Vulcan mods to make the hammer/spring assembly consistent.
This mods were performed on Zonk .22 Vulcan. his issue was sudden change in pellet speed.
in my testing —–> it was consistent for 5-12 shots or so around 900fps then drop down to 840fps for about 2 to 6 shots then back up to 900fps keeps doing this for 4 fill and can’t complete a string without the speed dropping to 840fps.
So the 1st thing I did was tuned the reg down to 120b with some polishing and better orings, didn’t see anything wrong with the reg during dissemble.
When testing the tuned reg I still see the speed drop in every fill. So I know now it’s in the hammer assembly so heres the mods I done in the photo:
1. In the middle of the hammer spring there is no spring guide so the spring flex where less resistant (rainbow) so the spring end at the HSTA rub on the threads in the action for the HSTA. to prevent the spring drag I sanded and polish the coils that’s making contact with the action threads and that also was sanded and polish.
2.The hammer was given a high polish for less friction.
3. The brass bushing for the hammer spring has an edge that side in the hammer chamber—- sense the hammer has a loose clearance that edge hits the action 1st at times that prevent the full travel of the hammer spring—the fix I reduce the OD.
4. after the hammer open the fire valve it will slam back at the brass bushing guide so to prevent metallic noise and still have a clearance for a de bouncing device (hammer is free floating so the hammer isn’t pressing on the VS when uncock) i installed a nylon slim.
here is a photo of a delrine spring retainer with a longer spring guied to replace the brass spring retainer and hopefully will keep the hammer spring from binding out ward so the back end of the spring from rubbing on the threads and reduce the impact noise.
if you want one contact John.
After all this mods I got her shooting consistently after 200+ rounds here are 3 shot string with the reg set a 120b. with 18.1g pellet.
pressure 205b to 105b
String #1 string #2 string #3
#shots 65 65 62
high: 900fps 907fps 902fps
low: 892fps 895fps 895fps
ES: 8fps 12fps 7fps
Not every Vulcan will have this issue but some useful info for others.
All Replies
Ernest, if you solved ping!!!! Vidieo PLEASE!!!!!!!!! 😀
Does the valve – regulator come out the valve end of the air cylinder?
I’m trying to picture pushing the reg and spacer back into position, and it seems you would do that by putting the reg in first, then spacer, then push them back with the valve until they stop. But you said they had no back stop…how do you know how far back to push them?
Can’t quite picture this in my head because I have not taken the gun apart yet.
Hoot:
slide reg half way in till both oring are in the tube then slide the spacer body flush with the tube screw on the firing valve it will push the reg and space to the right location when the firing valve bottom out.
:hoot:
Does the valve – regulator come out the valve end of the air cylinder?
I’m trying to picture pushing the reg and spacer back into position, and it seems you would do that by putting the reg in first, then spacer, then push them back with the valve until they stop. But you said they had no back stop…how do you know how far back to push them?
Can’t quite picture this in my head because I have not taken the gun apart yet.
Hoot:
I hope that helps.
didnt have the RIGHT size spring so I lube the F_ _ _ out of it. those spring are like acoustic strings if left un lube on BP.
Zonk, here’s is the pellet sample after and before the barrel was lap,polish and cleaned.
Finally found the ping sound after the shot, its the reg and firing valve spacer–since the reg has no back stop like the cricket, edgun so you can push the reg out the other end—so that spacer can be loose so what I did was added a thin oring on the reg side and added a electrical tap around the spacer, so the key point for the other owners is to use the firing valve to push the reg and spacer into position, if not you can over shoot the vent hole for the reg.
Your Vulcan is all done, a lot quieter then before —PM me
Ernest, have you tried a different spring in place of the hammer lever spring #111 to see if it changes the sound any? I’m thinking it may be interacting with the main spring. My hearing is not normal as I hear low frequency better than average, like an elephant LOL but don’t hear normal high frequency.
I hope that helps.
Hammer slap, Jap slap is that the same???
I think its the nature of the beast—you can tame it so much—>just shoot it and enjoy unless your like me that don’t enjoy the sounds it makes when fired. one time I removed the shroud and use a HW100 LDC it sounded a lot better and quieter up front then the ping, hammer slap got louder at the rear.
Not sure why you didn’t hear a difference with the Delrin retainer, but even my wife noticed it right after the first shot. I didn’t even tell her what I did but just asked her if it sounded different than yesterday. Not sure if the .177s are that much different than the .22s, but I guarantee there’s a noticeable reduction of hammer slap with the Delrin retainer.
You have it Ernest, do what you do best….
Thank BP Tuner
Zonk, in the cocking rod linkage now has a lot of play and vibrate and makes noise when fired — have to silences it.
The part I made looks similar to the one Ernest showed in his post, and I made a couple of the features a bit thicker for added strength. No need for any nylon washers when using Delrin or a similar material for this part. I’ll keep the TAG posted on this topic.
Please if all turns out well I will be the first to buy one from you if you are making them.
Sorry oakey, I tested the sound level without the brass retainer for a whole fill of 50 shots—> didn’t notes any significant reduction or not at all even with 120 reg pressure and both spring loosen to shoot 18g around 895fps. don’t get me wrong I got big ears and great hearing totally surprised me big time. you can try it your self—just remove that brass retainer and shoot it and hear for your self. the only thing I notice is lost of shot count and wasn’t that much. so wasn’t worth the effort in making the delrine retainer to replace the brass.
I think its the nature of the beast—you can tame it so much—>just shoot it and enjoy unless your like me that don’t enjoy the sounds it makes when fired. one time I removed the shroud and use a HW100 LDC it sounded a lot better and quieter up front then the ping, hammer slap got louder at the rear.
You Oak and probably many others…..
The part I made looks similar to the one Ernest showed in his post, and I made a couple of the features a bit thicker for added strength. No need for any nylon washers when using Delrin or a similar material for this part. I’ll keep the TAG posted on this topic.
Please if all turns out well I will be the first to buy one from you if you are making them.
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Ernest… did u measure the OD of the spacer … the regulator plenum right???
What’s the ID of the airtube and the od of the spacer…..
Maybe make one that is a little closer in tolerance. Maybe even give you a little more reg chamber