FN Commercial Mauser problem

[spiska]

I recently purchased a nice 1952 FN commercial Mauser in 7x57. It's very clean and looks like it's been in a safe since 1960.

The bolt seemed a little sticky but I assumed it was dried oil and the chamber being a little dirty.

I cleaned it up when I got it home and it was still sticking, so I took the action out of the stock. When not it the stock, the action was smooth and not sticking.

I reassembled and the binding occurs if I torque the rear action screw to more than 15 inch-lbs, which isn't much based typical torque specs. Front screw torque didn't seem to matter.

It looks to me like the barrel channel was glass bedded. It is very smooth and matched the lines and contour of the barrel. I don't see much if any bedding material on the action or lug but the fit to the stock is clean. But I've also never bedded a stock so I could be wrong. There are steel pillars in the action screw holes that are fixed/glued in place. I don't know if this is how they came from the factory? They are a tight fit when I push the screws in. I'm used to seeing the spacers on a military Mauser, where the screws have room.

Front action screw will hit the metal pillar and tighten pretty quickly. Rear seem to have more travel to reach that point, and I don't come close to it before the binding starts.

The bottom metal and magazine also appear to be bedded to the stock, but they may just be in there tight or stuck from age and I haven't worked up the nerve to smack them any harder to see if they will come out. I don't want to damage the stock if they are bedded in by accident or on purpose. Not sure if that is normal or not.

Any issues with using light torque on that rear action screw before I take it out and see how it shoots? My best guess is maybe the bedding material in the barrel channel is resulting in pressure on the action when I tighten the rear and causing it to bind when I tighten the rear? But the bedding is forward of the front action screw so not sure that makes sense.

I don't see any stock warping side to side or tip to butt, but I'm not an expert by any means and not sure how to test for it.

Any thoughts on how to asses/fix the issue? Would a brass shim on the rear action screw potentially help? Or is light rear torque not necessarily a problem?

These may be dumb questions, but I've never really owned a rifle where the action binds like this so it's a foreign concept to me. And I really want this gun to be a good shooter and a rifle I hunt with regularly.

Thanks,

Matt

 

[spiska]

The bolt isn't dragging on the rear action screw. I did check for that.

 

[Ontario Hunter]

Look at how your magazine fits against the receiver. There should be a slight gap between the two. It sounds to me like your magazine is jammed against the receiver and when rear action screw is torqued down, the tang is bent slightly causing the bolt to drag in the track, specifically the cocking piece sear. I encountered this very issue when I dropped my 404 Mauser build into a used stock that was designed with a very thin wrist. I had to trim a very little bit of metal from sides of top of magazine box and also had to shorten the rear action screw. Ah ... look for that too. Is the rear action screw protruding through the hole into the track for cocking piece sear? Depends on what make of Mauser but this might be possible (not possible for my Springfield as the screw hole is not threaded all the way through the tang).

Also, look at the back end of the mag box. See the tab that extends up above the edges to guide cartridge rim to bolt face. Does it look shiny on top edge? That would indicate bolt is rubbing against it. This would be caused by box that is for whatever reason too short on sides. I think this unlikely but a possibility to check out.

If none of these are fixes, I suggest bedding the back end of the action and tang. Before bedding put the action back in the stock and slowly tighten the rear action screw a half turn at a time, counting turns until the bolt just starts to drag, then back off enough to free things up. That's where you want to tighten screw after bedding is added.

Try tapping lightly on top edges of the mag box with rubber hammer to see if the bottom metal can be shook loose. Hopefully. Don't beat it up.

 

[Ontario Hunter]

And finally, does your rifle have an aftermarket trigger? Timney trigger often requires some sear adjustment or the bolt will bind. Is the trigger housing gold colored? Instructions that come with Timney trigger specify shaving the sear as needed. I chose to modify the sear on cocking piece instead. Cheaper to replace it than trigger if something goes wrong.

 

[spiska]

Factory single stage trigger as far as I can tell. Doesn't appear to be aftermarket.

Magazine box looks flush on the sides when the rear screw is tightened to where it isn't binding. Maybe that's the issue then.

The tab at the rear of the magazine has some clearance and I don't see any signs of rubbing but I'll tighten it and see if the bolt drags.

Action screw doesn't appear to be high enough to impeded anything when the biding occurs.

The stock appears to be factory as best I can tell so maybe things got wonky when they bedded the barrel channel. I'll try to post some pics in a bit. I may be making assumptions that aren't correct.

