Siamese Mauser in 303

[AbitNutz]

I have a Siamese Mauser and I'm not interested in converting it to 45/70 as I have a butt load of .303 British brass. The .303 would require no alteration to the bolt face, extractor or magazine. I'd like to have a new barrel put on chambered for .303 but with a .308 bore. I believe that the die neck expander would work fine and if it didn't I could always get a .308 neck expander.

I considered doing a 303 improved or a 303 Epps but the cost of dies, ($35 vs a $125) the lack of available reamers and dies what appears to be minimal performance increase, has put me off.

Can anyone comment on the difference in 303 and 308? Please keep in mind that the 303 will be chambered in a much stronger action than the Lee Enfield and the 303 and 308 are almost identical in capacity. Although the 303 has a greater body taper and sloping shoulder.

The stock would be a bit of a challenge as I understand that the magazine is a bit tapered and a stock 98 Mauser would not fit. There are several stock makers that list the Siamese Mauser but significant inletting would be required.

 

[Kp321]

A 303 with a .308 bore is essentially a 30-40 Krag. Why not just go there and have the opportunity to use factory loads if you need to.
By the way, I think it is a good idea either way you go. I'll bet it gets shot more than a 45-70 would.

 

[AbitNutz]

I definitely would have gone 30-40 but I happen to have a mountain of .303 brass.

I thought of going with the .303 Epps/303 improved but the ballistic difference wasn't great enough and the cost of dies is ridiculous not to mention the reamer. Also, there are more that a few versions of each and I'm not sure they'd match. Then there's fire forming... It would turn out to be a pain. I've been down the wildcat path before. At least I'm sure that a .303 British is standard.

I know I could work up a hotter load in a Siamese Mauser than in a Lee Enfield if I got the urge. After all, you can load the 45/70 to almost 458 Winchester magnum loads in the Siamese Mauser...which to me, borders on self abuse.

All in all I think you're right...I will use it more as I expect it to be very pleasant to shoot. If I want to punish myself I can haul my 300 RUM from the safe.

This is going to be a reasonable cost, for a custom rifle, project, Green Mountain barrel, Richards Microfit stock and a factory spec chamber. I bet at a 100 yards the holes in the paper will indistinguishable from my 300 RUM.

I bet it groups better too as I won't be flinching as much. The 300 RUM has trained me to flinch.