300 blackout

[milsurpshooter]

I have an AR15 300bo have not shot it yet, i really want to load cast in it but i have run into problem .I have a Lyman 314299bv mould .314- 205 gr gc that i use for my Argie that would like to use ,i have sized the boolit.309 alox lubed and seated into a case at neck deep,seated to fit magazine thing is wen chambered i have rifle engraved into 1/4 of the ogive ,here is the stumbling block.I could seat it deeper but then you go against the common rule of not seating below the neck.I see some commercial boolit like the Leatherhead 240 gr witch look a lot like the Lyman but much heavier and sized at .311.How can they be loaded without jamming into the lands? Then i still have to deal with the magazine but that is a different topic.Can anyone help me figure out this problem?

[blikseme300]

Seating with the GC below the neck is not a problem as long as the GC is crimped on good. You can test by first checking the GC fit after sizing and then making a dummy load without primer & powder and then pulling the CB to see if the GC stays put. This dummy load can be used for testing the OAL that will chamber in your rifle before pulling the CB.

[skeet1]

In my .300 Blackout I shoot the 311299 at .311 dia. This bullet is the same as yours except for the diameter. I seat the bullet with about 1/32" showing of the first driving band. At this depth the gas check is below the neck and has shown no problem. Accuracy is very good. The only thing that would concern me about your bullet is the diameter of the bore riding nose but if your rifle will accept it you are good to go.

Ken

[milsurpshooter]

That is all i have done this far,dummy rounds,i have pulled the boolit and the check stayed put , the Lyman after sizing in a Lee .309 mike .310 at the gas check ,309 driving bands and .303 the bore riding end.I also have a dummy made up from a Lee 312-160 2r also sized at .309 wen loaded it will jam into the throat and retracting the bolt require a bear of effort ,upon releasing the bullet will come out with the shell ,not stay lodged in the throat.

[milsurpshooter]

Finally got to shoot this new 300 bo ,i was more concerned to how it function than accuracy.I will say it was perfect with both jacketed and cast,also had no problem with the 2 magazine used 1 a usgi 20 rounder the other a 30 rd Thermold this one i did some filing of the rib before trying to use it ,maybe it did not needed any thing done to it but i will never know.For cast i shot the Lee 160 gr next time i will try the same sized .311 ,today was sized .309,for the jacketed only thing i had on hand was the Hornady 150 gr fmj.Next time i will try the accuracy of the loads ,today was just to try if the thing worked,it did.