I'm wanting to rebarrel a Ruger Precision 556 to a cast bullet friendly cartridge 300 black out with a custom throat for powder coated NOE 311-299 RN.
I'm looking for subsonic range toy. No real use. I'm thinking 1/10 twist bullet is 1.2 long. Any thoughts?
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Well, a 1/10 Springfield will shoot the #311284 (218 grain) down to 800 f/s well.
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Shot the 300 Whisper (Blackout) in a Savage bolt gun, same bullet subsonic. Never really attempted match accuracy but did hit the gong at 340 yards. Well, not exactly on the first try but they got there.
John Carlson. CBA Director of Military Competition.
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Savage had 8.5 twist, 22 inch barrel.
John Carlson. CBA Director of Military Competition.
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Just my opinion but if I was going to build a 10 twist rifle for subsonic use only I'd probably go with something like the one inch long Saeco 315 or the 179 grain NOE copy. It'd also be a plain base to cut down on cost since you don't need it at the velocities you're going after. The RCBS 165 SIL might be a good choice also although I don't know if anyone makes a PB copy. If you want to shoot a longer heavier bullet subsonic I'd use a faster twist. Downside to that is if you want to go with higher velocity eventually you might lose some accuracy...maybe.
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In my 1:10 ROT .30- cal rifles, I get slightly oval holes with 200grs+ bullets at subsonic velocities. They still group well. But the unstable flight will be somewhat detrimental to the flight characteristics, which probably motivated the choice of such a heavy bullet, in the first place.
Still, the 1:10 twist is a versatile and good option that will also facilitate the use of higher velocity loads.
I would avoid the bore- riders if you plan to powder coat, custom throat or not. Particularly a design with such a long nose.
I would go with the 1:10 twist, but choose a lighter bullet without bore-riding like the excellent NOE311-179 suggested above. Coated PB is good not only for subsonics, but also for quite feisty loads in more potent cartridges.
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in one of the CBA match results a fellow was shooting a 700 in 300 BO with a long bullet and IIRC shot some good scores .I'll see if I can find it.
"if it was easy we'd let women do it" don't tell my wife I said that!
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10 or even 8 twist sounds good ... but be sure to plan ahead and cut a throat length to match your intended bullet ...
if you are shooting moderate velocities at only 100 yards you might consider optimizing for one of the good 165 gr cast bullets ... and then throat especially for that particular bullet. I am guessing a standard 300 blackout chamber has a very long throat that might lose a little support for the 165 gr. bullets.
my thought is that the lighter 165 gr will be easier to shoot recoil-wise after 5 or 10 shots to make up for probably a teensy more ultimate idealized accuracy from the longer 220 gr. bullets. if at only 100 yard shooting.
interesting project ...
ken
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Thanks for the information guys. I had a T/C custom shop barrel in 300/221 1/10 twist that shot cast great.
I'm kind of thinking about just doing this in the same. I can play with subsonic suppressed and some supers. Just not sure I want to do an 1/8 twist.
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I do shoot a few lubed, GC'd cast through my 30 cal sealed suppressor, not many so I don't worry about leading it up. Just a few occasionally for small game for the pot in camp or for vermin extermination when the smaller 22LR suppressed weapons aren't with me.
I recently switched out scopes on my 10" twist 308W sporter with a suppressor on it. The new scope on it is a Bushnell DOA 3x9 "600". My standard sonic load is a 165 Hornady SPBT over 41.5 gr IMR4895 in LC Match cases. That load runs 2670 out of the rifle. Zeroed at 300 yards with the 300 yard dot POA/POI It hits 1/2" high and 1/2" left at 100 yards with the crosshairs. I already had an accurate subsonic load so I figured out the zero for it at 50 Yards. My cast subsonic load is a GB Lee C314-170-FN loaded over 6.5 gr Bullseye (no filler) in M80 ball cases with the flash holes drilled. Velocity runs 1110 fps.
With just a Harris bipod for a rest on the bench I shot 3 shots out of the fouled barrel (had 10 shots of the sonic jacketed load through it) using the crosshairs centered on the 1" paster with the power at 9. That's the 3 shots low at 6 o'clock. I then kept the crosshairs centered on the paster and adjusted the power down until the 400 yard dot just covered the 3 shot group. Then I used the 400 yard dot centered over the paster and fired 10 shots. That's the group cutting out the left half of the paster. The zero for 50 yards with the subsonic load is then the 400 yard dot with the power set at 6 3/4. Close enough for government work......
Concealment is not cover.........
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Aaron
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Wm Cook
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linoww
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beagle6
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John Alexander
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John Carlson
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RicinYakima
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delmarskid
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Wilderness
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Bud Hyett
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