Got a project, replacing a barrel (PRod). Original barrel has an internal oring, and I’d rather not fool around cutting an internal groove in the new barrel. So my preference is for an oring on the bolt instead. Seems like many, maybe most, pcp guns use the internal oring. Any reason to go internal v bolt, other than ease of machining for me.
Quote from: eeler1 on April 19, 2024, 12:21:52 PMGot a project, replacing a barrel (PRod). Original barrel has an internal oring, and I’d rather not fool around cutting an internal groove in the new barrel. So my preference is for an oring on the bolt instead. Seems like many, maybe most, pcp guns use the internal oring. Any reason to go internal v bolt, other than ease of machining for me.If the bolt travels through a magazine, it’s generally best to have the oring in barrel to save wear/tear on the oring. Single shot doesn’t matter so going with ease of manufacture is ok. Dave
A .177 MROD barrel would also work if you pair it with a .177 Fortitude bolt and probe assembly.It’ll be a single-shot though; use a MROD SST, file the base a bit, then voila 👍My PROD uses .22 MROD/UMAREX Gauntlet SST, but I had to sand the bottom a bit (1 mm or so).
Barrel bore I.D. groove tools are FUN to make ... Not !!!Even more fun to use and Not break doing so.
So you did something similar to your PRod? Caliber? How'd it turn out?I got turned on to 20 cal for pcp guns by Scott S (Motorhead), who has had good results with similar conversions. I did a 20 cal conversion on a MRod using a Weirauch barrel a while back, and it turned out really well, lots of shots and super accurate. Don't know why more people don't try 20 cal, I guess the bigger pellets have everyone under spell.I tried Krale for a 20 cal LW barrel, but it would have been a long wait for an expensive barrel, like 200Euros. The Air Force barrels were too short for what I wanted, and still pricey. So I went to Air Venturi and got a barrel by Beeman (actually made by Weirauch according to pyramid air). 22 inches choked. Although I had to cut about 3 inches of a larger diameter off at the breech end in order to fit the receiver, so it's 18-19 inches long now.Still kinda pricey at a little over $200, but I couldn't find any other 20 cal barrel available. Plus this one comes with a shroud that has essentially the same OD as the original PRod shroud. Turns out the Weirauch shroud is threaded at 18mm-1.0mm, while the PRod shroud is 11/16-24, which by chance are compatible with each other.Right now I'm at the decision point for the barrel v bolt oring.
Quote from: Motorhead on April 19, 2024, 10:47:44 PMBarrel bore I.D. groove tools are FUN to make ... Not !!!Even more fun to use and Not break doing so.Exactly! I did the internal barrel groove once, years ago, on a BSA S-10. Must not have enjoyed it as I’ve avoided doing it since.
Another alternative is to use a flow through bolt. The o-ring is placed in the back of the barrel pocket in the breech. The barrel presses against the o-ring, sealing both the barrel and the bolt.