Anyone reaming 300BO case necks?

[kstone803]

So I'll start by saying I have a love hate relationship with 300BO. I reload over a dozen other calibers and nothing has ever been as finicky and a PITA as 300BO. I have issues with loaded rounds not passing a case gauge after reloading. The brass all drops out of the gauge great but after loading many won't gauge. I've tried multiple expander dies, the m series I've got now seems to cut down on the issue some but it's still prevelant. Multiple bullet types as well, mostly 190+ grain for subs. I think the issue is case wass thickness from processed brass. I've got a few thousand I had MS process a while back and it was all mixed headstamp. So does anyone here ream their 300BO case necks and did it help with chambering issues? My other option I can ponder is having someone cut the neck on the chamber just slightly oversized. Will this have a negative impact on accuracy? Most likely, but I'm slinging subs 100 yards not whacking antelope at 600. Thoughts?

 

[guzma393]

So I'll start by saying I have a love hate relationship with 300BO. I reload over a dozen other calibers and nothing has ever been as finicky and a PITA as 300BO. I have issues with loaded rounds not passing a case gauge after reloading. The brass all drops out of the gauge great but after loading many won't gauge. I've tried multiple expander dies, the m series I've got now seems to cut down on the issue some but it's still prevelant. Multiple bullet types as well, mostly 190+ grain for subs. I think the issue is case wass thickness from processed brass. I've got a few thousand I had MS process a while back and it was all mixed headstamp. So does anyone here ream their 300BO case necks and did it help with chambering issues? My other option I can ponder is having someone cut the neck on the chamber just slightly oversized. Will this have a negative impact on accuracy? Most likely, but I'm slinging subs 100 yards not whacking antelope at 600. Thoughts?

Is this 300 blk hs cases or 223/556 mixed convertted hs cases? If converted cases, there are certain hs that are not compatible with the case necks being too thick. LC brass is a definitive convert hs, and I never had issues with clambering once I figured out what HS worked, and what HS I didn't want to deal with, I.e. certain batches of federal hs not chambering.

Otherwise, If it's 300 blk commercial hs cases. I don't think you'll run into issues, and can rule out if your chamber or something else is out of spec.

 

[John from MD]

There is a list of which .223/5.56 brass is acceptable for making 300 BO cases. Some manufacturers use thicker brass and it doesn't work well. This link will take you to it.

STICKY - Good/Bad brass list converting 5.56->300blk » 300BlkTalk

 

[kstone803]

It's mixed batch 5.56 and .223 brass I had converted. I know there's a list of headstamps to use/not use. But I have about 5000 converted cases I would like to make more usable. Thus why I'm asking about reaming the case necks.

 

[85MikeTPI]

There is a list of which .223/5.56 brass is acceptable for making 300 BO cases. Some manufacturers use thicker brass and it doesn't work well. This link will take you to it.

STICKY - Good/Bad brass list converting 5.56->300blk » 300BlkTalk

^this…

I was doing mix headstamp when I first started and soon realized some brass is just too thick in the new neck region

I only convert LC/NATO brass now, the neck is good and the generous temper allows you to not have to temper the converted brass

 

[guzma393]

It's mixed batch 5.56 and .223 brass I had converted. I know there's a list of headstamps to use/not use. But I have about 5000 converted cases I would like to make more usable. Thus why I'm asking about reaming the case necks.

If heard of people neck turning it, but the amount of effort doing that could be used to just convert more 300 blk cases. What headstamps are the 5000 convertted cases? I would sort it and use definitive hs brass i.e. LC, winchester, remington on the top of my head, and experiment with the other headstamps to get a correlation on which work and which doesn't.

 

[atblis]

You need to get a micrometer and measure. What’s the OD of the neck on a loaded round that fails your case gauge?