GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Topic started by: OTmachine on January 05, 2023, 09:19:50 AM
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I have this barrel which is 22” long and from what I recall, a little oversize for pellet use. Thought about either upsizing .22 pellets or downsizing .25 pellets by use of a custom made swage type die. Paid $35 shipped for the barrel in relatively good condition. In comparison to a PCP barrel, I would consider this to be a Bull barrel. I have several platforms to try it out on. I would cut off the chamber area and machine the lead-in. Thoughts?
TIA, Keith
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The leade is pretty much there unless you’re just wanting a tighter chamber because 22rf uses an external lubed healed bullet with case being same od. Some rimfire manufacturers use a pretty loose chamber in semi’s to promote reliability, so it may be better to cut a new one.
I have used several rf barrels for slugs because of availability to me and the twist is correct. Micro groove as well as standard rifling. I like the Shilen ratchet the best.
You will find 22rf barrels are all over the place when you slug several. I have .2205 up to .224 (very old).
There are slugs available for early hubens (I think) that are correct diameter. I make my own molds because the available slugs (with correct diameter) are sparse.
All my builds in 22 use rf barrels so I know they work but I haven’t tried any pellets with them. I will be interested in your results.
Dave
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Dave, thanks for the reply. I just retired so I should have time to get back to some of my hobbies. Need to clean off the layout table cover and start doing some checking. I am going to slug the barrel also.
Thanks again, Keith
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following with great interest in this topic.
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I did a little bit of measuring. Marlin model 49DL Micro-Groove Barrel, Cal 22LR.
Chamber measures ..2315 inch diameter. Bore at both muzzle and breach ends measures .2205 inch diameter. CCI .22 Cal LR measures .224 diameter casing & .2235 diameter bullet. Checked some 22 Cal pellets sizes, head then skirt. CPHP .2155 / .220, RWS Hobby .2155 / .2245,. RWS Super-H-Point .2155 / .225. Pushed one of the RWS through with a 1/8 brass rod. Skirt measures .2215 after pushing through. The chamber either needs to be cut off or bushed and machined. Probably will just cut it off and machined a new lead-in. Going to check a Savage bull barrel to see how it measures up. That's all for now.
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I agree, that chamber is way too loose to be useable. Sounds like the bore will be just right though and it will have minimally invasive rifling.
The ratchet rifling I like is similar in its intent. It uses a triangular shaped land instead of square, essentially cutting its footprint into the slug in half.
Have you decided which platform to try it out on? You mentioned you have several.
Good luck on this! Keep us updated.
Dave
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Evanix rex guns have microgroove rifling. I read somewhere that this rifling in general causes issues with cast projectiles but I don’t quite understand how/why/if that is actually the case. I haven’t really had a chance to test performance in my Rex guns with the slugs I cast. Curious if anyone has knowledge about this.
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Microgroove got a bad rap with cast bullets in LARGE caliber due to undersized bullets and ‘slippage’ when being pushed at higher velocities.
None of this has anything to do with the .22lr barrel.
Dave
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That makes sense.
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heads on the Seneca pellets tend to be around .22... and should work well...
I have a new unused model 883N .22 mag barrel... and an old very seasoned model 60 barrel... have pushed Seneca(EUNJIN) domed thru both... they have good head engagement and very good skirt engagement...
most pellets you would probably have to make a bumping jig to have sufficient head size... also years ago when I ask Bob to draw up some light .22 BBT I also asked for the larger .22/.222 mold BBT 30g for the L.W. and some powder barrels... though I have not used the Marlin barrels yet they look just big enough looking at some 30g BBT 220/222 that I pushed thru each barrel...
https://www.airgundepot.com/seneca-hunting-pellets-22-cal-28-5-gr-125ct.html (https://www.airgundepot.com/seneca-hunting-pellets-22-cal-28-5-gr-125ct.html)
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Thanks for the replies. The Seneca pellets sound good. A bumping jig should be pretty easy to get any size I make it for, (do the head and the skirt at the same time), especially if I use a hollow point. Need to get my comparator setup to get some better slugging measurements. I am leaning towards setting it up in a Sentry for now. Have to check clearances. Will keep you posted.
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I have both a 22 cal and 257 cal Marlin Micro bbl's,
just waiting for the best platform to come along................ 8)
So I am following along........ ;)
Don
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Also thought about using a QB79 1100psi bottle fed setup that I have on the shelf. Need to setup hydrostatic testing adapters before I get to tweeking pressures. Probably get around to checking clearances tomorrow as I am reworking Grandkids’ ATV’s at the moment. No more weekends for me, every day is Sunday.
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well 1100 psi not sure I would bother with the work necessary...just not going to get the fpe for anything over 14g... the stock qb barrel is a better fit imo...
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I have an avenger that I could put it in pretty easily, if that would be better. It is pretty consistent. Don’t need the shroud. I was just looking for ease of fit up and kicking things around in my head. The Sentry is not regulated, so would be harder to establish a basis. I fill the Avenger to 3800 psi and reg set at 2100 does pretty consistent 880 fps with 25 gr. JSB’s. Do not have any high end guns. The main problem that I seem to have, is that if I see a problem, I have to fix it and I know that the Avenger, ( as with most Chinese things), is not perfect.
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Thoughts on a pellet sizer. Pellet lengths for .22 cal seem to be about 7 to 8mm. If I make a T Robb style pellet sizer with a .3 degree taper (.006 per inch) and a straight lead in bore for an adjustable skirt pedestal, I could adjust pellet head and skirt diameter. The adjustable plunger from the head end would determine the amount of swage. Have to experiment with hollow point or meplat and decide on head profile. Just thinking out loud.
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Just read in projectiles area, already been done before.
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Keith
This information is from my pellet data base, may help you.
22 Caliber
Lightest Weight 9.0
Heavyest Weight 34.5
Smallest Head size .209"
Largest Head size .220"
Smalest Skirt Dia .209"
Largest Skirt Dia .228"
Shortest Skirt Depth .052"
Longest Skirt Depth .204"
Shortest Bearing Length .148"
Longest Bearing Length .280"
Shortest Over All Length .228"
Longest Over All Length .382"
Shallowest inside skirt angle in degrees 07.40*
Steepest inside skirt angle in degrees 28.69*
HTH's
Don
Thoughts on a pellet sizer. Pellet lengths for .22 cal seem to be about 7 to 8mm. If I make a T Robb style pellet sizer with a .3 degree taper (.006 per inch) and a straight lead in bore for an adjustable skirt pedestal, I could adjust pellet head and skirt diameter. The adjustable plunger from the head end would determine the amount of swage. Have to experiment with hollow point or meplat and decide on head profile. Just thinking out loud.
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Thanks Don, Yes that info helps a lot! I also like Triggertreat’s approach using a 2 step die.
Looks like that barrel is going in my Sentry 705-9K, a .22 cal.
Thanks again, Keith
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Re-sized some H & N Baracuda 18’s. The pellet on the left is stock, out of the tin, head size .2165, Skirt size .2215, Length .312 inch. Middle pellet Head size .221, Skirt .224, Length .284. Right side pellet head size .221, Skirt Size .224, Length .292. Process seems to be repeating and I can adjust the Head / Skirt size proportionately using my sizing swage jig to find the best sizes for this barrel. Did not want to machine the barrel until I could make adjustable pellet sizes. Need to set up a stop or gauge on my little press. These were just done by feel. Slugged the barrel and it feels pretty uniform in size. Wish me luck.