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Basic
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Posted: 10/16/2011 3:30:19 PM EST
Are the piston systems more forgiving on the amount of gas needed to function the action properly as compared to a DI system using the 300 blk/whisper ? From the reading I'm doing about that ctg. its very specific on what loads will function and what wont .Would a piston system allow some more flexibility . Or are there other factors that come into play here like gas port size ect.

Thanks,Tim
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Posted: 10/16/2011 3:47:01 PM EST
I haven't messed with a 300BLK piston upper yet but Stacy from PWS tells me their Mk109 won't run unsuppressed with subsonic ammo.
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Posted: 10/16/2011 4:05:25 PM EST
[Last Edit: 10/16/2011 4:13:19 PM EST by Plissken]
LWRC just unveiled their upcoming 300 BLK upper, which works with both super and subsonic ammo.

http://forum.lwrci.com/viewtopic.php?f=2&t=10288
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Posted: 10/16/2011 6:53:23 PM EST
+1 for the lwrc offering.
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Posted: 10/16/2011 7:22:18 PM EST
[Last Edit: 10/16/2011 7:22:49 PM EST by sinlessorrow]
Originally Posted By Plissken:
LWRC just unveiled their upcoming 300 BLK upper, which works with both super and subsonic ammo.

http://forum.lwrci.com/viewtopic.php?f=2&t=10288


is the gun that guys holding real? the guy in the blue?

i mean it looks tiny and like a toy, i mean if thats real that dude is like 8' tall
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Posted: 10/17/2011 8:29:20 AM EST
HAHA, the pic is real, real gun, and real Man. He's not quite 8 ft. but not far off,
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Posted: 10/17/2011 8:46:08 AM EST
Originally Posted By LWRC-JARRED:
HAHA, the pic is real, real gun, and real Man. He's not quite 8 ft. but not far off,


Too funny!

Jarred - if you really want to confuse everyone, re-post the pic that Jessie posted on the LWRC forum with him and the OCC crew. Hilarious!
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Posted: 10/17/2011 8:47:24 AM EST
I think that lil stock makes it appear smaller, looks like my 7.5in just with a smaller stock
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Posted: 10/17/2011 3:56:06 PM EST
[Last Edit: 10/17/2011 3:59:15 PM EST by TCBA_Joe]
I believe since it's a UICW variant it's collapsed OAL is 22" (vs the PSD's 25" OAL).

Also, the buffer section has been shortened. Compare the UICW CAR stock to a standard CAR stock and you'll notice it's been shortened forward of the locking mechanism.
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Posted: 10/18/2011 7:55:24 AM EST
Originally Posted By Plissken:
LWRC just unveiled their upcoming 300 BLK upper, which works with both super and subsonic ammo.

http://forum.lwrci.com/viewtopic.php?f=2&t=10288


Will it run subsonic without a suppressor? I don't think anyone can get their .300BLK or .300 Whisper upper whether it is DI or Piston to run unsuppressed with the subsonic loads without the back pressure boost of a can.
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Posted: 10/18/2011 12:30:44 PM EST
[Last Edit: 10/18/2011 12:31:03 PM EST by Sleeper396]
Originally Posted By Nekulturny:
Originally Posted By Plissken:
LWRC just unveiled their upcoming 300 BLK upper, which works with both super and subsonic ammo.

http://forum.lwrci.com/viewtopic.php?f=2&t=10288


Will it run subsonic without a suppressor? I don't think anyone can get their .300BLK or .300 Whisper upper whether it is DI or Piston to run unsuppressed with the subsonic loads without the back pressure boost of a can.

Since the video in that thread shows them running it FA with both types of ammo I would say...
YES
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Posted: 10/19/2011 4:19:49 AM EST
I shot a DI 300 Blackout with both types of ammo from CMMG on full auto at Knob Creek over the weekend.
8" barrel with pistol length gas port.
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Posted: 10/19/2011 5:29:45 AM EST
[Last Edit: 10/19/2011 5:31:20 AM EST by Nekulturny]

Since the video in that thread shows them running it FA with both types of ammo I would say...
YES

It had a AAC can on the whole time, my question refers to unsuppressed.
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Posted: 10/19/2011 1:47:47 PM EST
Originally Posted By shadowcop:
I shot a DI 300 Blackout with both types of ammo from CMMG on full auto at Knob Creek over the weekend.
8" barrel with pistol length gas port.
Dave N


