Bonding a picatinny rail to an action

[adamsls1809]

I bedded a Talley rail on a Cooper stainless M52 earlier this year using regular JB Weld. Pretty much did this like Form describes except for using a release agent, and being extra careful to keep the JB Weld out of the screw holes. First I cleaned everything well with some acetone , and the I used some Hornady Unique case lube as a release agent on the receiver and in screw holes just in case something didn’t go right. First time ever bedding a rail so I was a bit anxious about putting any permanent adhesive on the receiver, and I wanted to have the option to remove the rail in the future if I decide to change something. Put the rail down with the wet JB Weld, snugged the screws without over tightening, cleaned up the fit edges with some toothpicks & w-tips. And let it dry overnight. Next day removed the screws, removed the rail with just a light tap, cleaned the receiver top good, vigorously cleaned the screw thread and holes to be sure no JB Weld was in them, and then properly remounted the rail. Fit was perfect.

Why would you remove the entire rail after putting epoxy dowm, doesn’t that defeat the purpose?

 

[SloppyJ]

Why would you remove the entire rail after putting epoxy dowm, doesn’t that defeat the purpose?

No, just makes it removable. It ensures that the rail is getting perfect contact with your action. Same thing as bedding an action.

 

[adamsls1809]

No, just makes it removable. It ensures that the rail is getting perfect contact with your action. Same thing as bedding an action.

Isnt the idea to make it more rigid w the epoxy AND allow perfect congruent contact? Seems like you should just not even epoxy it if you want to remove, rail manufacturing today seems like the variability and warp is little to none and removavle epoxy’d rail seems like little return of benefit. Just my thought

 

[Carl Ross]

No, just makes it removable. It ensures that the rail is getting perfect contact with your action. Same thing as bedding an action.

People do bed rings or rails for perfect contact, but that isn't what this thread is about. The idea here is to glue them together to strongly reduce the chance that the action-rail interface ever shifts, aiming to eliminate a potential way to lose zero.

 

[SloppyJ]

Lord, he was just asking a question on why you would want to do that so I answered. 90% of people who bed a rail are going to use release agent to be able to remove it in the future. Who knows what you'll want to do 10yrs down the road and maybe that rail needs to come off. I was actually the person who told him to permanently bed it first. Just trying to be helpful for people who are reading. Read the info and make your own decisions.

If you think modern manufacturing can provide a perfect fit every time then you couldn't be more wrong. On my clone actions without integral rails, they fit great. One manufacturer making both pieces at the same place/time. If you go buy a EGW rail for an off the shelf rem700 then I'd be willing to bet that 9 times out of 10 it could benefit from bedding.

 

[adamsls1809]

Lord, he was just asking a question on why you would want to do that so I answered. 90% of people who bed a rail are going to use release agent to be able to remove it in the future. Who knows what you'll want to do 10yrs down the road and maybe that rail needs to come off. I was actually the person who told him to permanently bed it first. Just trying to be helpful for people who are reading. Read the info and make your own decisions.

If you think modern manufacturing can provide a perfect fit every time then you couldn't be more wrong. On my clone actions without integral rails, they fit great. One manufacturer making both pieces at the same place/time. If you go buy a EGW rail for an off the shelf rem700 then I'd be willing to bet that 9 times out of 10 it could benefit from bedding.

I did buy an EGW rail lol! I am definitely bedding but think I will leave intact without release agent for permanent. Thanks for help, just trying to understand everything. Pretty new to tinkering w my 110 UL 7prc.
One question I did have if anyone knew was what to do / use (acetone vs wd40 vs break cleaner) for any JB weld that gets down into the action? Should I put a layer of KIWI wax on the inside of the top of action to prevent epoxy contact and for easy removal. The 110 action has full thickness screw holes that communicate with the action. Which is different than some other actions, I believe. thanks

 

[SloppyJ]

Clear shoe polish works fine. I've also used furniture wax. Put some on your screws and into the threads on the action. You want to leave a bit of space between the the screw holes and your JB weld because it will squish. Line up the rail and place it on there and hopefully you haven't got any compound in the holes.

Alternatively, if you can find some allthread small enough, screw that into your action and have it sticking up out of your gun a few inches. Then put the rail on, use some washers and nuts on the top side against the rail and snug it up. This is how I do my actions and it works better IMO.

Clean all the extra squished out compound from around the rail and wait. Then after it cures you get to pop it off. That's the part that's always makes me nervous but I haven't had anything get stuck yet.

Be sure to degrease everything very well and reassemble.

In your case, if the rail is working loose, you might consider bedding it permanently.

 

[wapitibob]

A pinned and bedded rail isn't going to move enough for anybody to see the difference on a target. There are no scenarios where I'm permanently bonding a rail to a $1,500 action.

 

[Carl Ross]

"Permanent" isn't as permanent as it sounds. All the commonly recommended epoxies I'm familiar with will release with heat. Don't know about the black loctite there.

I've had a pinned-screwed-epoxyed (not just bedded) rail come loose to the tune of 7 moa. I ended up off paper at 100.

Integral would be my first choice, welded second, pinned-screwed-glued third.

 

[Formidilosus]

"Permanent" isn't as permanent as it sounds. All the commonly recommended epoxies I'm familiar with will release with heat. Don't know about the black loctite there.

Loctite Black comes off with heat. Unlike epoxy and JB Weld can at times, I don’t think it’s coming loose unless you want it to.

Integral would be my first choice, welded second, pinned-screwed-glued third.

Yes indeed.

 

[bowrunner81]

Loctite Black comes off with heat. Unlike epoxy and JB Weld can at times, I don’t think it’s coming loose unless you want it to.





