Drilling out Remington Model 7 rear screw to accept 700 screws?

[diegocn]

I'm looking at a Remington Model 7 receiver where the rear action screw is broken. The original M7 rear screw is the tiny #8-36. I heard people has been drilling the rear screw hole to accept 1/4-28 screw used by the M700 receiver. I'm mainly concerned with how much meat is left in the receiver and the rear trigger guard after enlarging the hole.

Can it be done? Has anyone done it before? Does it provide any benefit or it just shift the weak point from the screw to the receiver or other parts?

 

[bearhunter]

You're looking at a miniscule amount of metal removed.

The 1/4 screw is stronger and readily available from several different sources if you do your due diligence.

Your biggest issue is going to be getting a screw of the proper length or your personal ability to shorten the screw to fit.

The rear hole of the trigger guard will have to be opened up as well.

If you don't have the tools or knowledge on how to do this job, take it to someone that does. Most gun shops, other than the Big Box stores, who job such work out, will have someone capable of doing the job correctly.

It's very simple but it has to be done properly so that the drilling and tapping of the hole are 90 degrees to the receiver internal flats and properlay aligned with the front receiver action screw.

 

[guntech]

I have never done one. My preference would be to simply get a replacement screw, make sure the action is bedded correctly and don't over tighten the screw. Good and snug with a small screwdriver is all it needs.

 

[Potashminer]

An acquaintance recently broke off a M5 (?) HSS tap in a Mauser receiver. He did not want to mess up the receiver - amazing to both of us, he was able to source a tiny diameter carbide end mill - set up the receiver in an X-Y vice and precisely located (as best he could) and successfully drilled through that broken off HSS tap endways - then moved X a smidgen at a time and was able to enlarge that through hole until the tap broke in pieces and could be removed. Did not even mark the receiver. Did not even get to the threads that he had managed to cut - a new tap threaded on through. So, would think that your broken off action screw much less hard than a HSS tap, but idea might work for you? Is not a thing for hand holding a 3/8" drill though - I believe he did in a drill press, because he does not have a mill - will would have been "better" in a mill, except he did get done what he wanted to do.

It was not clear in OP's post - be aware that the hole to be drilled is a specific size for that tap and thread count - is NOT a 1/4" hole drilled for a 1/4"x28 thread hole - is a #3 numbered drill for a 1/4"x28 tpi tapped hole. You might want to "cheat" a bit and try to get by with a 7/32" drill bit.

 

[diegocn]

Thanks for the response. Yes I mainly wanted to know if there's enough metal. Already have the broken screw extracted and new screw is on the way.

If I recall correctly both action screw holes are 90 degree to the receiver dead bottoms center, right? I can clamp the receiver in a v block and find the center with gauge pin maybe? And maybe even confirm squareness with another gauge pin on the front hole, then go to down with the drill bit? I think the trickest part is to make sure the receiver bottom is facing straight up, which I can't tell with an wobbly finder on the hole alone.

 

[Potashminer]

Aligning screws - might want to know that the P14 and M1917 rear action screw is about 85 degrees to the bore centreline - is a bit unusual, because it is not "square" front to back. Action screw head is forward of the hole in the receiver tang - hole does not go down "plumb". But that action screw is "square" left to right. Is actually a bit of conundrum to me why they did that - would seem as that rear action screw is torqued, would tend to move that recoil lug on receiver to forward - opposite what I would think is wanted?? Contrast to Ruger 77 - front action screw at significant angle - I had read idea was to pull that receiver back into the recoil area tightly.

 

[bearhunter]

Thanks for the response. Yes I mainly wanted to know if there's enough metal. Already have the broken screw extracted and new screw is on the way.

If I recall correctly both action screw holes are 90 degree to the receiver dead bottoms center, right? I can clamp the receiver in a v block and find the center with gauge pin maybe? And maybe even confirm squareness with another gauge pin on the front hole, then go to down with the drill bit? I think the trickest part is to make sure the receiver bottom is facing straight up, which I can't tell with an wobbly finder on the hole alone.

