Diana 34 scope slipping. What is the solution?

Is the scope slipping in the rings or is the mount slipping on the dove tail? If the mount is slipping then a stop pin should solve the problem.

Is there a provision to put a roll pin thru the mount into the hole on the top of the reciver(if it has one). My BKL rings has that provision, I have had no problems. The roll pin into the receiver acts as a stop for the secondary rearward recoil 

All those fasteners for the rail and only 2 per ring cap...I presume you mean the scope is slipping in the rings. But whatever the case...

Before resorting to a more aggressive approach, borrow or buy an inch*lb torque wrench. Clean all surfaces with a clean-evaporating solvent like paint thinner (stoddard solvent) to remove any residual oil from manufacturing or human hands. Then torque the base screws to ~30in*lbs and the ring screws to ~15in*lbs. Then test it to see if it still moves (tip: place a piece of masking tape on the tube right where it meets the edge of one of the rings...if the scope slips, it will be easy to recognize right away).

If that fails or if you want to move on past it, some guys have had success with applying rubber cement to augment the grip.

And if you want to go all out, lap the rings to improve contact with the scope tube. Most of these extruded aluminum rings have fairly poor surface contact. See an example https://www.gatewaytoairguns.org/GTA/index.php?topic=109966

On a wild bucking springer that has not been domesticated, I use 58 in-lb recipe on base and 25 in-lb on the rings. Works well.

Be very careful not to over tighten the scope rings. Those BKL rings pinch quickly and will bend a scope. The mount to receiver portion as mentioned must have a stop pin added else it will slide back no matter how tight you crank the screws. I’m not understanding the where the scratch is coming from. Can you please explain this better?

That mount is cracked already. Either your rails are too wide, or too narrow, and it's been overtightened or overstressed already. 

A set of cheap two piece UTG mounts will probably fix you up fine. RWS used to make their own one piece mount, the "Lockdown" that would also work. 

The BKLs are great mounts, and I use them a lot. But have had the same issue on guns with funky rail widths. Yes, yours "should" be 11mm, but there's unfortunately a lot of leeway in the tolerance there and they just aren't perfect on all guns. 

I've used the two piece BKLs on lots of guns with no slipping and they didn't need a stop pin. But, they have to fit well to begin with. 

Try em on a Daystate and they have to be spread to the max to fit. 

Put em on my HW100 and they have to be extra cinched down. 

Put em on an HW77K and it's like they were made for em. 

Just the way it is sometimes, those have all been my personal experiences. 

The BKL mount is more suited to the dovetail on a Feinwerkbau 124 than the M34. I have a BKL on my 124D and it doesn't have any provision for a stop pin. That said, it hasn't moved on my rifle but the 124 doesn't have as harsh of recoil snap as the 34 does. This is the RWS one-piece mount I use on my 34 with no problems. It has both the stop pin and .025" droop compensation.

https://www.airgundepot.com/rws-lock-down-scope-mount-1-inch.html

Good eye to notice that crack!! Cant say if bkl does this or not but sportsmstch has a two sided clamp for the base to allow for different dovetail widths, by any chance does bkl?

Is there a provision to put a roll pin thru the mount into the hole on the top of the reciver(if it has one). My BKL rings has that provision, I have had no problems. The roll pin into the receiver acts as a stop for the secondary rearward recoil

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No !

" That mount is cracked already. "

You can make that determination from those two photos ?? I guess that long mark could be a crack or a bad scratch.

RWS lockdown mount. It was designed for this application.

Your mount appears to be a BKL 3/8” rimfire mount. I have used this UTG mount for years and it’s works well. It has a pin for scope stop.

" That mount is cracked already. "

You can make that determination from those two photos ?? I guess that long mark could be a crack or a bad scratch.

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Yes, because I have a cracked set here myself that look the same. 

The silver line on the inside of the dovetail is the metal spreading apart.

Mine cracked from being on a dovetail that was too wide. 

Contact BKL Air Force for warranty. They do not have life time warranty and you will need your purchase receipt proof with in warranty period. 

Explain the problem to them and they may suggest an alternative set of rings exchanged under warranty.

They are expensive so better do the warranty.

Something is definitely wrong if those mounts are slipping. I have had the BKL one piece mounts on a Diana 34 for quite a long while and they have done a wonderful job and have not moved even a mm. They are good mounts....







Hope you can get it squared away.

" That mount is cracked already. "

You can make that determination from those two photos ?? I guess that long mark could be a crack or a bad scratch.

Click to expand...

Yes, because I have a cracked set here myself that look the same. 

The silver line on the inside of the dovetail is the metal spreading apart.

Mine cracked from being on a dovetail that was too wide.

Click to expand...

Good to know ! Thanks for sharing that. When I really zoomed in in you can see the silver crack line. I'd say it cracked as a result of the different dovetail. Maybe just a wee to much torque as well.

" That mount is cracked already. "

You can make that determination from those two photos ?? I guess that long mark could be a crack or a bad scratch.

Click to expand...

Yes, because I have a cracked set here myself that look the same. 

The silver line on the inside of the dovetail is the metal spreading apart.

Mine cracked from being on a dovetail that was too wide.

Click to expand...

Good to know ! Thanks for sharing that. When I really zoomed in in you can see the silver crack line. I'd say it cracked as a result of the different dovetail. Maybe just a wee to much torque as well.

Click to expand...

Yep, had that happen a couple times using "bargain" mounts. Switched over to Sportsmatch" and never had another issue, no matter how much torque was applied. Also beware that some bargain mounts use softer aluminum and I have saw the dovetail clamps themselves crush from to much torque. The material in Sportsmatch mounts is a much harder/tougher forged aluminum, not billet machined.

It should be noted that the BKL mount base screws are torqued to 35 in lbs.

" That mount is cracked already. "

You can make that determination from those two photos ?? I guess that long mark could be a crack or a bad scratch.

Click to expand...

Yes, because I have a cracked set here myself that look the same. 

The silver line on the inside of the dovetail is the metal spreading apart.

Mine cracked from being on a dovetail that was too wide.

Click to expand...

Good to know ! Thanks for sharing that. When I really zoomed in in you can see the silver crack line. I'd say it cracked as a result of the different dovetail. Maybe just a wee to much torque as well.

Click to expand...

Yep, had that happen a couple times using "bargain" mounts. Switched over to Sportsmatch" and never had another issue, no matter how much torque was applied. Also beware that some bargain mounts use softer aluminum and I have saw the dovetail clamps themselves crush from to much torque. The material in Sportsmatch mounts is a much harder/tougher forged aluminum, not billet machined.

Click to expand...

@Airshot

Sportsmatch rings are NOT forged, they ARE machined from aluminum. 

Tougher and likely heat treated better than cheap mounts, yes. But forged, no. Forged rings are much more expensive than even Sportsmatch. 

For the sake of accuracy..