Hammer springs?????

[scion19801]

just got an email this morning....not happy or impressed at all. they now say that my springs are on backorder. they couldn't have told me this prior to my order. So much for using a big name company to get my springs from.
Now on the long dreaded search for another source to get a replacement JSAR super tune kit spring. this &^^& is getting out of hand with supply chains be all messed up. Almost makes me want to buy my own lathe, so i can try to create my own custom parts.

[scion19801]

ok so the factory gauntlet hammer spring is 2.775" long, .343" od, .227" id, and .057" wire, 21 coils.
i get a measured depth inside the uncocked hammer of 4.101" to the back of the tube., and 3.619" when cocked.
spring guide is .453" in length, with a .659" long spacer, and with a .379" rear cap.

spring rate of 31.861 Lbs/In
max load of 27.872 lbF
minimum load height    1.900 In
max travel of 0.875 In
these are the stock setup measurements.

the jasar super tune rear cap is .987" long
maintain same spring guide at .453" long with what i think is possibly a 2.25" - 2.5" spring?

current setup is running factory spring and spring guide with a custom mds spacer .430" long and factory rear cap

If i try to run factory spring with jsar rear cap, with no spacer, i get preload right off the bat. I'm trying to eliminate any preload.
I'm trying to figure out what spring length to get so that i can put the jsar RVA cap back into service. and also what my compressed length for the replacement spring should be. i have found two possible springs to get.
one has:
Music Wire Compression Spring, Steel, Inch, 0.30" OD, 0.047" Wire Size, 1.487" Compressed Length, 2.25" Free Length, 16.1 lbs Load Capacity, 21.1 lbs/in Spring Rate
the other:

Music Wire Compression Spring, Steel, Inch, 0.30" OD, 0.049" Wire Size, 1.526" Compressed Length, 2.25" Free Length, 17.98 lbs Load Capacity, 24.8 lbs/in Spring Rate

spring rate of 24.939 Lbs/In
max load of 20.523 lbF
minimum load height    1.427 In
max travel of 0.823 In unknown coil number
final one:
Music Wire Compression Spring, Steel, Inch, 0.30" OD, 0.051" Wire Size, 1.732" Compressed Length, 2.5" Free Length, 20.17 lbs Load Capacity, 26.3 lbs/in Spring Rate

I don't want to collapse another spring so I think need to pay attention to the compression length.
i know that there is 2.661" from the uncock hammer to the back of the jsar cap using the spring guide, and 2.179" when cocked. so i guess i say all this to figure out what would be a good length and weight spring so as not to over stress the spring. should i be paying attention to load capacity or to the spring rate? i don't want to have a wicked hard cocking effort. i'm also a bit lost on the load versus spring rate numbers.
Or is it that when the springs get close to the compressed length they are producing their respective load capacity? i know when i initially setup my jsar kit i had it turned in 11-1/4 turns which is around .340" beyond the end cap and was giving me my 890 FPS, but i would like to eliminate that much stick out, even if i have to make a custom mds spacer to get it so there is very little stick out and still have no preload. also current setup had .085" no preload gap. running 1700 psi at 886 FPS

[scion19801]

wow... I almost hate to do anything else to this gauntlet. just shot 64 shots with reg set at 1700 psi, on my .38l bottle through flex regulator and factory spring with a .085" gap. efficiency of 1.34 fpe/cc @ 44.3 FPE average. next will be to do a full shot string over the crony to see what it is doing shot to shot.
I'm thinking hammer and valve work may be next, to calm down the shot cycle.
58 gr hammer just seems way too heavy, for the way it is currently setup. I may need to get heavier ammo to get it up to the 55 FPE range.
I need to pull it down and get all the valve measurement out of it. i know that it has a .194" valve exhaust. but don't have the throat, or actual valve body opening around the poppet. the valve is stock, except for the aftermarket poppet. custom transfer port .194" inlet- .187" outlet. then .187" the rest of the way to the barrel.
I know my poppet diameter is .343"

[scion19801]

