Crosman nitro venom

[josh1236]

Hey everyone, I have a nitro venom dusk that I can't get to shoot well for the life of me. I can shoot a tight group at 20 yards then after 3 or 4 shots the group will move 6 inches and even off the target sometimes. I know I'm not hitting the scope and I went through and tightened everything on the scope and the gun. I have the stock 3-9 CP scope on it but I dont know why it would move that much on its own. Thanks for any suggestions

[mentolio]

How many shots in a tight group before problems arise? Does re zeroing put you back on target? How tight are your groups, and do they stay tight after the point of impact changes significantly? My experience with these guns is that they can be very hard on the bundled scopes until they get a tear down and lube. If you can access a Chrony, knowing how your gun shoots with a variety of pellets could help determine if the problem is an internal one (bad seal, no lube, binding, etc). Here's some stuff easy stuff you can check

Stuff to check:
all screws tight? Not just scope mount stuff, but the screws that hold the "action" in the stock.
Breach seal good? Lay a tissue over the breach after cocking, and watch for movement when firing. Tissue moves:breach seal leaks.
Barrel clean? If not, clean it out.
Barrel pivot sloppy? Grab your barrel and see if there is any side-to-side play. Could be the pivot bolt is loose, more likely the plastic bushings are shot. A little "wiggle" isn't bad. If the end of your barrel swings more than an inch, I'd say you need to address that.
Are you holding/shooting consistently? Are you resting the gun on your hand or something solid? If resting on a solid object...don't. Using a solid rest without your hand in between the stock and the rest will lead to inconsistent groups at minimum.
How many pellets have you tried? If you've only run the stuff like CP Hollow Points, Destroyers, RWS super domes, anything Gamo, etc...you may want to try some better lead: H&N and JSB are usually good bets.

Now, if all that is up to snuff...try re-centering the scope. Sometimes we over-adjust either wind age or elevation, and that can cause the scope to bounce, and lose zero. Fastest way I know to do it is to set magnification to minimum and objective to infinity (if it's the AO scope). Next, place the objective end flat on a mirror in a well lit room. You should be able to see a "ghost image" of the reticle, and a clear image of the reticle...kinda like the reticle is casting a shadow. Adjust your turrets until both reticles become one. Now it's re centered. Next, mount it back on the gun, tighten everything down, and draw a line on the tube along each edge of the mounts. As you shoot, keep an eye on those lines and see if the scope is walking. Also note how much adjustment you have left on the turrets before and after zeroing. If you're nearly "maxed-out" in either direction before re zeroing you likely need a new scope (call Crosman first, they'll likely send you a new one for free). If your adjustment is nearly maxed after zeroing, you likely have another issue (severe barrel droop, bent barrel, etc). Best of luck!

[maraudinglizard]

Which brand of pellets and caliber are you using. I have the venom in .22 and it was not the scope or the gun, it was the pellets. The cphp's were all over the place. It does better with JSB's or the crosman pointed pellet. I order my rifle without the stock scope and put a Centerpoint 4x16 40mm IR AO on mine. Mentolio has it on the money for the things to look for with it. Good luck.

[josh1236]

How many shots in a tight group before problems arise? Does re zeroing put you back on target? How tight are your groups, and do they stay tight after the point of impact changes significantly? My experience with these guns is that they can be very hard on the bundled scopes until they get a tear down and lube. If you can access a Chrony, knowing how your gun shoots with a variety of pellets could help determine if the problem is an internal one (bad seal, no lube, binding, etc). Here's some stuff easy stuff you can check

Stuff to check:
all screws tight? Not just scope mount stuff, but the screws that hold the "action" in the stock.
Breach seal good? Lay a tissue over the breach after cocking, and watch for movement when firing. Tissue moves:breach seal leaks.
Barrel clean? If not, clean it out.
Barrel pivot sloppy? Grab your barrel and see if there is any side-to-side play. Could be the pivot bolt is loose, more likely the plastic bushings are shot. A little "wiggle" isn't bad. If the end of your barrel swings more than an inch, I'd say you need to address that.
Are you holding/shooting consistently? Are you resting the gun on your hand or something solid? If resting on a solid object...don't. Using a solid rest without your hand in between the stock and the rest will lead to inconsistent groups at minimum.
How many pellets have you tried? If you've only run the stuff like CP Hollow Points, Destroyers, RWS super domes, anything Gamo, etc...you may want to try some better lead: H&N and JSB are usually good bets.

