.321" cast bullets in 8mm Mauser J bore

[David LaPell]

I picked up a custom 1888 commission Mauser that had not been converted over from the old .318" J bore to the later .323" 8mm Mauser. (I've slugged the barrel to confirm it), I'm having trouble locating .318" bullets, and I was wondering if .321" cast lead bullets (170 grain) would be too much for it. I plan on keeping the velocities down to around 2,000 fps since that's what those early loads are rated at.

[NEKVT]

I believe the reason 8x57 saami max pressure level is so much lower than CIP is to allow a .323 bullet mistakenly fired in an .318 barrel to be successfully swaged down without damaging the rifle so a .321 cast bullet should not be an issue. And it's not unusual for a cast bullet to be .003 over groove as long as it fits the chamber neck. I just checked a commercial hard cast .321 bullet (for a 32 Special) for fit into both PPU and Win 8X57 cases full length sized in Lee dies and it couldn't be inserted by hand so looks like you would be all set using regular dies as well.

[samari46]

My 1888 slugs out to .321 in the grooves. So in my case I could use a standard cast bullet in .323 diameter. And in your case I see no reason why you could not use a .321 diameter bullet (cast of course) in your 1888. Frank

[Gtek]

Chamber cast followed by some math for neck or soften up some necks and fire form a couple to see what you can go with.

[LAGS]

You can always Beagle out a 316-299 mold to get it just a little larger diameter.
I am sure there are other .316 molds that you can use.
Casting the .321 slugs and sizing them to a diameter .001" larger than your bore with a Push Thru sizer that can be made by Lapping out a smaller sizer to the size you want.
I did something similar for a Mosin Nagant that had a .318 bore that was worn but still shootable.

[Eddie1971]

Are you sure its got a .318 groove diameter? Most original 88's have .320-.321 grooves. I use a .323 boolit in mine.

[john.k]

As 003 oversize is just about ideal for cast,I d say providing your reloads chamber easily,you are good to go.......Although you should be aware that seating a cast bullet in an undersized case neck,may well swage the bullet diameter down considerably.

[K43]

https://hawkbullets.com/bullet-selection.html#/
https://www.buffaloarms.com/catalogsearch/result/?q=.318
https://www.midwayusa.com/bullets/br?cid=19785&targetLocation=%2F_%2FN-19785%2B4294943530%3FNp%3D2%26Nr%3DAND%2528p_visib le%253A1%252Ccustomertypeid%253A1%2529%26Nrpp%3D24 %26Ns%3Dp_priceperunit%257C0%257C%257Cp_metric_sal es_velocity%257C1%26Ntpc%3D1%26Ntpr%3D1

Or buy a 318 bullet sizer die and smoosh .321 or .323 J-bullets down to 318. I squeezed down .323 J-bullets to .322 for my 1888 before I started doing lead. It slugs @ .322 and I size cast at .323. Sizing cast to .319 - .321 should work fine for you.

[sharps4590]

If a .321 bullet slips easily into the neck of a fired case, you're good.

[huntj3]

I own a Turkish 88/05 that slugs at .319. I use the Lee 324-175 gas checked and sized to .323 with great results. It’s really what your chamber will allow.

[swheeler]

I picked up a custom 1888 commission Mauser that had not been converted over from the old .318" J bore to the later .323" 8mm Mauser. (I've slugged the barrel to confirm it), I'm having trouble locating .318" bullets, and I was wondering if .321" cast lead bullets (170 grain) would be too much for it. I plan on keeping the velocities down to around 2,000 fps since that's what those early loads are rated at.

Size your bullets to the throat, keep velocity in the 17-1800 fps and you will find an accurate load easily. I shoot .325" sized 170 Lee and 25 gr IMR 4198 with enough kapok filler fluffed to fill air space in case. NO dacron for me, you can if you want.

[frkelly74]

As 003 oversize is just about ideal for cast,I d say providing your reloads chamber easily,you are good to go.......Although you should be aware that seating a cast bullet in an undersized case neck,may well swage the bullet diameter down considerably.
Bingo!!

[swheeler]

If you want accuracy you will learn throat diameter is the number you are interested in, actual groove diameter plus ANYTHING is fine.