lee 312-155 2r / 300 blk COAL question

[cstrickland]

ok so I am finally getting around to doing some cast loads in my AR. I bought the lee 312-155-2r and cast, sized and powder coated some boolits. I was loading them last night and seam to have a COAL issue for some reason. I see most people claiming around 2.02" - 2.10" COAL for this boolit , but if I load anything longer than 1.99"ish , the ogive of the bullet jams into the end of the chamber and sticks.I get a nice ring around the end of the boolit. At a COAL of 2.02" the ring on the boolit was about .26 from the tip of the boolit, with a case trim length of 1.358" - 1.360". Now if I load to the 1.99 there is no issue and everything hand cycles just fine

I actually had a dummy round get stuck, which pulled the boolit out of the case. I had to use a dowel to pop it out.

So what COAL are you loading for this combo?

thanks charlie

[petroid]

I load to 2.010 with DTPC boolits and 2.030 with Alox lubed. How are you coating and sizing? I size to .310 with a push thru. DTPC often gives a thicker coating which makes COAL different. Also, what does the nose of the boolits measure? If the mold has a really fat nose it will not chamber properly. Remember, that mold is designed for the x39 and is made to drop with a nose of .302 or so which is larger than SAAMI spec for 300BLK. Couple that with a short throat and you hit the lands before the boolits is fully chambered.

[cstrickland]

I load to 2.010 with DTPC boolits and 2.030 with Alox lubed. How are you coating and sizing? I size to .310 with a push thru. DTPC often gives a thicker coating which makes COAL different. Also, what does the nose of the boolits measure? If the mold has a really fat nose it will not chamber properly. Remember, that mold is designed for the x39 and is made to drop with a nose of .302 or so which is larger than SAAMI spec for 300BLK. Couple that with a short throat and you hit the lands before the boolits is fully chambered.

I use a .309 push through then DTPC back to roughly .310". the OD of the bullet where the ring is at is .304, which now after I look at the sammi drawing the max bore is .302. it just looked funny as I do not see any other marks on it only a ring.

[petroid]

I would suggest a pound cast of your chamber. It will tell you what you need to know

[popper]

Now if I load to the 1.99 there is no issue and everything hand cycles just fine Now you know your COAL. Maybe drop back another 0.01" for safety (2.90). Other solution is to get a nose swage die.

[Jeff Maney]

ok so I am finally getting around to doing some cast loads in my AR. I bought the lee 312-155-2r and cast, sized and powder coated some boolits. I was loading them last night and seam to have a COAL issue for some reason. I see most people claiming around 2.02" - 2.10" COAL for this boolit , but if I load anything longer than 1.99"ish , the ogive of the bullet jams into the end of the chamber and sticks.I get a nice ring around the end of the boolit. At a COAL of 2.02" the ring on the boolit was about .26 from the tip of the boolit, with a case trim length of 1.358" - 1.360". Now if I load to the 1.99 there is no issue and everything hand cycles just fine

I actually had a dummy round get stuck, which pulled the boolit out of the case. I had to use a dowel to pop it out.

So what COAL are you loading for this combo?

thanks charlie

I load the same Lee 312-155 boolit to 1.973" for my DPMS 300 Blk. It shoots great at 1,907 FPS.

Jeff