Dovetail mounts off center.

[Bayman]

I believe what you are dealing with is scope cant ...
https://www.gatewaytoairguns.org/GTA/index.php?topic=129954.0

yes I know. Thanks for posting this link though. There's a great diagram on that thread that explains my situation perfectly. I'm just reluctant to deliberately mount the scope crooked to the gun and then hold the gun crooked to correct the cant. As suggested here I will try flipping the rings on the guns the can be. This however would only make an improvement if the barrel is bent to one side. Other than that flipping the will only shift the cant error bias to the other side. So far nced UTG rails and weaver mounts may be the best way to center the scope over the bore on a dovetailed rifle.

[nced]

Ed (nced), I have an email into BKL about their technical data sheet & where to find it. Stay tuned.

IF there are actual torque specs for the top straps that would be great. Going by this "copy and paste" from their web site I really doubt it and the warning "do not close the gap between the edges (etc)" does seem to indicate that it's possible to over torque the top strap screws if the "allen wrench twister" wasn't careful.

"How do I know when the scope tube is properly clamped?
When the oval shape of the ring becomes a circle around the scope tube and no gap is seen between inside diameter of the ring and the outside diameter of the scope tube. Important: Do not close the gap between the edges of the ring (the flat surfaces where the screws are) as this might crush your scope tube! Please refer to our technical data sheet for more information."

Anywhoo....I do know that when using 10in/lbs of top strap screw torque the relatively light 4-12x40 Vortex Diamondback shifted in the rings after only a couple hundred shots, then the scope tube was damaged using 15in/lbs torque.

[Habanero69er]

Received a response from BKL.

Hi Dave,
 
The Torque recommendation for the cap screws is simply to hand tighten with no more torque than 15 inlbs.
 
Thanks!
Leah
 
 
Leah Chesser
Auto-Numatic Corp. Retail Products Division
AirForce Airguns|BKL Technology| AirForce International|Rapid Air Weapons

[nced]

Received a response from BKL.

Hi Dave,
 
The Torque recommendation for the cap screws is simply to hand tighten with no more torque than 15 inlbs.
 
Thanks!
Leah
 
 
Leah Chesser
Auto-Numatic Corp. Retail Products Division
AirForce Airguns|BKL Technology| AirForce International|Rapid Air Weapons

Hummm.....I do dispute the BKL torque claims because I have a couple 1" scope tubes that were damaged using 15in/lbs torque with the two piece BKL "double strappers".

There was no scope tube damage using 15in/lbs top strap screw torque with the one piece BKL mount since the single top straps are wider but the wider BKL top straps did allow my scope to shift in the one piece mount unless I lined the rings with cloth electrical tape. I never did solve the one piece BKL mount/scope shifting on my Beeman R9 OR HW95 scope dovetails even though the base screws were torqued to 40in/lbs (5in/lbs above BKL max recommended torque) ..............



Anywhoo.......when using 15in/lbs top strap screw torque with a 1" tube scope it seems that scope tube damage depends which BKL mount is used.......damage for two scope tubes with the "double strappers" and no scope tube damage using the one piece BKL with th ewider top straps. If scope slippage or scope tube damage wasn't an issue using the NORMAL 15in/lbs of torque then why does BKL offer this gem.........


When I used the UTG Universal Adapter plus a set of Weaver Quad Lock mounts there is no 1" scope tube damage using 15in/lbs, plus the scope was held firmly in the rings using only 10in/lbs top strap screw torque (narrow tops straps like the BKLs). The universal adapter costs about $13.............
https://www.pyramydair.com/product/utg-universal-dovetail-to-picatinny-weaver-adapter?a=7311
The Weaver Quad Lock rings for a 1" tube scope only costs about $10 at "WallyMart" ($23 for both). For my new Hawke compact scope with 30mm tube I bought this set of Sniper rings (about $9) to mount on the adapter. Total cost for adapter and rings ($22).............

[Mossonarock]

In this thread I finally figured out how BKL's mounts are self-centering.

When messing around with peep sights the past couple months, I realized that not all dovetails are the same width; before hand, I had never bothered to measure and compare them between rifles. If the mounts you are using aren't made for the exact width of your dovetails, your scope will not be in-line with your barrel no matter what you try to do. Really frustrating. Now, I'm cringing from the thought of how many of my rifles have mounts that aren't appropriate for the rifles they are on.

It would be neat if scope mount manufacturers would make their mounts so that the end consumer had to file the dovetail claw on the mount to customize it to the rifle that it will be installed on. Of course, a way to do that simply and easily would have to be devised for the end consumer- center marks on the mounts, something.

[Yogi]

In this thread I finally figured out how BKL's mounts are self-centering.

When messing around with peep sights the past couple months, I realized that not all dovetails are the same width; before hand, I had never bothered to measure and compare them between rifles. If the mounts you are using aren't made for the exact width of your dovetails, your scope will not be in-line with your barrel no matter what you try to do. Really frustrating. Now, I'm cringing from the thought of how many of my rifles have mounts that aren't appropriate for the rifles they are on.

