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subsonic rifle cartridge

6K views 18 replies 9 participants last post by  nortac 
#1 ·
I'd love to see a subsonic rifle cartridge ie 300 whisper or 338 spectre etc but from talking to tech it would have complications with the full 16" bbl. Anyone have any ideas?
 
#2 ·
If you do a search on here from way back Alex posted about a 300 Whisper but it had some troubles. You could experiment with different loads and such but reliable cycling is the bane of all such endeavors in autoloaders.
 
#3 ·
I get that. I'd almost be ok with a single shot but honestly I would like it to cycle. I wonder about getting a piston and custom drilling the holes or as was suggested running a pistol/micro gas system on a 14.5 bbl with a 3 lug welded adapter 1.5" long.
 
#6 ·
The 300 Whisper is actually a very awesome round. I don't have one but one of my close shooting buddy's does and he & I spent endless hours tinkering with its capabilities. When loaded with supersonics, we used Speer 130 gr FBHP @ 2400 fps the damn thing shot sub moa. The upper was straight from JD Jones SSK 16.5" bbl.
With the 240 MK's it wasn't quite as accurate but still did very nicely hovering around 2 moa. We were firing it through a AWC Thundertrap which is designed to quiet down full power .30 cal rds and the subsonic .300 whisper didn't get the full benefit. We did get reliable full auto out of it suppressed and it was a little louder than my 9mm Uzi and can but slightly less mechanical noise. I think you could find a suitable powder to operate a piston set up like the XCR but it might take a lot of time and effort and would end up being a reloader only proposition. We used mostly H110 and 296 in our tests .
 
#7 ·
I own a custom Remington Model 7 in 300 Whisper. Have gotten 3 deer with the Sierra 125gr pointed softpoint at about 2300fps. All bullets expanded, all 1 shot kills, all shots went in one side and out the other (broad side lung shots). I have a Whisper upper for my AR on *order. I would think that the XCR, with its adjustable gas system, would be great in 300 Whisper. Since we can get the AR to function with anything from subsonic to supersonic, having an adjustable gas system (XCR) to play with should be a lot of fun (oh well, I can dream)

*= The intention is to shoot WWII 30 cal frangible bullets through it for cheap playing. They can be gotten for under 5 cents each in quantity.
 
#8 ·
Well I'm certainly willing to put in the time and effort, i'd like to get a gas plug blank and do custom holes and i'd certainly be ok with it being a reloading project. If it would generate more pressure/gas i'd even be willing to run a 338 spectre with the 6.8 bolt.
 
#9 ·
I want one!

Add me to the list for .300-221 (which is 300 Whisper but designed for resized 5.56 brass and no license fee to SSK Industries ;) ), if no better options are found. That would be a barrel-only upgrade for anyone with a 5.56 bolt. Make sure it's 1/8" twist so that it can stabilize 240gr bullets. I'll take an 11" for use with my SBR!

DSM: I could only find a post where Alex said he was going to try it; can't find any by him that say there were problems. And I'd be surprised if a short barrel with a can on the end boosting backpressure wouldn't be reliable.
 
#12 ·
OK, here's what I found. There wasn't as much info as I recall, but given that he seems to have dropped the idea Alex might be willing to discuss what issues he had with it. Since they are now selling barrel extensions it wouldn't be far fetched to turn your own barrel to run it.

Guys:

If we made as many 7.62x39mm rifles as we do 5.56, the price would be about the same. You guys on this forum are right, the R&D costs are higher. The 7.62x39mm varies much more than the 5.56 does. We had to do a lot more testing with a lot of ammo.

The 7.62x39mm ammo is cheap now but may go up a lot. For this reason, we may look at a .22LR conversion. On the other hand, We've had a few people want other .458 SOCOM and other weird calibers.

The 7.62x39mm does kick more than the 6.8 or 6.5. Our brake really helps a lot.

The advantage of our rifle over an AK or something cheaper is the accuracy. This darn XCR shoots tight groups using good 7.62x39mm ammo. I'm talking MOA or very close thereto.

BTW, the .300-221 didn't fly so well.

Also, if there's a moderator around these parts, he or she should put these posts under the 7.62x39mm thread.

Sincerely,

Alex J. Robinson
Manager
 
#16 ·
i like ur guys thread i invented the 300 whisper sabertooth bullet and r&d for a lot of diffrent rifles from Thompson's to ars never the xcr Ar's are easy to modify to shoot the subsonic bullet u can check out my bullet design on corbins.com subsonic to super sonic the bullet is great as far as brass u can go with cut down 223 or plain 221 fireball the xcr would need a softer spring to shoot sub sonic as far as accuracy i would like to know what bullets robinson tried if they were match king etc and at what velocity's i truly would love to see a caliber conversion in the xcr
 
#18 ·
I just started kicking around the 9x39 idea. I was looking into subsonic 762x39 but I think this would be interesting too as we'd be looking at reloading anyways. A standard 250 grn 9.3mm bullet many from midway usa and probably elsewhere gets loaded into a x39 necked up case. I was thinking a standard x39 bbl reamed out with a reamer and boom XCR/VSS...not that its that simple but it could be fun. I still think the 762x39 is the better way to go as you can still use standard rounds but this could be fun.
 
#19 ·
I look forward to working up some 7.62x39 subsonic reloads as soon as I receive my XCR and get it thoroughly broken in.
 
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