by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

    • GrandpaDan
    • BB’s response
    • What can you do?
    • Velocity is not at fault
    • GrandpaDan continues
    • Staying with the brand name doesn’t always work
    • Back to GrandpaDan
    • BB responds
    • The solution?
    • GrandpaDan concludes
    • BB sums up
    • Geo791
    • BB’s last word to GrandpaDan

You readers tell me you like it when I write about general topics. So, when I get a question from a reader, I try to answer him in this blog. Today’s report will be the biggest report I’ve ever written, because I’m going to include much of what the new reader has asked as the lead-in to my answers. I’ve also included another reader’s comment from the experimentation he has done to achieve more-or-less what the new reader is asking.

Here we go.

The new reader’s handle is GrandpaDan, and he signed-into the blog this past Monday. Here is his situation.

GrandpaDan

“I’ve been reading and researching airguns for a while. This grows out of frustration with my Gamo Hunter 440 in .22 cal. that I bought about 4 years ago to kill chipmunks. That year we were overrun with the critters. I had been running a trap-and-release program and had trapped 21 chipmunks when the state game folk told me that was illegal. Oh well, I’ll just get a spring gun and shoot the pests.

“Just to allay any concerns, I was not dumping the trapped chipmunks on neighbors. We live in a rural area, about 10 miles from town and are surrounded by active farms and state forests and hunting land. Mine was a humane relocation program for both man and beast.

“More recently squirrels have become a nuisance. I’ve managed to do away with a couple but that has been more by luck than any ability that I have to predict the shot placement. Who knew that airguns would be so finicky? Pellet choice, shooting hold, lots of break-in shooting, and more. WOW! Back to the Pyramyd Air Blog.”

BB’s response

GrandpaDan’s situation is much the same as that of many new airgunners. He buys an airgun to do a job — in this case eradicate chipmunks. He doesn’t want to learn everything there is to know about an airgun, any more than someone buying a claw hammer wants to learn how it was made and the history of claw hammers. He wants to do a certain job that, before buying the airgun, seemed reasonable to him. Now he discovers he has entered a strange new world where he has to learn other things to make his new “tool” do what it is supposed to do.

Because many people come into airguns this way — thinking that the guns are exactly what they imagine, and not realizing there will be things like the artillery hold, pellet head sizes and loopy trajectories to learn. This happens all the time. I jumped on this opportunity because it allows me to address the problem from both sides — before and after it happens.

GrandpaDan — it would have been better for you to have bought a different air rifle than the Gamo 440 Hunter. The 440 is accurate and powerful, but it is very twitchy in its operation. A better rifle would have been something less powerful and easier to shoot accurately. The Diana 34P would have been a good choice and the Air Arms TX200 Mark III would have been the best choice. Here is a rule to go by — if you buy a .22-caliber spring-piston rifle for pest elimination, make certain it shoots at 900 f.p.s. or less. All that’s needed is about 700 f.p.s. with a medium-weight pellet to kill the animals you are after, with squirrels being the toughest.

What can you do?

The best thing for you to do at this point is to de-tune your rifle. Make it shoot slower. That will calm it down and start giving you the accuracy it’s capable of. If you must have all the power it has, then you need to shoot about 10,000 shots to gain the experience you need to be as accurate as you want to be. Yes, the Gamo 440 Hunter is an accurate air rifle, but it takes a huge amount of skill to realize its potential. It’s like playing a Stradivarius — you don’t want to learn on one!

You probably don’t want to take your rifle apart. The easiest way to de-tune your rifle is to squirt the mainspring full of something viscous like Tune in a Tube grease. Enough of that stuff can slow your gun down 150 f.p.s., or so, with the side benefit of it becoming dead-smooth.

You can also slow the gun down with heavy pellets. Try H&N Baracuda Magnums for both accuracy and slower velocities. Remember Baracuda Magnums come in head sizes ranging from 5.50mm to 5.53mm, so try them all to find the most accurate one for your rifle.

Velocity is not at fault

I’m not saying that too much velocity makes an airgun inaccurate, because velocity by itself doesn’t hurt accuracy. But too much power in a spring-piston powerplant makes any gun very sensitive to things most guns aren’t bothered by — things like the hold. That’s why those mega-magnum spring guns are so hard to shoot well.

