New Guy with a Hammerli 850 Magnum that won't Shoot more than 5 times

[DizzysDad]

Hello Airgun Nation. I picked up a used Hammerli 850 Magnum used and having trouble getting more than about 6 shots out of a brand new CO2. I have examined the O-Ring which looks good, used the pell gun oil and I don't hear any obvious leakage. When I bought it the previous owner said it shot fine (of course right?) and I shot it before I handed over the money. When I got it home and loaded up another magazine I got about half way through that mag and the pellets were falling 5 feet from the end of the barrel.

I assumed the CO2 was empty but when I removed it I had ALOT of gas escape which makes me believe the CO2 was not empty. I put a new CO2 cartridge in, screwed it all the way in and heard no gas escape and got the same results, 6 or 7 shots and power dies.

I'm using Umarex CO2, probably not the cheapest but I was assuming good compatibility.

Thanks for any Thoughts, ideas or comments?

Bob

 

[Why]

Try screwing it in and count five seconds pray to Jesus then unscrew (back it out) roughly 1/4 turn. 

 

[rangur1]

If you shoot too fast. The co2 can’t recharge itself fast enough. Shoot 1 shot every 15-20 seconds. Other culprit could be temperature if way too hot. Pressure in bottle to high for hammer. 

 

[Arch_E]

After my dad borrowed mine, it wouldn't shoot well either. So I took it all apart... and found 3 pellets in the casing that were evidently interfering with the airflow or dispersal. I cleaned it out and put it back together. Now it's shooting well enough (not sure it's back to pre-Dad days but I had not chronied it before letting him shoot it). 



Taking it apart was tedious but not hard.



Arch_E

 

[DizzysDad]

89 degrees here in Florida today. Not miserable but warm. Is that hot enough to cause the pressure in the CO2 to rise too high and shut the gun down? If so I guess I figured out why the guy wanted to sell it

 

[Why]

Have you already followed my suggestion above exactly? I assume not.

 

[scratchcoobster]

Maybe Jesus wasn't listening.

 

[Lemensd]

Here's the deal I had with mine , when the piercing part of the cap is screwed down it drills a hole in the cartridge rather than poke a clean hole thru the top of the co2 cartridge and metal shavings clog the valve just under it creating a massive blockage.

The valve assembly can be removed with a socket and cleaned but I don't know how to keep it from happening again.

I bet when you wait awhile the first shot or two is fine, that's because the pressure will s seep thru but become restricted again very quickly.

Don

 

[DizzysDad]

Have you already followed my suggestion above exactly? I assume not.

I ordered some more CO2 and praying it comes in tomorrow. Does that count?

 

[Lemensd]

I bought a new valve but same thing happened.

I removed the screen and it worked great but debris will get under the valve seat. I was able to rapid dryfire when that happened and clear the shavings from under the valve seat.

Don

 

[Why]

Can't you just drive to Wal-Mart?

 

[DizzysDad]

Can't you just drive to Wal-Mart?

I can, but it's a waste of gas and time unless I need something else from there. The two Walmarts in my area do not carry this size cartridge

 

[fivestar45]

I would check in the direction of a loose pellet somewhere in the action. This has been noted on the old 850 forum. That will slow down the striker hit. Turn the rifle upside down and shake it. If you hear something rattling around, you might have to take the side cover off to clear them.

 

[Lemensd]

Unless they redesigned it, mine was a early model, when you screw the cartridge in to puncher it the pin will drill a beautiful hole thru the cartridge but cuts metal shavings and where do you think those go? The shavings are in front of the pressure , they installed a very fine metal screen between the port and cartridge and while the screen does catch the shavings it also clogs up thus restricting the flow of co2.

Co2 is around 1200 psi I believe, depending on temperature so it really blast the shavings into that screen and I couldn't clear them out, no matter what I tried. So to confirm that was really the issue I ordered a new valve assembly, then removed the screen,from the old valve, it's stamped in place making it non r replaceable and tried a new cartridge...full power again!!!

Put the new valve in when I got it and all was fine for awhile then same problem.

The only way I could make it work was without the screen. I had to rapid fire a couple of different times because of the shavings caught under the valve seat but the quick blast cleared it.

The reason I knew it needed a couple of quick blast was I could hear co2 hissing out the barrel.

I'm not saying they haven't corrected this design flaw nor am I saying what I did is the best remedy , just my experience. The new valve assembly was inexpensive and installation easy as was drilling thru the screen. 

 

[Yo]

Have you gotten your gun sorted out yet?