Cannot get rifle to group

[Nod]

My neighbor brought me 3 rifles to sight in for him. A Gamo Silent Stalker Whisper  , a Crosman Phantom  & a Crosman Quest. Using new Crosman Premium HP 7.9gr @ 18 yds I got both the Gamo & Phantom to 3/4" groups. BUT, the Quest (which is the same model as the Phantom, with wood stock) will not group at all. I was getting shots all over the place. It would shoot high then right, left etc. No matter where I adjusted the scope. It would sometimes put 2-3 in a 1-2" group and then the next shots were wild again. I  moved the target up to 10 yards and still could not get a consistent group and could not adjust the scope to get a decent grouping. I removed the scope and could not adjust the sights to hold a good pattern. I checked the barrel to see if it was bent, didn't seem to be. I remounted the scope, got 3 shots within  an inch and then they started flying all over the target again. I've never had this problem before with all the rifles I've had. What am I missing or what should I look at next. Unfortunately, the Premiers are the only pellets in .177 that I have. The neighbor just got these rifles and didn't have any pellets other than some corroded ones that came with the guns. I hate to give up but it's frustrating.
Thanks for any help you can give.

[Goose]

I feel for you.  I truly do.

A friend gave me his old Quest 1000(!) and I still haven't forgiven him for it.  It had the worst trigger and harshest shot cycle that I've ever experienced.  I found that it would group best with Crosman pointed pellets.  It also helped a lot to use the 'artillary hold' when firing it.

Soft-bedding the action helped some.  Some trigger-work helped too (but it still stinks).  Coating the spring heavily with lithium wheel-bearing grease helped even more.  That cost it a hundred fps, but I figure that a 890-fps hit is better than a 990-fps miss.  The screws holding it in the stock still really like to come loose, so they have to be checked before shooting it.  Cleaning and waxing the barrel helped some as well.  It now shoots into 1-1/2 inches or so at 25-yards when a 4X scope is used.

Good luck,

J~

[Nod]

Thanks, every problem you mentioned is the same with this gun. I haven't torn it down and probably won't as he didn't give it to me and I don't want it. As far as 'artillery hold' I actually just lay the gun on a block of stiff foam and pretty much just hold it by the trigger finger so I'm not really holding it at all. What amazes me is that the Phantom grouped after 30 shots or so and it's the same model. It has a different scope but not much better.

[Goose]

Well, that's validating.  Glad to see that I'm not alone.

I'd accepted this gun sort of planning to adapt the barrel to a QB78 that I have.  But curiosity really got the best of me...

Have you pushed any pellets through the bore?  It sounds like your friend got one with either a bad barrel or a bad breech seal.

Cheers,

J~

[Nod]

I'll check both ! thanks

[Matchstickshooter]

Well, that's validating.  Glad to see that I'm not alone.

I'd accepted this gun sort of planning to adapt the barrel to a QB78 that I have.  But curiosity really got the best of me...

Have you pushed any pellets through the bore?  It sounds like your friend got one with either a bad barrel or a bad breech seal.

Cheers,

J~

Might also compare the barrel crown of the Quest to the Phantom....jmho

[Back_Roads]

Had a Crosman gun that only shot copper plated lead pellets.

[mikeyb]

Have seen similar with LARGE velocity spread. That usually means bad piston seal, breech seal, or both. If velocity is consistent (low ES) then IMO it is not a bad seal.

Have had a couple Crosman springer and QB CO2 barrels with bad muzzle crowns. Shotgun patterns ~2" at 10 yards. I KNOW I can get 1/2" 10 shot groups with similar air rifles so went through my checklist. All screws tight, barrel lockup solid, tried artillery hold and DEATH grip (some springers need it), and chronograph read low ES = consistent velocity.

Everything seemed good until I got to the muzzle (last place I checked). Crowns "looked" uneven, smeared, or just plain missing. Very disappointing factory finish. I could probably get better results with an angle grinder and a chainsaw file!

A Q-tip left fibers behind. Shot & captured pellets (in wadded poly bags) had sheared/smeared rifling on one side... same with pushed pellets. Re-crowned barrels using GTA tutorials until I could SEE clear rifling lands and grooves all around muzzle. Accuracy got much better.

Good luck!

[Ike the GSD]

By chance did ya check the stock screws my beloved R9 started acting whacky and when I checked the action it went clunk clunk in the stock LOL I put blue loc-tite on the stock screws and she's held ever since? Just throwing things out there hope you can fix her,


Wes

[Goose]

Might also compare the barrel crown of the Quest to the Phantom....jmho

That's a good idea.  It's kinda back in there because of the plastic piece that holds the (horrific) front sight on though.

