.222/223 is the best caliber for bullet shooters on a budget!

[scion19801]

Very tru. Hence the reason for caliber down grade. I'm pretty sure ports should be a touch bigger in .25 cal I'm hoping versus the .22. which makes the .223 option a maybe. I'm thinking of trying to set the .223 barrel up to fit like an fx barrel. Basically a slightly tensioned barrel setup. Especially since is such a small od liner, and not a full barrel.
Edit: jsb 25.39 hit 45 fpe in stock form at 1900.

[rkr]

Very tru. Hence the reason for caliber down grade. I'm pretty sure ports should be a touch bigger in .25 cal I'm hoping versus the .22. which makes the .223 option a maybe. I'm thinking of trying to set the .223 barrel up to fit like an fx barrel. Basically a slightly tensioned barrel setup. Especially since is such a small od liner, and not a full barrel.
Edit: jsb 25.39 hit 45 fpe in stock form at 1900.

If you want to avoid tinkering tuning and headaches, then CF tube sleeving that small liner is the "play it safe" way to go.

[KnifeMaker]

Yep! Exactly the way I went.

[Sbak]

Im not very familiar with the gauntlet, but from what has been said I dont think it will be a realistic option for you unless you can run it unregulated.

[scion19801]

If i could manage to get close to 70 FPE with the combo i'd be happy. I know that in modded form the gauntlet has been able to push 65 FPE with mods in .25 cal. The biggest increase is changing out the poppet in the vale which will allow it to breathe way better. That is part of what the JSAR super tune kit give.

RKR & Knifemaker. I do plan to sleeve the liner.
Knife did you make a tight fitting sleeve to liner, or is their air gap between sleeve and liner?

[rkr]

If i could manage to get close to 70 FPE with the combo i'd be happy. I know that in modded form the gauntlet has been able to push 65 FPE with mods in .25 cal. The biggest increase is changing out the poppet in the vale which will allow it to breathe way better. That is part of what the JSAR super tune kit give.

RKR & Knifemaker. I do plan to sleeve the liner.
Knife did you make a tight fitting sleeve to liner, or is their air gap between sleeve and liner?

You use epoxy to attach the CF tube to the liner. If needed you can use two CF tubes to increase the diameter even further. If you can make 65 fpe with pellets you should do more with bullets, my .25 BSA was tuned for 60 fpe and I used the same basic valve system for the .224 and achieved 100 fpe - although with 5.5" longer barrel.

[scion19801]

thanks RKR. so my thought was to make a spacer to fit the breech come out an inch or so beyond the receiver have the o'ring slot cut and transfer hole ( basically same as factory barrel end), then bore the adapter to allow liner to sit just before barrel port. Spacer beyond the receiver sized to say 10mm. i think barrel liner is .310" (7.8 mm +/-) make a spacer/ air stripper for the muzzle end (also 10mm, but larger and ported to allow for shroud). glue 10mm od x 8mm id tube over barrel, then a 15mm od x 10mm tube over this to attach barrel to spacers and flush everything smooth. Then the factory shroud could be placed over it all. i'll try to draw a pic of this.

[rkr]

I would probably make a thimble for o-rings and TP and then just do a leade in the barrel breech end and sleeve it to fit the breech.

[scion19801]

barrel liner is green. black outer would be shroud. yellow is inner carbon fiber core bonded to barrel. red on left is breech adapter. red on right is air stripper adapter. middle black is outer carbon core locked to adapters and inner carbon tube.
 would be nice to be able to change the liner out in this assembly......

[rsterne]

Just because a gun will make 65 FPE in .25 cal does not mean you can reach that in .22 cal, that is a common misconception.... In fact more likely you will drop down to about 55-60 FPE, depending on the port size.... When comparing maximum possible power with the same barrel length and pressure, and with bore-area porting, a .224 cal would only give about 80% of the FPE of a wide open .25 cal.... The FPE is directly related to the bore area, which for a given pressure determines the force available to launch the slug.... 

Bob

[rkr]

Just because a gun will make 65 FPE in .25 cal does not mean you can reach that in .22 cal, that is a common misconception.... In fact more likely you will drop down to about 55-60 FPE, depending on the port size.... When comparing maximum possible power with the same barrel length and pressure, and with bore-area porting, a .224 cal would only give about 80% of the FPE of a wide open .25 cal.... The FPE is directly related to the bore area, which for a given pressure determines the force available to launch the slug.... 

Bob

Pellet guns usually have 75-80% max port size while bullet shooters use 100% port size. That more than makes up the difference. In my example the .25 had 4.5 mm ports while the .224 had 5.5 mm ports.

[rsterne]

Absolutely, but you are then talking apples and oranges.... Had you done the same mods to your .25 cal, you would have been well over 100 FPE....

My comment was directed at the idea that a 65 FPE Gauntlet .25 cal should be able to get 70+ FPE in a smaller caliber.... Maybe it can, but not without extensive other changes....

