An interesting experiment with the 1740

[GreyCoyote]

I installed a 2300 valve in my 1740 and wanted to find out how many more shots I gained from a cartridge due to the smaller valve size.  Today I shot 80 rounds while checking out some different pellets to see how well they worked in the 1740 with the new valve.  One of the was the Blue Arrow, a plastic base, pointed sabot pellet.  I did so poorly with it that after the first ten, I substituted in a different pellet in the testing.  After 80 rounds, I wanted to see how many more shots I would get from the cart.  So, out came the Blue Arrows, which seemed to be the perfect pellet to just shoot for the sake of it.  The first 8 or so were all over the place.  The next three seemed to start grouping, so I changed over to a different aim point on the target.  The next four went through the same hole.  I had never done that before.  The next five dropped a bit and made a vertical hole 1/4" long.  I am posting a picture of the target I was shooting at.  It still amazes me.

All I can figure out is that there is something going on with the skirting on the pellets.  The plastic base has a very small lip that runs around the bottom of the pellet, which I expect is designed to work as the skirt.  I am guessing that when the pressure is higher, it tends to blow through the skirt and cause instability for the pellet as it travels down the barrel.  A lower pressure might not do so, which would let the pellet remain stable and fly true.  I am going to check out this guess the next time I take the 1377 out by starting with three pumps and working up from there to see if the lower pressures give better groupings than the higher.  If it does and the pellet works as well as it did today at the lower pressures, this may be a real find.

I also discovered that I get about 94 shots from a cart with a 2300 valve before the drop gets bad.  I think this will stand as one of the better mods I have done to the 1740.

[bgmcgee]

That's a bunch of shots. Good work. 

[Flex]

If you are interested in eking a few more shots out of your CO2 carts, you might consider a lighter hammer spring or even a "power adjuster" to reduce the amount of valve "dwell" (period of time that the valve stays open).

I "back-modded" a 2240 pistol into a .177cal carbine (18" barrel) and added a Crosman pressure adjustment assembly (aka Power Adjuster) for ~$15. I haven't done a formal study as how many more shots per powerlet I'm getting but it's a lot more than the standard 50! YMMV.

Nice thing about the "power adjuster" is that I can crank it back up to near factory power if I really need to whack a varmint.
I read a thread a while back about how to make a DIY power adjuster (probably for a lot less than $15). Flex

[GreyCoyote]

A power adjuster makes a lot of sense.  Davio has one that I have my eye on.  Just need to fit it into the budget.