M48 chamber issue
- Thread starter r.fallon
- Start date
I have experienced something similar. My Yugo 48A chambers new factory ammo (eg Remington, Norma, Sellier+bellot) with no issues.
I have a sporter in 8x57 and I handload as well. I decided one day to shoot some of my handloaded ammo in the M48A. The bolt was really difficult to close on the M48A but the handloads fed perfectly in the sporter.
When relaoding, I always full length re size the brass.
I discovered that the M48A does not tolerate brass that has stretched more than a couple thou over the recommended "trim to" length (Lyman reloading manual. Trimming the brass every 2 or 3 firings has solved my issues.
I have some Remington brass that has been fired 5 times now from the 48A. I just make sure to check the case length each time I reload and trim as necessary.
I have a sporter in 8x57 and I handload as well. I decided one day to shoot some of my handloaded ammo in the M48A. The bolt was really difficult to close on the M48A but the handloads fed perfectly in the sporter.
When relaoding, I always full length re size the brass.
I discovered that the M48A does not tolerate brass that has stretched more than a couple thou over the recommended "trim to" length (Lyman reloading manual. Trimming the brass every 2 or 3 firings has solved my issues.
I have some Remington brass that has been fired 5 times now from the 48A. I just make sure to check the case length each time I reload and trim as necessary.
That doesn't mean anything more than the chambers differ, and doesn't necessarily say anything about good or bad headspace. If you are working with a never fired round, or a freshly F/L re-sized round, AND the chamber is clean, AND you're feeding from the mag with the extractor over the rim, AND the bolt still won't close with reasonable pressure then you would seem to be short on chamber depth and need a gunsmith to correct it.
A new never fired American factory round should be .002 (two thousandths) shorter or smaller than the minimum SAAMI head space setting and should chamber without a problem.
A full length resized case can end up longer than the slightly undersized factory round and be a snug fit in the chamber or even hard to chamber.
A full length resized case “grows” in length during the resizing operation and if the case is a tight fit in the chamber and the base of the die is firmly contacting the shell holder firmly you have a slight problem.
If a new or different resizing die and shell holder does not fix the problem you will need to remove several thousandths from the top of the shell holder to allow the resizing die to push the case shoulder back further.
Note: My uncle has a European made Mauser in .270 Win, factory shells fit the chamber BUT if you full length resize these same cases they are hard to chamber. RCBS told me to lap/sand the shell holder until the cases would fit and then remove at least .001 to .002 (one to two thousandths) more from the shell holder. This particular rifle had the head space set just at or very slightly below the minimum head space setting and I keep a separate “shorter” shell holder just for his .270.
If you have a BO M-48 or an M-48 without any markings (scrubbed) it may be a different caliber, and you may need to slug the bore.
A full length resized case can end up longer than the slightly undersized factory round and be a snug fit in the chamber or even hard to chamber.
A full length resized case “grows” in length during the resizing operation and if the case is a tight fit in the chamber and the base of the die is firmly contacting the shell holder firmly you have a slight problem.
If a new or different resizing die and shell holder does not fix the problem you will need to remove several thousandths from the top of the shell holder to allow the resizing die to push the case shoulder back further.
Note: My uncle has a European made Mauser in .270 Win, factory shells fit the chamber BUT if you full length resize these same cases they are hard to chamber. RCBS told me to lap/sand the shell holder until the cases would fit and then remove at least .001 to .002 (one to two thousandths) more from the shell holder. This particular rifle had the head space set just at or very slightly below the minimum head space setting and I keep a separate “shorter” shell holder just for his .270.
If you have a BO M-48 or an M-48 without any markings (scrubbed) it may be a different caliber, and you may need to slug the bore.
Just to put my two cents worth in:
Make sure you are chambering the correct type of 8mm Mauser. There are two major types out there, the 7.92x57mm I round (or round nose bullet for .318) and 7.92x57mm IS (or Spitzer; pointed round for .323). I have noticed the problem, where I tried chambering a "I" round in a .323 bore and the bolt will not close. I believed this to be the length of the bullet and not being able to feed in the chamber and getting stuck just outside on closing the bolt.
Hope this helps.
Make sure you are chambering the correct type of 8mm Mauser. There are two major types out there, the 7.92x57mm I round (or round nose bullet for .318) and 7.92x57mm IS (or Spitzer; pointed round for .323). I have noticed the problem, where I tried chambering a "I" round in a .323 bore and the bolt will not close. I believed this to be the length of the bullet and not being able to feed in the chamber and getting stuck just outside on closing the bolt.
Hope this helps.
Thanks everyone for your info. It is a resized dummy round that I built for reloading 8x57. As for "I" and "IS" loadings does any North American manufacture make a round that is equal to the Euro loads as for as velocity/bullet construction. Maybe I should also ask this question in the hunting,and sporting arms forum.
