300 Blackout loads issue

[AZPaul]

I have a 10" pistol that I have had to work with to get them to hand cycle with my LEE 230gr tumble lube bullets. It seems sizing the case length down to the minimal Wilson Case checker length and shifting the COAL down to 2.16 I can finally hand cycle them. My question is, is that an okay length for 10gr of H110?
Please give my your feedback.

[missionary5155]

Good morning
I do not have a 300 pistol but every post I have read about good shooting and cycling pistols with multiple loads are all equipped with the adjustable pressure valve.
With my rifle (16") I found certain boolit nose shapes were somewhat prone to not feed well. The Lee 155 was awful. Pointy styles feed well. Any type of RN design was asking for frustrations. I have read it can be due to the smoothness of the feed ramps and the angles. Mine are polished as slick as my cloths can get them which helped .
Mike in Peru

[AZPaul]

What was happening was my bolt would slide shut but would not open. I trimmed my case down lower because I could see a ring around the very tip. But my bolt was still getting stuck. So I seated my bullers lower and that seem to have done the trick. But I'm going to slug the barrel and see if maybe the bullet are sized to large.

[wlc]

You may have already found your problem. I was going to suggest that either the bullet is just a bit too big, or you are seating too long for your chamber.

[petroid]

You will have to find what OAL works with that boolit in your gun. I can seat mine at 2.235 and they feed fine. Others have issues. 10gr H110 is a good starting point for subsonic loads with that boolit. My 12.5" pistol gas cycles and LSHO down to 8.5gr at 850 fps. 9.6gr gives me about 1000 fps. With the Lee 155 I had to seat to 2.010 or it would engage the rifling and was difficult to extract. I cycle subs and supers with or without suppressor just fine. Pistol gas system is the way to go.

[popper]

Cases should be trimmed, sized & expanded to fit the Case Gage. Then check in the chamber. Load a dummy in a properly prepped case & check OAL, seat a few thous. deeper. Adjust charge for pressure desired. I mic my loaded cases & pull any that are over my max neck dia. Either toss them or plan on neck turning them.

[AZPaul]

I guess my biggest question is that to short for that round? Will it cause over pressure?

[leadman]

The first thing you will want to do is slug the bore and size no more than .001" over. The bright ring you saw might be because your boolit is too fat and the case neck is too tight in the chamber. This can drive pressure way up.
If you have a case fired in your gun and not resized measure the outside diameter of the case neck and keep this figure. Check your loaded case and measure the outside of it to compare to the fired case. If it is larger then you need to size the boolit smaller.

Once you have the correct size boolit then you can check the max oal with a dummy case. A case with just about an 1/8" or so of the neck sized will hold a boolit tight enough to chamber. Load it long and ease the bolt home and this will push the boolit into the case. You will need to load a little bit shorter than this case to allow for variance in boolits and so a boolit is not pulled out of the case if you have to unload an unfired cartridge.

[petroid]

I guess my biggest question is that to short for that round? Will it cause over pressure?

Subsonic loads only develop about half of full pressure. You won't be over pressure