Custom AirForce .224 slug barrel project advise

[KnifeMaker]

Rather than all the pie in the sky guess work, why not treat the requirements the same as a sub sonic .22 projectile. It has a "very" long track record the world over.


Standard twist for the subsonic is normally 1 in 16 twist. I tried the  1-16 and the twist rate for the .22 short. Oddly enough, the slower twist rate was more accurate.


 You will notice soon that the only AG company that has really paid attention to slug use in their guns is FX. The twist rate in the New Superior line is slow as well. Looking forward to the new specs in the forthcoming Superior bbl's.  I know what they are, but no doubt get blasted here as many would simply dis. it.


For your purposes, I would go with TJ's. They are very accurate!


Knife/Mike

[Ribbonstone]

Mixing firearms and airarms can often  get us in trouble (pressure/obturation is part of it), do think that 1:20 would be enough twist for a .22 AIRGUN slug of  somthing like 22-27grains. at 800-900fps.

Considering the .22short started off as a black powder round,and 1:20-1:22" was most often used for that sub-sonic bullet....why would airguns be drastically different?

(Lets avoid CB caps....short or long...they have other problems besides twist.)

If you want to be modern,then there are sub-sonic (30gr).22 shorts and sub-sonic (or even "reduced noise") .22LR's that pretty well dupicate the BP speeds (820-900fps)...which is NOT far from hot PCP speeds (reachable with common PCP's)....and pretty close to observed BP speeds of the orginals.

Stability does not always equate to accuracy....nice round holes (not ovaled or key holed) is a  good indication of stability...but they still may not group worth a hoot.

Using the same twisted-comparsion of fire vs airarms,where some .22LR pistols made back in the day with a 1:10 twist....they let that go pretty quickly as too much of a good thing.

Personally....I'd listen to KnifeMaker.

All I wanted to do was turn ONE rifle into a slug shooter and didn't want to rebarrel it.  Trial and error got me there,but was casting  slugs in a shortened mold and figuring out my own sizging system.....if I didn't have all that happy-whappy-stuff on hand,would have been hosed.

[luge007]

True you could compare .22LR sub-sonic to our airgun world, however I'll likely (but not a definitely) be shooting 55 grain lead bullets, where as .22 subs are generally 40gr and under, with the exception of the Aguilla SSS round.  From what I understand the longer 55 grain bullets should require a faster twist rate than a shorter 40 grain?  If I hit the lottery I'd be happy to try every twist rate from 1:10 through 1:20, however at $50- $200 per blank, that is highly unlikely.  I was hoping with the specific projectile in question with the guesstimated velocity, an actual calculation for an appropriate twist rate would come forth.  Appears there is more 'Voodoo' to this barrel topic than meets the eye.

Knife, I hear you loud and clear, and value your input especially the PM's you sent (thank you), but are you shooting 55 grain, long projectiles in that 1:20?  I thought you said you 'decked' your  mold and are shooting lighter, shorter bullets.  Wouldn't the longer bullets need a faster twist rate?  Can you PM me with the new FX slug twist rate, and does FX specify a projectile weight range for their barrels? (I promise not to blast you)

M

[UnderPressure]

Under Pressure, where did you come up with the 'print' for the Lee projectile?  It does not look like the Lee "Bator" projectiles dropped by my mold (though mine is about 20 yr old).  My Lee mold drops what can be described as cylindrical projectiles with a 'dome' nose and a few lube grooves.  I'll post pics if I get a chance. 

I found it while searching images for Lee Bator.

It does indeed look like it comes from this mold:

https://www.midsouthshooterssupply.com/item/0000690459/point225-diameter-6-cavity-mold-c225-55-rf




Maybe they changed the design of the Lee Bator sometime in the past 20 years?

[UnderPressure]

 You will notice soon that the only AG company that has really paid attention to slug use in their guns is FX. The twist rate in the New Superior line is slow as well. Looking forward to the new specs in the forthcoming Superior bbl's.  I know what they are, but no doubt get blasted here as many would simply dis. it.

