M40 and M40A1, A2 and A3 barrel contour dimensions

[Frank Green]

So being as I keep getting asked about contours for the M40 and M40A1 series of rifles. I put a note/sheet together and tried to make it as clean as I could for everyone to follow.

I did list the actual print dimensions from the A1 packet, A2 packet (even though the A2 never officially took off other than prototype rifles it seems like) and from the A3 packet.

There was no tolerance dimension listed for the breech diameter on the original M40A1 drawing. Just shows it as 1.200". If I would assume a standard +/-.005" for that like normal 3rd place tolerance but if you look at the muzzle it is listed as +/-.010" for tolerance. So that is the reason for no tolerance listed on the breech diameter for the A1 as it's not on the print unless I totally missed it.

I also listed the take off barrel from the M40A1 Atkinson barrel supplied by Ryan and the take off barrel I have in my possession from Mr. Land.

You can see how much the tolerances and lengths varied on the drawings as well as how much the two original take off barrels I measured varied.

Hope this helps everyone.

Later, Frank

 

[B'N'F]

Thanks for putting that together, Frank!