Snowpeak M60B thread question.

[kainevil]

Hey all, I was looking for a thread adapter to change the metric thread on the 30 cal to 1/2 x 20. Not a whole lot of luck there so I figured I can look the other way. Does anyone know the thread inside the barrel that the end cap screws into? I've emailed snowpeak about a different end cap or information about the cap but it's crickets on that end too.

Also big thanks to Firewalker and Dr. Kralenstein for the educational guidance. I'm not a stranger to air rifles but for some reason this one makes me feel like I am.

 

[Firewalker]

DonnyFL makes a lot of adapters, check there.

 

[JimD]

Airgun Archery Fun says on their website they have shroud end caps with 1/2 20 threads to replace the earlier metric ones.

 

[kainevil]

I had, they make a 14 and an 18 but no such luck with the 16.

DonnyFL makes a lot of adapters, check there

 

[kainevil]

Unfortunately that only applies for the lower calibers. 30 and up is stuck with the metric. They say it's because of needing the bigger aperture but that really makes no sense.

Airgun Archery Fun says on their website they have shroud end caps with 1/2 20 threads to replace the earlier metric ones.

 

[JimD]

It's easy to get a moderator in a metric thread. Krale has them, for instance.

 

[JimD]

The recommended drill bit for a 1/2×20 tap is .453 inches in diameter. So that is pretty close to the peak of the threads. Valley is probably at least 1/10th less or .44. Might really be .4. Is that too small for a 30 caliber? Or a 35? The moderator hole must be bigger than the projectile to avoid clipping. There also needs to be enough metal left for the male thread to withstand handling loads. Seems like 1/2 20 might be a little small for a 35. What do other "big bores" use?

 

[JimD]

Looks like DonnyFL moderators for 35s and up all use metric threads. I think it was 14x1.25 or 18x1. You can get a 1/2 unf for a 30 caliber, however.

 

[kainevil]

Looks like DonnyFL moderators for 35s and up all use metric threads. I think it was 14x1.25 or 18x1. You can get a 1/2 unf for a 30 caliber, however.

So there's something to the metric for big bores. I'm running a .30 on that one and it comes with a moderator in that metric thread. It's hollow chambers and while it does have some effect it could definitely be better. I've already got a pretty decent investment in a yokozuna and some silent thunder mods which go up to .30. So I'm trying to be able to get some use out of those for better effect. If I can find out what the inside threads of the shroud where the cap screws in I might be able to get one made.

Because every other manufacturer has something just a little bit different I don't want to order a cap that is built for X rifle that may not fit my Y. Information opens up options, alternatively if I knew how to measure/determine that thread at the end that could work too. There's definitely a learning curve on this one for me. I do appreciate all the information, suggestions, ideas that help get me around that curve.

 

[JimD]

My tap and die set came with thread gauges that look something like feeler gauges. They give me the thread pitch and a caliper gives me the diameter. I'm sure you can get metric thread gauges. Amazon probably has them.

 

[JimD]

Looks like they are about $10 and available at some hardware stores and Amazon. I found some googling "thread gauge".

 

[Dr. Kralenstein]

The 30 mod adapter is m16x1.5 thread. I never was able to turn up an adapter to go 1/2". I have know idea what the barrel thread itself has.

 

[kainevil]

I went with the gauge suggestion and picked one up. A little bit of a surprise because there are no shroud threads. The top cap is attached to the air stripper which threads on to the barrel. That thread matches the 1.5, the caliper says 13.8 which allowing for my own user error is 14 x 1.5. Considering the integrated air stripper build that really kills any chance of finding a piece from another manufacturer that would work. It looks like it's a new search for someone who can make the part from scratch.

 

[JimD]

Interesting design. It's venting into the shroud presumably to provide a little sound suppression. The P35 has a much different and even larger aluminum piece screwed to the end of the barrel but it is short of the end cap by several inches to allow space for baffles.

I don't think we can discuss it here but if you pm me I can refer you to guys on GTA who might be able to help.