Has anyone successfully tightened up an underfolder?

[mmbasser]

Mine has some slop, unfolded more than I'd like, folded, a LOT!

I've searched at a few places, and have come up with nothing more than "tighten the nut". Not really helpful in this case.

Has anyone tackled wobbly underfolders, and how did you tighten them up?

[Shady]

more info needed

[thedrickel]

In my experience they all wobble at least a little bit. You will have to either narrow the hole the locking lugs fit into, or add material to the locking lugs (JB weld would probably suffice for this purpose).

[mmbasser]

Polish kit, it looks to me like the trunion holes are a bit egged vertically. I could peen the trunion a little to take up the slop, but I'm not certain that would last very long.

What other info would be needed?

[Ford8N]

Just tighten the nut. You might have to move the pin that holds the nut in place, so you will have to restake it. If the trunnion hole is egged out that holds the main cross piece, look in to shimming it with some thin wall tubing. Or, if you are saying the lock holes on either side are egged I would tig a bit of steel on the "leggs" of the locking piece to tighten it up. And just file to fit. Remember the old gunsmith rule of work on the cheap part first. Post pics, we will be better able to know what the problem is.

[mmbasser]

The Center hole is a nice fit, so it's not an issue, I think the slop is mostly from the trunion holes for the locking lugs.

Made some measurements to see where most of the slop comes from:

Locking lugs:
At the base of the lugs, all are 0.230 to 0.231.
At the ends they are the same, 0.231
From this I can say they are under size, but not tapered, good!

The holes in the stock are all 0.240

The trunion holes range from 0.253 to 0.255

So, even if I tighten up the trunion holes, I'll still have +\- .005 from the stock holes. This could be OK since ALL UFs have slop, as so many say.

So , if I'm OK with the remaining clearance for the stock holes, what would be a good way to tighten up the trunion holes? Weld and refit, or could the peen approach work for 0.010 on the top/bottom of the lug holes?

By peening, I'm thinking perhaps using a solid backing bar, and a series of center punch hits around the holes on both the inside and outside.

You think I can move enough material to take up 0.010 that way? I'm a little skeptical that I could move that much.

Thoughts?

[nicoroshi]

Is this a 'functional' underfolder or one that is 'pinned' for minimum 30" OAL requirement?
If functional I wouldn't tighten up any of the holes since that would make it's function more difficult.
If it's pinned I would tack weld the locking lug to the trunnion on the inside.
That could be ground off if laws change or if you move to a free state (without any exterior blemish), and would totally eliminate any 'slop' the UF had if pinned in the open position anyway.
Yep. I would tack weld it on the inside.

[mmbasser]

That's a damn good question Nico, since I have't yet decided whether to add length to the barrel, or to pin/fix the stock for 30" compliance.

I'd rather keep what ever I do less than permanent if possible, in case the opportunity to go back comes up.

I'm leaning on adding length to the barrel, and keeping the folder action, but If I decide otherwise, then welding the stock open is certainly one way to make it solid.

Thanks

[nicoroshi]

I did the add muzzle device route on my M-70AB to keep the underfolder operational. Thing is it needs to be over 5" long since folded the M-70AB is 25.5" long.



Made for one looooooong rifle, and I realized that the only time it was folded was on the way to the range, on the way home, and in the safe.
I never once shot it with the stock folded.

Locked the stock open, and never looked back



IMHO a much more natural look to the rifle (lost the red dot too since I found I shoot it just as well iron sighted).

My UF(s) do have a little slop to them but never notice it when shooting.
Once it's locked tight into the shoulder that little bit of 'slop' is gone.

[SJgunguy24]

If it's really getting ok your nerves, you could drop a small brass rod in the hole(just smaller the the locking lug) and add in some weld material then drill out to size.

[nappy]

I carefully tightened up mine with my HF press, using varying sizes of ball bearings, punch and a backing plate. Not too much tonage was required... just need to be careful as you can potentially screw things up.

Ooops... I didn't read the entire thread. Mine also has a little slop at the rear trunion though, not enough to annoy me.

Mine has some slop, unfolded more than I'd like, folded, a LOT!

I've searched at a few places, and have come up with nothing more than "tighten the nut". Not really helpful in this case.

Has anyone tackled wobbly underfolders, and how did you tighten them up?

[mmbasser]

The reason I brought up the peen option was because I currently don't own a welder. This brass/copper rod suggestion has got the wheels spinning, I think I could pull that off!

Would a flux core welding machine from HF that is going on sale soon work?

I have an acquaintance that has a mig, but he's an hour away, and I'd rather not beg for assistance since he's a very busy guy.

Thanks