Hard Air Magazine is reporting their will be two different families of Superior liners:

https://hardairmagazine.com/news/fx-superior-stx-liners-the-latest-introduction-from-fx-airguns/

There are two families of barrel liners being released for most calibers; a standard Superior STX Liner and a Superior STX Heavy Liner.

FX Superior STX Barrel Liners

These standard barrel liners have been created to shoot standard weight pellet and Hybrid Slugs. FX tells us that indoor 100 Yard controlled testing has confirmed that the new Superior STX Barrel Liner shoot standard FX pellets even better than the previous STX Pellet Liner!

Keeping in mind the amount of championship wins the STX Pellet liner has, that is a strong statement! The standard Superior STX Liner also maximizes the accuracy of the ground-breaking FX Hybrid Slug.

FX Superior STX Heavy Liners

These new barrel liners will be replacing the STX Slug A liners in the coming months. ‘Heavy’ denotes that this liner has a different twist rate better suited for heavier pellets and heavier slugs (as opposed to lighter weight Hybrid Slugs).

P.S. The regular superior liner could have a relatively slow twist and yet stabilize many of the commonly available slugs.

Even the 27.5 grain .217 Neilsen Doesn't need that much twist according to Kolbe:

http://www.geoffrey-kolbe.com/cgi-bin/barrel_twist.cgi?diameter=.217&length=.3295&nose=.120&meplat=.150&base_diameter=.217&angle=&boat_tail=&b_twist=&secant_radius=&unit_length=inches&temperature=59&humidity=0&local_pressure=29.92&pressure=29.92&altitude=0&density=11.4&custom_density=

[UnderPressure]

I did some more digging on the twist rate for the FX .22 Superior slug liner but couldn't find it.

FWIW Here is a older list from April 2019:

https://www.trenieroutdoors.com/fx-airguns-twist-rate-data/



So if the Superior slug liner for .22 ends up 1 in 23" twist could it be the Superior heavy slug liner for .22 is 1 in 19"?

[Bunyboyz]

 You will notice soon that the only AG company that has really paid attention to slug use in their guns is FX. The twist rate in the New Superior line is slow as well. Knife/Mike

This here.  I bought that new superior barrel near launch.  I don’t have an FX but I figured I could put it in one of mine.

Then I discovered it wasn’t really for slugs that’s what the forthcoming heavy superior barrel is for.

I’d be interested to see what they do. But I doubt it makes much sense to put this 600mm Superior in my talondor. I’m slowly making my way to the .257 on my Airforce

If I recall right for my .25 600mm superior its 1-23.575   But I’ve been reading too many twist rates now to keep track

And that’s likely too slow for say 50 grain projectile.  Because of the length

[KnifeMaker]

True you could compare .22LR sub-sonic to our airgun world, however I'll likely (but not a definitely) be shooting 55 grain lead bullets, where as .22 subs are generally 40gr and under, with the exception of the Aguilla SSS round.  From what I understand the longer 55 grain bullets should require a faster twist rate than a shorter 40 grain?  If I hit the lottery I'd be happy to try every twist rate from 1:10 through 1:20, however at $50- $200 per blank, that is highly unlikely.  I was hoping with the specific projectile in question with the guesstimated velocity, an actual calculation for an appropriate twist rate would come forth.  Appears there is more 'Voodoo' to this barrel topic than meets the eye.

Knife, I hear you loud and clear, and value your input especially the PM's you sent (thank you), but are you shooting 55 grain, long projectiles in that 1:20?  I thought you said you 'decked' your  mold and are shooting lighter, shorter bullets.  Wouldn't the longer bullets need a faster twist rate?  Can you PM me with the new FX slug twist rate, and does FX specify a projectile weight range for their barrels? (I promise not to blast you)

M

No, my heaviest in .25 is 51 gr's. My .223 is one in 20 and the bbl that JSAR sent me in .25 is 1 in 22. Shoots very well! I only know the twist in the .25 superior, and waiting for info on the up coming heavy and .22 bbl's. 

