Getting out of valve lock ?

[Peashooter]

On my Vulcan 3

So i wanted to see if i could push the 13 grain slugs just a little faster than the 1020 FPS i was on from my last session, but as chance would have it that was right on the max hammer spring setting and also the MAX pressure ( ??? BAR )
But today upping the regulator only dropped my FPS to 950, and i think that mean i am valve locked.

So what are a guy to do here ? My own peashooter mind say a couple of things.

1. Get a heavier hammer spring
2. Get a heavier hammer weight

Problem i have never seen any of those options for a AGT Vulcan ( 1-2-3 ) though i must of course also admit that i have never looked for that.

I figure even if the barrel are just 500 mm faster speeds should be attainable.

The Vulcan 3 seem to have a narrow power band, with 0 compression on the 32 mm long hammer spring, to max compression ( 1/2 turn before i am not able to cock the rifle )
And seemingly with the max pressure the fastest i can get with the 13 grainers are just over 1000 FPS.

Maybe i should look closer at the slower speeds i have tried too of course, just it seem the gum are more accurate the faster i shoot, but at the 1020 FPS i was on the shot string was a bit saw tooth like, hence why i upped the reg a little today, and BECUZ in my Maverick the same slugs do really well at 1060 FPS

Also i am inclined to think the same rifle in larger calibers, well i assume those have a heavier hammer spring and maybe a heavier hammer weight, and maybe valve return spring too + of course more REG pressure then the 90 i assume the .177 Vulcan 3 shipped with too.
For sure not with the internals that are in my Vulcan 3

 

[nervoustrig]

Any or all of the above will help mitigate the partial valve lock:

1. Stronger hammer spring (more lift)
2. Heavier hammer (more dwell)
3. Weaker valve spring (more dwell)

Other options include:

4. Harder poppet material such as changing from acetal/Delrin to PEEK (not sure what the Vulcan OEM material is)
5. Smaller diameter valve stem.
6. Longer hammer stroke / retractable striker

 

[heavy-impact]

My .306 Vulcan 3 came with a 37mm hammer spring that is 9.97mm wide and made from 1.3mm wire.
The valve stem diameter is 2mm and the poppet is Delrin
You can back off the valve spring adjuster which is just above the poppet (center part in pic) I modified mine by milling the 6 holes into three.

 

[Peashooter]

The "thing" that hold the valve return spring in place, i dont have anything that can loosen that, i have tried needle nosed pliers and that did not work.
At the time just me being nosy wanting to see how things looked like here.

I have found some springs that might work for the hammer, but they are a little larger OD than the factory 10 mm spring, i have not yet measured the diameter of the screw that the spring go into ( the one you turn to up / lower hammer spring )
My hammer spring are just 32 mm long and made of 1.2 mm material, the ones i am looking at are 1.3 and 1.4 mm

I like your MOD on that part

 

[heavy-impact]

Needle nose pliers will work just apply a little heat to the part as you apply pressure until the thread locker softens.

 

[Peashooter]

I did not heat the parts i have to admit, i think that would necessitate a vice to put the part in, and all i have are my living room table and a few hand tools.
BUT ! My M8 do have a vise so maybe i will give it another try during the off season / winter.
He also have a heat source that are better than the couple of lighters i have in my apartment.

Mins you the AGT tank, i applied a lot of heat to that and was not able to unscrew the fitting from it ( wanting to put in a valved fitting like on FX bottles )
So i now have the 480 CC FX tank on the Vulcan 3 and a new 500 CC tank on the Maverick, so when i unscrew the vulcan tank all the air i loose are the air in the plenum pipe,,,, which are also a substantial amount.
I have no idea what to try with that damn AGT tank next, i am afraid adding even more heat would just ruin the carbon fiber, i had a propane weed burned on the part and heated it pretty well i would think.

I could put in some black powder, that would make for a mighty expensive firecracker.

 

[heavy-impact]

You can put your valve housing in the oven at maybe 65-75c if your oven will go that low. If you have to set a higher temperature just leave it in less time. Hold the part with a leather glove. Do not do this with the CF bottle. For that you need a friend with a very strong grip. If you have a strong soldering iron you can heat parts with that.

 

[Peashooter]

I dont know what the compression force are on the original 1.3 mm spring.
BUT ! i have just ordered two 1.3 mm springs and two 1.4 mm springs, one stainless and one piano wire in each size.
If thats not enough i can see i can go to 1.5 and 1.6 mm too, though then their listed compression force look to be A LOT more than what it feel i need to exsert of force to cock the gun with the original spring.

Then some experimenting, and if the kettle still dont fly, well i will have to take a look at that valve return spring too.
Fortunately the spring company i found, well it is in the same town where my grandmother lived and i spent many happy hours as a child, and it is on the route when i go visit my sister, so i dont even have to pay for shipping or go out of my way to collect.

