Shimming A.R.M.S. style mount.

[redshooter]

After much effort I have removed my stripper clip guide, and discovered my A.R.M.S. Clone is just a wee bit off. I'd prefer to keep the rear sight, but I'm thinking it's time to seriously consider a CASM (well more than considering, just don't want to spend more coin than required). Has anyone used shims, or JB Weld to get the mount to line up with the bore? Also is there any greater risk to stripping fasteners with the mount being slightly out of alignment with the receiver?

 

[Boomer686]

M14/ M305 are notoriously hard on optics because of the mass of the bolt slamming home. Best bet is to get rid of the clone mount as I think the shimming / JB weld idea will result in an exercise in futility. You need something solid and reliable.

 

[chalkriver2]

Do you have the c clip installed on the inside of the mount holding the mounting screw in place? 45ACPKING advised to remove the clip ...could that be causing the misalignment issue ? Sorry we didn't see you up here in Petawawa much this summer ...hopefully next year as it will be a busy season for us with lots of competitions/clinics.

 

[ipscgraz]

One of my M305's has a receiver that is slightly thicker than standard on the forward left side; this caused the ARMS 18 to point off to the left a bit. After a bit of fumbling around with options I went for a CASM mount.

 

[45ACPKING]

yup, you should be tossing the horseshoe washer that comes with the side bolt..... this applies to ARMS 18 and the promag copy.

I have found that sometimes the horizontal key along the bottom edge of the mounts that mate with the horizontal slot on the receiver, are a bit proud at the forward end. Necessitating the removal of very minor amount of material off the mounts key to allow it to properly mate to the receiver slot.
genuine arms 18 scope mounts are and always will be my choice for scoping the m14 rifle , with no exceptions.
The sights on these rifles are excellent and I like the fact that the arms 18 affords full use of the irons when the scope is removed

 

[Claven2]

FWIW, many (perhalps half?) the M305's I've fitted ARMS mounts too had either a mis-positioned vertical slot over the mounting hole, or the hole itself was off one way or another. If this happens, you either have to change the mounting bolt hole geometry in the mount, or alter the slot key. Neither is ideal, and you don't want to alter the receiver itself. When the ARMS is mated with an in-spec receiver, like say an LRB, it provides good results. I much prefer the earlier variant with a split rail.

I've also installed the Pro-mag ones, and the mounting hardware was soft junk. I've actually ordered replacement ARMS18 hardware and used it to install promag mounts where the screws, bolts or dovetails failed during install. They also have raw cast locator splines that sometimes aren't straight and needed filing to align to slots properly. I've even had to heat up and twist the front rail section to get it to be parallel to the rear rail segment. I don't recommend the Promag ones unless you have talent to fix what might not be right with it.

That said, I now exclusively use the Sadlak Airborne mounts on my own guns. They essentially rely only on a lower slot that is parallel to the bore. They allow full use of the irons, are lighter than the SEI and brookfield version of similar design, I find they mount with less hassle and at least as much rigidity and aren't as prone to stovepiping.

I've not used the steel CASM mount yet, but the aluminum one of the same design did not impress me, in particular it applies a significant bending moment to the rear sight pocket once installed if there is any impact force to the scope. For this reason alone, I don't use them on my own guns. They also take away the option to use real irons.

 

[45ACPKING]

I on the other hand have seen very few norinco receivers with an offset vertical slot. Some unmarked early ones and some polytech receivers that had the mid point take down notch, but can't recall any norinco marked (cja import) receivers showing that problem. I have one here that is a flat side and never had a scope mount detail at all. It's a collector piece among some of my other early receivers.
More commonly, folks don't install the arms 18 correctly and are surprised that sometimes when a product says "should be installed by a qualified gunsmith"..... it does not install at home on the bench like they thought it might.
Even on springfield M1A rifles that I have installed the Arms 18 mount on, sometimes the horizontal key must be honed to fit the receiver's slot. The mount will sit angling to the left if not. This has been by far the most common fitment problem I have encountered over the course of installing at the very minimum 30 + arms 18 mounts over the years, primarily to norinco receivers.
I do not know why the horseshoe washer is even supplied on the side bolt of the arms 18. It is not required and perhaps is put on there to stop the bolt from bouncing around in the packaging and marking up the mount?
I dunno..... come to think of it I never asked arms about it but maybe should have LOL regardless, on every install, that horseshoe washer gets tossed in a little bin in my parts cabinet. I have over 30 of them

I have always been a solid supporter of the ARMS 18 mount since i first installed one on my own rifle. I notice that resident guru Tactical barney is also using the arms 18 on his new faxon barrelled m14 build.

Sadlak makes good mounts too and never had any issues that I recall mounting thier stuff same for smith enterprise , nice mounts for sure.
I like anything that lets me retain the iron sights as sometimes I really enjoy shooting the irons and like that i do not have to touch the mount to do so.

 

[redshooter]

Do you have the c clip installed on the inside of the mount holding the mounting screw in place? 45ACPKING advised to remove the clip ...could that be causing the misalignment issue ? Sorry we didn't see you up here in Petawawa much this summer ...hopefully next year as it will be a busy season for us with lots of competitions/clinics.

I took it off, seems to be better, but I won't know for sure until I can get my paws on the part that goes in the stripper clip guide. I have the part from an A.R.M.S. 18 but it's not the same, that said I'll bet I could make it work with access to a good drill press, or lathe. Bummer I couldn't make it up there this Summer, I've worked pretty much every Saturday since mid May...how I had the money to pay for the M-305. I've squirreled away enough supplies to keep me shooting through the winter which is a good since I'll have the time in about 40 days.

Thanks for the replies gents! I think I may continue to try to make use of the A.R.M.S. clone...at least until I'm convinced I can't get the part, or modify the part(s) I have.