I'm working on an FN which is opened up for the .458 Lott. When the customer works the bolt he keeps rifle at his shoulder and is putting quite a lateral force, pushing against the back end of the bolt, as he pulls back and the bolt binds up badly. I removed everything and with a bare receiver and just the bolt it still binds up. Action has been opened up to the rear extensively so the rear bridge is quite a bit narrower than original. I think it may be working as well as it can considering the modificaiton but I would apprecieate any other ideas as to where the problem is. Thanks.

quote:

I removed everything and with a bare receiver and just the bolt it still binds up.

Are you doing this with the action out of the stock?

Yes, I've tried it both ways so as to eliminate bedding as an issue. The bolt binds up hard about once it's 2/3 the way back if you put any lateral force on it. It will fall out if you hold the aciton vertical and let go of the handle.

TT

I am looking at my FN action (30-06 Sears Model 50) and even though it is in extremely good nonaltered condition it too has the bind that you describe your customer has in his. I am not a gunsmith, but if I had to analyze the problem it would be that the bolt guide hole is to big, thereby allowing too much of that lateral movement, which causes the binding (which is exactly what you have already said). About the only thing that would correct it might be to somehow weld some sort of sleeve in there that makes the hole a bit smaller in circumference.

As far as falling out, I don't see how that can happen with the bolt stop in there.

That, and a buck, will get you a cup of coffee!

I would look at the extractor to see if it is binding/rubbing the rear raceway. Gravity, when the weapon is held vertically, would try to center the bolt, but with a hand pushing it sideways it may be just enough to bind the extractor against the side of the raceway. Just a thought, having not seen the weapon.

22WF, thanks for taking a look at your FN. Your analysis matches mine as I had the same thought about the relationship between the bolt diameter and rear bridge. I also know that one of the advertised features of the Montana actions is the anti-bind dovetail lug and raceway, probably for this very reason.

Rick, the bolt does in-fact bind slightly on the extractor but even with the extractor removed it binds up. I replaced the extractor collar with one that was a little thicker as the bolt stop/ejector was catching on the edges of the extractor collar recess, but it didn't cure the main binding area which seems to be at the bolt body--rear bridge area.

I now have three blisters--seriously, three blisters on my right hand from working the bolt and haven't gotten it any better. I think I'm going to lose this one.

My commercial FN mauser that I am having built into a 264Mag has some binding in the bolt travel that is caused by the extracter having a slight arch which drags on the reciever when cycled. I think this is a common malady for this action, maybe this is what is going on with yours.

rebed it and try..
bet it doesn't hang out of the stock

jeffe

quote:

Originally posted by jeffeosso:
rebed it and try..
bet it doesn't hang out of the stock

jeffe

Jeffe

Reread. He said he has tried it out of the stock and it hangs up out as well as in the stock. Lets face it, when you try to put a round piece of steel into a round hole from an angle its going to be harder to do than if you put it straight in. don't need to be a gunsmith to figure that out.

Geez, and I thought Paul Mauser had thought about all of these problems when he “devined†the design of his rifles???

Good thing this isn’t a Remington or we would be hearing all the “poor design†dialog from the Mauser lovers!

Have you tried taking black magic marker to everything shiny in there, working the bolt a bit so it binds, then look at the rubbed areas?

I think you should take a dremel tool with a diamond bit about .100 in diameter and chamfer all the interior edges that run perpendicular to the bolt travel. One other trick, hold the action upside down in a vise and chamfer the edges of the guide rib slot in the rear bridge with a file, or take a 1/4 in piece of steel about 5 inches long and cut it with a slitting saw so it can hold a piece of emery paper then put your " wiggle stick" in a electric drill or a 1/4 inch die grinder and insert it into the inside of the rear bridge and spin polish the inside of the rear bridge use 320 grit paper and then scotch brite. be carefull there is such a thing as too much polishing back here, go just enough to take the corners off.
Timan

Great ideas from all--Thanks! I've put a slight chamfer on all perpendicular edges as Timan has suggested before I posted this question. But last night we pulled off the ejector box and swapped the ejector with a military version--the hole in the FN is round, not oblong like the military--and that cured about 70% of the binding. It's still not perfect, and the owner probably will not be satisfied. To put it into perspective, he absolutely raves about the MPI as being the best stock ever made bar none. I forgot there are some jobs you just shouldn't take. Thanks again!

quote:

Originally posted by Rick 0311:
Geez, and I thought Paul Mauser had thought about all of these problems when he “devined†the design of his rifles???

Good thing this isn’t a Remington or we would be hearing all the “poor design†dialog from the Mauser lovers!

He did,

He created the magnum length action for cartridges longer than 3.340" or thereabouts.

One of the often left unsaid side affects of lengthening the action for long cartridges is increased bolt wobble when the bolt is fully retracted. Anything you do to the satndard action that reduces the support area for the bolt will exacerbate this problem.

I won't comment on why this action in particular may have problems because there are so many possible causes or contributors.

Poleax, you're definately on the mark. Reminds me of when I was in high school and a friend put a Chevy 350 into his Vega; it worked, but that car wobbled like hell!

quote:

Originally posted by Toomany Tools:
Poleax, you're definately on the mark. Reminds me of when I was in high school and a friend put a Chevy 350 into his Vega; it worked, but that car wobbled like hell!

I knew a gent that shoehorned a straight six out of a Triumph TR6 into a spitfire chasis. The front two cylinders poked out of the front of teh hood. The car was fast unless you were trying to accelerate in aven a slight curve. The weight bias made for some poor handling.

Good luck.

quote:

Originally posted by Poleax:

quote:

Originally posted by Rick 0311:
Geez, and I thought Paul Mauser had thought about all of these problems when he “devined†the design of his rifles???

Good thing this isn’t a Remington or we would be hearing all the “poor design†dialog from the Mauser lovers!

He did,

He created the magnum length action for cartridges longer than 3.340" or thereabouts.

One of the often left unsaid side affects of lengthening the action for long cartridges is increased bolt wobble when the bolt is fully retracted. Anything you od the the satndard action that reduces the support are for the bolt will exacerbate this problem.

I won't comment on why this action in particular may have problems because there are so many possible causes or contributors.

I was only kidding!

Mauser, like all other designers of military rifles, designed a certain amount of wobble/slop into the bolt and rear raceway when the bolt is in the retracted position so they weren’t as susceptible to dirt and gunk that would lock them up.

The bolt rides on the bottom of the locking lugs sliding on the rails (not on the bolt body sliding on the rear raceway) when it is pulled to the rear.

quote:

Originally posted by Poleax:

quote:

Originally posted by Toomany Tools:
Poleax, you're definately on the mark. Reminds me of when I was in high school and a friend put a Chevy 350 into his Vega; it worked, but that car wobbled like hell!

I knew a gent that shoehorned a straight six out of a Triumph TR6 into a spitfire chasis. The front two cylinders poked out of the front of teh hood. The car was fast unless you were trying to accelerate in aven a slight curve. The weight bias made for some poor handling.

Good luck.

too funny..
I had the 4.3?.6?L "caddy" motor with a 4 spd in a monza, factory.. dropped a 350 with a 327/325HP cam in it into the car.. AFTER I had put a .411 rear end into it... it wouwld do one hundred... NOT 101, but 100... you couldn't get it to go anymore downhill...

sold that and put a buick v6 turbo into a tr7conv.. had a guy buy it before i got to drive it much... did the same with a tr8.. ot to drive that a little.. at least THAT one was almost reasonable to drive...


3 of the dumber cars I built!!!

jeffe