Running a few shots over the chrono to see how much the velocity varies are might give us a clue or two.  (Mine has been very consistent.)

Cheers,

J~

[mpbby]

With good quality pellets, after some recurrent nightmares, I stopped start thinking about the multiplicity of possible causes. Nowadays, I only go that way after eliminating these first 2 suspects - ES and scope.

As a rule of thumb, if the ES is up to 4% of the medium, and the medium is reasonable, spring and seals are ok.

For the scope there is a simple test.  Center the scope with the mirror method. Give some shots, no needing a target; all you need are the recoils of that specific gun.  Check again at the mirror if the scope is still centered, meaning it is holding 'adjustments' - for those recoils of that gun.  If you have a small mirror (makeup), you don't even need to disassemble the scope.

As the centered position is also the center of the scope's confort zone, you can't abuse when zeroing.   As a rule of thumb, the confort zone limits are a maximum of +- 1 turn from the 'optical center'.  Start zeroing with the scope centered.  If you need more than 1 turn in a turret, you are abusing the scope.  I usually bend the barrel to stay within these limits.

If a scope is reproved, remember that the test was for - that gun.  The scope may be still useful on guns with irrelevant recoils, as PCP, .22 LR, etc.

If you are also strongly suspecting about the pellets, test them with 'iron' sights.

[Nod]

Well, I checked the crown (I removed the front sight) it looked fine. I thought maybe the pellets were clipping the sight. I checked all the screws, all good. I checked the fps when I first started and had a fairly consistent 870. Then I cleaned the barrel, it wasn't too bad but after cleaning I got 6 shots to do a 1" group @ 20 feet. Moved back to 30 feet and the group got a little worse, went back to the original 18 yards and got the shotgun pattern again. I'm not going to tear it down to check the seal as it's not my gun. I'm giving it back to the neighbor and he can decide what he wants to do.
I appreciate all the great advice from you folks, as always GTA members are the go to source for any problems.
Thanks again !!

[lefteyeshot]

Q-tips in the muzzle is a good idea. If the crown is right no fiber should be pulled from q-tip.

[mikeyb]

Don, You have obviously shot springers before (Diana 34 .22 ) and got acceptable results with the other 2 rifles so there is something off with that particular rifle.

If you still have it and want to investigate further I suggest pushing some pellets and examining the rifling on head & skirt. The push test should indicated if/where any choke(s) exist and if there are any bore defects. This is not a definitive test, just one piece of the puzzle.

IMO the next step would be to shoot and capture a few pellets and examine skirt expansion into the rifling. Depending on the rifle the skirt expansion can be minimal to WOW!

I use 12-15 wadded poly (HDPE) shopping bags inside a 3" diameter cardboard tube. Poly bags are now outlawed in this silly state but I can still find some. The cardboard tube was the core of a large roll of 18" wide stretch-wrap (not food wrap, full pallet wrap). Pellets get caught about halfway though the tube with surprisingly little pellet damage.

Small but uniform rifling imprints present on the push test is usually a good start. Bore defects or a large muzzle "burr" (like on my Vantage) should become very obvious during the push test.

Skirt expansion during the shoot & capture test should have small to HEAVY rifling imprints on pellet skirt, depending on skirt expansion. Some of my magnum springers deform the pellet skirts a lot more than I expected.

If all the bore/muzzle tests are "good" then I'd try a selection of different brand & shape pellets. I have one or two really picky springers that can only shoot one brand/style pellet accurately.

One example is an older (Walmart clearance) Prowler 22 which LOVES (stacks) Daisy "pointed" 22 pellets. NONE of my other 22 springers can shoot the Daisy pointed 22s well and I was ready to "recycle" them in my scrap lead pile until that Prowler came along. That rifles accuracy with other pellets was less than expected and I was ready to put it in my "parts" bin. They both got a lucky second chance ;-)

fyi ... image links... my Vantage after a recrown...

[Nod]

I gave the rifle back to him. I would like to have tried other pellets but he doesn't have anything but some old corroded ones. I bought a tin of CPHP's just to sight in the rifles. He's not really into air guns that much just the occasional rabbit or squirrel.

[Goose]

I gave the rifle back to him. I would like to have tried other pellets but he doesn't have anything but some old corroded ones. I bought a tin of CPHP's just to sight in the rifles. He's not really into air guns that much just the occasional rabbit or squirrel.

You sound like a really good neighbor to have.  A lot of effort went into all of that.  Sad that it won't perform.

I've tried to give the one I have back to the guy that gave it to me twice.  He ain't having it...

Cheers,

J~