.300/221 - .300 Whisper AR questions

[Slimjim]

The only problem is getting brass, as they want 2.00 a round for the ammo. Nobody makes the brass because SSK has a patent and wont let anyone produce the brass except whoever corbon gets it from.

 

[Russ D]

The only problem is getting brass, as they want 2.00 a round for the ammo. Nobody makes the brass because SSK has a patent and wont let anyone produce the brass except whoever corbon gets it from.

Can't you make your own with existing brass?

 

[smores]

The only problem is getting brass, as they want 2.00 a round for the ammo. Nobody makes the brass because SSK has a patent and wont let anyone produce the brass except whoever corbon gets it from.

I bought Cor-Bon ammo to test-fire it, headstamp says "SSK 300 WHISPER".

Can't you make your own with existing brass?

Yes. You can either neck up .221 fireball, which produces supposedly non-concentric necks which lead to cases splitting - or chop .223/5.56 and neck it up.

There's a guy on Snipers Hide that sells pre-formed .300-221 brass, I should have some here within a week or so to check out for myself. $25/100 rounds.

 

[smores]

Ok, ready to test fire tomorrow. If all goes well a guy at school is going to engrave the chamber/barrel info and I'm either gonna fill the characters with paint or throw the barrel back in the bluing tank. Then the flash hider will be fully tightened/indexed... After that all I need is the Troy Industries 13.8" rail I'm waiting for from Brownells (it's on backorder), and of course a suppressor down the road.

 

[smores]

Ok, second range trip today. Took a bunch of reloads (if specific data is listed I can put it up here) and had much more success. Last time, 1 out of 3 rounds would jam feeding into the chamber, catching the case mouth and deforming the case - causing a complete stoppage. Brass is wrecked on those. I checked the upper receiver and it did NOT have M4 feed ramp extensions to match the barrel extension, so I busted out the file and made the cuts.

This time, out of 80 rounds fired, only 2 had that issue. The most common problem I had was the bolt would not strip a round from the magazine and chamber it. It was not a gas system issue as this happened especially when loading a fresh mag. I noticed this was frequent if my hand touched the mag - as I don't have handguards yet and was holding the front of the magwell with my pinky touching the mag, and I noticed a lot of failures to feed happened then.

If I slapped the mag in, released/charged the bolt, and did NOT touch the mag, it usually ran fine. A buddy at the range suggested tightening the mag catch, and after I did the issue appeared to go away.

I've been running with the JP adjustable gas block full open, and ejection is nice. The shells are landing within inches of each other (some are bouncing, but the place where they first hit the dirt is pretty much always the same). This thing is starting to run nicely. There's hardly a kick at all, just a SLIGHT bit of muzzle rise. Hopefully once I get the rail and AFG on there, the extra weight and a hand towards the muzzle might help minimize that.

 

[midcountyg]

The only problem is getting brass, as they want 2.00 a round for the ammo. Nobody makes the brass because SSK has a patent and wont let anyone produce the brass except whoever corbon gets it from.

Several people out there are making affordable 300 whisper brass from LC 5.56 brass. I haven't bought any, as I have been making my own, but they are out there.

Finally got to spend some time getting my Rem 700 barreled in 300 whisper up and shooting. I still have to debug it a bit. It is going to need a Sako extractor, as the Remington extractor isn't reliable enough for me. I have some minor work to do to get it to feed from the mag reliably to, but that shouldn't take much. On a good note, through a YHM Phantom suppressor it is nice and quiet

 

[smores]

Several people out there are making affordable 300 whisper brass from LC 5.56 brass. I haven't bought any, as I have been making my own, but they are out there.

Finally got to spend some time getting my Rem 700 barreled in 300 whisper up and shooting. I still have to debug it a bit. It is going to need a Sako extractor, as the Remington extractor isn't reliable enough for me. I have some minor work to do to get it to feed from the mag reliably to, but that shouldn't take much. On a good note, through a YHM Phantom suppressor it is nice and quiet

I have a source on a guy who converts Remington .223 to .300-221 specs. Loaded it and out of 200 rounds only had 2 FTF. Ejected brass is perfect except for a slight dent on the case mouth from hitting the shell deflector. Should be able to fix that during resizing.

A couple of guys at school built .300-221 bolt guns, one a cheap Savage and the other a Rem700. Both had problems with the shells ejecting inside the receiver due to the shortened case. One of the guys converted his to a single-shot rifle with no magazine at all because of it. No biggie for him since he's a reloader/target shooter and it keeps his brass fresh.

