Unusual problem??

make&mend · Joined: 11 Dec 2009 Posts: 10

Here's the problem:-

Every few shots, (1 in 6 or 8 or so), I experience what I believe is called a 'tank dump'.

Here's the cause:-

The pellet is falling from the barrel, into the breech, and being trapped between the tophat and the hammer slide when the gun is fired. This results in the valve being kept open and hence the 'dump'.

I have tried various sorts of 'bits of bent wire', assorted pieces of plastic, paper clips, pipe cleaners, etc. to push the pellet further into the barrel.
I have even grown my thumbnail and filed it to a point. Embarassed

(No it didn't work!!)

I have tried the largest diameter pellets I can find (daystate 5.53. almost exactly a JSB 15.9) but still they fall out.

The barrel is not an AF barrel. I think it came from a Crossman. It is 18" long and seriously accurate! I don't really want to take the grinder to the end of the barrel!!!!

Here's the answer:-

Any ideas welcome! Smile

M&m

Bean · Joined: 29 Sep 2008 Posts: 512

I had that problem ( once ). I won't shoot a pellet that sits so lose in the barrel that it would fall out just by pointing the gun up. If the 5.53's are so lose they fall out I think you have a problem with the barrel that you are not going to be able to fix short of replacing the barrel.

From a Crosman? Into an AF?
Sure it's not a powder burner barrel?

Jeff · Joined: 22 Jul 2009 Posts: 993 Location: Ohio

I guess the only thing you could do is keep the barrel pointed down slightly. What is the diameter of the barrel? Crosman barrels are smaller in diameter than the LW barrels. How accurate is it? I can't see it being worth a tank dump ever half dozen shots. If your rifle is consistant a LW barrel should get you 1 inch groups out to 75 yards.
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WalkonKing · Moderator Joined: 01 Sep 2007 Posts: 8756

Make sure you seat the pellet completley in the barrel and do not use pellets that are loose.

JJ.. · Posted: Tue Feb 02, 2010 2:22 pm Post subject:

Prolly a daft question but .. are you sure of the calibre of the barrel ?

Was it in a differant gun before the Talon ?
if so how did it perform then ?

JJ..

crowpopper · Joined: 06 Jan 2009 Posts: 2415 Location: upstate ny

sounds like a rimfire barrel to me
but i could be wrong
do u have access to northamerican arms bullets? they are 30 grain bullets for their black powder pistols
if u can get some n try em see if thats better
or take a 22 lr bullet and pull it outta the case and see how she fits should find out quick if its a rimfire barrel
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gimmick · Joined: 13 Jan 2010 Posts: 433 Location: Resident Asshole

My 177 SS drops Crosman Pointed pellets (from Meglomart) in the same way you describe.

My standard "go to" pellet is the Beeman Kodiak MATCH 10.6gn. They are sold as H&N Barracuda MATCH also (same pellet). Be sure to get the MATCH pellet for uniform and smooth fitting.

The Beeman / H&N Crow Magnum also fit snug and are reliable out to 20 yards.

I suggest buying several tins of pellets and trying them. I've had nothing but good luck with the ones mentioned above.

make&mend · Joined: 11 Dec 2009 Posts: 10

Hi all!
Firstly, thanks for the replies.
Sorry to have been so long in replying but I have been doing a bit of work on this problem from what some of you posted.

I have contacted the previous owner of this barrel and he put me in touch with the guy who had it before him!

It is a Crossman barrel (od 11.1 mm) and has been machined down to fit a Talon.

It seems that the guy who did the machining also machined 'a bit' off the i/d of the breech to make it easier to insert the pellets. Shocked

I stuck a piece of 'plasticine' (kid's modelling clay) into the breech and then carefully withdrew it.
This showed a rough i/d of 5.63mm for the first 3mm (1/8") of the barrel but a rough i/d of 5.51 thereafter towards the muzzle.

I have very carefully ground off the first 3mm of barrel and moved the barrel back towards the stock by that amount in it's bushings.

Not had the chance to field test it yet but have had it in my garage with a pellet in the breech and swung it around a bit! Laughing

Seems o.k. so far!
Thanks for your help and pointing me in the right direction.
M&M

gimmick · Joined: 13 Jan 2010 Posts: 433 Location: Resident Asshole

WalkonKing · Moderator Joined: 01 Sep 2007 Posts: 8756

Sounds good

Subssonic · Joined: 24 May 2008 Posts: 567 Location: central WA

Ya know I had the same idea of tapering the breach ...but then I had horrible visions of pellets falling out when it came time to squeeze one off into a pest...I'm glad that I didn't now after reading this...
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make&mend · Joined: 11 Dec 2009 Posts: 10

Latest update.

Went out in the field tonight. (Well the garden anyway).

Had to re zero of course and then went about putting a few shots into small groups.

No problem putting 3 shots into 1" at 43 yards. (my zero range). But most importantly NO TANK DUMP!!!!

Thanks to all for your help Very Happy

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WalkonKing · Moderator Joined: 01 Sep 2007 Posts: 8756

That is nice to hear!