One of the lads at school wants to mill the receiver on his rifle to accept scope mounts.
1) is this an acceptable procedure/will it weaken the receiver to where it will need proof testing again? 2)how much of a dovetail needs to be milled in, or does it depend on the the mount being used? These are not usual questions for my metal shop teacher buddy. This young man took, if I remember correctly, 2nd. place in the local 1000 yard shoot - and yes this IS in Canada!! :-)Mike in BC
Is he sure that there is no mount kit made for his rifle?
Some mounts can be bolted on, such as on my Mosin-Nagant.
i
Can't answer that without knowing what kind of gun, and maybe not even then. Does he just need to mill a flat or two in a curved surface, then drill and tap, or are we talking dovetails ? Receivers aren't proof-tested.
Yes, depends. But the .22 dovetail is generally IIRC 60-degrees, 3/8 apart. Airguns are often 10mm apart, but it's close enough to make them interchangeable most of the time.
Dovetail scope mounts are generally for small-bore guns, but I can't imagine using one for 1000-yd competition.
========= In most cases you don't have to mill anything. Just a drill and tap job to fit a mount to take the scope rings. Later rifle actions may be already tapped and have screws in the threaded holes. Loctite can be helpful to keep anything from shifting or shooting loose.
Be reminded that many gun manufacturers use proprietary threads so you may need a special tap/drill.
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Unka' George [George McDuffee] ============ Merchants have no country. The mere spot they stand on does not constitute so strong an attachment as that from which they draw their gains.
Thomas Jefferson (1743-1826), U.S. president. Letter, 17 March 1814.
you would want to determine the hardness of the receiver to see if it's suitable for milling or drilling. Perhaps intoduce the lad to a Rockwell tester, and test the receiver in an inconspicous spot.
What rifle? How long IS 1,000 yards in Canada? What's the exchange this week?
Are you quite sure? It used to be defined like that in the USA, but never in Great Britain, so I would have guessed that it wasn't defined like that anywhere in the Commonwealth.
The Mendenhall Order, issued 1893, defined the American yard to be
3600/3937 meter. Then, in 1959, the American Standards Association re-defined it as equal to the so called International Yard, which was exactly 0.9144 m. The International Yard was used for scientific purposes in both Great Britain and the USA.In Great Britain, the Imperial Standard Yard was defined in the Weights and Measures Act of 1855, as the distance between two lines on a ruler used as a standard for measurement. The distance was approximately
0.9143992 m. Later, in 1963, another Weights and Measures Act was issued in Great Britain, and it re-defined the yard to be equal to the International Yard.Originally, some 900 years ago, the yard was defined as the distance between the tip of the middle finger and the tip of the nose of King Henry I.
(The above information was taken from "Mått mål vikt", a book on metrology by Knut Birkeland. The Danish original is called "Mål og vekt". I don't know if it has been translated to English.)
S.
Most commercial receivers are already drilled and tapped to take scope mounts, buy same and attach. Surplus military guns almost all have aftermarket mounts available, no machining needed except for drilling and tapping. Some don't even require that. If the kid wants to design his own mounts, milling on the receiver is probably NOT the way to go. Parts of receivers are highly stressed on centerfires, milling on a receiver ring is probably not a really good thing to do. If the kid needs to look at what's available on the commercial market, Brownell's has a lot of mounts on their website. If he's got one of the old external adjustment mount scopes, he needs to make dovetail blocks and attach them, not mill on the receiver.
Stan
Thank you all for your suggestions, they have been passed on to the young man and his teacher. Mike in BC
Try asking over here:
Very true. The inch is exactly 2.54 cm, and the meter is exactly 39
47/127 inches, and since the fraction 47/127 can't be expressed exactly in decimal, those who say that the meter is exactly 39.37 inches are wrong (although not by much).Right! And a remarkable feat it was, too!
S.
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