Kral Puncher Breaker - back in service

[Flatpicker]

After breaking a valve stem with just over 2600 rounds thru my PB, And being the impatient person that I am rather than wait for a replacement to arrive from PA, I sent the stem and valve body to Will Piatt who machined a new stem. He commented on the overall mass of the Krals stem, saying it was one of the largest he had seen for a smallbore rifle. He also lapped the valve seat saying it looked pretty rough. Got the goods back on Monday and in about 15 minutes had the PB reassembled and ready to shoot over the chrono. The original stem was heavier (but I didn't weigh it vs. the new stem) and had a slightly smaller diameter in the transfer port area. It also sported an O-ring. Will's stem has no O-ring and no smaller diameter in the transfer port area. Velocity is down slightly as I would expect but functions just fine. I was getting around 950 fps with 14.3 Crosmans, but now it is shooting just below 900 fps. Probably a couple factors at play here: lighter valve may have reduced dwell time coupled with no reduction in stem size in the port area. Accuracy is still there with 1/2"-5/8" groups at 50 yards.  It's good to have it back up and running as I still enjoy this little tinker toy. 

[Vance H]

Does Will Piatt plan on offering these valves for sale?

[Flatpicker]

I don't know whether he will or not. He asked for some feedback, so I plan on calling him tomorrow. I will ask and post after I talk with him.

[Extreme]

   Piatt is a great tuner!!! He has my Career 707 Carbine .22 converting her over to a .177
Glad to know he will built Kral parts!

Thnx Brother Man

[Old Corps]

Glad she's back among the living!

Ed

[Flatpicker]

Does Will Piatt plan on offering these valves for sale?

Spoke with Will today and yes, he will make the valve stems.  Give him a call or drop him an email.  Just google Saddle Mountain Gunsmithing for contact info. I was mistaken about my new stem not having a reduced diameter like the original.. Dimensions are identical. The reduced velocity is simply because the lower "plunger" portion is made of Delrin which reduces valve stem  weight. To boost velocity I must add hammer spring tension, lighten the valve spring, or increase the hole diameter from the main air tank to the pre-chamber (very carefully). The other method would be to do as Travis has said: port the entire gun up to .160" throughout the system.  I think I might try the lighter valve spring first as it seems to be the most forgiving of all options. I'm a little hesitant to crank up the hammer spring tension too much as I don't want to ruin another stem, but Will said I shouldn't hurt this one.