Rear action screw stressing action? Interarms Mark X

[MGilbert]

Hi all, this is my first post after lurking for a while. I'm an adult onset hunter in western Washington, and have been enjoying all the different hunting opportunities here. I'm a leatherworker and saddlemaker by trade, and have recently started tinkering with some of the older guns I own.

To the point, I inherited my grandpa's Interarms Mark X in 30.06, and after replacing the old Tasco scope, I couldn't get it to shoot groups under 3 inches. I'm going to put better rings on than the old Weaver band style rings, I replaced the non-adjustable trigger with a Timney, and I free floated the barrel (The stock was contacting the barrel on the right side).

Now, as I was putting it back together I noticed that while the front action screw easily went in until it hit the bottom metal and tightened up, the rear action screw required a small amount of torque the whole way in (Even with the front screw removed). The threads are clear, as it threaded in the tang just fine apart from the stock, and the screw is not tight in the pillar or bottom metal. I assume this is putting some small amount of stress on the action which contributes to the poor accuracy I was getting.

So my question is, how do I go about chasing this problem? Does this signify that the inletting isn't quite right around the rear of the action? The action does not rock when I hold it into the stock, so it seems like it may be a side-to-side interference.

Thanks in advance for any tips.

 

[Forkasauras]

Make sure the recoil lug is seated propertly in the stock. Leave the screws a little loose and tighten them sequentially, like putting on a tire, until they are hand tight. Then torque

 

[Cherokeeguide]

The action screw torque on a Zastava commercial Mauser in a walnut stock (Interarms Mark X, Interarms Whitworth, Herter's J-9, etc) is 30 to 35 inch-pounds.

On these, the drill is to always torque the front screw first, to insure proper seating of the recoil lug.

When you do this, have the floor-plate open and the follower out of the magazine box. If you do it with the floorplate closed, the follower spring is strong enough to rock the rear of the action upward and can cause the kind of binding sensation in the rear action screw that it sounds like you're experiencing.

 

[Choupique]

how do I go about chasing this problem?

Buy some belzona and bed it.

Its just as likely to be the trigger guard youre fighting as it is to be the action. Figuring it out for sure would take about as much work as epoxy bedding it, so just do that and see.

 

[Cherokeeguide]

I'm going to put better rings on than the old Weaver band style rings

There's nothing wrong with the Weaver USA strap-style ring mounts. I used Weaver bases and those mounts on my Interarms Whitworth rifles in .270 Winchester and .300 Winchester magnum. Those are just fancy versions of the Mark X. The .270 was a "minute or less" rifle. The .300 was, too, with a narrower variety of loads.

The strap style Weaver mounts might not be considered cool among the younger folks, but they DO have some positive attributes. One of them is light weight. The other is that the spring-steel strap is intended to keep screws from loosing under vibration and recoil and it works at doing that as Mr. Weaver engineered it to.

Another thing.... I could remove and replace the scope and would never be "off" by more than an inch. They're kind of the original QD scope mounts.

 

[Cherokeeguide]

One more thing....

Grandpa was probably in the generation which believed that WD-40 belongs in and on a firearm and that can be a problem when it is used to keep a barrel from rusting inside and that barrel doesn't see a cleaning patch for the next decade or two.

Check the muzzle crown, too, if you haven't. A lot of my deceased relatives had a habit of ruining rifles by letting their muzzles bounce off the floorboards of Jeeps and Broncos that were soiled with decomposed granite. That's not good for the muzzle crown.

A nylon stocking will reveal burrs in the muzzle that you might not feel with your fingers or see with your eyes. That's why I always use one to find burrs on fret ends of my guitars, banjo, and mandolin. Works a treat on firearm muzzles, too.

 

[markXshooter]

Is there a rear pillar / ferrule or are you just up against wood in the rear screw hole?

 

[MGilbert]

Thanks everyone for the advice. I think I may have found the issue.

When you do this, have the floor-plate open and the follower out of the magazine box.

Is there a rear pillar / ferrule or are you just up against wood in the rear screw hole?

Opening the floorplate did not change the binding, however there was no binding when I removed the pillar, or when I ran the screw through only the pillar and not the bottom metal. I believe this means that the pillar hole is not concentric with the rear screw hole in the bottom metal.