It would be neat if scope mount manufacturers would make their mounts so that the end consumer had to file the dovetail claw on the mount to customize it to the rifle that it will be installed on. Of course, a way to do that simply and easily would have to be devised for the end consumer- center marks on the mounts, something.

Or just use a picatinny rail and ditch dovetails all together!

-Y

[nced]

I'm wondering, ha

In this thread I finally figured out how BKL's mounts are self-centering.

When messing around with peep sights the past couple months, I realized that not all dovetails are the same width; before hand, I had never bothered to measure and compare them between rifles. If the mounts you are using aren't made for the exact width of your dovetails, your scope will not be in-line with your barrel no matter what you try to do. Really frustrating. Now, I'm cringing from the thought of how many of my rifles have mounts that aren't appropriate for the rifles they are on.

It would be neat if scope mount manufacturers would make their mounts so that the end consumer had to file the dovetail claw on the mount to customize it to the rifle that it will be installed on. Of course, a way to do that simply and easily would have to be devised for the end consumer- center marks on the mounts, something.

Have you noticed any ACCURACY issues with slightly canted scope mounts?

Years ago both my brother and I used two piece mounts with separate clamp plates and neither of us had "accuracy issues", only mount slippage and stop pin hole damage. Here are a few groups shot decades ago by my brother and I using "canted mounts". All my groups were shot sitting on a bucket resting the R9 on cross sticks but my brother's groups were shot "bench rested". First two of my brothers "3 shot powder burner groups" shot back to back..........

Here are a few of my "bucket and sticks" groups from "way back when" using two piece "canted mounts"...........


As mentioned previously, I started using this adapter with Picatinny rings not long ago and it solved my mount/scope slippage issues with this $13 one piece design plus a set of $9 Weaver Quad Lock rings from "WallyMart".........



Anywhoo......except for "non slipping of mount and scope", I haven't found that the "one piece design" to make my break barrel springers more accurate than the "slightly canted mounts" I used a few years back.......

[Bayman]

I'm only experiencing cant issues because I test and zero at ten yards in my basement. Being that close brings cant errors to light when I target shoot outdoors at 25 and 50 yards. The shots run high and to the right outdoors. When I zero at 25 yards my 50 yard groups are close enough laterally. When I return home the guns zeroed at 25 yards print low and left. I obviously expect vertical changes and can use the mildots for correction, but having to readjust the windage all the time gets old. It's pretty much a non issue if you zero rifle at 25 or 30 yards and normally shoot outdoors but it is if you have to shoot at close ranges most of the time.

[mobilehomer]

The easy solution is to zero at 25 yards. Then when testing indoors, don't worry about WHERE the pellets hit, you are looking for GROUPS! This also lets you shoot the same POA without messing it up with holes. Looking for groups, not location, should help with the OCD.

[nced]

I'm only experiencing cant issues because I test and zero at ten yards in my basement. Being that close brings cant errors to light when I target shoot outdoors at 25 and 50 yards. The shots run high and to the right outdoors. When I zero at 25 yards my 50 yard groups are close enough laterally. When I return home the guns zeroed at 25 yards print low and left. I obviously expect vertical changes and can use the mildots for correction, but having to readjust the windage all the time gets old. It's pretty much a non issue if you zero rifle at 25 or 30 yards and normally shoot outdoors but it is if you have to shoot at close ranges most of the time.

I have a suspicion that the "mount cant" isn't the issue but a matter of the scope reticle not being lined up with the bore. I used to have the same issue but I started leveling my R9 barrel pivot block, then lining up my scope verticle crosshair with a hanging plumb bob............

After using this method the "poi alignment issue" went away even though I was using mounts with a separate clamp plate at that time.

Here is a target I shot sitting on a bucket resting the gun on cross sticks using my .177 R9. I was checking out the pellet trajectory after a new tune to see if it came close to the ChairGun computer software output ( LOL....not even close). This target shows the poi of 165 consecutive shots from "bucket and sticks" at ranges from 10 yards to 50 yards and all groups are lined vertically even though the mounts had a separate clamp plate...........



Anywhoo....whatever works for you is best. If using a "one piece mount like the BKL" solves you "poi issues" that's good, however my poi "windage issues" at different distances was due to my scope reticle alignment, not the mount clamping method.

[Bayman]

I'm only experiencing cant issues because I test and zero at ten yards in my basement. Being that close brings cant errors to light when I target shoot outdoors at 25 and 50 yards. The shots run high and to the right outdoors. When I zero at 25 yards my 50 yard groups are close enough laterally. When I return home the guns zeroed at 25 yards print low and left. I obviously expect vertical changes and can use the mildots for correction, but having to readjust the windage all the time gets old. It's pretty much a non issue if you zero rifle at 25 or 30 yards and normally shoot outdoors but it is if you have to shoot at close ranges most of the time.

