A friend of mine has obtained some nipple replacements which with small modification to the hammer allow the use of shotgun primers in his .45 Cattleman repro . He has been told that he can put up to 3 grains of nitro in it, which he has been using with no ill effects (so far). The gun is clearly marked "BP only". It has not been re-proofed for nitro.

Unfortunately he has now obtained a Chrono and is finding MV to be far too low with ball and (naturally) even lower with the much heavier bullets he has started casting. He wants to up the load. I have expressed some concerns at this (both the starting point and his ambitions to up the load) since I believe that the pressure curve with nitro is much shorter and steeper than with BP.


Anyone admit to doing this?

Anyone know what BP vs nitro proof load pressures are?

Short of re-proofing it is there any way to safely explore this whole idea?

How can you determine if safe limits are being reached?

Would it be feasible to assume that if MVs are kept within reason (he wants to get to 750fps) then peak pressures are not excessive?

He is shooting on land he owns and AFAIK there is no legality problem with this.