, in many cases, arguments based on one vs the other are based on personal opinions/conjecture/experience and are no different than the age old Chevy vs Ford debate. DI vs Piston Driven is one of them. If the Chevy vs Ford is a sticking point, we can always use .45 vs 9mm in its place
There is no real answer other than try both if you can. Buy what you like.

[JohnnyC]

I would go DI for a 300BLK. It's optimized powder burn really negates any "cleaner operation" theory. It's proven that a properly lubes DI system will run dirty (see "Filthy 14") and really all that's required is proper lubrication. I can see why the SEALs went with the 416, because the operating requirements may not lend well to keeping lots of lube in the gun, and piston will require less. That being said, I cannot for see any situation a civilian would face that would keep them from finding some form of lube, be in actual purpose-designed firearms lube, or 10W-30, even old out of a broken down truck engine.

In a short barrel, the lack of full powder burn contributes to a dirtier gun, but again as long as the parts are dimensionally in spec (a very good read on this is on m4c written by our own Robert Silvers in the HPT/MPI really necessary discussion) all they require is lube. If 5.56 were optimized for full powder burn in a short barrel the difference would be even less, I would say potentially negated fully when compared to the piston system. The amount of fouling coming back through the barrel is the same be it DI or piston in a 5.56 gun. It's the DI action that is the sole reason for a "dirtier" gun, but then again the whole "dirtier" issue has been proven a moot point when you use properly dimensioned parts and keep the gun well lubed. Because the 300BLK is designed for short barreled operation (gas port distance and such), the difference is completely negated, and a piston really offers no pros and quite a few cons.

My 300BLK will be a 12.5" with a DD MFR, DI on top of a KAC lower as soon as I get around to ordering the barrel.

ETA: When I'm talking about short barrels and incomplete powder burn, I'm referring to the carbine gas system. I should have clarified. As the gas port moves further away, the problems diminish even further.

[silencertalk]

Piston guns tend to be louder. If you can build a pistol gun better than a DI gun in 300 BLK, it would be interesting, but surprising.

[Selectedmarksman]

Piston guns tend to be louder. If you can build a pistol gun better than a DI gun in 300 BLK, it would be interesting, but surprising.

I'm not an engineer so this may be somewhat of a stupid question. Has anyone tried to create a baffle system for gas blocks to combat the extra noise? I know most piston designs I see right now vent straight to the air. Even under a handguard that can be loud.

I don't know if the ATF would consider such things silencers. It depends on how they define 'report' of a firearm.

[din]

the OP wasn't asking if he should build DI or piston, he was asking if the adams piston kit would work with 300BLK, and if he'd need to do any port hole resizing to make it work. I'm curious about this too.

[silencertalk]

If it is pistol gas location, then it will work. I would say use the same gas port size and try different buffers. If you need to open it later, you can decide that after using it for a while.

[din]

If it is pistol gas location, then it will work. I would say use the same gas port size and try different buffers. If you need to open it later, you can decide that after using it for a while.

if you opened the ports enough would it work with carbine length gas? I'm just a pistol-gas bigot is all.

[silencertalk]

If the barrel is 16 inches or over, probably.

If the barrel is under 16 inches, then it depends....

On a DI gun, you can only open the gas port to 0.125 because after that, the gas tube becomes the limitation. It is possible with some piston guns for you can open the gas port to 0.180 or more. So maybe.... but it depends on how big the hole is in their gas block.

[din]

cool, thanks. I shall experiment! well, when my wife lets me buy a barrel. :0(

[renegade]

I just bought a 10.3 inch 300 blk upper from delta arms http://www.deltacompanyarms.com/product ... 52d15.html.

Now I need to order the rest of the parts. I was thinking a flat top upper. Mostly run suppressed with some super thrown in. I'm learning to reload my own ammo, and I want this gun to be able to cycle subsonic. Ammo. Any suggestions/tips? Can an adams arms retrofit piston system be used on a 300 blk upper, would you have to drill out the gas port? Also what buffers and springs are recommended.

Thanks in advance

I went with the AAC 9 inch BBL, and added a VLTOR 7 inch VIS.

[LYNRDSKYNRD]

I think I'm on the same waiting list, I ordered it two weeks ago, still has not arrived. No worries though, I need time to figure out what other components to use.

As far as the piston kit goes, does anyone foresee any problems using an Adams arms retrofit piston on a 300 blk barrel? Things like barrel diameter or gas port sizing?

Call Adams and ask they should be able to tell you if it will work or not.