Pellet Jam?

First off Hi... 1st post

Just got an XS78  (UK) ...and have been very impressed, mostly. However every dozen or so loads the bolt seems to catch as it pushes the pellet into the breach, then the gun fails to discharge  giving a sort of anemic cough which may or may not clear after several re-cocks..
Am I doing something wrong? Could it be the cheap pellets that were supplied (SMK pointy spitfires).. Or is this something that needs work.

I have also noticed  that some CO2 seems to escape from the transfer seal when this happens (I guess it has to get out somewhere) could this be blown?

Any clues?

Don

[DanoInTx]

Sounds like odd sized pellets getting jammed in the breach, VinceB describes a similar jammed pellet ordeal with cheap pellets in his review here:
http://www.gatewaytoairguns.com/airguns/forums/thread-view.asp?tid=1270&mid=6732#M6732

Might not have blown the transfer port seal, one way to tell is by placing a paper towel or Kleenex over the breach of the gun while it's fired and noting any movement caused by blow by.  I would first try a better quality, more consistantly sized pellet and see if that cures the problem, if it does, toss those cheapo pellets in the trash.  Ian at QBTune UK could probably direct you in the right direction for a good pellet selection in your part of the world.  Good luck and welcome to our little forum!

QBTune address:
http://www.qbtune.zoomshare.com/

Dan

[IJL]

My money would be on a burr the size of a small car in the breech, where the CO2 enters. That will foul up the accuracy too. As to the leak, replace the oem seal with a piece of poly tubing, about 1-1.5 mm.
I've had a few QBs through that do not discharge on every shot. It is caused by inconsistent hammer strikes and can usually be cured with a good polishing.
Good pellets in UK QB rifles include Bisley Pest Control/ Magnum and H&N Field and Target. The smk pellets are fine for "running in" but as Dan says, some decent ones will be better.

Last but not least, welcome to GTA.


Ian

Hi
Thanks for the replies guys. I got some better pellets, called WASPs .. just looking at them the consistency is much better and having put 50 through it ..not a single jam or grind and as a side benefit grouping has improved massively.

I'll still strip it down soon and de-burr etc but that'll need to wait until I've sourced some replacement seals etc cause I'm bound to wreck some.

Now if only it will warm up a little I've lost feeling in my fingers and the '78 is drinking gas like a wino...


And oh ...'bout the poly tubing can anyone describe it a bit better .. I've been looking around and not seen anything similar for sale here ... we are metric (damn the french) and what is the stuff made of.  I think there are about 3 fridges in the whole country that have ice makers built in so asking @ BQ for ice maker tubing will just get one of those special looks from the knuckle-draggers that inhabit such emporia =).
 

[IJL]

I find the tubing at the council dump, just rummage through the dead fridges until I find some then out with the pen knife. One day I'll try windscreen washer tubing, just to see.
The only O rings you should need are the barrel O rings and then only 2 of them and once the screw hole is deburred hardly any at all. You can get these at Focus / Wickes  but they are expensive as you have to buy 2 of their packs.
Alternatively give SMK in Colchester a call or even Archer Airguns in the USA.

Ian

Thanks Ian

I am not worthy ... I have to go down the dump tomorrow as the car is full of cardboard Xmas remnants anyway, I'll take a knife.
Don't suppose you know the sizes and materials for the o-rings off the top of your head?
Otherwise ill re-read Charlie's guide

Ta

Don

[IJL]

Er, quite right, I dont know but they are in a Wickes / Focus O ring selection pack, You should only need 2 and the size/ material type is not super critical on the barell rings. Check out the automatic washing machines too, some have a lovely soft tube in them.

Cheers

Ian

Here's picture of my gizmo to cut the tubing into 1/8 inch bits, it shows a little piece of tubing in the gizmo.