Ross MkII*** Barrel Locking screw

[Simon P]

I need to make a replacement barrel locking screw for a MkII***, I have a sample from another 3 star rifle as a pattern and on the shadow graph the threads look a little distorted but appear to be metric form 60 deg 5.5 x 0.9mm.

has anyone else had to make one of these and do you think it is a metric form 60 deg 5.5 x 0.9mm thread.

The only imperial thread that looks close is 7/32 BSF but that is 55 deg

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[M94/14]

Hello Simon

Although Sir Charles was an Englishman, he used inch pattern threads on his North American made rifles. Just get an inch pattern thread gauge and match the TPI count to your example and go from there. It's likely not a common size but I think the Ross used 60 degree threads on the machine screws.

[oldpaul]

I think Jakester is correct about the use of American threads on Ross rifles. Perhaps look at No. 12-28, Diameter 0.216", 28 tpi, thread depth 0.02319". This is from Ian Bradley's Screw Threads and Twist Drills, Fourth Edition. Regards. Tom

[Simon P]

Thanks chaps.