[jacobtowne]

On both my New Service M1917 and Army Special there is an oval scoop milled out of the underside of the topstrap at the barrel breech. Does anyone know what the purpose of this is?
Thanks.
JT

 

[lonewolf]

Yup,Jacob. This was designed to help prevent flame cutting/errosion. Some argument on this Forum,I think,as to if it was needed. Only gun I can think of that had this as a chronic problem were the Ruger Super Blackhawks in .357 Maximum. Weren't on the market long,and William B. yanked em off the market. Bought up a lot of .357 Maximum brass dirt cheap-to mill the rims down,slightly shorten and use in my '07 Winchester .351 Semi Auto. A helluva lot cheaper than factory brass especially the way that 86 year old girl sprays em out!-AND-they work fine! Bud

 

[Majic]

I once heard that this was on the older frames for powder residue to collect in. When shooting black powder the fouling would bind the cylinder and the cutout would give the fouling someplace to go.

 

[jacobtowne]

Thanks gents. I can see that it is not needed to prevent erosion. I have a Blackhawk that I bought 33 years ago and have fired tens of thousands of rounds through, mostly .357. The forcing cone looks like grated cheese, yet there is no discernible erosion on the backstrap.
JT