Yes indeed.

I used blue Loctite on the bottom of my rail as well as the screws instead of black. I missed that detail. Is there any worry with that, or should i pull it and redo it?

 

[Formidilosus]

I used blue Loctite on the bottom of my rail as well as the screws instead of black. I missed that detail. Is there any worry with that, or should i pull it and redo it?

The blue might still be liquid. It definitely is not a bond.

 

[bowrunner81]

The blue might still be liquid. It definitely is not a bond.

Yea you are right. I pulled it and it’s still liquid. It’s for a Browning X bolt. In the XBolt 2 review you did, you used a paint pen for both the screws and between the base and the action. How does that compare to the loctite 380?.

 

[Fireflyfishing]

I’ve been asked a bunch on how to bond or glue a rail to an action. I had one today to do, so…


This is a Tikka T3x and Leupold Backcountry Rail. The has a lip around the edge of it, it’s not flat with the action. So you lose all friction that would come when the rail and action are mated together. It also does not have recoil lugs. Wouldn’t recommend.
For a bonding agent I’m using Loctite 380 Black Max this time.

First degrease the action, action threads, the rail, every screw, the holes in the rail, etc. Using acetone, brake cleaner, etc get all the oil off.

Then, coat the rail with the adhesive, try to stay away from the screw holes-
View attachment 577944


Set the rail straight down over the holes so you don’t drag the adhesive into them, then put one screw at a time in, just to snug.

Then pull one screw out at a time and clean the screw and the threads in the action well with acetone/brake cleaner to get any adhesive off that might have gotten in. Out of the four screws one got adhesive in it-

View attachment 577946

Clean each one off, then usnibg Blue Loctite, a paint pen, or fingernail polish, put some in the screw and torque down. Repeat for all the screws.
View attachment 577947




Once they are all cleaned, painted and torqued, I go back and put a dab of paint/Loctite around the screw heads. I ran out of orange, so shifted to purple.

View attachment 577948



Finished rail with a line of adhesive showing-
View attachment 577949




Scope mounted, index marked and ring base screws-
View attachment 577950


And on ring cap screws-
View attachment 577951





If something comes loose, it’ll be obvious. But it won’t. Done as shown, this base, ring, scope combo isn’t moving unless I want it to.

After listening to your podcasts and recently seeing this method, I’m doing this from now on. I just completed a scope base and rings last week using Sally Hansen’s. Thanks for a great tip @Formidilosus.

 

[jjohnsonElknewbie]

Picked up some Loctite 380 on Ebay last week for like $13. Followed directions and cleaned/bonded Salmon River Soutions 20 MOA rail to my stainles T3 action last night. With a couple q-tips it was easy peasy with a clean look and finish. Scope should be here today and rings tomorrow, and looking forward to getting it put together and shooting.

The integral rail on this action is damaged, so in this case the rail is permanent. Thanks to Form for posting!

 

[SDHNTR]

Does Loctite 380 have enough “body” to it, and does it resist compression enough to fill in voids to serve as a bedding material? I understand it’s adhesion qualities as a CYA based material, but it doesn’t seem like it would make a very good liquid shim like epoxy.

 

[jjohnsonElknewbie]

Does Loctite 380 have enough “body” to it, and does it resist compression enough to fill in voids to serve as a bedding material? I understand it’s adhesion qualities as a CYA based material, but it doesn’t seem like it would make a very good liquid shim like epoxy.

So, here's what I'd say.. Blue loctite is fairly runny before it cures. The 380 is black and viscous right out of the tube, even a little stringy kinda like the old plastic modeling glue out of the tube. Not as bad as say rubber cement.

I would think 380 would fill voids after it cures, but you may just need to test in a non-crucial area first. YMMV

 

[SDHNTR]

So, here's what I'd say.. Blue loctite is fairly runny before it cures. The 380 is black and viscous right out of the tube, even a little stringy kinda like the old plastic modeling glue out of the tube. Not as bad as say rubber cement.

I would think 380 would fill voids after it cures, but you may just need to test in a non-crucial area first. YMMV

And once it hard cures and fills in voids it also resists compression enough to withstand 25ish inch lbs of torque?

 

[jjohnsonElknewbie]

And once it hard cures and fills in voids it also resists compression enough to withstand 25ish inch lbs of torque?

I'm not certain, but I have it under my rail, and it's screwed down with 15ft. lbs to the action (SRS guidance).
Here is a bit of information on it.
https://next.henkel-adhesives.com/u...tral-pdp.html/loctite-380/BP000000153507.html

"There are several methods to toughen CA adhesives, but the most popular ways are using rubber or anhydride toughening agents. The toughening agents are designed to absorb and distribute impact and stress applied to the adhesive bond line resulting in a tougher bond."

 

[SDHNTR]

I'm not certain, but I have it under my rail, and it's screwed down with 15ft. lbs to the action (SRS guidance).
Here is a bit of information on it.
https://next.henkel-adhesives.com/u...tral-pdp.html/loctite-380/BP000000153507.html

"There are several methods to toughen CA adhesives, but the most popular ways are using rubber or anhydride toughening agents. The toughening agents are designed to absorb and distribute impact and stress applied to the adhesive bond line resulting in a tougher bond."

I get that. I’ve used rubberised CYA adhesive for installing inserts in my arrows for years. It’s much better than standard CYA at absorbing impacts. I just don’t see it being hard enough to withstand much compression. Seems to me that epoxy would still be a better fit to create the liquid shim, and then you could apply the CYA afterwards for better adhesion?