Talon ss shot string
I did a shot string today and this is what I got. 22 cal talon ss with stock 12″ barrel.
My question is, why did my velocity start to drop off if my tank is still at 2500 psi?
I think I still need to work on the tophat and PW settings, it just doesn’t seem right.
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I would like to bring this back to life because i still don’t know why my velocity started dropping off so early. Does anyone know??? maybe the tophat is smashing into the valve body?
Abe,
If the body face face is in the way, next time you have the valve out lap off the face edge to get it out of the way.
Yep, 40 fpe is possible with the 12″ modified SS valve,, but you will need to do more to get there.
I was concerned with the safety issue regarding the valve guide. One really does want that guide seated.
Keep in mind it is really about the “lift” you push into the stem. In other words opening the valve. The measurements can vary from one rifle to the next with respect to the TH position.
Bikin,
Already adjusted to level with the body. It was low enough to be visible and easily catch a finger nail. Unmeasured and at a guess, ~10-15 thousandths below the valve body. Just enough to throw off reading with a feeler gauge. Oh, yeah, I found that, rather than stack up a whole bunch of shims, a 0.050″ allen key, if it really IS 0.050″, helps with measuring. You only need a couple of feelers that way.
I have a feeling that a polished valve and barrel may be good for 40 or so fps. That’s the next project. That and vent the bushing. Thanks for the info. I don’t think we’re too far apart here. Location is another matter.
mikemv,
The guide wasn’t screwed in all the way to begin with. Took very little torque to back it out under 1/8th turn to get it level.
Thanks all. Great site with LOTS of useful and interesting info.
Abe
ALF
Would you mind taking a picture so we could see how far below it is?
ALF
Don’t leave the brass guide unseated. You don’t want that thing leaking or backing out.
There are a lot of unstated variables in the situation with respect to each rifle, conditions and so on and that can have a significant influence on what one might get for numbers.
If your brass guide face is significantly below the steel valve body lip plane that is unusual.
m
Mine looks like it is pretty much level with the steel valve body. What are you using to measure the gap? I used a feeler gauge, because my calipers could not fit in the gap.
The only mods I have done are: Vented bushing, vented frame, somewhat polished valve, and a fully polished barrel, where the hammer and breach slide. The only ones I could picture adding any velocity are the polished valve and barrel. I did notice that after I polished the barrel it felt smoother, and easier to cock.
Bikin,
A question, please. I noticed on my TSS that the brass(?) valve stem guide is actually screwed in BELOW the steel valve body. Is this or was this the case with yours? It made it very difficult to get an accurate measurement of the TH clearance. Emptied the tank and screwed the guide out until it was flush with the valve body (as in the picture in the TH adjustment link).
Still haven’t been able to top 810 fps with ~16 grain pellets, PW at 5. Any other mods to your rifle?
Thanks.
Abe
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A question, please. I noticed on my TSS that the brass(?) valve stem guide is actually screwed in BELOW the steel valve body. Is this or was this the case with yours? It made it very difficult to get an accurate measurement of the TH clearance. Emptied the tank and screwed the guide out until it was flush with the valve body (as in the picture in the TH adjustment link).
Mine is also screwed in past the top, by .023 +/- .002. It looks like my top hat is .11 or .12, although it’s difficult to get an exact reading with it in that position. I have not yet tried to adjust the top hat. With a 8.2g .177 pellet, I was getting 920fps +/- 5fps pretty consistantly at PW8, and 875fps +/- 15 fps at PW4 (not quite as consistant as the higher setting).