GrandpaDan continues

“Before I bought my Gamo 440, I had done some research, including reading some (obviously, not enough) of the Pyramid Blogs. I learned that 22 cal was a better choice for a humane kill. I also learned that not just any scope would survive a spring gun recoil. I bought a Leapers UTG airgun rated 3×9 AO scope and mounted it carefully. Since I was buying a Gamo airgun, I bought 5 tins of Gamo Hunter pellets as well. Reading now, those probably were not the best choice, but what did I know?”

Staying with the brand name doesn’t always work

GrandpaDan learned the hard way that staying with the same brand for both the air rifle and the pellets isn’t always foolproof. Sometimes the company that sells the pellets doesn’t make them. Beeman is an example of that. Beeman makes nothing. They buy everything from outside sources. But the higher-end Beeman guns and pellets are made by quality manufacturers like Weihrauch and H&N, so buying a Beeman brand can be a reassuring thing. Just don’t use brand names as your buying habit, because it doesn’t always work that way. GrandpaDan knows that now.

But congrats on the UTG scope. That was the right choice.

Back to GrandpaDan

“At this point I’ve been chasing the point of impact around the target with the scope settings. Shoot 5 shots adjust scope, shoot 5, adjust scope and on, and on… Shooting a fair amount but not with any improvement in repeatable accuracy.

“Recently read a blog by BB that explained the internal mechanics of a scope sight. I think that I may have done what BB described, having backed the settings so far out that the tube and reticle is floating with each shot.

“If that is the condition of my scope, then I need to get “control” of the reticle movement. I’ve read of “centering” a scope sight by backing out both settings out fully, then turning them in fully, while counting the turns, then backing out half way. I think that should stabilize the reticle, though I’m sure that the POA and POI will be far apart. Any thoughts about that?

“Read a series of three articles by BB regarding accuracy in which he pointed out that a “true” barrel is not a given. If I understand the article correctly, a “true” barrel is less rather more likely. So rather than just parking the scope on the gun and assuming that it and the barrel are in correct alignment, I bought a 22 cal laser bore sighter. I am thinking to try to shim the scope to get close to the laser dot as a place to re-start my quest for accuracy. I also bought a tin of the JSB Test pellets.”

BB responds

Okay, let me simplify this. You are chasing the point of impact around by adjusting the scope? That screams just one thing to me — that the scope is adjusted too high in elevation (or too far to the right) and the erector tube is now “floating” on top of the relaxed erector tube return spring. That’s the spring that’s inside the scope that moves the reticle (inside the erector tube) when the knobs on the turret are adjusted. Adjust too high or too far to the right and all the tension will come off that spring. After that, your erector tube will bounce everywhere when the vibration of firing jars it. You will be chasing the point of impact that seems to change at will.

The solution?

If your rifle has open sights, take the scope off and shoot some groups with the open sights. If those groups are small but with a scope mounted they are large, your erector tube is floating. The solution, 99 times out of 100, is to jack up the rear of the scope, either by shimming or with an adjustable scope mount. That allows you to crank the elevation down and get some tension in the erector tube return spring.

If you don’t have open sights on your airgun, crank in a LOT of down elevation — maybe 60-80 clicks — into your scope’s adjustments. Then on a large piece of paper, shoot a group. This groups will be very far below the aim point, but if your groups are also tight you know the problem was caused by a floating erector tube. The scope needs to be shimmed again. Go back and jack up the rear of the scope as described above.

GrandpaDan concludes

“At this point I just want to be able to dispatch marauding squirrels. I think that Gunfun1 said, “I like to plink accurately.” So while my primary goal is not punching super tight groups of holes in paper targets, I think that is the path along which I will need to travel in order to find the kind of accuracy that I want.

“I welcome any suggestions, recommendations from the forum. There are forum contributors who have decades of experience and significant mechanical skills (and workshops). I’m hoping to short-cut some of those years by hitch-hiking on the generous sharing of the experience of others.
Are there things that are must-do to improve the gun other than selling it and buying a much better quality airgun?”
GrandpaDan

BB sums up

GrandpaDan is not interested in becoming a diehard airgunner. He just wants the airgun he owns to work for him. If his refrigerator conked out or got too cold he would not look into taking extension courses in refrigeration. He just wants things to work. I don’t think he is asking too much. But in the world of spring-piston airguns, things are not always straighforward. To GrandpaDan, we airgunners sound like we are telling him to put boiling hot water into his ice cube trays when he wants to make ice!