[KnifeMaker]

True you could compare .22LR sub-sonic to our airgun world, however I'll likely (but not a definitely) be shooting 55 grain lead bullets, where as .22 subs are generally 40gr and under, with the exception of the Aguilla SSS round.  From what I understand the longer 55 grain bullets should require a faster twist rate than a shorter 40 grain?  If I hit the lottery I'd be happy to try every twist rate from 1:10 through 1:20, however at $50- $200 per blank, that is highly unlikely.  I was hoping with the specific projectile in question with the guesstimated velocity, an actual calculation for an appropriate twist rate would come forth.  Appears there is more 'Voodoo' to this barrel topic than meets the eye.

Knife, I hear you loud and clear, and value your input especially the PM's you sent (thank you), but are you shooting 55 grain, long projectiles in that 1:20?  I thought you said you 'decked' your  mold and are shooting lighter, shorter bullets.  Wouldn't the longer bullets need a faster twist rate?  Can you PM me with the new FX slug twist rate, and does FX specify a projectile weight range for their barrels? (I promise not to blast you)

M

So far, the .25 superior is 1 in 24. Waiting to see where the .25 heavy and .22 bbl's. will fit in.


Mike

[rsterne]

So the .25 Superior 1 in 24 must be a pellet barrel?....

Bob

[UnderPressure]

So the .25 Superior 1 in 24 must be a pellet barrel?....

Bob

Pellet and hybrid slug (so slug too)......but they claim the standard Superior STX liner shoots pellets better than the previous STX pellet liner which is interesting because the twist is 3" faster.

https://hardairmagazine.com/news/fx-superior-stx-liners-the-latest-introduction-from-fx-airguns/

There are two families of barrel liners being released for most calibers; a standard Superior STX Liner and a Superior STX Heavy Liner.
FX Superior STX Barrel Liners

These standard barrel liners have been created to shoot standard weight pellet and Hybrid Slugs. FX tells us that indoor 100 Yard controlled testing has confirmed that the new Superior STX Barrel Liner shoot standard FX pellets even better than the previous STX Pellet Liner!

Keeping in mind the amount of championship wins the STX Pellet liner has, that is a strong statement! The standard Superior STX Liner also maximizes the accuracy of the ground-breaking FX Hybrid Slug.

FX Superior STX Heavy Liners

These new barrel liners will be replacing the STX Slug A liners in the coming months. ‘Heavy’ denotes that this liner has a different twist rate better suited for heavier pellets and heavier slugs (as opposed to lighter weight Hybrid Slugs).

[UnderPressure]

I did some more digging on the twist rate for the FX .22 Superior slug liner but couldn't find it.

FWIW Here is a older list from April 2019:

https://www.trenieroutdoors.com/fx-airguns-twist-rate-data/



So if the Superior slug liner for .22 ends up 1 in 23" twist could it be the Superior heavy slug liner for .22 is 1 in 19"?

Here is the Kolbe twist for the FX .22 hybrid slug (using my estimate for nose length and meplat):

http://www.geoffrey-kolbe.com/cgi-bin/barrel_twist.cgi?diameter=.217&length=.322&nose=.160&meplat=.135&base_diameter=.217&angle=&boat_tail=&b_twist=&secant_radius=&unit_length=inches&temperature=59&humidity=0&local_pressure=29.92&pressure=29.92&altitude=0&density=11.4&custom_density=

So my mistake twist should be faster than 1 in 23" for the standard superior liner in .22.

[mtnGhost]

I did some more digging on the twist rate for the FX .22 Superior slug liner but couldn't find it.

FWIW Here is a older list from April 2019:

https://www.trenieroutdoors.com/fx-airguns-twist-rate-data/



So if the Superior slug liner for .22 ends up 1 in 23" twist could it be the Superior heavy slug liner for .22 is 1 in 19"?

Here is the Kolbe twist for the FX .22 hybrid slug (using my estimate for nose length and meplat):

http://www.geoffrey-kolbe.com/cgi-bin/barrel_twist.cgi?diameter=.217&length=.322&nose=.160&meplat=.135&base_diameter=.217&angle=&boat_tail=&b_twist=&secant_radius=&unit_length=inches&temperature=59&humidity=0&local_pressure=29.92&pressure=29.92&altitude=0&density=11.4&custom_density=

So my mistake twist should be faster than 1 in 23" for the standard superior liner in .22.

