Which Caliber??? Piston System....

[CaptnC]

I'm trying to figure out which option is the best, might not be the smartest...but the best for short range hogs at night with a digital NV scope.

Here's where I am; I just received three AR rifles with Osprey piston systems. Only one is a chambering I find desirable.

They are 300 BlackOut, 6.8 SPC (not the II) and 7.62x39. They all have 16" barrels and carbine length gas systems.

Here is what I want; I want to put a can on it when it gets out of jail this September (fingers crossed) but I'm not interested in doing anything subsonic. So that almost knocks the 300BO out right up front.

While .270 Winchester is a long time favorite of mine, I'm not big on the 6.8 SPC. With it not being the type 2 chamber, even more so. So is it a big deal breaker for 6.8 SPC because it is the old chamber?

7.62x39 is what I have set up with the night vision right now. I just finished moving parts this past weekend to this rifle so I would have my most preferred parts on it.


Now I'm thinking, should I buy a 16" carbine length GS 6.5 Grendel barrel and scrap either the 300 BlackOut or the 6.8 SPC? I have three 6.5 Grendel's already so brass, bullets, powder and dies are all on hand. I can say the same thing for the 7.62x39.

The Night Owl NV has limited range. From what what I've seen so far it would be a bit of a challenging much past 100yds. That said I don't want to go to a pistol length barrel and deal with pistol brace or a SBR.

[A5BLASTER]

Go with the grendel. Your not going to get anything more with the 6.8. And since you already load grendel less money to go that route.

300 blackout is for me personally a look what I got guys kind of thing. I wouldn't even hunt with it a bow ranges but that's me.

6.8 spc- I know several guys in my area that have them and the II version and after direct comparison side by side at the range with several weight bullets in both factory and handloads.

They don't get anything more then what my 16 inch AA barrel gives.

Well I shouldn't say anything more, a few of them had handloads that would do close to 70 fps average faster then my 16 inch grendel could do.

But then again they did tell me their brass was toast after one shot.

Out of the 17 guys that I know that use that range and shoot 6.8 spc and spc II. Eleven of them have grendels now.

Not trying to sound like a salesman but it's kind of a no brainer to me with what you listed go with the grendel.

As far as the 7.62x39 it's a good round but I wouldn't use it if I already had a grendel. That's just me.

[grayfox]

For the 16" grendel (ditto what A5 said), go with the mid length gas, not the carbine length.

[CaptnC]

For the 16" grendel (ditto what A5 said), go with the mid length gas, not the carbine length.

Well gfox I still want to use the Osprey piston system. I'm told that it is the cleanest way to run a can. Osprey recommends using a carbine length system. Personally I'd prefer to use the longer gas system because the barrel selection is better.

I don't own dies for the BlackOut nor the 6.8...I can almost buy a new barrel for the cost of a good set of dies.

It's a shame the gentleman who passed had not heard about the Grendel. He appearantly really enjoyed building AR's. I have three piston AR's but none are 6.5. My purchase from his Estate gave me 4 300 BlackOut, 3 6.8 SPC (only one 2) and one 7.62x39....the rest are 5.56. The 7.62x39 (M4 contour) just happens to be a piston system.

I can tell you I never planned to buy any of the "other" calibers for the AR platform until this deal fell in my lap.

Also the Osprey piston system seems to need a lot of room. All three have M4 contour barrels. The SS 7.62x39 barrel I put on the piston 7.62x39 is a heavy contour. I had to clean up the bottom of the operating rod so it would move freely.

Anyone here running a piston system? Which one do you have...it seems the Osprey is the least desirable! At least it is to me...

[MaineAR]

Nothing wrong with the 6.8. 95% of ammo available for it isn’t the “tactical” loads that require the SPCII chamber. If you have your heart set on attaining “tactical” pressure you can ream out the chamber to SPCII specs and from what I hear it isn’t hard. The 6.8 is a nice round, it just can’t reach out as far with the efficiency and effectiveness that the 6.5G can. Depending on the make of the 6.8 barrel, it may be a good one to hang on to. But if you’re already invested in the 6.5G and 7.62x39, then it makes sense to hang on to them.

[Forgottenben]

Well gfox I still want to use the Osprey piston system. I'm told that it is the cleanest way to run a can. Osprey recommends using a carbine length system. Personally I'd prefer to use the longer gas system because the barrel selection is better.

I don't own dies for the BlackOut nor the 6.8...I can almost buy a new barrel for the cost of a good set of dies.

It's a shame the gentleman who passed had not heard about the Grendel. He appearantly really enjoyed building AR's. I have three piston AR's but none are 6.5. My purchase from his Estate gave me 4 300 BlackOut, 3 6.8 SPC (only one 2) and one 7.62x39....the rest are 5.56. The 7.62x39 (M4 contour) just happens to be a piston system.

