I upgraded my Crosman 2240 to a steel breech so I could use a red dot. I have a couple of little Vortex Venom red dot sights, and tried both. using the UTG pitcnanny to Weaver adapters. With both sights, at about 8 yards my point of impact is 5 inches low, with the internal red dot adjustment turned to the max on up adjustment. Any suggestions. I suspect barrel droop, and if that is the case how do I fix it. I hate to remove the barrel band as the barrel appears to have a dimple in the top for the band set screw.
Can't zero red dot
- Thread starter jkingrph
- Start date
You will have to shim your scope rings. An option would be to take a 2 liter soda bottle, cut the plastic to fit between the scope and the rear scope ring base. Be careful to not overtighten the scope ring tops. some people use metal from a soda can, some use thick card stock paper. I used plastic from a soda bottle and on another used layers of blue painters tape.
You could also go with adjustable scope rings, like the FX No Limit rings. Thats what I did on another rifle and it worked way better. There was more room for adjustment with them. If you go this route, 68 Whiskey on youtube has a very dumbed down fx rings install video that even I was able to grasp. I'm sure you could figure it out on your own though.
Good luck with whatever you decide!
You could also go with adjustable scope rings, like the FX No Limit rings. Thats what I did on another rifle and it worked way better. There was more room for adjustment with them. If you go this route, 68 Whiskey on youtube has a very dumbed down fx rings install video that even I was able to grasp. I'm sure you could figure it out on your own though.
Good luck with whatever you decide!
Upvote 0
The Vortex Venom is not a tube-type red dot.
I already advised him to remove the barrel band in another forum.
That barrel dimple can be covered by 3 thin O-rings, just saying.
Upvote 0
For a tube-based red dot, the recommendation above will work. However for the Vortex Venom and others of similar open construction, you will need an angled mounting rail or "drooper mount" as they are sometimes called.
The problem though is the magnitude of correction needed. The commercially-available drooper mounts I've seen provide 20 - 30 MoA and you're needing more like 60 MoA to produce 5 inches of correction at such a short distance of 8 yards.
So yes, your best bet is to look first for the barrel band pulling the muzzle down. The Crosman steel breech offers plenty of support for a 2240 even with, say, the longer 14" barrel so I'd try setting the barrel band aside and see what happens.
Also check that the breech is sitting flush to the air tube. If the transfer port isn't fitted correctly and causing the breech to lift at the front, and the barrel band is then pulling the muzzle down, that would explain why your sight and barrel are so divergent.
The problem though is the magnitude of correction needed. The commercially-available drooper mounts I've seen provide 20 - 30 MoA and you're needing more like 60 MoA to produce 5 inches of correction at such a short distance of 8 yards.
So yes, your best bet is to look first for the barrel band pulling the muzzle down. The Crosman steel breech offers plenty of support for a 2240 even with, say, the longer 14" barrel so I'd try setting the barrel band aside and see what happens.
Also check that the breech is sitting flush to the air tube. If the transfer port isn't fitted correctly and causing the breech to lift at the front, and the barrel band is then pulling the muzzle down, that would explain why your sight and barrel are so divergent.
Upvote 0
You could also shim between the barrel and tube up front at the barrel band giving the barrel some distance from the tube up front so the barrel slightly points up.
Upvote 0
I had to shim one of mine.
I used HVAC aluminum tape (Lowes) on the rail. The aluminum is stronger than any paper tape.
You'll have to experiment on the thickness. The tape I used is .004" thick. I had to use two layers. I'd start out with two layers on your gun too. Then add if you need to.
A sharp (new) (small pointed) x-acto knife will help shape the tape so you can't see it when you are done.
Shim the scope rings...that's funny.
Mike
I used HVAC aluminum tape (Lowes) on the rail. The aluminum is stronger than any paper tape.
You'll have to experiment on the thickness. The tape I used is .004" thick. I had to use two layers. I'd start out with two layers on your gun too. Then add if you need to.
A sharp (new) (small pointed) x-acto knife will help shape the tape so you can't see it when you are done.
Shim the scope rings...that's funny.
Mike
Upvote 0
I think my first thin is going to be to loosen the set screw on top of the breech and wiggle the barrel a bit to hopefully ensure it is prpperly seated over the gas port, Then try it with the barrel band loosened and see what happens. It shoots good with iron sights, so I might leave it with that.
Upvote 0
That's most likely NOT your problem at all.
Your problem is the short distance that you are shooting. Plus possibly the height of the sight. The taller it is, the steeper the angle must be to get the point of aim and the point of impact to converge.
Mike
Upvote 0
I have about the same set-up (same platform and Vortex red dot) and it gives me no trouble.
The problem with the OEM barrel band is that it pushes the barrel downwards----set screw is on top.
My bands have set screws on the sides and angled downwards (presses tube instead of barrel), thereby negating the inherent barrel droop.
It is an all stainless Don Cothran build:
The photo shows a Vortex Sparc, but I did try my Vortex pistol sight on it with no ill effects.
I believe the OP uses a mini UTG adapter (read it somewhere), so it is very low.
Upvote 0
Like Darkhorse, I’ve used reflex sights on top of Picatinny adapters and was able to zero them at 10 yards. That’s not 8 yards but my example also doesn’t represent anything like 5 inches high at 8 yards.
So while the short distance and sight height are indeed factors aggravating the problem, they aren’t the primary cause.
So while the short distance and sight height are indeed factors aggravating the problem, they aren’t the primary cause.
Upvote 0
We have misty rain today, so cannot get out to try. l loosened the set screw on the bottom so the band is more free floating on the bottom tube, so the top screw cannot force the barrel down, will try that hopefully tomorrow. The Vortex Venom is a micro red dot, on scope rings involved, just a small footpring in the mounting grooves, probably about 1" long the same as one ring.
Upvote 0
just for your info I use 3 different reflex Red Dots (all cheapys) and 1 Leapers Laser on my Airgun pistols, using 11mm Dovetail to Picatiny Adapters for mounting & otherwise keeping as low as possible to the barrel, no problems high or low...also i am shooting 8mm-10mm nothing longer.....just wanting to provide some info for you....your problem maybe the Vortex.....
Chuck
Chuck
Upvote 0
I am thinking the problem may be the sights. I installed both on another airgun, a Crosmann 2300s, with exactly the same results, POI. I have a cheapie red/green dot a lot larger and may give it a go.
Upvote 0
Hell, if that gun were mine, it would have NO barrel supports. They'd be in a drawer somewhere.
That barrel doesn't need them whatsoever. Full sized target rifles have the full length of the barrel, unsupported.
Mike
That barrel doesn't need them whatsoever. Full sized target rifles have the full length of the barrel, unsupported.
Mike
Upvote 0
Your problem might be in how you installed the breech. See if you can slide a $ bill between the front bottom of the breech and the air tube.
Upvote 0
I use some cheap Victory red dots, made by Vector. It's their budget line. On my red dot up means moving the "dot" up, not POI.
Upvote 0
DISREGARD THIS IT WONT WORK AND WILL AMPLIFY THE ISSUE! -
OH MAN I would loosen up the breech screws and run a shim at the back end of the breech to jack it up a little to fix your problem. A small washer in between the rear breech screw and tube or piece or two of water bottle cut to fit.
Upvote 0
I am sitting here thinking about the trigonometry of everything. How would shimming the breech up from the tube help, It seems to me as if the problem is in the breech -barrel- red dot mounting. Shimming up the breech would not change that , UNLESS it would make the barrel band push up on the barrel. I tried the same sight on a HW75 and it also showed a poi well below the point of aim, I may slip the sight onto my FWB 300, and see how it performs there.
Upvote 0