I have recently started loading up .300 AAC / blackout. I have posted a picture about primers being pushed out on some cases, even factory ammo. I've found that the brass I've purchased and the factory ammo both seem to have the shoulder pushed back to far. I checked the cases and new rounds with my LE wilson case gage and everything is .005-.007" below the lower step! I'm trying to find good brass for reloading so I don't have to deal with the shoulder pushed back so far. Would I be better off making my own from .223 cases?
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Good .300 AAC brass
- Thread starter mohr308
- Start date
Whisper 300
New member
First off, I have been playing with the 300 BO long before it was BO and if I were blowing out primers I would initially check my powder selection and throw weights- pretty easy to get pressures up on 240 and 250 (yes there were Sierra 250 gr made). However, since you said factory ammunition and I read between the lines and you seem to suggest that it is more than a one time occurrence my thoughts lean towards headspacing of the rifle not ammo.
More information would help sort out the problem.
Now, as to what to purchase in the way of cases, I cannot help as ALL of mine were made from either 221 Fireball (initially) or selected 223 Rem brass that has been appropriately cut down and properly sized and trimmed.
Good luck and add more information to the next posting if you have it.
Maybe beg, borrow or acquire a set of go and no-go gages for it and know for sure you are head spaced properly.
Gary
More information would help sort out the problem.
Now, as to what to purchase in the way of cases, I cannot help as ALL of mine were made from either 221 Fireball (initially) or selected 223 Rem brass that has been appropriately cut down and properly sized and trimmed.
Good luck and add more information to the next posting if you have it.
Maybe beg, borrow or acquire a set of go and no-go gages for it and know for sure you are head spaced properly.
Gary
Geezerbiker
New member
it wouldn't hurt to have your chamber checked by a gunsmith or at the very least do a chamber cast. There's no way in H that factory cases should have the shoulder too far back. Something's hinky here...
Tony
Tony
"it wouldn't hurt to have your chamber checked by a gunsmith "
That would be a good start. I've used 4 or 5 different factory loads and loaded several hundred rounds using brass someone made in their basement. Despite the variability of this practice, I've not had any primer setback problems.
That would be a good start. I've used 4 or 5 different factory loads and loaded several hundred rounds using brass someone made in their basement. Despite the variability of this practice, I've not had any primer setback problems.
I contacted Ruger yesterday and I'm sending the rifle in for inspection. But when it comes the to factory cases sitting low in my wilson case gage, they are low no doubt about it, I used depth mics to double check. I don't know if I have multiple issues or something I'm not seeing. Also, the factory ammo did push out a primer, another one of my posts shows the image.
With my Hornady Headspace Gauge set in 2 AR Blackouts a case with the shoulder pushed back to 1.077" will barely chamber and the bolt close. Factory 300 BLK cases typically have the headspace at 1.068"-1.069". I try to size my brass to 1.073" for my 2 rifles. Appears factory brass is sized to chamber in all rifles but they are a little too short in my rifles. I'd prefer to make my own brass from once fired LC cases.
RG1, I decided to cut down a fired hornady .223, I sized it just to the point where the bolt on my rifle closes with no resistance. I sized it .001" at a time till I found that sweet spot. I checked it with my wilson case gage and the head sits .001" above the lower step. The factory rounds I had purchased (Hornady) sat well below. This makes me think Hornady had sized there brass to chamber well in semiautomatic rifles, like what you said All rifles.