I can tell you I never planned to buy any of the "other" calibers for the AR platform until this deal fell in my lap.

Also the Osprey piston system seems to need a lot of room. All three have M4 contour barrels. The SS 7.62x39 barrel I put on the piston 7.62x39 is a heavy contour. I had to clean up the bottom of the operating rod so it would move freely.

Anyone here running a piston system? Which one do you have...it seems the Osprey is the least desirable! At least it is to me...

[Klem]

I have used an Adams Arms but not Osprey. I have since taken it off and replaced with DI. The piston worked flawlessly in 223 but is bulkier and heavier than a DI system. Plus you end up stuck with a limited number of handguard options.

A piston won't be any cleaner than DI when running a can. The crud that makes your gun run dirty comes from the chamber, not the gas system.

I am not aware that any piston system can reliably run a Blackout when subsonic (see 300BLK forum). It requires more gas than is available to move a piston. Even with a suppressor attached you will likely find the gun will jam when using a piston, with subsonics.

Pistons were a fashion that has been and gone.

[BCHunter]

My thoughts, since it is dedicated night rig inside 100 yards and you already are leaning towards the 7.62x39. Keep with your first tendency.

Flip the 300 bo and 6.8 spc to fund your next project.

[Double Naught Spy]

I run a Superlative Arms piston on my Grendel. I do feel that it runs cleaner, not that you would notice after 200 rounds. The comparison reminds me of folks shooting different powders in pistols back when I used to compete and lamenting on which was cleaner. After firing a couple hundred rounds, you could not tell the difference between any of them. However, for a piston system on my Grendel and hunting, there is a noticeable difference when shooting a few rounds when comparing piston versus non piston, particularly as it relates to what it does to the cartridges in the magazine.

I definitely like the reduced amount of gas in the face that comes from running a piston with a can.

You are limited in the handguard choices. Yes, they do add a bit of weight.

If I wasn't running a can, I would not care one way or the other about running the piston system.

[CaptnC]

Well guys I've not been very impressed with it. The HG issue is a pain. I don't care for the big sewer pipe style HG it takes to give the piston room to run.

5 shots will most likely be a lot of shooting in one night, so I feel I'm wasting time messing the piston system.

[Forgottenben]

Well guys I've not been very impressed with it. The HG issue is a pain. I don't care for the big sewer pipe style HG it takes to give the piston room to run.

5 shots will most likely be a lot of shooting in one night, so I feel I'm wasting time messing the piston system.

Why not just sell em or trade em?

[Double Naught Spy]

Well guys I've not been very impressed with it. The HG issue is a pain. I don't care for the big sewer pipe style HG it takes to give the piston room to run.

I run a thin profile handguard on mine. I believe I am running this one... https://www.brownells.com/rifle-part...czxc%2bINCxzzx

[CaptnC]

Why not just sell em or trade em?

It's entered my mind but I would like to try one for a while. I know there is no reason to keep all three of them.

[CaptnC]

I run a thin profile handguard on mine. I believe I am running this one... https://www.brownells.com/rifle-part...czxc%2bINCxzzx

DNS are you running an Osprey system?

https://www.brownells.com/rifle-parts/gas-system-parts/gas-piston-conversion-kits/ar-15-gas-piston-conversion-kit-prod31987.aspx

I can't find it now, but I read it somewhere that you need a 1.8" ID to clear.

If yours it's like this you can get by with the smaller HG.

https://www.brownells.com/rifle-parts/gas-system-parts/gas-piston-conversion-kits/ar-15-adjustable-piston-system-625-solid-gas-block-prod86822.aspx

Never mind DNS...I see your running the Superlative Arms piston. I sure wish that was the system this man had used.

[CaptnC]

Hey A5B...I'm inviting you to join my thread!

I'm like MudRunner, 6.5 Grendel to my core. I have already been digging around looking for a 16" SS heavy profile carbine length gas system before I even started this thread.


I've had 7.62x39 AR's in the past still do. But it lacks the thump at longer range that I had been waiting from the AR platform. Then the Grendel comes along and I scrap almost all of my 5.56 rifles to convert them into Grendel's. I even scrapped a 7.62x39, but ended up buying the parts to build it back again.

This is a cut n paste from one of my posts, same subject line, from the Long Range Forum. Hell...it worked.

I think you can see I'm not deeply attached to the 7.62x39, but at one time it was a better choice over a 5.56 for deer and hogs.

So the 6.5 Grendel is still solidly in the hunt, but I want to work with the BlackOut a bit before I buy a barrel. Mainly because I'm not sold on the piston system. I'm waiting on my stamp so I can get my can.