I have a suspicion that the "mount cant" isn't the issue but a matter of the scope reticle not being lined up with the bore. I used to have the same issue but I started leveling my R9 barrel pivot block, then lining up my scope verticle crosshair with a hanging plumb bob............

After using this method the "poi alignment issue" went away even though I was using mounts with a separate clamp plate at that time.

Here is a target I shot sitting on a bucket resting the gun on cross sticks using my .177 R9. I was checking out the pellet trajectory after a new tune to see if it came close to the ChairGun computer software output ( LOL....not even close). This target shows the poi of 165 consecutive shots from "bucket and sticks" at ranges from 10 yards to 50 yards and all groups are lined vertically even though the mounts had a separate clamp plate...........



Anywhoo....whatever works for you is best. If using a "one piece mount like the BKL" solves you "poi issues" that's good, however my poi "windage issues" at different distances was due to my scope reticle alignment, not the mount clamping method.

Thanks Ed. I use levels on the scope and the rifle and then check the reticle true with a plumb bob like you do. I'm terribly ocd and I can't tell you how many times I found scopes with reticles canted to the turrets. Thank you for taking the time to post your reply. I greatly appreciate your input.
Ps I'm not using the BKLs ever after the information you posted. Thanks for that too.

[nced]

<B>"I'm not using the BKLs ever after the information you posted"</B>
BKL mounts are indeed high quality mounts that are used successfully by many airgunners. The ONLY issue I have with them is the fact that the narrow top straps of the two piece mounts can damage scope tubes using 15 in/lbs of "top strap screw torque" and the scope slipped using 10 in/lbs of torque. The issues I've had with both the one piece and two piece BKLs is the fact that they slipped on the dovetails of both my .177 Beeman R9 and .177 HW95 which are tuned to no more than 14fpe (usually 12.5fpe). I did stop the scope slipping in the BKL one piece mount by lining the two rings with cloth electrical friction tape, however I never solved the mount slipping in the receiver dovetails, even when torqued to "excessive base screw torque" that deformed the metal inside the "clamp"..........

LOL.....with the BKL mounts the excess base screw torque I used even stripped out the mount threads so I retapped the mount for larger screws. The larger screws did stop the thread stripping but still didn't stop "mount slipping" even when using 40 in/lbs of torque (5 in/lbs more than the BKL recommended max).........


Anywhoo.........if the BKLs hold your scope and on your receiver dovetails they are certainly a good mount to use!

[Bayman]

<B>"I'm not using the BKLs ever after the information you posted"</B>
BKL mounts are indeed high quality mounts that are used successfully by many airgunners. The ONLY issue I have with them is the fact that the narrow top straps of the two piece mounts can damage scope tubes using 15 in/lbs of "top strap screw torque" and the scope slipped using 10 in/lbs of torque. The issues I've had with both the one piece and two piece BKLs is the fact that they slipped on the dovetails of both my .177 Beeman R9 and .177 HW95 which are tuned to no more than 14fpe (usually 12.5fpe). I did stop the scope slipping in the BKL one piece mount by lining the two rings with cloth electrical friction tape, however I never solved the mount slipping in the receiver dovetails, even when torqued to "excessive base screw torque" that deformed the metal inside the "clamp"..........

LOL.....with the BKL mounts the excess base screw torque I used even stripped out the mount threads so I retapped the mount for larger screws. The larger screws did stop the thread stripping but still didn't stop "mount slipping" even when using 40 in/lbs of torque (5 in/lbs more than the BKL recommended max).........


Anywhoo.........if the BKLs hold your scope and on your receiver dovetails they are certainly a good mount to use!

Still way to much work for me Ed. I like mounts/rings with arrestor pins and wide 4 screw clamps. Chasing scope shift and damaging scope tubes doesn't appeal to me. I'd rather re-zero my rifles.

[nced]

"I like mounts/rings with arrestor pins and wide 4 screw clamps"
I tend to agree and prefer mounts with stop pins. For some reason I found that the $9ish Weaver Quad Lock rings from "WallyMart" also have narrow top straps but will hold scopes in the rings of my Beeman R9 and HW95 using 10in/lbs top strap screw torque, yet the scope tube wasn't damaged using 15in/lbs top strap screw torque...........


"Me thinks" the reason is that the Quad Lock ring top straps wrap more than 1/2 way around the scope tube and the screws are at an angle........



I'm currently using an inexpensive "Sniper brand" Picatinny mount for my new Hawke Compact scope which has a 30mm tube and the Weaver Quad Locks only come in 1" tube size. LOL, my 4-16x44 Hawke Compact scope is a real short scope after mounting to the UTG dovetail to Picatinny adapter to my HW95........


I got the notion to add a 4 1/2" long sunshade to the Hawke Compact scope and now the scope looks "almost normal size" mounted to my Beeman R9. The sunshade was made from 2" PVC pipe and fitting machined for a snug fit over the end of the scope bell. Then it was painted black (inside and out) and secured with a wrap of black PVC electrical tape.