Now, if all that is up to snuff...try re-centering the scope. Sometimes we over-adjust either wind age or elevation, and that can cause the scope to bounce, and lose zero. Fastest way I know to do it is to set magnification to minimum and objective to infinity (if it's the AO scope). Next, place the objective end flat on a mirror in a well lit room. You should be able to see a "ghost image" of the reticle, and a clear image of the reticle...kinda like the reticle is casting a shadow. Adjust your turrets until both reticles become one. Now it's re centered. Next, mount it back on the gun, tighten everything down, and draw a line on the tube along each edge of the mounts. As you shoot, keep an eye on those lines and see if the scope is walking. Also note how much adjustment you have left on the turrets before and after zeroing. If you're nearly "maxed-out" in either direction from the re zeroing you likely need a new scope (call Crosman first, they'll likely send you a new one for free). If your adjustment is nearly maxed after zeroing, you likely have another issue (severe barrel droop, bent barrel, etc). Best of luck!

I have tightened all the screws in the stock and the one that the barrel pivots on. I cleaned the barrel as best I could but there wasnt really any difference. I have another CP scope laying around here somewhere that I might try tomorrow. Thanks

[Roadworthy]

You say you can start shooting with a tight group, then it moves.  Which way?  Does it always move in a specific direction and continue to group at the new point of impact?  The direction in which it moves can give a hint to the problem.

My Nitro Venom was doing a vertical thing, by the way - and it WASN'T the scope.

[josh1236]

You say you can start shooting with a tight group, then it moves.  Which way?  Does it always move in a specific direction and continue to group at the new point of impact?  The direction in which it moves can give a hint to the problem.

My Nitro Venom was doing a vertical thing, by the way - and it WASN'T the scope.

Mine seems to move in a random direction. And it groups after it moves. What did you do to fix yours?

[Roadworthy]

My FIRST Nitro Venom did some REALLY crazy stuff - on an intermittent basis even with the GRT III trigger and some cleanup and lube inside.  I eventually returned it on warranty after putting back the original trigger.  When it shot well it shot very well but I couldn't depend on it.  The replaced it but the replacement was defective.  It would sometimes jam when cocking and sounded like sand and gravel grinding inside.  I returned it, too.  My third one was okay for starters but started doing some vertical stringing.  I was not inclined to send yet another gun back to Crosman and another member here (OleTomCat) suggested the piston seal was often the culprit.  I replaced it with one from Air Rifle Headquarters and sure enough the stringing went away.  I have not had any side to side problems but that may be because I make bronze pivot washers.  Not having your gun I can't even begin to address your problem but don't rule out the scope.  If you have another one to try for comparison that would be good.  The gun itself could be fine.

[longhunter]

it could also be the plastic pivot washers, that are causing the problem. even though you think the pivot bolt is tight, the washers could be toast. look at your breech block. do you have any unusual amount of rubbing, or wear, on the block, where it arcs through the compression tube forks?

[jus Tom]

All of these posts covers the usual suspects of tinkering with the NV. Mine was the same way until I did all the upgrades.
 
GRT lll was first and made a good difference. Still noticed the gun dieseling after a couple hundred shots, it would show moments of decent accuracy then go erratic, just as yours does. With the action out of the stock I noticed oil on the gas piston and just about everywhere. I could've sent it back but chose not to with the possibility of getting another with the same issues.
I broke the gun down completely, found a bad seal, cleaned out the oil, smoothed the inside of the tube, ordered new seal and another gas piston (just to have on hand for future use) and while waiting on parts, made brass washers for the barrel pivot.
Once the gun was back together it was very smooth cocking, dieseled maybe 25 shots, shows consistent accuracy at 25 yards and now is my gun that stays out of the safe and ready for backyard pesting.
If you can do the upgrades on your gun, you should see the same improvements. Good luck with it.