Bob

[Scotchmo]

Just because a gun will make 65 FPE in .25 cal does not mean you can reach that in .22 cal, that is a common misconception.... In fact more likely you will drop down to about 55-60 FPE, depending on the port size.... When comparing maximum possible power with the same barrel length and pressure, and with bore-area porting, a .224 cal would only give about 80% of the FPE of a wide open .25 cal.... The FPE is directly related to the bore area, which for a given pressure determines the force available to launch the slug.... 

Bob

That is true. The limitation being "with the same barrel length".

FPE is force x distance.

Maximum FPE is then psi x barrel_volume. For an equal slug+air mass, the .22 would need about a 30% longer barrel in order to have the same velocity and FPE as the .25 caliber.

Since the acceleration down the barrel is lower for the .22, we'd also need a 30% longer dwell in the valve.

Up until now, all my PCP work has been to design for either 12fpe or 20fpe in .177 caliber.

I'm currently working on my .22 benchrest gun design, with no rule constraints on FPE, so I'm following threads like this.

[rsterne]

Absolutely correct, since the force is bore area times pressure, and the FPE is that force times barrel length, you can simplify that to pressure times barrel volume (making sure you correct the units)…. The maximum FPE is give by....

FPE = Pressure (psi) x Barrel Volume (cu.in) / 12

However that requires constant pressure (hence infinite volume), no friction, and no allowance for the mass of the air.... Very few PCPs meet even 50% of that, so a good "lofty goal" is given by....

FPE goal = pressure x barrel volume / 24

Bob

[scion19801]

ok. so then i would need to increase the barrel length to maintain or achieve the 65 fpe. hmmm. the next longest liner is 32" , but that one is $95.55 three times more in price over the 25" liner. so i'm guessing that with the 24" as they say the liners do need to be trimmed down, that i would be hard pressed to attain the 65 fpe. without really upping the pressure. No one is truly sure what the stock tube will handle, but sure the small plenum available is also a limiting factor. So it would look like the lower tube would need to be swapped out for a tube of a know mswp and adding in more plenum volume.

edit:getting a liner at that price would be a no go. so it would be back to a full euro LW barrel. as they are $120+ s/h. by the time the carbon tubes and adapters are made for the liner it would be over the price of getting a blank barrel and having it machine to fit breech.

[rsterne]

I don't know how big the plenum is in a Gauntlet, but for an 80 FPE gun you would like 80 cc, but can get away with half that (40cc) if you increase the pressure about 10%.... It may well be that the Gauntlet is a poor choice for this project.... unless you build it to shoot lighter slugs, like 25-30 gr....

Bob

[scion19801]

I'm just about thinking you are.correct bob. Currently I believe the gauntlet has 20-25 cc plenum. Which probably accounts for y it has a 1900 regulator set point from factory. Guess I'm gonna have to wait for my gauntlet to get back from factory service to see what I end up with. If the accuracy issue isn't fixed I'll definitely be looking for a new barrel for it. Would be nice if I could get slugs running it, as well as pellets. But may be hoping for too much from the platform. I did try avs slugs. But due to barrel issues they kinda worked. But I'm learning g that even though they were pure lead they needed to be sized down. They were .254. I should have .249's as the barrel measures out as .248.

[Scotchmo]

I don't know how big the plenum is in a Gauntlet, but for an 80 FPE gun you would like 80 cc, but can get away with half that (40cc) if you increase the pressure about 10%.... It may well be that the Gauntlet is a poor choice for this project.... unless you build it to shoot lighter slugs, like 25-30 gr....

Bob

My upcoming benchrest project is a .22 Armada (Marauder based). The plan is to get as much as I can in stock form, running at 3000psi. Shooting 18.1gr and maybe 25.4gr pellets. Then add a 450cc 4500psi bottle, regulated to 3000psi, with a 200cc plenum, then some valve work, and finally a 27.5" long tensioned liner in a CF shroud. The goal is to shoot 25gr pellets up to 60fpe. My ultimate goal for airguns using current technology is to shoot 40gr slugs at 1060fps (same as a standard velocity .22LR).

Maybe using  a barrel like this:
https://www.cparifles.com/products/douglas-22lr-caliber-barrel-blank-1-in-16-twist-29-5-long?variant=7579203909

I have a mold to make 40gr 22LR, and 25gr 22short bullets. I could modify the mold slightly to make it more suited to slug use (no cartridge):

[oneshot61]

Not a pro here by any means, but you goal seems attainable. I have a Jkhan .22 that I ported to .201 and 24 grain swagged will hit 1000 FPS @ 3k psi. Also have an ace precision .22 that at 2400 psi shoots the huben cast 35.4 @ 940. No clue what it will hit at 3k psi, so a 70 ft lb .224 should work on the armada. Plus the .224 has a nice bc. An after market valve and porting should get you there. I’m running an older war valve in mine(.25)

[rsterne]

First time I have seen a mould for CB (conical ball) .22 rimfire ammo....

It is certainly possible to duplicate the performance of a .22LR target load, my .224 Hayabusa does that at 3000 psi.... 1077 fps with a 41.3 gr. swaged RWS bullet....



That setup is used a lot, tethered at 3000 psi, in the Netherlands for 100m benchrest…. This 17mm group at 100 metres is not untypical of their results....



They most often use a 15" twist Hornet barrel....

Bob