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supercharged86 · Member

My otherwise accurate and consistent GAMO Varmint Hunter (about 750 rounds to date) with a Centerpoint Adventure class 3x-9 50mm AO using Crosman Premier Ultra Mag heavy's (still the same tin) @ 15 and 20 yards has suddenly become very inconsistent. One shot will be dead center and the next will be off by more than an inch. What happened??? any thoughts or ideas??? Thanks in advance. Steve

ps. The barrel gets regular cleanings

AirGunEric · Site Admin

Tighten up the scope mounts.

No, seriously- you need to determine if it's the rifle or the scope. Are you willing to take the scope off and shoot with open sights for testing?

supercharged86 · Member

I would except this rifle has no open sights. The scope mounts all seem tight, but I guess anything is possible, right? I guess I could try putting the original GAMO 4x 32mm scope (which I hated) back on to see if things improve. If there was an internal problem in the scope, would I get such an inconsistent grouping with an occasional bull's eye (at 15 yds)? Thanks again. Steve

Slavia · Moderator

The little video on Crosman's site implies that the scope can be used on springers:

But airgun use isn't mentioned in any of the individual descriptions:
http://www.crosman.com/optics/riflescopes/adventure/CP395AORG

So who knows if the scope is actually rated for springers. Anyway, I agree with Eric. Check the mounts and swap with the original Gamo scope.

Is there any play in the barrel pivot?

Brutuz · Senior Member

How do you clean the barrel?

AirGunEric · Site Admin

Mentioning the cleaning of the barrel- if you only have 750 shots through it- your total cleaning schedule up to this point should have been: Once- when you first bought the rifle and again when you get near 1000 shots. No need to clean the barrel constantly, it's not likely doing you any good unless you use extremely dirty pellets.

I think Brutuz is going in the direction of "you may be cleaning incorrectly or too often, resulting in the barrel rusting" which could cause an accuracy issue. (Some) lead residue helps keep corrosion from developing in the barrel.

Slavia · Moderator

How quickly did this happen?

supercharged86 · Member

supercharged86 · Member

Thanks guys for the input, much appreciated. As far as the cleaning goes, sounds like I'm "over" cleaning. Knowing the importance of regular and almost immediate cleaning with my centerfire firearms, I generally run a .177 Hoppes Boresnake down the barrel once every couple of outtings with some #9 solvent. But thinking it could use a "good" cleaning not that long ago, I ran a bore brush down the barrel followed by the usual light coating of oil to prevent corrosion and rust. There's definately no corrosion or rust in the barrel, it shines perfectly.

supercharged86 · Member

AirGunEric · Site Admin

Bore brush? The rifling in most airgun barrels is alot shallower than is found in "firearms" proper and more prone to damage. Clean with cleaning patches- not a rigid steel or brass brush- and solvent isn't required as no powder residue to worry about- oil/penetrating oil is A-Ok.

At this point, change the scope, try to sight it in and see what happens.

fritz · Silver Status Member

I have a feeling it's the scope.

Maybe if you're feeling ambitious, take the scope off and try to get a consistent (lack of) sight picture to shoot at 10 yards. Avoid using powder solvent on your airguns, this can lead to dieseling, and likely inconsistency. Is there any smoke after you shoot?

Eric- he used a boresnake, not brush. The boresnakes are like shoelaces. I wonder if a shoelace would work to clean smallbores?

supercharged86 · Member

I would agree with you that the rifling is unlike that of a traditional firearm, but I guess I just didn't think it could be damaged by a brass bore brush, seeing that it is made of steel. You would think that the rifling would get "clogged" up with the soft lead and be the cause of, none other than, "accuracy" issues. Thanks for the tip.

supercharged86 · Member

fritz · Silver Status Member

IMO, bore brushes don't do anything harmful if they are not steel. Before knowing any better I used one on my D34 every couple tins. Never lost accuracy. Still use one every 2,000 shots. Still use WD-40 to dissolve any lead. Just have to wipe everything down very well and patch it out. Again, never have problems.

Dieseling is when a lubricant, solvent, or other petroleum product (e.g. WD-40, Hoppes) is introduced into the chamber, barrel, or transfer port areas. The high pressure forces the petroleum to combust, like in a diesel engine. This yields a nice BANG, smoke, often makes the pellet go supersonic, good smoke cloud, and can damage the gun. Damage is usually nothing for the small bangs, but if you go pouring down the petrol... expect a broken spring, burnt seal, maybe even a cracked compression tube.

Keep your the flammables to a absolute minimum and there's nothing to worry about.