9mm hammer size /weight
im building a 9mm gun , its guna have a big valve in it , about .41 od on the head of the valve seal ,and run about 3000psi ,just wondering if some of you have any commment on the weight of the hammer. i figured id start heavy , probably 300 grms .
any input ? more weight ?
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good to hear . i know m bording on to big , but with all the other guns iv built i figure i should be able to open it with the right hammer / spring ,
310 fp is pretty good , im hopeing for 425 , ( shooting hi 🙂 ) haha .
good to know yours will open it well , glad my post provoked ya .
i figured 3000psi would be my top psi , wish could do 4500psi ,
Jezx:
You know, I think your right! After you said you were using a .3 seat size for .22, I took another look at what I was doing.
This morning, I adapted a valve from my .458 cal gun to my 9MM gun.
Old valve was .270 seat and .375 stem
Newly adapted valve is .320 seat and .437 stem
I was surprised to see that it opened just fine!
9mm was doing:
920 FPS with 150 grain, for 280 FPE
and
1027 FPS with 105 grain for 246 FPE
Now its doing:
965 FPS with 150 grain, for 310 FPE — About the power of a .38 special
and
1067 FPS with 105 grain, for 265 FPE
26 inch barrel 3200PSI fill
Mark
Jezx:
Your right, the bigger the hole, the more power you get.
36″ barrel will get you massive power. I’ll bet you get over 325 FPE.
I am getting about 280 FPE using a 26 inch barrel (920 FPS and 150 grain bullet).
Keep us posted!! Post pictures!
Mark
guess i should have said more about the build .
its not a AF gun , its guna be a bull pup with an inline valve,
im hoping to get some major power from it , so i figured id go big , also it will have a 36” barrel , so i want lots of air .
ive built many guns , just fugued id ask what some of you used for hammer weight, since none were inline 9mm’s . i think i build stuff different then most would , all my .22 cal condor style guns have .3′ valve seat or lil bigger , so i figured .4 would be good for a 9mm . i could be wrong quit easy 🙂 . i have alot of it already built , so i could always put a insert in the valve and a smaller seat . just seems to make sence to me to have a larger hole feeding into the 9mm size , i’ll keep ya posted .
Jezx:
A .41 valve is huge! (too big!)
Three things go into how hard the valve gets hit:
1 hammer weight
2 strength of the spring
3 stroke of the spring.
These 3 things must be balanced aganst the size of the valve seat.
The bigger the valve seat, the harder you need to hit the valve to open it.
I think the strength of the spring has the most influence on the size of the valve you can open.
My custom built 9 mm gun (not an AF frame) uses:
150 grams hammer weight – i think
2.125 inch stroke
10 pound initial spring force and 35 pound fully cocked force
I think the valve seat is about .27 inch (??)
My .458 gun has about the same hammer stroke and hammer weight, but the spring force is twice as big as the 9mm gun. The valve seat opening is about .34 inch.
There are two springs in my gun, one inside the other to get the 35 pounds force (the O.D of the small spring fits inside the I.D of the big spring)
If you use an AF frame, then the hammer stroke is fixed, and you cant extend the stroke (the more stroke, the harder you hit the valve).
When you build the valve, start out with a small seat opening.
If you can knock the valve open when you have 3200 psi, then you know that the valve seat can be opened up a little more, and still open @ 3000 psi.
Keep opening up the valve seat untill it will not open up @ 3200 psi — then you know it is as big as it can be using the existing hammer weight, spring force and hammer stroke.
Are you modifying an Air force gun?
Mark
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Jezx:
Go for it! With that long barrel, you got a good chance at it.
My first attempt today, was to just open up my existing valve.
I punched it from .270 to .290 and got no increase in power.
I figgured it was limited by the .280 hole in the stem.
I got the power increase when I used the .437 valve stem diameter (with a bigger hole through the stem).
With this in mind, you might consider building the valve with a big stem diameter.
I got a spreadsheet to calculate average barrel pressure.
With my valve and 26 inch barrel, I got a theretical pressure of 1429 PSI.
If you use a 36 inch barrel and develop 1390 PSI, you get 418 FPE.
So it looks like it may be possable to develop over 400 FPE with that long barrel. I think you will need a heavier bullet (I was using 150 grains) to stay subsonic.
Imagine, over 400 FPE in 9MM !!!! –> Thats twice the power of a stock 50 cal. Dragon Slayer!!!!
Mark