Talk to me about 300 BLK supers

CWLONGSHOT

Well-Known Member
I have a few of them and I LOVE them. They are a wonderfully accurate pleasant gun to shoot. They work very well as a close range hunting tool. That accuracy really is a benefit, the low recoil and report also big plusses!!

I have used most appropriate weight bullets on game. Some work other work well still
Others have been miserable failures. MOSTLY cause of not enough velocity. MOST jacket bullets START expansion about 1800fps.

As stated and my experience as well the twist and rotation it affords destroys much possibly for accuracy with cast lead leaD. Unless you stick with low velocity and subsonics.

I have started using two new bullets in 2018. The Speer Gold Dot 150g (Designed expressly for the lil 300) and the Hornady 135 FTX. BOTH have been super accurate in my guns. In my Ruger Bolt MP300 and that 135 is clocking 2150 and sub MOA accurate. The load isnt safe in the AR. The 150, gets pushed by 4227 @ about 1800 fps. I have taken one deer with the Speer and THRU/THRU with good sized exit.

BUT...If I picked just one bullet for ever all around use. I would choose a 125 Hornady SST. The V Max in 110 (as well as the Nosler 110) would be close contenders.

For powders, H110/296 & aa1680 is all Id ever need. (Sure many others work)

Here is a few target pics of various loads fired from my 300's. Weather ya want a pleasant target gun a defensive tool or a close in hunting gun the lil 300 can deliver in spades. PLUS its frugal on powder and can shoot surplus 30cal fodder nicely.
E8175F2A-CF81-47ED-B095-83E7AAA5B3D5.jpegF847FB1F-B676-48AB-B78B-C6F56519D586.jpegB51400B3-A503-4A55-B12E-26B722DDAD55.jpeg790332C8-EC77-4F55-86E2-5930F402B60D.jpegAE45F3F2-2E73-417F-AE0D-41D8A0162AD0.jpeg3A08D771-5955-42E4-A16C-0A9983CF827B.jpeg731C4769-7737-4DDD-BCE2-8E3BE47ECA11.jpeg
 

popper

Well-Known Member
Plus the 170gr RD PB PCd @ 1500 in the pistol. I like the 125ST and 150 GD as well, found the GD is rather soft so pushing hard (2k fps) accuracy tends to be poorer. Didn't fine dimensions of the 316, if the SWC feeds and aligns with bore it may do well. I set the HJ up so jacket filled the neck. Set the Vmax the same. Vmax @ 50, vert was me. i was loading 2 in the mag and setting back on bags. Wasn't loaded real hot.
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Ian

Notorious member
You’re not allowed to spin that fast. You will get a ticket if you go over 125,000.

Weeeelll, don't tell the RPM police but.......

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CMMG 1 in 7", 16" barrel with carbine-length gas system.

Bad news is it jams so badly that I had to scrap three cases and load 5 more for the chronograph testing, all single-fed. Proof of concept for the speed, anyway.
 

Joshua

Taco Aficionado/Salish Sea Pirate/Part-Time Dragon
I’ll never tell. I ain’t no snitch!

Josh

P.s. Nice shooting.
 
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Ian

Notorious member
Should have tried the Lancers I guess, but when it choked with 300 BLK pmags my interest in continuing went to zero.

This would be a heck of a load for a bolt-action though.
 

popper

Well-Known Member
For some reason my lance BO mags will take the short OAL better for large meplat. But yours are much shorter than my 145 gr. or the RD style 170. You got the freebore filled but large meplat hangs on feeding. Neck length spacer behind them might work.
I like the 150 GD for BO but never could get them as accurate as heavier jacket 150s when pushed hard. They have a weaker jacket to expand @ 1400 so can't take the high pressure. Tested in 1:10 carbine with H110/W296. Rx7 may work better.
 
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Tomme boy

Well-Known Member
Try to find someone near to you with a 350L mag. Or if you whisper in my ear and call me daddy I could send you one to try.
 

popper

Well-Known Member
223 Pmags are interesting. Ribs are there only to stop lower cases from riding forward (shoulder stop). Front curves in to help pointy bullets aim right and the front lip is tall to point the nose up. Lips are only long enough to let the base pop up when 1/3 of nose is in the chamber. Straight wall or BO style cases have 2 problems, first is no necked down portion that goes into the bigger 'hole' easily. 2nd is trying to get the nose to rise properly without hitting the top of the chamber (or the bottom feed ramp and 'bouncing' high). I tried to make a bump on the follower to get rise right, not consistent enough. Tall nose on the Pmag didn't help either. If the bolt hits mid on the case, usually rnd is too low and bolt 'slips' - carrier hits base but bolt hits case as nose is too high. Sometimes the carrier pushes the case down, when the case tries to pop up the bolt hits it. Video will catch the problem but hand cycling isn't fast enough (usually) to cause it. The slightly rounded entrance to the chamber doesn't help much. Don't know what material the laser printer uses but probably won't last long. Delrin casts OK, ABS isn't real dimensionally stable as is hot cast. JBweld (steel filled) can be machined and wears well.
Local Cabelas never did carry gen3 BO mags that I could look at. I did get a Bob Sled single load (delrin) mag that works well and has a single 'channel', made for 223 but works for BO. Has a real gentle slope to the follower.
 
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Ian

Notorious member
Video will catch the problem but hand cycling isn't fast enough (usually) to cause it

This is the case. I was using the G3 300 blk pmags, not 5.56 pmags. Tje shoulder rib is perfect for blk subs with a long bullet but there needs to be a point on tje short bullets to work right. The jam is from bullet nose bouncing off of feed ramp and going high, hitting end of chamber and case head slipping under bolt and riding into tje case body, pinning it against the feed ramp. Hand-cycles fine and chamvers from bolt release fine. I think it's way overgassed and rebounding the bolt too quickly, there's a sharp whack from the buffer slamming the end of the buffer tube.
 

Tomme boy

Well-Known Member
@Ian does your barrel have the wider m4 ramps? The BO has different feed ramps than the regular m4 ramps. I have tried the different BO mags in the 350l and they did not work. But it will chamber even this bullet with the legend mags. https://www.midsouthshooterssupply.com/item/0000690303/double-cavity-mold-358-158-rf

If it will feed that wide faced bullet, it should feed the one you show. One thing I noticed on all the 350l mags is very high tension on the follower. Almost 2x the force it feels. That is to keep the base of the brass up and not letting it release till the very last second. Maybe stick something in the bottom of the mag to push up the spring to create more spring pressure. Easy way and won't cost you anything but time to try it.
 
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popper

Well-Known Member
Tomme, part of problem is the short OAL, case moves pretty fast forward til hitting the ramp, then bounces. Lips may need to be back farther to allow head to pop up but hey, hate to ruin a BO mag to experiment.
 
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popper

Well-Known Member
Changed the scope mount on the CVA back to the burris. Checking sighting @ 50 today. 110 vamx and 146 GC & 170 PB. Acceptable now. Did adjust the scope couple times. Groups pretty good for just off sandbag.
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