A piston driven gun? I didn't know CMMG was making such a critter.
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Posted: 10/19/2011 2:36:27 PM EST
[Last Edit: 10/19/2011 2:37:46 PM EST by shadowcop]
No, it was a DI but my point was, it fired subs and super sonic with and without the suppressor. I'm having one built with an 8" barrel.
CMMG builds a lot of stuff you don't see on the web site. I always tell guys to call.
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Posted: 10/19/2011 2:44:00 PM EST
Originally Posted By Nekulturny:

Since the video in that thread shows them running it FA with both types of ammo I would say...
YES

It had a AAC can on the whole time, my question refers to unsuppressed.

My bad, I wasn't paying attention. I am pretty sure it does though.

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Posted: 10/19/2011 3:45:45 PM EST
Originally Posted By shadowcop:
No, it was a DI but my point was, it fired subs and super sonic with and without the suppressor. I'm having one built with an 8" barrel.
CMMG builds a lot of stuff you don't see on the web site. I always tell guys to call.
Dave


Thanks for clarification. I'm curious to read about your experiences.
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Posted: 10/20/2011 5:23:36 AM EST
Originally Posted By Sleeper396:
Originally Posted By Nekulturny:

Since the video in that thread shows them running it FA with both types of ammo I would say...
YES

It had a AAC can on the whole time, my question refers to unsuppressed.

My bad, I wasn't paying attention. I am pretty sure it does though.



Well, not one other manufacturer has been able to do so without making it severely over gassed with the full power loads, so I was curious.
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Posted: 10/20/2011 5:32:53 AM EST
Piston guns will be louder, for those who care about such things.
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Posted: 10/20/2011 5:52:07 AM EST
[Last Edit: 10/20/2011 5:52:21 AM EST by Nekulturny]
Originally Posted By Combat_Jack:
Piston guns will be louder, for those who care about such things.


That is dependent on the method that it vents its gas. Some piston weapons explosively vent right as the piston reaches its full length of travel, some don't.
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Posted: 10/20/2011 6:33:03 PM EST
Originally Posted By Nekulturny:
Originally Posted By Combat_Jack:
Piston guns will be louder, for those who care about such things.


That is dependent on the method that it vents its gas. Some piston weapons explosively vent right as the piston reaches its full length of travel, some don't.


examples of each?
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Posted: 10/21/2011 6:02:40 AM EST
too much pressure differences, you may be able to toe the line and get ok results with the 2 extremes, or you could have a regulator, and turn it for the different scenarios(I know its a tough concept ). Look at the difference in cycle energy, the direction the brass..
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Posted: 10/22/2011 3:12:54 AM EST
I would think an over sized gas port with an adjustable gas block would work.
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Posted: 10/22/2011 3:27:18 AM EST
Originally Posted By shadowcop:
I would think an over sized gas port with an adjustable gas block would work.
Dave N



http://www.300blktalk.com/forum/viewtopic.php?f=128&t=77810
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Posted: 10/22/2011 3:54:50 AM EST
[Last Edit: 10/22/2011 3:56:07 AM EST by shadowcop]
I don't understand Noveske's response. My reading it just sounds like they did not want to mess with it.
And it doesn't state what the gas system was. Carbine or pistol.
I would think the cyclic rate would only apply to full auto. I'm sure I'm missing something here.
I may have to do some experimentation.
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Posted: 10/24/2011 5:42:55 AM EST
Because of the challenges with the small case for the .300-221 variants, the .30 HRT was developed to give a larger case and perhaps add some flexibility. One of our customers had us build a 16" barrel upper, carbine gas system, using the Adams Arms piston system. It required some tweaking including minor modifications to the AA piston set up (replaced the spring with one with a lower constant). In the end, however, the customer was able to shoot anything from 110 gr to 240 gr bullets without issue, suppressed and unsuppressed, using the adjustment knob on the AA piston system.

Just a thought...
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Posted: 10/24/2011 5:54:43 AM EST
Originally Posted By naverno:
Originally Posted By Nekulturny:
Originally Posted By Combat_Jack:
Piston guns will be louder, for those who care about such things.


That is dependent on the method that it vents its gas. Some piston weapons explosively vent right as the piston reaches its full length of travel, some don't.


examples of each?


