Molds for Blackout Giving Troubles - 311365, 311413 etc. Ideas?

[psychbiker]

The 4 molds I have for my Blackout AR are - 311365 PB, 311291 GC, Lee 312-155 GC, 311413 GC.

I've casted and sized to .310 A LOT of these boolits. Plan was to use them for blackout and an M1A.

I made some dummy rounds for the blackout just now and struggled to get any to cycle. My manual lists COAL for all at 2.000 and above. There's no way that's happening. I was able to get a 311365 to chamber and eject at around 1.980". These fit and drop from a Sheridan gauge.

I'm using a Lee Taper Crimp.

Any ideas what could be the problem? Do I have to load these deeper? What about taper crimping? I run the bullet up in the ram and turn the crimp die until it stops, lower ram and then add a quarter turn.

Maybe size them to .309? I'd have to order a new sizer as I polished mine out to .310.

The 311291 did not chamber from the mag well either, it was awfully short. I think it's a good round for the M1A.

[curator]

Getting cast boolits to properly "cycle" in the .300AAC on an AR platform requires cases with "thin-enough" necks to chamber with .310 diameter slugs, A boolit nose that will both feed and chamber, as well as powder charge/burn rate that will reliably function the action. I have reasonable results with the Lee 309/180*, Lyman #311041, and a LBT 310/180SP bullet moulds. I load them to fit the magazine length and check that each will chamber. Lyman #311291 shoots accurately but hangs up on my feed ramp about 1 out of 3 rounds. Many Mil-surp "converted .223/5.56NATO cases hat necks too thick to chamber with these boolits. I also lightly taper crimp to prevent bullet set-back upon feeding.

Send me a PM with your off list e-mail and I will send you a list of brass that works for conversion to .300AAC and will feed cast boolits

[Geezer in NH]

Well duh!!

I made some dummy rounds for the blackout just now and struggled to get any to cycle. My manual lists COAL for all at 2.000 and above. There's no way that's happening. I was able to get a 311365 to chamber and eject at around 1.980". These fit and drop from a Sheridan gauge.

Your rifle seems to like the 1.980 OAL it is nor rocket science load them to that length. Seriously you are trying to hard.

Load for YOUR gun not someone else's.

[psychbiker]

I got the OAL Hornady gauge and am rocking and rolling now. Most have to be loaded a tad short it seems than manuals. I was able to get the 311365 to load long and cycle in two ARs. It's crazy how they are near the same in couple bullets and off by .030+ on others.

Still debating on reaming the throat with a .311 reamer. I emailed a reamer maker, reputable one, and they said that converted 223 brass is thicker than factory blackout brass around the neck which causes chambering issues.

I'll just have to adjust powder now and start low compared to the manuals.

[destrux]

With the Lee 155gr I load them to where the case to the top groove on the bullet and they feed just fine in my AR. I size them to .309 though, not .310.

You also have to watch what brass you're using with the .300 Blackout. Not all 5.56 and .223 brass will convert well. There's a list of brass brands that work and don't on the 300blktalk forum. Be sure you're not dealing with converted brass that's too thick in the neck to function period, let alone with oversize cast bullets. The brass that does convert well will not be much thicker (if at all) than factory .300 brass.

You also should consider what magazines you're using. With the longer bullets (usually 170gr+) I had to file the guide ribs inside the P-Mags to make them stack and feed flawlessly. I have to run P-mags with those since aluminum mags can't be filed like that.

The 155gr feed nice from normal mags though.

[marvelshooter]

I am building a 300 Blackout with a 16" KAK barrel. Dummy rounds in converted cases will not chamber with .310 boolits. At .308 they chamber fine. The converted cases are both Federal and Remington.

[Motor]

Take your boolit. Paint the front half with a marker. Take your caliper and open it to .250" then slide it over the point of your boolit. Rotate the boolit so it scribes a line on it where it is .250" in diameter.

Now take a GI magazine. Hold it front facing right. Push the fallower down so you can see the rib stamped into the wall of the magazine. This rib is about 1.760" from the back of the magazine in the side wall.

Seat your boolit so the scribed line is aligned with the rib. Then see if it will cycle.

Motor

[Wedgie]

Have a look at the D&H 300 Blk 20 and 30 rd magazines (Bravo Co. has them). They have the rib set back and allow stuffing fatter bullets (247 NOE) etc. into a magazine without binding. I load the 247 to mag length and have no problems at all with the magazine. Widening M4 feed ramps will help to not shave lead during feeding and will reduce feeding issues and leading. Also use a good crimp to prevent any setback which will rob the action of energy along with potential pressure problems created by the setback. I use a Lee FCD and crimp as shown below:
183031

[popper]

Just finished a 10" KAK (cheap/OEM barrel) pistol. I size 3085, neck turn all my brass, factory or converted. Chuck the case in elec. drill and use the hand-held turning tool. doesn't take much time and insures no problems.

[clearcut]

I turn all the necks down to .012 with a RCBS neck tool and reduce the OA length till they chamber I was ready to go back to .223 till I did this now it has no problems. I'm sizing to .309 w/PC and GC now I love my 300 aac bo again. PM me if you have ??

CC

[therealhitman]

https://www.youtube.com/watch?v=_08yZXnk7ro