Can it dump the tank?
I had came across a Talon barrel which measured 5.35mm at lands & the pellets he wants to shoot are having heads of 5.40 & skirts of 5.80mm. The pellets are causing tank dump & not moving from breech at all. The same pellets are flying at approx 750-800 after resizing them to 5.50 at skirts. Tank pressure is 2700 psi
Very often I read here that many types of heavy pellets are very tight fit in barrel yet they are shooting it without tank dump then why this perticular airgun is not being able to shoot above mentioned pellet? Does it need to have stronger valve spring or the barrel id should be more to have easier fit?
Masters please suggest me the best remedy.
All Replies
Here are chrony figures after all above rectifications carried out. Thanks guys for all the guidence provided.
21grains- Talon in 0.22 -70grams Brass Hammer-2300psi-1500psi
1 860
2 860
3 855
4 865
5 878
6 878
7 878
8 870
9 868
10 872
11 868
12 865
13 861
14 860
15 865
16 865
17 860
18 858
19 855
20 860
21 855
22 855
23 848
24 845
25 852
26 850
27 846
28 849
29 849
30 840
Thank you guys,
Because of your suggestions pin pointing problem areas I could solve the riddle.
There were 4 causes. Bad pellet material, undersized barrel, rough stem, & loose ‘O’ ring in breech.
Today I carefully removed the stuck pellet & found it slightly mashroomed around barrel breech end which made it virtually impossible to be pushed out towards muzzle end. The soft metal & undersized barrel must have caused it. Because of this gun was creating back pressure & loose ‘O’ ring was allowing it to pass out of the breech-tophat-valve area causing tank dump.
Replaced both the ‘O’ rings in breech. I also checked the valve & found it very rough on stem & transfer ports. I think this was also sticking sometimes & helping keep valve open beyond requirement. I polished the same with 800 & 1200 grit paper.
Finally I enlarged breech end I.D. upto 5.6mm. Now I can push pellets completely in the barrel & there is no scope for it to get mashroomed around barrel. I did so because getting another .22 LW barrel here is next to impossible. Now it is shooting perfect. Tomorrow I will post some chrono figgures as well.
One thing still remains to be known is that if all LW barrels are having I.D. of 5.35 or this one is a rouge. Will appreciate to know the same.
Thanks once again to all of you. TAG surely is the best forum & has most knowledgeable members around to help.
These are not any bigger than a Kodiak at 0.228″ skirt. This must be one gutless airgun to not shoot these pellets.
What weight and what power level are you at?
2500psi will develop 95 pounds of pus in .22 cal so cannot see that pellet resisting that force.
Walter…
Can you check the alignment between the top-hat and the breach to make sure they’re line up evenly and sealed? It’s sound like when the hammer strike the valve not hard enough to open-up the valve all the way which only allowed a small volume of air pass-through and pellet jammed in the barrel which also could leave the valve opening and caused the tank dump?
I think you’re on to the cause Synopsys. The pressure likely isn’t pushing the breech block, but the top hat itself, and bleeding out between the two.
That’s a powerfully stuck pellet. 😯
Sounds like a bad scenario in the making.
LOL. Have no idea?
Sam
Hey Sam, he called you “dear”…
Anything you want to tell us? 😆
If the pellet seals the barrel wouldn’t the air push the breach back against the tophat holding the valve open until the pressure equalizes and the valve seals again… 😕
All this is happening right next to your face… 😯 Careful with those pellets… 😕
I think the desired piece of information here, is “Where is the air going?”
You mentioned that the tank is dumping, but the pellet is stuck in the barrel.
If the pellet is still in the barrel, the air obviously isn’t taking that route. Is the breech/transfer block in place with lubed and otherwise good o-rings??
Try different pellets of different sizes and use the pellet that groups the best.
Sam
Dear my problem is not resizing the pellets but I want to know the exact cause of tank dump because it normally does not happen in simmilar scenario. So I am trying to find out real cause behind it.
Is it a pellet size & material, an off center barrel, weak valve spring, stickey stem or something else.
Use pellets of this size 5.50 and throw out the pellets that are larger. If you haft to resize the pellets, that’s your problem.
Try different pellets of different sizes and use the pellet that groups the best.
Sam
the barrel is the way out….
All other pellets with maximum 5.55mm skirt size are doing upto 800fps from same setup. I have also checked barrel concentricity with laser & found it OK. Tank dump happens only when this oversized pellet is used. This pellet is also very soft compaired to other pellets. It kind of sticks to barrel.
Very often I read here that many types of heavy pellets are very tight fit in barrel yet they are shooting it without tank dump then why this perticular airgun is not being able to shoot above mentioned pellet? Does it need to have stronger valve spring or the barrel id should be more to have easier fit?
Masters please suggest me the best remedy.
How can you have a tank dump and the pellet not leave the breech?
the barrel is the way out….
Get better pellets.
You mean the quality of pellet is bad. I had same thoughtline but still wanted to take an opinion.
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Wow,
That string look damn good, look like you got 20 good shots there.