Would the solution be to bore that hole larger, and then epoxy the pillar into the stock with everything installed to keep it concentric?

Grandpa was probably in the generation which believed that WD-40 belongs in and on a firearm and that can be a problem when it is used to keep a barrel from rusting inside and that barrel doesn't see a cleaning patch for the next decade or two.

Check the muzzle crown, too, if you haven't.

Fortunately the gun is very clean and seems in excellent condition, I don't have a borescope but from what I can see, the bore looks clean and shiny the whole way down. The crown is missing its bluing, but there are no burrs that I can feel with a cloth.

There's nothing wrong with the Weaver USA strap-style ring mounts.

This is good to hear, I was worried that the strap style of ring might stress the scope differently than symmetrical, horizontal split rings.

 

[markXshooter]

Enlarging the hole and floating the pillar in it w epoxy or bedding compound I think would do the trick. Also a different pillar might help - thinner walls/ larger hole etc.

 

[MGilbert]

Enlarging the hole and floating the pillar in it w epoxy or bedding compound I think would do the trick. Also a different pillar might help - thinner walls/ larger hole etc.

Thank you - This is turning into one of those projects where each problem fixed reveals two more, but I'm making progress. With a round file I carefully adjusted one side of the hole and now the pillar is not causing any binding. I didn't glue it in yet as I'm not sure the best way to locate it up and down.

I then found the bottom metal was rocking around the middle so I shaved a tiny bit of the inletting just under the front of the trigger guard until it sat solid. However, now (and probably before too) the top of the magazine box is pressed tight against the action.

I thought about relieving that top edge, but the bottom metal is actually set a little too deep in the stock, by about 1/16". What's the best way to push it out to relieve the mag box pressure and achieve a flush fit with the stock? Bedding, shims, washers?

Additionally, I decided to remove, clean, and reinstall the scope bases and found that the rearmost hole is stripped out, and the next one forward is pretty close as well. It looks like moisture had got into the threads and rusted/weakened them. I'm looking at the 0.146"-48 screws and tap from Brownells to fix this, to avoid enlarging those holes to 8-40 and possibly messing up the base alignment. Any tips for fixing this, and ways to avoid it happening again in the future?

Thanks again, learning a lot with this project and getting excited to get it shooting well

 

[markXshooter]

Re: the stock - easiest would be to pick up some of the thin shims that midway and like sell to space the bottom metal to the action better.

Sounds like you’re in it pretty good now. Honestly might be easier to relieve the action inletting and bottom metal and bed the whole action and bottom metal (and that rear pillar in the process). But becomes a bigger project.

Re: the screws iiwm I’d have a smith drill out your action and whatever bases you want to eight-forty

Good luck!

 

[Ramem7mm]

Thank you - This is turning into one of those projects where each problem fixed reveals two more, but I'm making progress. With a round file I carefully adjusted one side of the hole and now the pillar is not causing any binding. I didn't glue it in yet as I'm not sure the best way to locate it up and down.

I then found the bottom metal was rocking around the middle so I shaved a tiny bit of the inletting just under the front of the trigger guard until it sat solid. However, now (and probably before too) the top of the magazine box is pressed tight against the action.

I thought about relieving that top edge, but the bottom metal is actually set a little too deep in the stock, by about 1/16". What's the best way to push it out to relieve the mag box pressure and achieve a flush fit with the stock? Bedding, shims, washers?

Additionally, I decided to remove, clean, and reinstall the scope bases and found that the rearmost hole is stripped out, and the next one forward is pretty close as well. It looks like moisture had got into the threads and rusted/weakened them. I'm looking at the 0.146"-48 screws and tap from Brownells to fix this, to avoid enlarging those holes to 8-40 and possibly messing up the base alignment. Any tips for fixing this, and ways to avoid it happening again in the future?

Thanks again, learning a lot with this project and getting excited to get it shooting well

I had the exact same issue with my fathers rifle and the guy that installed the pillars didn't do it correctly. The pillars were aluminum so I just used a round file and removed a very small amount until there was no binding on the rear screw. Maybe spent 5-10 minutes on it to get the clearance necessary.

The rifle would not group very well before and after the rifle was much more consistent.