12-32 mount bolt?
- Thread starter josey wales
- Start date
- Location
- Western Manitoba
I believe that one is sort of odd size, if yours is original or "standard" - #12-32, I believe. No doubt want a good grade of screw or cap screw - like Grade 8, I suspect? Starts with identifying the thread within your rifle though - multiple suppliers of threaded fasteners.
- Location
- Western Manitoba
Or, could go a bit "bubba" and re-drill / re-tap to something more common like a 1/4" x 28 thread in that receiver?? Would likely need corresponding clearance for the mount hole, as well - so will not be "standard", at all!!!
before anyone gets drastic and starts trying to retap or make a bolt LOL seriously?
WHAT M14 SCOPE MOUNT IS THIS FOR?
each model of scope mount usually has it's own bolt but they are all the same thread pitch as far as I know. I can't say for sure on the 7.62x39 abortions
Some Scope mount bolts can be interchanged, some are specific due to mount design. For example the springfield mounts(and their knockoffs) use a big knobby bolt and an ARMS 18 uses a stubby standard head bolt. There are several variations in between.
Some folks on this site have spares so it might help to know what the mount is that needs a bolt. post that here and if no one sees it here then put an EE add up and ask for one.
Most "made in the usa" m1a scope mount manufacturers will sell replacement mount bolt/hardware , or they have in the past. Many CGN'ers have upgraded the promag ARMS 18 clone mount with the genuine side bolt and bridge hardware by ordering direct from ARMS.
anyhow.... drilling and tapping , if done as a last resort , should be done on a milling machine with the appropriate tooling , cutting speed and coolant for hardened forged steel and not a bubba job with a drill press and a tap kit. Even then.... why go to all that trouble?
WHAT M14 SCOPE MOUNT IS THIS FOR?
each model of scope mount usually has it's own bolt but they are all the same thread pitch as far as I know. I can't say for sure on the 7.62x39 abortions
Some Scope mount bolts can be interchanged, some are specific due to mount design. For example the springfield mounts(and their knockoffs) use a big knobby bolt and an ARMS 18 uses a stubby standard head bolt. There are several variations in between.
Some folks on this site have spares so it might help to know what the mount is that needs a bolt. post that here and if no one sees it here then put an EE add up and ask for one.
Most "made in the usa" m1a scope mount manufacturers will sell replacement mount bolt/hardware , or they have in the past. Many CGN'ers have upgraded the promag ARMS 18 clone mount with the genuine side bolt and bridge hardware by ordering direct from ARMS.
anyhow.... drilling and tapping , if done as a last resort , should be done on a milling machine with the appropriate tooling , cutting speed and coolant for hardened forged steel and not a bubba job with a drill press and a tap kit. Even then.... why go to all that trouble?
someone must have a spare kickin around.
I'll dig thru my bins but I don't think i have that bolt.
I have a few UTG tri rail side bolts but they differ from the arms style.
Many CGN'ers in the past have been able to purchase hardware direct from arms and I have done so myself a few times over the years.
I would also try brownells
if arms won't sell to us anymore , maybe a US friend/relative can order it and mail it up for you. Had to go this route for some fishin stuff i had to have LOL
I'll dig thru my bins but I don't think i have that bolt.
I have a few UTG tri rail side bolts but they differ from the arms style.
Many CGN'ers in the past have been able to purchase hardware direct from arms and I have done so myself a few times over the years.
I would also try brownells
if arms won't sell to us anymore , maybe a US friend/relative can order it and mail it up for you. Had to go this route for some fishin stuff i had to have LOL
Check the actual thread size and pitch and get back to us. Someone on here might have one or something that will work. - dan
I have bought 12-32 machine screws from a fastener company in edmonton, over on 156 st and 117 ave. - dan
Midnight Rider
CGN Ultra frequent flyer
- Location
- ......the Vanishing Point .
Tagged for reference .
- Location
- Western Manitoba
I would go with 45ACPKING, that best solution is to find OEM part for the base in question. Seems there is some variation in the screw heads - large knurled, smaller, etc. - likely want to replicate that?? As has been mentioned, "standard" threads in the receiver seem to be #12-32 (from tables on Internet, OD of male screw thread is about 0.216"?).
Then run into screw quality - for sure various "machine screws" bought in blister pack in local hardware for other uses - often shiny "zinc plated" - typically quite soft - likely "good enough" for intended use? I have multiple examples where screw head turned right off, as screw was tightened down - I likely went "farmer tight" (6-32, 8-32). Not sure they would last well as the single threaded attachment holding a scope base though? I do believe that virtually all "socket cap screws" are (or used to be) almost always "Grade 8" quality - likely the most resistant to shear and deformation, I think?? - if you can not find OEM?
And, as I have learned, almost all threaded fasteners come with an engineered torque spec for body stretch, etc. - so it works much smoother to find that spec and comply with it. Tightening "more" than spec, does not usually make the connection stronger. Over-tightening seems to lead to over-stretch in screw body, head starting to be ripped off, threads starting to strip within the hole or on the screw, and so on.
Then run into screw quality - for sure various "machine screws" bought in blister pack in local hardware for other uses - often shiny "zinc plated" - typically quite soft - likely "good enough" for intended use? I have multiple examples where screw head turned right off, as screw was tightened down - I likely went "farmer tight" (6-32, 8-32). Not sure they would last well as the single threaded attachment holding a scope base though? I do believe that virtually all "socket cap screws" are (or used to be) almost always "Grade 8" quality - likely the most resistant to shear and deformation, I think?? - if you can not find OEM?
And, as I have learned, almost all threaded fasteners come with an engineered torque spec for body stretch, etc. - so it works much smoother to find that spec and comply with it. Tightening "more" than spec, does not usually make the connection stronger. Over-tightening seems to lead to over-stretch in screw body, head starting to be ripped off, threads starting to strip within the hole or on the screw, and so on.
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That would be best, but a grade 5 would likely survive on scope mount. - dan
Dig through my post history. I *believe* I engaged Troy to buy one for my M14 troy chassis. Might be the same type, if not a bit longer. Engage ARMS and see who their importer is. Mount makers should be able to sell you one through an importer. But expect to pay more for it than any other screw in your life.