Instead of purchasing expensive gauge pins, just use the shank of the appropriate drill in your index

 

[guntech]

Thanks for the response. Yes I mainly wanted to know if there's enough metal. Already have the broken screw extracted and new screw is on the way.

Is the new screw a replacement or a 1/4 inch...?

 

[diegocn]

Is the new screw a replacement or a 1/4 inch...?

It's...well...both. Brownells stopped carrying the model 7 screws so I ordered the screw set for M700 ADL bottom metal. It's suppose to have 3 screws, 2 for regular M700 which are 1/4 and one that's #8-36 that requires almost no trimming to fit the M7. So I can go either way.

 

[diegocn]

Instead of purchasing expensive gauge pins, just use the shank of the appropriate drill in your index

Yes, actually I realized I can get a threaded rod and chuck that into the mill to find the center of both holes. 1/4-28 and #8-36 are both fairly common from hw store.

 

[diegocn]

Aligning screws - might want to know that the P14 and M1917 rear action screw is about 85 degrees to the bore centreline - is a bit unusual, because it is not "square" front to back. Action screw head is forward of the hole in the receiver tang - hole does not go down "plumb". But that action screw is "square" left to right. Is actually a bit of conundrum to me why they did that - would seem as that rear action screw is torqued, would tend to move that recoil lug on receiver to forward - opposite what I would think is wanted?? Contrast to Ruger 77 - front action screw at significant angle - I had read idea was to pull that receiver back into the recoil area tightly.

That's interesting. I checked a few M700 drawings it does seem the holes are square. I guess if I'm finding the center by chucking a threaded rod, then the receiver should be well aligned to the drill bit.

 

[tiriaq]

The original factory screw works fine. Drilling out the hole and threading it to 1/4-28 is a permanent alteration to the receiver.
Botch the job, and the receiver is pooched.
Seems to be taking a chance for no good reason.

 

[piker]

It's...well...both. Brownells stopped carrying the model 7 screws so I ordered the screw set for M700 ADL bottom metal. It's suppose to have 3 screws, 2 for regular M700 which are 1/4 and one that's #8-36 that requires almost no trimming to fit the M7. So I can go either way.

The center adl screw is too short to reach in a model 7.

 

[diegocn]

The center adl screw is too short to reach in a model 7.

These are extra long at 2.250". Let's hope it works.

 

[piker]

If it’s extra long you should be good. I just know the standard length is too short.

 

[diegocn]

The original factory screw works fine. Drilling out the hole and threading it to 1/4-28 is a permanent alteration to the receiver.
Botch the job, and the receiver is pooched.
Seems to be taking a chance for no good reason.

I was hoping to add some rigidity to the setup. Maybe I'm over thinking this.

 

[bearhunter]

I was hoping to add some rigidity to the setup. Maybe I'm over thinking this.

The rear screw only needs to be snug, not knuckle whitening tight.

It's the fron screw that does most of the work and the rear screw just keeps the rear of the receiver from wandering around.

I had a very good friend that did some experiments, using a 98 action, to determine how much effect the rear screw had on accuracy, when the receiver was tightly bedded into the stock.

He used a front pillar between the bottom metal and torqued the retaining screw to 45 in pounds, when setting up the bedding.

The rear of the receiver was allowed to establish itself in the bedding compound, without torquing the screw at all, it was only there as a guide.

If memory serves, the rifle was chambered for 257 Roberts.

That rifle was loaded well beyond book specs, 100 grain bullets at 3000fps out of a 22 in bbl.

Even then, recoil would be considered moderate.

We put well over 2000 rounds through that rifle and it maintained excellent accuracy, with only the front retaining screw.

The rear of the trigger gaurd was held in place with a wood screw. There was a piece of dowel glued into the hole for the original screw.

I don't know where that rifle went.

We were both surprised but it was by no means an original idea.

Lots of rimfire receivers are held in place with one screw and they shoot very well.

I have never repeated the above experiment and likely never will, but it was interesting at the time and showed where the work of holding and stabilizing the receiver in the stock is done, depending on the bedding.