cold weather shooting...

[jr28]

It's been pretty cold here lately (35* all day) and when shooting my Hunter Elite I've noticed a weird pattern...I'll put about ten rounds through the rifle, and they'll be on target, but successive shots will be significantly low in POI, often as much as 6 inches, but not consistently so.  Now, I am shooting at 50 yards, which I know is long range for a pellet rifle.  But, the fact that the beginning shots are on target seems to be reasonable insurance that the misses aren't caused by me.
Unfortunately, it now seems that perhaps there is something mechanical causing the problem because it warmed up today (mid 50*s) and the problem continues.  Adjusting the scope does nothing; I've adjusted it to maximum and there is no change in POI once the beginning shots are through the rifle.  I have the factory scope mounted, and it was mounted out of the box.  I have never cleaned the barrel, but...it's a pellet gun.  That can't be causing this much variation can it?  Also, I have noticed that the rifle tends to diesel after 50 shots or more consecutively.  
I apologize for the mumbo-jumbo of information.  Hopefully someone can make sense out of it.  Thanks in advance!

[dank]

jr28 - 3/18/2008  4:20 PM  It's been pretty cold here lately (35* all day) and when shooting my Hunter Elite I've noticed a weird pattern...I'll put about ten rounds through the rifle, and they'll be on target, but successive shots will be significantly low in POI, often as much as 6 inches, but not consistently so.  Now, I am shooting at 50 yards, which I know is long range for a pellet rifle.  But, the fact that the beginning shots are on target seems to be reasonable insurance that the misses aren't caused by me. Unfortunately, it now seems that perhaps there is something mechanical causing the problem because it warmed up today (mid 50*s) and the problem continues.  Adjusting the scope does nothing; I've adjusted it to maximum and there is no change in POI once the beginning shots are through the rifle.  I have the factory scope mounted, and it was mounted out of the box.  I have never cleaned the barrel, but...it's a pellet gun.  That can't be causing this much variation can it?  Also, I have noticed that the rifle tends to diesel after 50 shots or more consecutively.    I apologize for the mumbo-jumbo of information.  Hopefully someone can make sense out of it.  Thanks in advance!

The important stuff,

ten rounds through the rifle, and they'll be on target, but successive shots will be significantly low in POI, often as much as 6 inches, but not consistently so.

there is no change in POI once the beginning shots are through the rifle.

I have noticed that the rifle tends to diesel after 50 shots or more consecutively

Dieseling after 50 shots?

Does this sound like a bad piston seal to anyone? Possibly loosing compression as it warms up lowering velocity and as a result poi then there's the dieseling ? Somehow grease is getting past the seal?

Do you have access to a chrony?

I'm no expert but I do play with them a lot.

[Big_Bill]

Hello Nick,

First, you have never cleaned the barrel ? It's important to clean out the junk that the factory leaves in the barrel, just so you know that you started with a clean barrel.

You haven't mentioned what pellets you are using ? That may be important ?

And 50 yards is beyond most springer's real accurate range . It's fun but I wouldn't count on hitting a soda can every time.

And are you shooting free hand or from a bench ?

I would check the screws that hold the action to the stock, and make sure they are very snug. I would also check to see if the scope screws have loosened or if you can see if the scope is moving.

There should be some change in the POI when you adjust the scope, you might have a scope problem .

The dieseling may be a bad compression seal, and this would cause inconsistency from shot to shot.

Bill

[jr28]

Thanks guys.
I'm using Crossman Field Tip pellets.  And for some reason I have never cleaned the barrel, so that's going on the list.  The screws that hold the actions to the stock tend to become lose after a couple hundred shots or so, but I keep them tight.  The scope screws are snug.  Since this rifle is a droop barrel, is it possible the scope isn't mounted correctly from the factory?  If so, how can I fix that?  And how about the seal?  Can I fix that myself, assuming it's bad?  
Once again, thank you both for the info.

[Big_Bill]

Hey Nick,

If everything is tight, did you check to see if the scope has moved, and that the scope is tight. These are basic when checking a POI shift problem.

However it seems that if it dieseling, and I can't tellhow badly, the seal is probably your problem.

Everything depends on your mechanical skill level, go into our LIBRARY, http://www.gatewaytoairguns.com/library/Library_MainPage.htm

and check TUNE UP GUIDES FOR ALL AIR GUNS. Then you can determine if you feel that you can replace the seal, it's the last part to come out...

If not, send it CharlieDaTuna, CDT, and it will be done correctly. He's the MAN !

Let us know ,

Bill