Crom to receiver.Originally Posted by Pnut
Crom to receiver.
Are you loyal to the constitution or the “institution”?
what about optic to CROM? same 10lbs?
I didn’t ask about that. Are those screws coming loose too?
Are you loyal to the constitution or the “institution”?
Since Aridus doesn’t offer an MRO mount, I decided to give the RUSTY NUTS (RN) mount a shot. I had the MRO mounted to the factory rail with the Trijicon LOW mount. With this setup, the factory iron sights were completely blocked and useless. I also have the GGG/Magpul stock on my gun and needed to run the 1/2” (medium) riser to get a good cheek weld.
The RN mount arrived today and it looks like a well machined part. They included stainless steel replacement screws for the optic to mount, SS screws for the mount to receiver, and some VibraTite.
I got everything mounted up, but used blue LockTite instead of the VibraTite. I torqued the optic to the plate at 10 in/lbs and the plate to the receiver at 18 in/lbs. I wanted to get the optic screws to Trijicons recommended 12-15 in/lbs, but I could feel the head of the included SS hex heads beginning to strip. They use a tiny 1/16” hex tool! The factory screws were torx heads.
Now the optic sits about 1/4” lower and the sights sit at about 1/3 co-witness height. After shouldering the new setup a few times, I changed out the cheek riser to the 1/4” (low) riser.
I also noticed the mount puts the optic further foreword, slightly pass the receiver and over the barrel. My guess it they did this to make the receiver mounting holes accessible.
I’ll hopefully have time this week to get it on the range to zero it and test it out.
Here’s some before/after pics…
Original setup
Rusty Nuts setup
I don't know yet. I still have to install all my parts. Just wondering about optic to crom.
Aimpoint calls for 7 inch lbs
Are you loyal to the constitution or the “institution”?
Most commercial stainless machine screws are 18-8, which is slightly above a good, hard cheese. As a bonus, they usually have undersize, poorly formed threads, so they don't have full engagement of the mating threads and the whole thing will strip out at even lower torque values than it would with better screws.
Much better to replace them with quality 10.9 or 12.9 black oxide screws. And in those sizes, Torx heads will be good if you can find them.
mcmaster.com is usually a good source for such things.
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Not another dime.
One thing about the RN MRO mount…the included plate to receiver screws were too long! With the gun fully assembled, everything mounts up fine. BUT when I went to disassemble the gun, the barrel got stuck. I had to back out the screws to get the barrel out.
The barrel has a cut out on the top side where the screws come out. There were no marks or scratches on the barrel, so screws never made contact with the barrel. There’s a rib behind the barrel cutout that kept the barrel from pulling out.
The screws are about 0.15” too long. I was able to reuse the factory screws. Once tightened down, they sit almost flush with the receiver and didn’t block the barrel.
Good thing I discovered this before getting the gun zero’d! Ammo is EXPENSIVE!
If anyone needs to know, the bolt that bolds the top rail in place is #8-36.
If you have an MRO, the mounting screws are #4-48x1/4”
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