300 BLK to check or not to check?

[MattN]

I was reading some posts in the PC area and decided not to hijack a thread. I have some questions.

I am working with my 10.5 300 BLK pistol (1-8 twist). Shooting a Lee C312-155 sized to .310 and powder coated, I can shoot a max or slightly over load of 296 (according to info based from my Hornady manual) with no leading. This is with boolits cast from straight COWW with no gas check. Accuracy isn't very good at that speed. I load it down significantly (low end of manual) and the group tightens right up. Would adding a gas check help increase the accuracy at a much higher velocity? With the slower velocity of current load, I was thinking of casting some at 50/50 COWW/pure the next time to see if that would still work. What about casting at higher BHN without checking to help accuracy? Thanks!

[44man]

I don't think so. Just being hard enough so as not to skid past the base band is good enough.
However, how would you know without testing? Give it a try. It is only money! :bigsmyl2:

[Jupiter7]

I still gas check supers even with PC if bullet has a GC shank.

[runfiverun]

I gas check my boolits in the 300 and I'm only pushing them to 1400 fps.
the accuracy is as good as jacketed.
I use a non gas checked boolit for the low velocity stuff.

[borg]

I find that without checks I get about a 5 " group @ 100 after brushing out the bore every two shots.
With checks, I get about a 1" group @ 100, brushing bore. ( I have a problem with a lead ring, so have to brush)
I'm just wondering if Alum checks will do the same.

[Boolseye]

I alway use gas checks in my 300BLK with the Lee 160 gr. version (CTL312-160-2R).
Size to .309", accuracy is excellent. 16" Carbine.

[MT Chambers]

For me the smaller diameter the bullet, the more it needs the gc., and .30 is small caliber.

[GhostHawk]

Depends on speed. I have shot the Lee .314 90 gr sized down to .311 with reasonable results. But I kept my speed reasonable.

I also shoot .312 155 and 185 and those are gas checked.

[blueeyephil]

Good timing! I just cast 200 of the Lee 312-155-R2 myself. I have checked and powder coated half of them. Just starting to do load development myself. I'll probably try a few without checks. I'm shooting an 8" barrel.

I'll be interested in your results. What range, accuracy and FPS ?

[popper]

Will GC help > 1400 - yes. Will higher BHN help - maybe. My normal alloy is close to WD COWW (~25 BHN), does OK 144gr PB in 300BO, ~1800 fps. Tried ~35BHN ~2700 fps No GC/GC in 308W, no GC didn't work. Another aspect on BHN, fps, sizing. Softer needs to be sized above groove, harder needs closer to groove. Still need to try the 35 BHN in BO.

[GooseGestapo]

I'm with Boolseye. I'm not powder coating, no need. Running max load with H110 for 1,950fps from 16"bbl.. 2" or so at 50yds. I do use SPG lube and Hornady GC's, but size to .311".