Update....
New springs arrived from grainger.... they are the 54MN28 springs. Put the jsar rear cap and new spring in. playing with different options to limit the max low point. so between the jsar adjuster and hammer spring guide i put a small washer that is .835" thick. at 1600 psi it gave 580ish FPS. A .176" spacer gave me mid 800's. effortless cocking. they are  closed and ground ends and 22 coils with 2 half closed ends. 2-1/2" long. and man are they consistent. shot at two different loads settings and managed multiple duplicates back to back.
cranked back up to 1900 psi to see what i max out at, and getting 930 fps, no coil bind in sight, 5 turns in from flush. this is with my NOE 250-27-rf 25.4gr pellets of pure lead.
Mind you there is no valve work done other than aftermarket peek poppet. running factory 60 gr hammer.
At 1700 psi max FPS is 900.
Almost seems like i need more lift in the valve. i could be wrong. i does only have .101" stick out on the stem

[nervoustrigger]

Maximum flow is attained when the poppet is lifted by 25% of the throat diameter.  I didn't find the throat diameter listed here but I suspect it's no larger than 0.25" which means that the valve is flowing the maximum amount at a lift of just 0.063" or so.  Therefore you should be in good shape with the 0.1" of exposed valve stem, particularly with the fairly hefty 60 gram hammer allowing for plenty of dwell.
 
FWIW, even when I'm using a lightweight hammer (10 - 15 grams) I only leave about 0.120" of the stem exposed under otherwise almost identical circumstances.  Despite the reduced dwell arising from the light hammer, I haven't encountered a case where I ran out of valve travel.  In other words, I've always been able to achieve the same velocity with the lightweight hammer as with the much heavier hammer.  Perhaps I could shorten the stem a bit but I've never had reason to chase an extra 0.020" to 0.060" of hammer travel.
 
I also wanted to point out something that could potentially trip you up.  You described trying different spacers to change the hammer spring preload.  Be advised that if you happen to go too far such that the valve stem is driven flush and the hammer impacts the back of the valve body, the hammer will rebound quickly.  The result is much reduced valve dwell and a lower velocity.  Based on your description above, I don't think that has happened yet but I wanted you to be aware of it because you may encounter it as you try to squeeze out the last bit of velocity.  That's especially true when doing the trial-and-error approach with spacers as compared to a fine adjustment like a screw (RVA or similar device).

[scion19801]

thanks for the info. will keep it in mind. the main reason for playing around with the space was to limit the amount of turns needed to achieve the FPS. With just the stock Jsar tune kit for the .25 cal gauntlet, i had to crank in 11-12 turns in from flush to get to where i wanted to be. the result was a lot of adjuster screw stick out. i figured that if i put in a spacer at the lowest FPS point i wanted to see, then be able to maybe only use 4-5 turns to get to my target speed. current spacer is just a washer at .083" and i think around 5 turns is and hitting 876 FPS with 27.2 gr.
I wasn't even considering that i might overdrive the stem with a spacer. was only looking at it as any change behind the sear wouldn't affect the valve stem side. i do still think i'm to the point were valve mods may be needed to get more FPE/FPS. The max was 930 FPS from the current conditions. Won't truly know till my AVS .2505" slugs arrive for further testing.
Had a few other odd issues pop up that i've been trying to figure out.
out to my 43 yard target, it's scary accurate.
at 52 my shorts are drifting high, and left by maybe 1/2 mildot.
out to my 100 yard plate, i'm way high and left.
Trying to figure out what is causing this. I know for sure that I'm not clipping. i know it can't be the ammo as they will stack at 43 yards no issue. I did pull my custom barrel band and found that my bottle had change relation to the shroud. got bottle back in place and custom band go's back on perfectly. re-sighted in. closer to being back on target, but still same issue high and left from 50 -100 yards. I'm almost thinking that it could be a precession (spiraling) due to speed. i can definitely see the pellet curve in to impact at 43 and closer to 28 that my zero is at. Crown is good and chambering is no issue. Odd trying to fight/figure out the precession issue. 1:20 twist is an animal it seems.
I visually check, and roll test each pellet. so i know they are consistent in that extent. I actually roll test before they even go into the mag. I have fully tested mags versus single shot tray, same outcome. probe orings are good. slight blowby, oiled every 10 mags, and changed every 3 tins. I have both the .254" od rings and the 6.35 mm's. i know my chamber area is .254". May just chalk it up and and be only a 43 yard with correction for 50 yard max.

[scion19801]

had another set of springs show up today. the grainger ones i got were 22# spring rate 2-1/2" long. the now ones are 24# spring rate 2-1/4" long. Need to figure out a spacer size before i test the 24# to see how they are in the gauntlet. Might be a good spring to use to set up my light weight hammer. Maybe not drill the hammer spring hole as deep and try them that way. that would leave more weight in the hammer with the hole not as deep.