Bonding a picatinny rail to an action

[Marbles]

I should have said that vision rail is way more better. I am very curious how it works.

It looks to me like it just slides over therail on the action, but doesn't clamp to it, so just a cosmetic difference (and harder to epoxy on).

 

[sndmn11]

It looks to me like it just slides over therail on the action, but doesn't clamp to it, so just a cosmetic difference (and harder to epoxy on).

It looks like set screws that act as recoil lugs push the rail up, which cause the integral rail part to tighten. Then it gets screwed down to the action? I couldn't really imagine it all out to make sense which is why I haven't ordered one.

 

[Marbles]

It looks like set screws that act as recoil lugs push the rail up, which cause the integral rail part to tighten. Then it gets screwed down to the action? I couldn't really imagine it all out to make sense which is why I haven't ordered one.

Perhaps. However , Ithink the recoil lugs just have to be threaded and screwed down into the holes once it is slid into the action.

Below is an over long and probably not clearly written discussion of why I think that.

Threads in aluminum are not very strong, plus pushing the rail up would result in the bottom of the dove tails being the only contact points. So, if tightening the threaded pins is to engage the rail with the dovetail, it is a pretty poor design and turns the screws threaded into steel into recoil lugs while minimizing contact between the action and the rail.

Really, screws are just a clamp and it is the friction between the bottom of the rail and the top of the action that keeps the rail from moving. Torque the screws to only 3 inch pounds and they will shear with a lot less force applied to the rail than if you torque them to 15 inch pounds. Shear resistance will continue to increase as clamping force increases, the limit is the fastener, once it stretches too far it will be prone to breaking, at which point there would the be no clamping force. If everything is done right, the screws themselves should never experience shear force.

It is the same as how a scope is held in the rings by friction.

 

[sndmn11]

. So, if tightening the threaded pins is to engage the rail with the dovetail, it is a pretty poor design and turns the screws threaded into steel into recoil lugs while minimizing contact between the action and the rail.

That's why I didn't order one!

The 419 one is easy.

 

[amassi]

If I had to run a pic rail on a tikka it would be the mtn tac with recoil lug. “Permanently” bonded to the action.
In fact I have just such a creature in 223 that has acted as a proof rifle for the last couple years when friends scopes go wonky

 

[Formidilosus]

Checked zero yesterday-




Then today checked four different types of ammo. Left to right, top to bottom- Winchester M118LR 175gr SMK, FGGM 175gr SMK, Federal Gold Medal Beger 185gr Juggernaut, handload 185gr Juggernaut. Max time between groups less than 2 minutes.




The Winchester M118LR is variable from lot to lot, some are very good, some like this lot are mediocre- about 1.4 MOA for 20 rounds. Federal Gold Medal Match 168gr and 175gr are the standard for a reason. Federal 185gr OTM generally shoots very well, this group had pretty bad barrel mirage. A breeze picked up for the last group getting rid of the barrel mirage.

 

[Dobermann]

Good timing as I have a rail I need to mount on a Tikka.

I got a Talley rail, but for future reference, does anyone make one with recoil lugs?

There's a whole thread here about rails for Tikkas: https://rokslide.com/forums/threads/rail-for-tikka.270437/

I know Marbles found a solution, but just referencing for others ...

 

[Marbles]

@Formidilosus I'm curious how thermal cycling and the different heat expansion coefficients of aluminum and steel effect the adhesive over time. While most people do not shoot enough for it to matter, it certainly is possible to shoot enough to surpass the heat rating of most adhesives/epoxies.

The other question is which adhesives hold up better to thermal cycling. The 380 looks to be a good choice.

As you have access to world class engineers, perhaps you can ask one. Or, I could also stop overthinking as it probably will never matter for me.

 

[Formidilosus]

@Formidilosus I'm curious how thermal cycling and the different heat expansion coefficients of aluminum and steel effect the adhesive over time. While most people do not shoot enough for it to matter, it certainly is possible to shoot enough to surpass the heat rating of most adhesives/epoxies.

The other question is which adhesives hold up better to thermal cycling. The 380 looks to be a good choice.

