roger (Login bhawanna) from IP address 167.7.16.100
OK, i know i'm going to get hammered for this and look like a total idiot but the rws ninjas need to comment. i just talked with the "gunsmith" at umarexusa about changing the barrel on my .177 350 mag. to .22 cal. he said all i had to do was change the "barrel assembly". he said they do it all the time and the action and EVERYTHING was the same except for the barrel assembly. i need the "real" story from the "powers at be" on this before i dump 2 bills on a barrel assembly.
I did say that you cannot expect the same performance form that gun as it would be expected from an out-of-the-box 350 in .22".
IIRC, at some point I wrote that the "system" is not completely tuned with a "simple" barrel exchange. Not that it does not work, it will simply not perform to the max.
The 350 may be the best rifle to try it on, as it has a long compression chamber and the swept volume comes from length, not diameter. Therefore the pressure spike is not as steep as in a 48-52-54 family gun and should be less sensitive to the transfer port size.
If you are aching to try it, perhaps that alone justifies the purchase of the .22" cal. barrel.
If it does not perform to the max then you can start fiddling with it, just remember that once the transfer port has been reamed out, you would need an insert to reduce it back to size. And that to ream the transfer port you will need to disassemble the gun and go 0.001" per 0.001". AND clean real well the compression area before assembling each time.
As far as I am willing to go on a limb and give you some guidance, I can tell you that the difference between the transfer port of an 0.177"/0.205" gun and a 0.222"/0.257" gun is only 0.025"
And that some of my experiments have shown that actually TAPPING a fine thread in the transfer port is more beneficial than simply opening it up. There's a lot to do with supersonic turbulent vs. subsonic turbulent flow of plasma gases through small apertures in that statement, and I really cannot tell you more, sorry. Too many possibilities to screw up a nice idea with a very simple oversight.
Do go ahead and change the barrel, chrono the gun and post the results, you may even get better than expected performance! Guns are individuals, we only learn through the collective efforts of all here, so if you feel you need to scratch that itch go ahead and do it!
Your post was still worth it with the creativeness of different fonts and colors. Very pleasing to the eye.. good job
BTW, there have been a couple of people on the GTA forum that just "upgraded" their 350 to .22. I remember them saying "it shoots hard" but I don't believe any of them chronied the gun. Even if the kinetic energy is the same, they should benefit from the larger wound channel (we assume they are doing all this for hunting). Another important thing to understand is that they must practice to learn the heavier .22 pellet's new trajectory and basically how the gun shoots all over again. A 350 that shot an 8.4gr (JSB Exact) at 1,030fps will have a drastically different POI with a 14.3gr pellet traveling at 800fps.
I just dont understand this comment Russ,,, When I talk on the phone with Curtis,(Usually a pretty LONG time!!LOL!!) I usually come away knowing WAY more about airguns than I knew before!! Of course, Im just Funnin Russ,, the next day,, I usually have serious abdominal muscle PAIN from laughing so darn hard!! It is great that a "simple ole home builder" like myself (he HATES it when I say that!!) can bond so well with those of such edumication!!LOL!! Curtis is as "Down to Earth" as the come!! I have made MANY good Friends here in a short time,, I will not make the mistake I have in the past by making a list,, "Colorfull Curtis" however is among them!! Kindest Regards to all my Diana Werks Friends,,, Tim.
Please note that while there are .177 and .22 0ptions for barrel caliber; there are no corresponding caliber options for comp chamber, Therefore, there is no difference in port size. This has been true for every airgun schematic I've ever examined.