Thank you for the input OH.

 

[Ontario Hunter]

So the barrel channel has been bedded end to end? Okay, not unusual for that time period. Especially for that caliber I would free float the barrel, though I don't think it will necessarily fix your problem with the bolt binding. Fix that first and then free float barrel back to chamber.

Okay, follow my instructions re half turn tightening. When the action screw reaches the bolt binding point, how does the tang look respective of stock? Is tang protruding above its stock pocket? If that is the case you should probably consider trimming the mag box a bit instead of filling the gap under the tang with bedding. It is preferable to have the tang flush with the stock. If you do trim the top of the box, you may need to shorten the rear action screw or it may either bind up if screw hole is blind ended or screw may protrude into sear channel in tang.

 

[Ontario Hunter]

What does your floorplate look like? Hinged or push-button detachable (military). It's possible someone changed the bottom metal and the new box is taller than what the stock was designed for.

 

[spiska]

It's the one where you push the button and slide it forward and the floor plate and follower come out.

 

[spiska]

Which is consistent on the FN commercial models I've seen. But I haven't seen many.

 

[rdog]

One simple test is to put a thin shim made out of a business card, punch a hole in it for the tang screw & cut it to shape put it under the rear tang & tighten it down see if that fixes the binding , in my opinion the stock spacer at the tang should not be tight in the hole & the screw not tight in the spacer.
As Ontario Hunter said the mag box should have about 2mm of clearance on top when its assembled not jammed up between the action & bottom metal.

 

[Ontario Hunter]

Hmmm. How does the bottom metal fit with the stock underneath? Is the rear of trigger guard recessed significantly below the stock? Only possible if there's no overhang with floorplate lid. If so, it may be possible to bring bottom metal out a bit flush with stock by adding bedding underneath the trigger guard at rear action screw. That would drop the box and relieve binding at top. However, I'm guessing the bottom of bottom metal is already flush with stock. If so, don't mess with bottom end.

 

[Grumpy gumpy]

Pictures would make the diagnosis easier
I would try the shim idea first before doing much else, this will let you see if the problem is there, then as OH said, check the mag well.
Gumpy

 

[spiska]

I'll try to get some pics up later this week. Work is keeping me busy this time of year.

 

[3nyala]

Spiska
Without any visuals to go by, it sounds like the bedding/pillars are working to bend the action as you bolt it down. You say "When not it the stock, the action was smooth and not sticking." so it something in the stock. Also "Front action screw will hit the metal pillar and tighten pretty quickly." Maybe the front pillar is too long or protruding low so the front screw is tightening so quickly. Easiest fix if you don't want to fiddle with spacers/rebedding/grinding is to buy a new stock. If that works you are off hunting. If you really want to keep the stock you should find one flat level surface and then start shimming off of that while checking for even contact front and rear. Its a mission if the stock is bedded unevenly. Its frustrating fixing others' bad work. Good luck.

 

[spiska]

I took it back apart and the gun is bedded tip to butt. I saw marking on the interior of the stock that I thought were factory stamps but realized they were mirror images of the stampings on the action. Not sure if the pics below will provide any clues to the issue.

Is the magazine box generally attached to the bottom metal or is the bottom metal a separate piece? I'm having trouble removing the bottom metal. If it's attached to the box, I think the box is likely glued into the stock, I assume via bedding compound.

 

[3nyala]

Spiska
Usually you dont bed the whole thing and flee float the barrel. The picture of the magazine not meeting the bottom metal is suspect. If magazine was stuck(expoxied) too high and you bolt down the front and rear screws it would bend the action around the magazine. Maybe if the magazine could move it would settle against the bottom metal and not put pressure on action. Good luck getting it out.

 

[Grumpy gumpy]

Spiska
Usually you dont bed the whole thing and flee float the barrel. The picture of the magazine not meeting the bottom metal is suspect. If magazine was stuck(expoxied) too high and you bolt down the front and rear screws it would bend the action around the magazine. Maybe if the magazine could move it would settle against the bottom metal and not put pressure on action. Good luck getting it out.