Well currently the only one that I personally know of that holds the gas for a bit longer is the PWS Long Stroke design in their uppers and rifles.

Everything else I've seen from the HK416, SCAR, and LWRC on down has a piston that only travels for .75 to 1 inch as it drives its Op-Rod rearward. Then that gas is dumped immediately at the onset or shortly after the action begins to open and cycle rearward. Even these designs will differ based on the internal shape and dimensions of the gas block and piston.
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Posted: 10/24/2011 11:43:28 PM EST
Originally Posted By Nekulturny:
Originally Posted By naverno:
Originally Posted By Nekulturny:
Originally Posted By Combat_Jack:
Piston guns will be louder, for those who care about such things.


That is dependent on the method that it vents its gas. Some piston weapons explosively vent right as the piston reaches its full length of travel, some don't.


examples of each?


Well currently the only one that I personally know of that holds the gas for a bit longer is the PWS Long Stroke design in their uppers and rifles.

Everything else I've seen from the HK416, SCAR, and LWRC on down has a piston that only travels for .75 to 1 inch as it drives its Op-Rod rearward. Then that gas is dumped immediately at the onset or shortly after the action begins to open and cycle rearward. Even these designs will differ based on the internal shape and dimensions of the gas block and piston.


cool, thanks for the info.
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Posted: 10/25/2011 4:54:38 AM EST
The short stroke tappet designs only touch the carrier for a split instant in time and then the carrier separates. They actually don't even push for their full strokes against the carrier. One of the advantages of the long stroke is non impact of the gap between op rod and carrier face of the short strokes.

If you were coming out of the water and shooting a long stroke would not be what you want, the piston would have to displace water before coming home....
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Posted: 10/25/2011 9:40:31 AM EST
If I wanted a non free floated long stroke system, I would just get an AK which is almost like having a 300BLK as it is.
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Posted: 10/26/2011 5:07:54 AM EST
Originally Posted By Sleeper396:
If I wanted a non free floated long stroke system, I would just get an AK which is almost like having a 300BLK as it is.


Except for the lighter weight, barrel quality and accuracy combined with the ergonomics and muscle memory to operate an AR you are right.
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Posted: 10/26/2011 5:09:24 AM EST
Originally Posted By ARMATAC:
The short stroke tappet designs only touch the carrier for a split instant in time and then the carrier separates. They actually don't even push for their full strokes against the carrier. One of the advantages of the long stroke is non impact of the gap between op rod and carrier face of the short strokes.

If you were coming out of the water and shooting a long stroke would not be what you want, the piston would have to displace water before coming home....


I think every AR, DI or Piston needs to drain before being able to function safely......the water in the bore will take longer to drain that that in the piston assembly.
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Posted: 10/26/2011 1:14:45 PM EST
Originally Posted By Nekulturny:
Originally Posted By Sleeper396:
If I wanted a non free floated long stroke system, I would just get an AK which is almost like having a 300BLK as it is.


Except for the lighter weight, barrel quality and accuracy combined with the ergonomics and muscle memory to operate an AR you are right.
That is if you buy crappy AKs, buy a Krebs and tell me if anything beyond muscle memory applies. Things are changing in the rifle world, you are seeing more and more AKs show up to Carbine courses. They are perfect for the type of work you see at those courses. There is no way possible to put those positive attributes into an AR without making some kind of compromise in the process.
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Posted: 10/27/2011 5:15:11 AM EST
Originally Posted By Sleeper396:
Originally Posted By Nekulturny:
Originally Posted By Sleeper396:
If I wanted a non free floated long stroke system, I would just get an AK which is almost like having a 300BLK as it is.


Except for the lighter weight, barrel quality and accuracy combined with the ergonomics and muscle memory to operate an AR you are right.
That is if you buy crappy AKs, buy a Krebs and tell me if anything beyond muscle memory applies. Things are changing in the rifle world, you are seeing more and more AKs show up to Carbine courses. They are perfect for the type of work you see at those courses. There is no way possible to put those positive attributes into an AR without making some kind of compromise in the process.


You are right, things are changing in the rifle world. A Krebs AK is not the end all be all of carbines though. Neither is a PWS. They both share the same method of operation however and for those looking for that style of operation in a less than 7 lbs AR, the MK1 rifles from PWS are pretty tough to beat.
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