As you have access to world class engineers, perhaps you can ask one. Or, I could also stop overthinking as it probably will never matter for me.

I can ask, though it will probably never matter.

 

[Southern Lights]

I do the same thing here on rifles with Weaver style two piece mounts as well as single piece pic rails. Use a two part slow cure epoxy called Aradite. I learned to do this from a former NZ Army armorer and gunsmith. If you need to take it off, remove the action from the stock and use a heat gun or carefully with propane torch to bring up to heat.

The tiny screws holding mounts onto actions are a problem waiting to happen if not glued. I've never had a mount come loose that I epoxied down like this.

 

[Phil Anderson]

@Formidilosus, I’ve just epoxy bonded (no loctite 380 nearby) a Leupold Backcountry rail to my x-bolt to mount my SHV 5-20 using Burris Signature zee rings.

The rail has a cutout to the rear for the screws.



Is mounting the rear ring over this cutout ok?


Regards
Phil

 

[Formidilosus]

@Formidilosus, I’ve just epoxy bonded (no loctite 380 nearby) a Leupold Backcountry rail to my x-bolt to mount my SHV 5-20 using Burris Signature zee rings.

The rail has a cutout to the rear for the screws.

View attachment 589853

Is mounting the rear ring over this cutout ok?

View attachment 589854
Regards
Phil

I wouldn’t have an issue with it.

 

[Veloci_Wrench]

I had been planning to epoxy my rail to my rifle all summer, and found this thread today. Glad I did, because I was planning to use Kiwi natural as release agent for the bolts, etc, but @Formidilosus just saved me lots of time by just removing the bolts, cleaning, and then re-installing.

I actually repeated that step twice for each bolt, and used an acetone q-tip to clean the bolt holes in the rail as a safety measure. I also discovered that my rail didn't sit flush to the receiver, so I only snugged down the front screws, and used the rear screws as locators while the epoxy cures. I used Devcon Plastic Steel epoxy, because I already had it.

 

[Dobermann]

grin. All actions should have integrated rails.

Okay ... now I'm confused.

Given the choice between UM Tikka rings direct to Tikka rail, or an integral Pic rail, which would you choose and why?

And if bonding a Pic rail well gives nearly the same outcome as, say, a Tikka factory-bonded rail, then UM Rings direct or self-bonded rail - and why?

I'm interested in your 'whys' - helps me work out my own. Cheers!

 

[Marbles]

Okay ... now I'm confused.

Given the choice between UM Tikka rings direct to Tikka rail, or an integral Pic rail, which would you choose and why?

And if bonding a Pic rail well gives nearly the same outcome as, say, a Tikka factory-bonded rail, then UM Rings direct or self-bonded rail - and why?

I'm interested in your 'whys' - helps me work out my own. Cheers!

My take is the Tikka has an integrated rail, it is nust not a pic rail.

 

[Dobermann]

My take is the Tikka has an integrated rail, it is nust not a pic rail.

Aha, got it.

Still curious, given this thread, if @Formidilosus's preference is UM direct on Tikka rail, or a self-bonded Pic rail ...

 

[Formidilosus]

Okay ... now I'm confused.

Given the choice between UM Tikka rings direct to Tikka rail, or an integral Pic rail, which would you choose and why?

If an integrated low profile pic rail in an option- that. If pic rail isn’t a necessity, then integrated Tikka rail. If pic rail is necessary, then pinned and bonded pic rail.

 

[Dobermann]

If an integrated low profile pic rail in an option- that. If pic rail isn’t a necessity, then integrated Tikka rail. If pic rail is necessary, then pinned and bonded pic rail.

Thanks ... in what scenarios/use cases do you regard a pic rail as necessary?

 

[Formidilosus]

Thanks ... in what scenarios/use cases do you regard a pic rail as necessary?

“Necessary” when you require inclination for the scope. Other than that it is a want, though picatinny is the standard of given a choice I would choose an integral pic rail.

 

[Stache Attack]

Next rifle I’ll definitely be doing this! Or when get the wife a new scope we will put a rail on and bond it