HiPac striker springs.

HiPac striker springs.

Joined: November 17th, 2006, 3:51 am

June 26th, 2012, 1:22 am #1

New spring from Alex. Have to admit, he sent me this one as a freebie...but he knows I will call a turd a turd and can expect an honest testing. He happened to be considering this while I was playing with a shortened RWS 850 spring. We came out about at the same place and he offered to send one of the new springs for testing.

A new run of experimental greensprings.

Original Crosman spring: .03 wire thickness...... .10 coil spacing....1.92 OAL...135BAR
Old Green spring: .035 wire thickness.....065 coil spacing.... 2.20 OAL.....145BAR
New Green spring: .035 wire thickness......088 coil spacing....1.93 OAL....165BAR

Not really going to test the Red spring as it is too stiff to cock and too high a sweet spot pressure.
Red Spring: .046 wire thickness.....09 spacing....1.93OAL...210BAR

OK...here is the test gun. HiPac converted 5mm 2250. carbine (11.7 5mm LW barrel). About 44cc of air volume, so shot count isn't going to be long. Stock valve. All the same settings, just the spring replaced between tests. All using 13.5gr JSB) 5mm pellets.
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In case you like more numbers. On this carbine, the distance the striker travels from at rest on the valve stem to sear caught: is .55. That's all the stroke you're going to get with a stock valve, striker, and end cap.

Original Crosman spring:
135 90BAR
10 shots from 620 590fps = 605fps averqage / 11 foot pounds

old green spring:
145- 100BAR
10 shots from 650 620fps = 645fps average / 12.5 foot pounds

new green spring:
165 110BAR
10 shots from 675- 645fps = 660fps.average / 13 foot pounds

The good news:
With the wider coil spacing, is some room for pre-tension with the new spring and still get it cocked before becoming coil bound. The old green spring's narrow coil spacing would allow it to become coil bound faster. On an educated guess, believe enough pre-tension could be added to get the new green spring to run right at 170BAR (and a proportional increase in energy).

The EFFICENCY INCREADED with higher pressure. From 19.3bar/cc to 16.2bar/cc. There is room for better than this, and I hope to get it to about 12 or 13...but that would only be 2-3 shots more in a string.

SUSPESIONS:

1.Sweet spot pressure rose by about 20% and energy rose by about 20%. At least in the short run over a narrow range of pressure, it is staying proportional. Which means if I increase the sweet spot pressure to 184BAR (or about 15%) should see enery at about 15 foot pounds for about 10 shots.
2.Good shot count really didn't change. Will need to limit air use, reduce speed, in order to see a real increase in shot count. Easiest way to do that would be to restrict the transfer port slightly (so it would run at the same pressures, but spread the shot count wider at lower energy).

UNLESS you are really in love with the way you have your HiPac conversion tuned, give Alex a call. Try one of the new springs and let Alex know that the new green spring is an improvement on the old one. Could get close to the performance of the old green spring with the factory supplied spring. The red spring isn't going to work unless you find a way of increasing the distance by way of a longer end cap (or a shortened red spring). Either way. Using the red speing is like compressing a Jeep suspension spring by hand.

The new spring will gt your gun running right at something like 2400-2500psi without any major changes.

PLAN:
If I nncrease volume by about 50% (which can be done with HiPac extensions), then shot count would increase to something close to what the P Rod is getting. If I do that, would have all 3 carbines running on an even keel (different calibers and pellets, but the same basic shot count).

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Joined: October 14th, 2006, 12:30 am

June 26th, 2012, 2:21 pm #2

I'm in the middle of tweaking a Custom Shop 2300 in .177 with a 10" LW barrel/HiPac set up as we speak. Might have to acquire a few of those new springs to try out.


I couldn't help but notice your shot strings are all on a "slope" and not a bell curve and was curious as to why you didn't try more fill pressure to push down velocity at the beginning of the shot string? Wouldn't that also increase shot count? Again, just curious, as I always learn something from your posts -






Vines



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Joined: November 17th, 2006, 3:51 am

June 26th, 2012, 9:06 pm #3

..rather than type something like 620 - 645 - 620, I just type the spread as 645-620.

Using a stock valve (or even one just slightly modded), to get it to run at over 2400psi, really need a stiff spring. Part of that is due to the short stroke (just not a lot of distance between striker fully down and striker cocked).
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Joined: October 14th, 2006, 12:30 am

June 27th, 2012, 7:15 pm #4

have you experimented with a softer spring insided the valve so that it doesn't require as much force to open it? Just curious.

Again, I almost always learn something from your posts and find them very informative.








Vines
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Joined: November 17th, 2006, 3:51 am

June 28th, 2012, 2:33 am #5

..is to give up on the 12 co2 option, change the Crosman valve stem to a non piercing design (which cleans up air flow a good bit) and to make it a Delrin sel. Clean air flow and lighter weight will do a whole lot more to increased power than just farting around with the return spring.

My goal was a 12 foot pound gun with as many shots as could manage inside of 25fps.....if not looking to limit energy to some specific level, then farting around with decreased transfer port size is a wasted effort.
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Joined: October 14th, 2006, 12:30 am

June 28th, 2012, 2:11 pm #6

I replaced the back half of the co2 valve with the back half of of a Discovery valve. Drilled out ever so slightly the valve retention screw hole in the tube to allow one of the Disco valve retaining screws to fit. Using the Disco valve stem with the valve return spring from the co2 valve. BTW, this was a brand new Custom shop 2300 with the 10" LW barrel. The valve is brass, and the spring inside the valve was lighter than the spring normally found, so I made use of it. Used a restrictive transfer port as well - very happy with the results.


From my observations, a lighter valve return spring seems to decrease hammer bounce, much the way a basketall bounces better on hardwood than say, your front lawn. Just something I observed while farting around.




You have a good day Sir







Vines
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Joined: November 7th, 2010, 3:57 am

July 22nd, 2012, 6:02 pm #7

of your transfer port. what material are you using? what is the port diameter> also have you done any chrony work? if so can you publish your data?
I've got a 2240 with a Hipac and am looking for information especially what works with these as far as valve work. I'm more interested in power than shot count but want to work with both areas.

Thank you.

Les

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No guns, no peace no liberty.
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