GrandpaDan wants to cut through all the lore and insider stuff we talk about and just get his air rifle to hit what he aims at. We don’t know whether he is a natural shot or a guy who thinks shooting means spraying and praying, but when we read his comments it becomes clear that he at least has given a lot of thought to what he is doing. He seems to be a careful guy. Enter reader Geo791.

Geo791

Geo791 is another newer reader who has been communicating with several other readers in the comment section of the blog over the past several weeks. He has been immersing himself in the same kind of experiments GrandpaDan has been reading about. Yesterday he posted this huge comment.

“Geo791
May 23, 2017 at 11:39 pm Edit

“B.B

I posted this in response to twotalon’s suggestions yesterday and wondered what your thoughts are also. The JSB Exact 15.89 pellets are fitting loosely in the breech of my RWS34 P .22. If I don’t seat the pellet deep into the breech until it engages the rifling, the pellet will fall out if I de-cock the rifle.

“twotalon,
Yes, the RWS 34P combo came with a Hawke 3-9x50AO IR scope with an RWS one piece lock down mount. I removed the scope today and will do some work on it to make sure it is centered optically in it’s range. Then I will attempt some groups with the open sights.

“Okay, I inserted a JSB 15.89 gr pellet into the breech and then used my cleaning rod to push it on through. For the first 6″ or so, the pellet pushed fairly easily. Then there was very little resistance until it reached within about 1″ to 2″ from the muzzle. Then there was a moderate amount of resistance towards the end of the muzzle, almost like the barrel was choked. Then I viewed the pellet with my jeweler’s eyepiece and there were no perceivable marks on the head from the rifling. The skirt had some slight marks and the skirt was crushed down to the same O.D. as the head.

“I thought the resistance felt strange going from slight resistance, to no resistance, and then back to moderate resistance. It’s like the bore is barrel-shaped (no pun intended) on the inside, meaning it’s larger in the center than on either end. I would say it was on the loose side but not bumpy or rough.

“Next I did a pellet analysis. I use my 1″ micrometer and jeweler’s eyepiece to carefully measure the head and skirt on 20 JSB 15.89 gr pellets. These are the ones that are fitting loosely in the breech.

“The pellets were very consistent. The heads measured 5.49mm to 5.50mm on a 20-piece sample. The skirts measured 5.69mm to 5.72mm on the same sample. Seems like the head size is a little small to me.

“I measured a sample of CPHP [Crosman Premier hollowpoint] pellets 14.3 gr. Heads measured 5.50mm to 5.54mm with one pc at 5.38mm (that’s probably a flyer). Skirts measured 5.61mm to 5.64 mm on (10) pc sample.

“I measured some left over RWS Superdomes I had enough for a (10) pc sample. Head measured 5.51mm on all (10) pcs, very consistent. Skirt measured 5.73mm to 5.74mm on (10) pcs.

“I also noticed that the RWS and the JSB pellets were of a much higher quality. They were more consistent and roundness was better than the Crosman Premier HPs which have a noticeable parting line from the molding process [Editor’s note — Crosman Premiers are swaged cold, not cast. Molding implies a cast pellet.]. I had some domed pellets and they are the same crude looking pellet. I was a quality inspector for forty years at a hydraulic pump division so I know quality.

“After I removed the scope from the rifle I cleaned the barrel again with JB bore paste and a brass brush as per Tom Gaylord’s instructions. I was advised to clean the barrel again after having shot the CPHP pellets through it and then re-season with the JSB pellets. That’s all I had time to accomplish today. Welcome your thoughts on my findings. You have at least lead me down a different path than most of the other posters.

BB’s last word to GrandpaDan

Now you know that you aren’t the only one who is chasing accuracy in his spring-piston air rifle. And Geo791 is shooting the RWS Diana 34P I recommended to you!

Let’s see if we can get your Gamo 440 Hunter to shoot well for you. Gamo makes a good barrel and they also make good airguns. The more powerful ones like your 440 Hunter are very sensitive to shoot, but when you learn what they like they can be wonderful.

One thing I can tell you is that Gamo triggers wear in, not out. After 3,000-4,000 shots your trigger should become very nice and light.

I’m sure our many readers have suggestions for you. One last thing, GrandpaDan. All of us all have partially used tins of pellets that we discovered did not work in our airguns. You may have to sort though some pellets to find what works best. But you probably do the same thing at the grocery store when you buy your food every week. That’s just how life works.