This ^^^
The bottom metal "should "be part of the mag well, but not always. Sometimes they have been modified if a custom mag well is made. Yours looks like a standard one that has been incorrectly installed ( can’t quite tell from the pic). If you can gently heat the mag well enough to soften any glue,(without burning the wood) you should be able to get it out .
Did you try shimming the rear screw?
Gumpy

 

[spiska]

I'll give the heat a try. I have a heat gun. I can try to insulate the other areas and keep it concentrated to the mag well. I need to find a small mallet that won't damage the metal. I tapped the mag metal a little with a screw driver handle and it moved the bottom metal out a hair so I think it's doable. Just need the right tools for the job. I boogered enough screws and marred enough finishes in the past using the wrong tools.

I agree on the barrel bedding. I've heard of it being done in the past, but not as a current practice.

I couldn't tell if that was a gap between the bottom metal and mag or if the mag was just designed with that ridge. Will be easy to tell when and if I get it off.

I'll try the shim tonight or tomorrow. I was thinking it needed to be under the bottom metal (which I haven't removed successfully yet) since that seems to be where it has the extra room to travel. Would that make sense? Where the action meets at the top seems to be flush. The bottom metal will go in deeper as more torque is applied to the screw.

Thank you both for checking in and providing additional insight.

 

[Grumpy gumpy]

The bit of the back of the mag well that has the little notch in it , is supposed to fit up inside the bottom of the receiver with the rest of the mag well sitting flush to the bottom of the receiver with both the front and rear parts of the bottom metal touching the receiver ( rear using the pillar, which may or may not be loose in the stock, don’t worry about it yet). If the mag well is bent, or as mentioned, too high at the rear, or the bedding is off, it can cause issues
Gumpy

 

[Ontario Hunter]

Floorplate/trigger guard and magazine box are machined one piece on the custom "bottom metal" for my 98 Mauser. It does appear that the back end of your mag box was a separate piece, perhaps tacked onto the box by brazing/welding? I see evidence of a seam in the corner of top image.

Start by free floating the barrel. This should be done in any event. Glass bedding rifles the full length was popular in the 50s and 60s when fiberglass first became available. It took quite a while before someone figured out the role barrel harmonics plays in accuracy. Free floating the barrel allows for uninhibited repetition of barrel harmonics (vibration during firing) in varying humidity and barrel temperature changes. For whatever reason some barrels don't like free floating (relatively rare) but this is usually fixed with a "pressure point" near the end of the forearm, not full length glass bedding. So, get yourself a thick wooden dowel about the width of the end of your barrel trough. Cut off a piece about a foot long, at one end rap it in coarse grit sandpaper, then by hand start opening the trough up to approximately the end of chamber. Keep opening the trough until a five dollar bill slides freely between barrel and wood all the way to chamber when the gun is screwed together. This may cure your problem but I kinda doubt it. How important is free floating? A member just posted in a thread on shooting sticks how inadvertently putting his finger on the barrel while on the sticks screwed up his groups significantly. I have noticed the same thing when shooting my 30-06 from a rest on the bench.

If that doesn't solve the problem, an accurate diagnosis will require removing the bottom metal and reassembling it naked in the action to see if the bolt still binds. You can try to knock the bottom metal loose from stock. It appears to be military design (removable floorplate, not hinged). In worse case scenario, bottom metal can be easily replaced. Try tapping the box loose with a nail punch. Flip the punch around so the broad striking end is against the forward end of top of box. Support the underside of stock ahead of and behind the floorplate. See if hitting the pointy end of punch with a hammer will knock the bottom metal loose. If that end of bottom metal moves, do the same at back end of box but try to avoid bending that much thinner metal. Yes, that end is supposed to extend above the rest of the box. It guides cartridge rim onto the bolt face. Consequently, it should almost touch the bolt which you can see is well above bottom of receiver.

The action screw sleeves are recessed which means they are not acting as "pillars." They are typically not free floating and are not attached to the floorplate. You might want to tap on them if the trigger guard starts to move after tapping on the top of mag well. You could drive those screw sleeves out all the way no problem. Just push them back in later. Don't worry much about buggering the top of the sleeve. Simply true it up later with a tiny rat tail file. As I understand it they were never intended to act as pillars. Just supposed to be minor reinforcement to keep action screws from digging into stock (which doesn't seem to be much of a function).

I think trying to heat the bottom metal with a heat gun would be very risky! I would try forcing the bottom metal free of the stock. Even if you messed up the bottom metal pushing it out, as I said lots of replacements are available. This is the great thing about building on a 98 Mauser. I know well enough! A good military surplus bottom metal could easily be cleaned up nice and replace the FN commercial one. Look around the net. There's lots of them.