Has anyone used 1/4 tubing for a transfer port for more power in their benjamin marauders does it hold up good and seal good? I'm building a .22 marauder slug gun
Benjamin Marauder .22 transfer port 1/4 tubing
- Thread starter anonymous_.457
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Sure, I'd get the most rigid tubing you can find if you do go that route, you'd want it to be around .475" in overall length so it can squish and seal...
However I prefer stuff like shown below, which I made for a fellow member here. He needed 2 different lengths as one of his marauders has a taller custom breach.
It's .265" tubing slid over .196" tubing and jb welded with a lip extended out for the gaskets to ride on, same style as stock. Hillairgun has the same style that is .161", however for the cost of that you could custom make what I show below with anything between .161" and .196".
However, for an unregulated .22, opening up to .196" will drastically reduce your shot count and pressure range availability due to a larger swing in FPS as pressure drops, so you'd either tune hot for a declining string with very few shots, or a smaller bell curve than you have now but more shots than a declining string.
A .196" ported .22 cal marauder could make 60 fpe till about 2500 psi before it falls off (needed very heavy ammo for this, 30+ grains), or maintain 50 fpe until 2100 psi with 25gr+. A .161" ported .22 cal marauder would do about 50 fpe until 2400 psi and to hit 60 fpe would need all 3000 psi and would immediately taper off each shot. Hopefully that provides some insight to what porting challenges you may face ahead...
For the valve porting to able to flow the full .196" you'd have to open up the throat or reduce the stem diameter within the throat, stock is .21X~, but for .196" porting you'd want .243"~ throat diameter. The downside to this is larger throat/seat diameters require more hammer energy to open, so you'd have to increase hammer preload. The stock throat can only handle around .161" porting or so, which would work okay with hills custom transfer port...
You'd also have to modify the bolt probe to flow for .196", I am unsure for .161" as I don't recall the stock probe diameter.
What I would do is...over complicated so don't ask me! LOL
-Matt
However I prefer stuff like shown below, which I made for a fellow member here. He needed 2 different lengths as one of his marauders has a taller custom breach.
It's .265" tubing slid over .196" tubing and jb welded with a lip extended out for the gaskets to ride on, same style as stock. Hillairgun has the same style that is .161", however for the cost of that you could custom make what I show below with anything between .161" and .196".
However, for an unregulated .22, opening up to .196" will drastically reduce your shot count and pressure range availability due to a larger swing in FPS as pressure drops, so you'd either tune hot for a declining string with very few shots, or a smaller bell curve than you have now but more shots than a declining string.
A .196" ported .22 cal marauder could make 60 fpe till about 2500 psi before it falls off (needed very heavy ammo for this, 30+ grains), or maintain 50 fpe until 2100 psi with 25gr+. A .161" ported .22 cal marauder would do about 50 fpe until 2400 psi and to hit 60 fpe would need all 3000 psi and would immediately taper off each shot. Hopefully that provides some insight to what porting challenges you may face ahead...
For the valve porting to able to flow the full .196" you'd have to open up the throat or reduce the stem diameter within the throat, stock is .21X~, but for .196" porting you'd want .243"~ throat diameter. The downside to this is larger throat/seat diameters require more hammer energy to open, so you'd have to increase hammer preload. The stock throat can only handle around .161" porting or so, which would work okay with hills custom transfer port...
You'd also have to modify the bolt probe to flow for .196", I am unsure for .161" as I don't recall the stock probe diameter.
What I would do is...over complicated so don't ask me! LOL
-Matt
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Oh I see now yeah I just drilled that out to about 0.203 then polished got it back in the marauder .22 just hit 300 fpe....lmao I'm kidding jk jk chrony results tomorrow. The stock transfer port restricts it a ton..
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Sometimes you need the restriction in order to get a Bell curve string with many useful shots at less energy instead of an off the cliff declining string with fewer useful shots but more energy for the first few.
The more I know the more I realize how little I know. But, and I am likely wrong, but it is my current belief that for a .22 or .25 M-Rod, porting larger than .161 is not needed for an unregulated gun. If regulated and the porting is consistent throughout the flow path, .196 porting is needed to get decent energy with typical regulator settings of 1800 to 2000 psi.
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I'm getting a way bigger transfer port and 18 pound heavy hammer spring from Jefferson state air rifles soon. I'm very excited.
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Picture help alot! Esp. after "custom" work.
Just going by what can be seen of your machining it would seem you may well need something totally custom to seal your rig and not like anything others might use.
John
Just going by what can be seen of your machining it would seem you may well need something totally custom to seal your rig and not like anything others might use.
John
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I’ve used the water line tubing for refrigerator ice makers for marauder transfer ports. Available at Lowes and it works great. Make it a little long and there’s no need for seals, but you can also use a silicone sealant for a seal if you want to.
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I am excited for you.
I really want to see the results. I am using the full JSAR kit in one of my rifles and with Huma regulator and .196 porting (.25) I can get 24 shots at around 56 fpe. The JSAR balanced valve does not require a heavy spring.What is your barrel porting?
I have given up trying to pull more than 60 fpe from an M-Rod, there is just not enough air capacity for a useful number of shots. I have also decided long ago that I did not like the heavy hammer springs and the wasteful hammer bounce of the factory hammer system which preloads the valve poppet stem and wastes air, bbrrrr--rrrr--rrppp.
For me, I am finding mid 50s fpe for my .25 rifles is about the limit to get a useful string and shot count, regulated or unregulated. And something in the upper 40s fpe is more practical. I just do not think at this juncture that heavy springs and greater than .161 flow paths are benificial to an unregulated rifle if trying to tune a Bell curve string, especially a .22.
I also have used the poly or nylon tubing but not currently. I heat the 1/4 tubing and expand it with a taper rod and let it cool. I then flame polish the ends after cutting to length and square. I have gotten okay results but as often get wasteful leaks. Such tubing can work though.
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Well…. I retract my last post. I just saw the video. You won’t be able to use the ice maker tubing. You are going to need a garden hose, duct tape, JB Weld, epoxy, five paper clips and a pocket full of dollars to finish that project.
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He can just hold the rifle upside down when he loads it so nothing falls in. Or he can load it like a muzzle loader maybe. We can’t let little details like that get in the way of MAXIMUM POWER!
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OP would need to jb weld that hole shut without creating more of a mess by over filling or having the jb weld expand too much inside or out when drying, and then drill central perfectly like the oem hole to .27", and then re-think his approach...or something of this nature.
-Matt
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