Accuracy falling off...


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gspn
May 22, 2014, 11:11 PM
I've revisited the problem every day as my free time permits. I've checked everything I can find to check and simply can't find a reason for the accuracy problem.

Today I broke down and ordered a new air gun. However…I kept going back to the 'problem' gun. As it turns out…the problem was rooted in how I closed the action. Apparently (and unknowingly) I had gotten into the habit of easing the barrel closed so that the squirrels wouldn't hear it. I mean i had no idea I was closing it that lightly. For 5 months I closed it normal, then, at some point I guess I started closing it lightly so the squirrels wouldn't detect me.

So today, after the die was cast on the new gun, I went back and tried the old gun again. For whatever reason I decided to sharply close the action…and that shot was pretty close to point of aim. Hmmm…coincidence? Maybe. I snapped it closed again and the second shot was touching the first. Hmmm…really big coincidence. Third time…snapped it shut…and it was touching the first two shots. Ultimately 10 or 12 shots dropped into what my old pattern used to be.

I was the problem. I had slipped into a really bad habit of easing the barrel closed and in the process I guess it was leaking air and not lined up right, and the shots were going everywhere.

So the old gun is back to normal and I have a new Benjamin Marauder on the way as well. Should be a fun week.

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I have a Crossman TR77. It's been shooting great since November…but in the last month the accuracy has really taken a turn for the worse. As part of my procedures to figure out what's going on I've cleaned the barrel, lubed the compression chamber (according to the manufacturers recommendation) and replaced the scope.

However…it's still throwing shots. I might get one or two good shots in a row, then it'll send a flyer…sometimes it's 2 inches away and sometimes it's more. The distance I'm shooting is about 20 yards, and I'm shooting from a position where I've always been accurate before. My old spread might have been an inch or an inch and a half (guessing)…now it's more like 4 or 5 inches.

To put it in perspective…for the last six months I've needed one shot to kill a squirrel…I noticed there was a problem when I had to take 5 shots at the same distances. Something is bad wrong. I tightened all the screws I could tighten…and there are no loose parts or joints anywhere.

I'm halfway through a box of 500 pellets…it was accurate for the first half and now the accuracy has really gotten spotty.

I know it's not the scope, I know it's not the shooter. That leaves the gun and the ammo as suspects.

I'd say the gun has less than 2,000 shots through it.

I'm going to test some more types of pellets tomorrow to see if maybe the ammo on the bottom of the can is for some reason less accurate than the pellets I used off the top.

Any ideas on what I might check to track this down?

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Comrade Mike
May 23, 2014, 01:54 AM
Check the pellets for deformed skirts. I used to shoot precision air gun and shaking a tin of pellets was a cardinal sin. If you're carting them around a lot this may be the case.

rcmodel
May 23, 2014, 12:47 PM
Check the stock screws and insure they are tight.

Also, the barrel henge screw, tight, but not so tight it binds the joint.
And lube the barrel/receiver joint.

Also lube the ball detent that locks the barrel shut.

If they get dry or loose it may not lock shut in the exact same place every time you cock it.

rc

gspn
May 23, 2014, 04:26 PM
Thanks guys…I tried all of the suggestions. Everything is tightened and lubed, barrel cleaned and then had some fouling shots sent through…even tried different types of pellets...but still the groups are awful.

After 10 or 12 shots it looks more like a shotgun pattern than a pellet gun…the thing just will NOT shoot a decent group. I can have the best sight picture in the world, followed by a flawless release…and that shot lands 3, 4, sometimes 6 inches away from the prior shot.

It's frustrating. This gun shot great for 5 months…then suddenly started shooting terribly.

readyeddy
May 23, 2014, 05:25 PM
My springer ate a Leupold in less than 10 shots. I was going to suggest shooting with open sights, but that's not an option with your gun. I would buy a Dampa mount and a tough etched reticle scope like a Hawke.

And if it's not the scope, then you have the optics and mount for super magnum springer.

geneo
May 23, 2014, 06:41 PM
My RWS 34 .22 cal was doing the same a month ago. I took off the scope and used open sights, it was the scope.
Put on a new scope four weeks ago [UTG scp-m392aolwq] problem was solved. Last week I took out 5 Squirrels, total for1 year 138.

gspn
May 23, 2014, 07:54 PM
Ah…I forgot to mention…I just replaced the original scope on Friday. After it took such a turn for the worse my first thought was it was a scope issue. So I bought a Leapers scope that got good reviews. Nothing changed.

ZVP
May 23, 2014, 08:04 PM
Check the breech seal, a leak can play hell! Use baby powder or a kleenex placed over the muzzle joint.
Worst case is a bad piston seal or a bad mainspring.
I'm not familliar with the teardown of your gun but you probablly need a spring compressor to do it. Springs are cheap as are seals. WHile inside, clean up all burrs and friction points and lube good.
HTH

gspn
May 25, 2014, 08:59 PM
update…see original post

au_prospector
May 26, 2014, 08:18 PM
Something has been getting into my peach trees. Likely squirrels but I never see them in the act. Could also be late night opossum raids I suppose.

What kind of animal likes ping pong ball sized green peaches?

Chevota
May 27, 2014, 05:15 PM
We've spoke before right? Did I send you the tuning guide I have? It has lots of helpful stuff for problems like that. If you don't have it just ask; chevota@hotmail.com and remind me of who you are and what you wanted.
Someone already mentioned greasing the catch, but you might also consider greasing the internals of it too. Leakage at the breech and main can cause problems. The barrels side washers can too, they're typically lame when new, but often wear out fast because the surface they ride on is rough. Depends on the gun but it happens. Scope parallax is an issue if you don't have an AO, and not shimming the scope can be a problem too. Lots of things to consider, and sometimes the barrel is just crap, but if it worked before then the barrel should be fine.

readyeddy
May 27, 2014, 09:09 PM
Interesting solution, snapping the barrel closed. I have have the same problem with a MM XS28M. I don't know if it's the gun, scope or me, but I have been in the habit of sometimes closing slowly and sometimes snapping shut. The results have been large groups, even though my fps standard deviation is only 4 fps.

gspn
May 28, 2014, 12:48 AM
Chevota - we have indeed spoken in the past. You were an invaluable source of info when i had trigger problems with the tr77. Ill go back and dig up the info you shot me back then. Thx

Chevota
May 29, 2014, 04:48 PM
I'm not sure how old the info you have is so you might want the latest version and pix. I haven't updated it as much I'd like, but I did do some work to it a month ago. Wouldn't hurt...
I was also thinking about the breech, on most guns the barrel block is hitting the receiver at the top, which will be obvious. This reduces pressure on the seal and may be a factor, and leakage may vary depending on how you close the barrel. Usually the top edge is what's touching, or a corner of it so the softer barrel block mushes up over time and the barrel rises. When I do a gun I sand the receiver side smooth for a good seal (see guide) and sand the block side so it has a much larger and even contact patch so it won't change much if at all. And since many touch at a corner it can upset barrel alignment. If you close it softly it may not, but harder it may move the barrel to the side a tad.
Just some thoughts...

gspn
May 29, 2014, 08:12 PM
I'll take whatever you've got! I'll PM you my e-mail address. thanks!

Ditchtiger
June 3, 2014, 11:58 PM
My RWS 34 .22 cal was doing the same a month ago. I took off the scope and used open sights, it was the scope.
Put on a new scope four weeks ago [UTG scp-m392aolwq] problem was solved.
Had read an article/intervene with the UTG company.
Supposedly all their scopes are air rifle tolerant.
That is the double recoil springers give.
I've several of their scopes and am happy with them.
The "Bug Buster" is a great scope.

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