It's definitely a cool cartridge, and loading rifle shells with 11 grains of powder and less is pretty sweet, especially since .308 bullets come in so many flavors it's easy to tailor loads.

 

[Russ D]

How consistant are velocities when the case has so much extra space?

 

[smores]

How consistant are velocities when the case has so much extra space?

No idea, I don't have a chronograph. But the case is shortened (don't have dimensions right here but can get them) and you're seating a .308 bullet decently deep within the case - so I don't think there's a terrible amount of space in there. It may be more of an issue with subsonic loads, but I'll be using much heavier/longer bullets (up to 240gr Sierra match kings etc.) so there should be less space in the case.

I have been using H110 for my initial loads, which is a faster-burning magnum pistol powder. I had no noticeable unburnt powder or anything with H110, but will try other powders as I get more time to develop my loads. I have yet to load another batch and go sight my rifle in so I have no idea how accurate my loads are but functionally their performance is better than the Cor-Bon loads I bought initially.

I will eventually get a chronograph but my budget ran out and I couldn't get my hands on one to test actual velocities. Based on my Hornady book, I should have been pushing:

~1500 FPS w/ 150gr FMJ BT (13.4gr H110)
~1600 FPS w/ 150gr FMJ BT (14.6gr H110)

~1300 FPS w/ 180gr Cor-Lokt (11.4gr H110)
~1400 FPS w/ 180gr Cor-Lokt (12.7gr H110)

I had pulled that 11gr weight referenced earlier off the top of my head, I was assuming I could use less than that for the subsonic loads I want to run eventually. The Hornady book does not list any loads under 1200 FPS or with bullets over 190gr. There are various sources for more load data that I'll pull from in later development.

 

[CKOD]

How consistant are velocities when the case has so much extra space?

But once you get to the heavier bullets there really isnt much extra space, the bullet seats deep, and with such a small shoulder, there isnt much space around it. and all is well

240 SMK's seated at 2.260, and using IMR 4227, with 100% filling according to quick load, its only reach 43000 PSI according to quick load (take with a grain of salt) and muzzle velocity would be 1247 fps (quite a bit larger grain of salt, since thats not accounting for barrel friction, and the last 10" or so would be < 10,000 PSI behind the bullet, and the last 7" or so with < 5000 psi behind it, so it could very well be subsonic)

Even with 185 SMKs loaded subsonic (actually shot and listened for the crack, not just calculated), with Win296 I got ~60% full, and the loads smores listed would both be 60-70 % full, a little on the low side for consistany velocity for sure, but they are loaded quite conservatively, Cor-bon sells .300 whisper, 150 grain JSPs loaded to 1900 FPS

Oh, and if It'll help any Smores, with a .070 gas port in the pistol position (4.7" I think not the shorter pistol position that some mfr I cant remember uses) I can run 185's subsonic with VV N110 and winchester 296, and 200 grain lapua subsonics with IMR 4227, subsonic, and not have issues with cycling. the 296 and N110 wouldnt cycle the action with subsonic 200 grain bullets.

 

[smores]

Oh, and if It'll help any Smores, with a .070 gas port in the pistol position (4.7" I think not the shorter pistol position that some mfr I cant remember uses) I can run 185's subsonic with VV N110 and winchester 296, and 200 grain lapua subsonics with IMR 4227, subsonic, and not have issues with cycling. the 296 and N110 wouldnt cycle the action with subsonic 200 grain bullets.

Cool. My gas port is .075", and I have the JP Enterprises adjustable gas block. Once I get some more reloading components we can compare notes.

I'm gonna load up some more this weekend hopefully, as I got my rail installed and want to get my sights dialed in. I probably won't start messing with subsonics until I get a can, which hopefully won't be too far off in the future once I get out of school and can work full time!

 

[midcountyg]

How consistant are velocities when the case has so much extra space?

I have been loading 220gr SMKs with 8.5gr of Accurate #9 with fair results, and like said above there isn't a large empty space. I also tried some H335 loads with 13gr, and it performed ok. I haven't chronographed any yet, but seeing the accuracy I don't think I'm getting much deviation in velocity.

On the bolt gun extracting problem, I have the same issue with my Rem 700. This will get corrected when I upgrade the extractor. The problem is, unlike the AR extractor, the Rem factory extractor doesn't have the extra movement ability to follow the rim as the short case begins to pivot coming out of the chamber. It's a simple fix with a milling machine and a couple extra parts.