Snowpeak Modding a M60B (.35cal) and found something odd.

After some hesitation, i started to increase the size of the transfer ports of my M60B in .35cal. This is my 1st airgun and therefore my knowledge is based on the uuuTube and reading up on what people discuss in here (mostly). So first of all, thanks for sharing experiences and knowledge, i really appreciate it.

My main question is: Why the hell is there a bump in the ridge for the o-ring at the beginning of the barrel?
that can't be right, since it must be the reason the original o-ring is broken at exactly that spot. luckily there was one spare o-ring in the bag of spares, that might fit. it has another color (green), and i wonder if that is because it is another material. if so. what might that be?
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original o-ring broken, first i thought it is due to the raw edges on the projectile probe,
but when i took it out, i saw a bump in the groove for the o-ring.
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above is the shape of the groove , which caused the o-ring to get ground up by the projectile probe over time.
i will try the spare o-ring (black) instead, but only after i manage to remove the bumb (unless anybody explains me that this on purpose and WHY?)
when poking at it, i realized it can move along the groove, so i thinK it is some kind of debris from manufacturing. but initially i was confused because it was aligned with the port hole at the bottom of the barrel.
below are some pictures of my process, in case you see coarse mistakes or have helpful and encuraging comments please let me know.
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above you see the polished projectile probe. i left it at the original oval size, which is 5mm wide and 7mm long.
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here's the valve taken mostly apart. the 4 transfer ports were each 4mm and are now 5mm.

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here's the barrel port, before (5,5mm) and after (6.5mm). the barrel also had a laser etched serial number, which surprized me somehow.

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and finally the barrel port with the probe port aligned. i'll polish this some more, for those who like it shiny. =)
 
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Did you open the transfer area in the action to match? If not, it will be the limiting factor now. Also, the valve and poppet are restrictive compared to the slug valve kit.
where exactly is 'the action'?

thank you, i am aware about the weak valve. as said i am considering trying to get one, if @Paul D makes them available again, hopefully the new version, if that ever comes out.
 
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where exactly is 'the action'?

thank you, i am aware about the weak valve. as said i am considering trying to get one, if @Paul D makes them available again, hopefully the new version, if that ever comes out.
The frame of the gun, where all 'the action' happens lol.

The part between the valve and barrel needs to be opened up. The valve kits comes with a jig to open it up to 6.35mm/.25". A 357 could benefit up to 7.5mm without having pellet tipping issues. That's when the port is too big and the pellet will drop into the opening while loading and can damage them. It's more common on smaller calibers.
 
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If you plan to keep the stock valve for now, I would at bare minimum put in a lighter spring so the valve opens easier. Not really much can be done to the stock valve that will do much to the 357. I'd think the power valve kit on a 357 could hit in the 130-150 fpe range. Going to need lots of air though.
 
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The frame of the gun, where all 'the action' happens lol.

The part between the valve and barrel needs to be opened up. The valve kits comes with a jig to open it up to 6.35mm/.25". A 357 could benefit up to 7.5mm without having pellet tipping issues. That's when the port is too big and the pellet will drop into the opening while loading and can damage them. It's more common on smaller calibers.
yes, i did that as well of course. carefully without the jig. thanks for the info on size, i did not go that big, though.
 
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If you plan to keep the stock valve for now, I would at bare minimum put in a lighter spring so the valve opens easier. Not really much can be done to the stock valve that will do much to the 357. I'd think the power valve kit on a 357 could hit in the 130-150 fpe range. Going to need lots of air though.
thank you for the tip. i might try, but also just saw that the power valves are available again. waiting for a response, since i don't need the jig.

have you had a weird bump in the same spot as i found in the barrel o-ring groove? that can't be right, or what?
 
thank you for the tip. i might try, but also just saw that the power valves are available again. waiting for a response, since i don't need the jig.

have you had a weird bump in the same spot as i found in the barrel o-ring groove? that can't be right, or what?
No, that's a defect. Maybe try and file or dremel it down. It should definitely be a full o-ring groove around, not bumps or irregularities.
 
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No, that's a defect. Maybe try and file or dremel it down. It should definitely be a full o-ring groove around, not bumps or irregularities.
yeah, it has been a steel chip from machining.
luckily, it came out pretty easy
has been there all the time, and i never knew. WTF!

another fault in that gun:
1st - the odd fill adapter, with a too short foster nipple.
2nd - chip in the barrel
 
I do not have a m60 but I have 3 P35s and they all came with a poor fill probe. They leak. But alliexpress has them for less than $4 and they work great. If they fit the M60 they are definitely worth getting.
this was the part to fill the bottle, that had to be taken off the gun to fill before i got the extra part from airgun archery fun. it was not a probe. but anyways thank you for the tip.