Now i just hope my sister are up for a visit tomorrow, CUZ i am going spring collecting for sure.

I could also put my valve housing in boiling water then, or just hot from the tab as it is blistering hot in my apartment, if that low temperatures are OK,,,,, i will for sure give it a try as it is a NO risk venture.

Also i have a small oven that can do lower temperatures, got that for working Kydex,,,,,, though i have mostly heated food in it

If it aint broke dont fix it.
If its not good enough, make it better
If it is broken, fix it and make it better, so it dont break again.

 

[heavy-impact]

All you need is a standard spring for the full power versions and you'll be able to adjust it to your liking. The V1 spring is even longer but way too much for your 177.

 

[Peashooter]

well it is a FAC rifle i have, at least it was supposed to be, no one i am aware of sell sub 12 rifles in Denmark unless we talk cheap anemic springers that might be that low.
Put PCP rifles are always FAC. They have taken all the other calibers from us, but FAC are still okay here,,,,,, though with gooberment here, that too are probably just a matter of time.

I have just dropped sleeping today, so gearing up on coffee right now and then i will go get 4 new springs to play with.

I also contemplated getting longer springs, the original when the adjuster "screw" are flush with the back of the rifle there is about 1/4 inch play for the spring so it can just rattle back and forth,,, the hammer too of course.

Weather forecast for the weekend = excellent shooting weather.

 

[Peashooter]

Just got back with new springs, and have done a little chrono work in the living room, the heaviest spring at full load, almost make the V3 rifle super sonic with the 13 grain KO slugs, where as the original spring at the same REG pressure and MAX hammer top out at 940 FPS, so a good +100 FPS with the new spring.
The #2 hardest spring too outperform the original spring but not as bad.

The new springs have more windings than the original spring, if say the original spring have 10 windings, the new springs have 13 - 14 windings,,,,, but they are still able to be fully compressed,,,,, but only barely, TBH i think i can back off a little and still do well. ( i have only tested the 3 springs today with MAX hammer )

I wanted to test with the hammer adjuster flush with the back of the rifle, but then the hammer can not open the valve, not even with the strongest new spring.

I will shoot a little tomorrow with the current REG setting, and then try to give the regulator 1/8 turn more pressure later on,,,,,, the Vulcan 3 / AGT regulator to me seem very sensitive to adjustment, i have only turned it 1/2 or 1/4 and 1/8 turn increments when i have messed with it.
ATM i am stock + 1/2 turn which are about as far as i have ever been on the regulator.

The current setting are a bit over the factory setting ( determined by measuring the overall length of the regulator with a caliber ) so i should not be at any insane levels or REG pressures unless it is way more sensitive to adjustment than i think.

Spec on the heavy spring i got today.

 

[Peashooter]

A FYI for anyone that might care, i am quite happy with my new springs, so shot my Vulcan 3 from 180 bar in the 12 L bottle and down to 110 bar ( with a REG change mid way to something lower as my initial REG must have been upwards of 140 BAR )
Clearly i hit a wall at some point around when my fill probe gauge said 140 BAR ( shooting tethered ), turned the REG down to 100 or so and kept shooting, and thoroughly enjoyed myself at 75 / 80 M range with 13 grain KO and Zan slugs,,,, and of course the 12.5 NSA too. ( i shot at least 1200 shots )
As the wind almost died totally i was shooting blades of grass, and hitting them too within a reasonable amount of shots, and i nicked the blades of grass often before they finally fell.
I consider a blade of grass a very OK target at 75 M with a .177 airgun, if anyone can cut several of them in a magazine i will tip my hat to the guy for sure.
I needed about 20 shots on average on the 3 blades of grass i cut the fun way.
I guesstimate the feed grass are about 2 mm wide, not super thick stuff, thinner than my .177 are for sure, but solid enough you can nick it so the grass shake but dont fall.
If you let the damn stuff grow, it can get well over 2 foot tall.

And the little peas i shoot also have some power left at 80 M, i put up a brownstone brick with the side of it facing me like it would if it had been in a wall, and it dident take many MAGs before it was cut in half,,,,,,, not a single miss while i did that, but there was a little up / down fluctuation, but good enough that i could drill my way thru the 4 inches or so a Danish brownstone brick are deep.
The standard Danish brick are 228 X 108 X 54 mm or 8 31⁄32 X 4 1⁄4 X 2 1⁄8 inch for the imperial inclined shooters out there.

With a refilled 12 L bottle at 300 BAR, i am returning with my Vulcan 3, with the REG set to a estimated 110 BAR.
CUZ i have more things to prove to myself.
Just too bad the next week, including the weekend at the end of it look to be weather not useable for peashooting.