Full Results Posted: MDS Nylon Hammer in 22XX

[Motorhead]

As too the COCKING pin hole ... Drill it with a .125" starter drill ALL THE WAY threw.
It will make a very snug correctly sized hole where as a conventional drill will go oversize a bit making a lose fit.

Been there & done that 

Here what one looks like FYI ...

[imadunatic]

Bob,

I definitely think if it was warmer, with heavier pellets and I ran out until it quit reading instead of stopping at first shot under 300 fps, I could definitely bump my number. Maybe when I don't have so many projects going on at the same time I'll fit the stock barrel and see what I can do. Many thanks for your fully internal SSG design, it's saved me bucket loads of co2 and air!

As you've said before, most efficient may not be the most effective. Lol.

[Bob Pratl]

Kevin, looks good. What was the final weight of the hammer and the spring specs? Did you add an adjustment to the hammer spring? Thanks. Bob

[imadunatic]

As too the COCKING pin hole ... Drill it with a .125" starter drill ALL THE WAY threw.

Thanks for the tip Scott. Never even crossed my mind that it would be so sloppy and so detrimental to function if it was. I ended up drilling them to .109 and reaming to .125 which worked well enough, but if I was building a bunch of these I'd definitely want to eliminate a step or 2!

Kevin, looks good. What was the final weight of the hammer and the spring specs? Did you add an adjustment to the hammer spring? Thanks. Bob

Bob,

Because I had to modify them slightly due to the sloppy cocking pin hole the aluminum ended up right at 13 grams; however, I found with my setup that the 1" deep spring pocket was too much and I couldn't get it adjusted perfect so I ended up running a 1/2" steel spacer in all of the hammers which added 2 grams for a total of 15 grams. I run a 5 lb spring in both the 2240 and 2400 (so far, it just got on the bottle) SSG. I detailed my prototype setup with part numbers here: http://www.gatewaytoairguns.org/GTA/index.php?topic=105520.msg1094903#msg1094903. I'm still using that same spring and ordered more for testing purposes, they are almost perfect for the 22XX platform with an internal SSG.

SSG:




My gut feeling is that the big thing here is making the exterior out of MDS so you can run them dry and shave a little weight, no matter what the hammer weight ends up at, you'll be able to adjust/tune it for maximum effectiveness (by that I mean a decent FPS at a decent efficiency). I think in my case, it just so happens that a 15 gram hammer is the sweet spot for what I currently have my spring preloaded to.

[Bob Pratl]

Kevin, thanks a million for the updates, I forgot that you all ready had the SSG installed. Another question, what was the length of the #10-32 SH screw that you used for the SSG? Thanks again. Bob

[imadunatic]

Kevin, thanks a million for the updates, I forgot that you all ready had the SSG installed. Another question, what was the length of the #10-32 SH screw that you used for the SSG? Thanks again. Bob

Bob,

1.75" long, it just so happens the head of a #10 SHCS is perfect for the spring pocket on a 22XX hammer.

This is a disassembled picture of my exact setup that is running in the 2240. In order to tighten the entire package up when I made my final setup I had to clip the spring slightly. To give you an idea of how much, the spring on top is brand new, never been used. My brass tube is cut to 1.25" long. This will probably change slightly once I start tuning for minimal gap on the aluminum hammer to try and tighten up the extreme spread (ES for the first 73 shots was 30 FPS with a .150" gap), but this is a good starting point for a stock-ish 2240 nonetheless.

[Bob Pratl]

Kevin, thanks again, you have been most helpful.  As soon as I get my lathe back together from CNC upgrade I will be fabricating the parts for my 2240/2250 CO2/HPA toy which has been setting unused for a few years until I started reading you inspiring posts. My 8 year old grandson LOVES shooting it as much as I enjoy modifying it. Bob

[JerryinWI]

Will be keeping a eye on this thread because it sure would be nice to get more than 30 to 35 shots from my co2 guns.

[imadunatic]

This will probably end up in my thread on the 2400 HPA build, but I thought it might be relevant here also. It's currently running a bone stock disco valve with a 22XX poppet spring and a 24" .177 barrel @ 900 PSI.

This setup currently maxes out at 760 FPS, and in order to do that with the nylon hammer I had to have it within .050" of coil bind; since I wouldn't be able to tune all hammers with a gap of some sort (which would affect efficiency greatly), I decided to just run each hammer with the exact same gap (.025") so we could see the effect that only changing the hammer mass has on power and efficiency.

Note: The pellets used in the numbers below were JSB 10.34g .177 heavies.

[rsterne]

Great chart, it really demonstrates what happens when you change the mass of the hammer.... thanks for posting....

Bob

[Bob Pratl]

Very interesting. Have you extended the shot count till the FPS take a nose dive? The steel hybrid looks very flat and consistent. Bob

[imadunatic]

Great chart, it really demonstrates what happens when you change the mass of the hammer.... thanks for posting....

Bob

Thanks Bob. I also really liked how well it exemplified what we all know happens when the hammer strike is too light: Velocity is all over the place. I think if nothing else changed, the steel core hammer would be about perfect for this setup with a 5 lb spring.

Very interesting. Have you extended the shot count till the FPS take a nose dive? The steel hybrid looks very flat and consistent. Bob

Bob,

I haven't, this was just to see which hammer was going to be most effective in a HPA conversion that is going to end up 900-1100 PSI (undecided yet, though I'm shooting for 20ish FPE out of a .177). Even with the steel hammer, it was only using ~9.4 psi/shot, extrapolating that over a 3000-850 psi fill means in the neighborhood of 225 consistent shots off the 13ci bottle. This build isn't staying at this level though. It needs some roto rooting to get the most out of such a low pressure build.