VM-68 questions - odd Smart Parts barrel milling and aftermarket bolts?

[The Inflicted]

I got in my first VM-68 last week and I've been puzzling over some of the included equipment.

First, it comes with a 15" Smart Parts barrel in beautiful condition, but there's a 1" segment about 3.25" from the threads that has been machined down a bit.
Anyone know what that's for?

Also, most of the bolts on the body retaining the valve and rear cap have been replaced with really nice stainless bolts which have what looks like holes for anti-vibration wires. Were these from a kit of some sort or did the prior owner source them himself?

[Painthappy]

Not sure on the rest, but that is a really clean gun. Nice find.

[The Inflicted]

Not sure on the rest, but that is a really clean gun. Nice find.

Thanks. I'm hoping to get it running this summer. I was really grateful that Palmers still had their detent fingers and striker O-ring still in stock.

Does anyone know what the correct size for the valve O-rings is? Literally every single seal on this thing, including the cupseal, crumbled into bits as soon as I touched them.

[Pumpytrilly1]

Maybe they had a f1 style thommy gun grip on the barrel?

[The Inflicted]

New problem just popped up- I've had the hammer and bolt out of it several times to inspect the O-rings but now the hammer is catching on something in the trigger group and getting very badly stuck- it's taking quite a lot of force to pull the hammer back sometimes, especially if I dry fire it. Any idea what could be causing this?

Edit: It was the Palmer O-ring that was catching on something somehow. Pulled it off, turned it around, and now the parts move smoothly again.

Glad I didn't try taking the trigger pack apart because apparently that tends to drive people to drink.

[Grendel]

Install it and the bottle, it looks like it might be some clearance - ing for the burst disk on the bottle.

[Ecapnation]

Or an on off

[Chaos]

Welcome to the world of the VM68. I have had many over the years that have several mods that I've done including getting rid of that stupid flat seal that's on the hammer. If you want to also eliminate the need for those finger detents there is a permanent spring loaded mod available. Good idea not messing with the trigger group because if you don't know what you're doing it can be a real nightmare. I do recommend however if you plan on keeping them for a while that you get a trigger assembly that you don't care about from a donor gun and deliberately take it apart and study it so you can learn how to take it apart properly, a lot of information still available online but VM68.com keeps going down so a lot of information can be a pain in the butt to get.
If you're on Facebook you should join the VM Empire

https://facebook.com/groups/552671518402392/

[infamoussmiley]

Hello!
The Smart Parts barrel is a seconds barrel. The previous owner most likely got it for 25$ instead of paying full price of 100$.


Smiley

[The Inflicted]

Hello!
The Smart Parts barrel is a seconds barrel. The previous owner most likely got it for 25$ instead of paying full price of 100$.


Smiley

Interesting.

I'm debating now whether I should have it cut down, freak-bored, and milled to fit my Bushmaster.

[Chuck E Ducky]

Before to cut that I would be interested in that barrel for my VM. I been looking for a nice longer barrel than my stock one.

[The Inflicted]

Had a devil of a time getting the valve on this thing squared away. Stock cupseal crumbled to dust but I was able to superglue an old Spyder clone cupseal face I had to the stem. Newer, bigger O-rings on the valve and now it's not leaking anymore.

The Palmer hammer O-ring was a bust. No matter which way it was turned, or how much oil I added, it was causing the hammer to become stuck fast in the forward position.

I can get it to cycle 3-4 times on a 12-gram using an adapter but it absolutely won't re-cock on any of my HPA tanks.
For those of you who have gotten a VM to work on HPA, was a higher output tank the solution? If so, what was the acceptable pressure to get reliable cycling and usable velocities?

[The Inflicted]

That seems counterintuitive to me. Wouldn't adding to the force needed to be overcome for the hammer to return to rest make it less likely that the gun recocks?

[Toestr]

With blowbacks you need to hit the sweet spot where the hammer hits the valve hard enough to recock, but not too hard that it comes back too fast for the sear to catch. I had a Tippmann that I was trying to tune for LP and I ran into this problem. I had a heavy spring and I was getting consistent 2-3 shot bursts (instead of the uncontrolled sputtering of too low pressure).

[Chuck E Ducky]

Mine runs fine on 800psi HPA input pressure.

[The Inflicted]

So against my better judgement I tried the SodaStream dry ice filling method with the tanks. This would have been a lot easier if tanks I had came with hexagonal valves instead of round ones- had to use a pipe wrench and a vice to get them off.

Unfortunately both of the ancient valves on these tanks have problems- after giving them overnight to come back up to temperature the 7oz was completely empty, and the valve on the 12oz is problematic- most of the time it doesn't want to properly open when you screw it onto the gun, and a lot of the time it won't properly close when you remove it.

Use on gun was very encouraging, though- with the smallest valve port facing upwards the gun cycled and re-cocked very reliably on the 12oz tank, though velocities were in the neighborhood of 140fps.

The gun was less reliable with the largest port going upwards, going full-auto sometimes and failing to recock, and some of the leaking returned, but it was still working well enough to probably be usable. Velocities ranged from 240-270 depending which way the tank was pointed. I think with a better tank valve it would work fine like this.

What I need to do now is source some newer, more reliable tank valves and buy another $9 worth of dry ice from Publix. Surely a bunch of people have these things lying around, right?
I'm also wondering if I need to try something even MORE dangerous, and shim an extra Guerilla Air regulator I've got here in the hopes of boosting its output pressure into the 1100psi range. Does anyone have any experience with doing that?

[Brokeass_baller]

I did the dry ice trick with some old tanks when the company bought a few tubs worth for freezing bushings. Worked great. I just used them for testing old gear, but I got about 60oz for free. Lol

[The Inflicted]

It worked! At least enough for a few games.

Shout out to autococker04 for the working CO2 tank valves.

Unfortunately, my VM is still not 100%.
I replaced the O-rings on the valve with new ones but the cupseal crumbled away. This I replaced by super-glueing a 'cocker (or Spyder?) cupseal I had onto the valve stem. I thought I had everything leak-free testing it at home on HPA, but the gun wouldn't re-cock on air. I've got one of Palmer's hammer O-rings in it at the moment and it's very tight- so much so that if I dry-fry it the hammer gets stuck forward and takes quite a bit of force to withdraw again.
I didn't want to risk testing it at home with the CO2 tanks, since if something failed I would have to go back to the grocery store, spend $9 on dry ice, and go through all the rigamarole of filling it again. When I got to the field last weekend there was still a slow leak, but it cycled fine on CO2 and shot around 260fps. I unscrewed the tanks between games and between the 7 and the 12oz tanks had enough to play 5 rounds of speedball before switching to different guns.