Someone should tell Ernest that. He posted a video shooting them at 1157 / 25y and surmised they would do well at longer range at that velocity 

I don't know what to make of that Kolbe graph. My Taipan can shoot them accurately at 100 meters at 990fps with both 600mm pellet (1:19) and slug (1:16) liners. I tested them with both liners from 1195 down, until they grouped well at 1030fps (even tighter at 990). Had identical results with both liners.

I'd say they're ok at that range, but they drift too much with crosswind for me to shoot with them further out.

[UnderPressure]

I did some more digging on the twist rate for the FX .22 Superior slug liner but couldn't find it.

FWIW Here is a older list from April 2019:

https://www.trenieroutdoors.com/fx-airguns-twist-rate-data/



So if the Superior slug liner for .22 ends up 1 in 23" twist could it be the Superior heavy slug liner for .22 is 1 in 19"?

Here is the Kolbe twist for the FX .22 hybrid slug (using my estimate for nose length and meplat):

http://www.geoffrey-kolbe.com/cgi-bin/barrel_twist.cgi?diameter=.217&length=.322&nose=.160&meplat=.135&base_diameter=.217&angle=&boat_tail=&b_twist=&secant_radius=&unit_length=inches&temperature=59&humidity=0&local_pressure=29.92&pressure=29.92&altitude=0&density=11.4&custom_density=

So my mistake twist should be faster than 1 in 23" for the standard superior liner in .22.

Someone should tell Ernest that. He posted a video shooting them at 1157 / 25y and surmised they would do well at longer range at that velocity 

I don't know what to make of that Kolbe graph. My Taipan can shoot them accurately at 100 meters at 990fps with both 600mm pellet (1:19) and slug (1:16) liners. I tested them with both liners from 1195 down, until they grouped well at 1030fps (even tighter at 990). Had identical results with both liners.

I'd say they're ok at that range, but they drift too much with crosswind for me to shoot with them further out.

Is the Standard Superior STX liner in .22 1 in 23"?

P.S. According to the Kolbe graph (using my estimate for meplat size and nose length) the FX hybrid .22 slug  needs 1 in 21.5" for 900 FPS and 1 in 19.5" for 1150 FPS.

[mtnGhost]

I did some more digging on the twist rate for the FX .22 Superior slug liner but couldn't find it.

FWIW Here is a older list from April 2019:

https://www.trenieroutdoors.com/fx-airguns-twist-rate-data/

So if the Superior slug liner for .22 ends up 1 in 23" twist could it be the Superior heavy slug liner for .22 is 1 in 19"?

Here is the Kolbe twist for the FX .22 hybrid slug (using my estimate for nose length and meplat):

http://www.geoffrey-kolbe.com/cgi-bin/barrel_twist.cgi?diameter=.217&length=.322&nose=.160&meplat=.135&base_diameter=.217&angle=&boat_tail=&b_twist=&secant_radius=&unit_length=inches&temperature=59&humidity=0&local_pressure=29.92&pressure=29.92&altitude=0&density=11.4&custom_density=

So my mistake twist should be faster than 1 in 23" for the standard superior liner in .22.

Someone should tell Ernest that. He posted a video shooting them at 1157 / 25y and surmised they would do well at longer range at that velocity 

I don't know what to make of that Kolbe graph. My Taipan can shoot them accurately at 100 meters at 990fps with both 600mm pellet (1:19) and slug (1:16) liners. I tested them with both liners from 1195 down, until they grouped well at 1030fps (even tighter at 990). Had identical results with both liners.

I'd say they're ok at that range, but they drift too much with crosswind for me to shoot with them further out.

Is the Standard Superior STX liner in .22 1 in 23"?

P.S. According to the Kolbe graph (using my estimate for meplat size and nose length) the FX hybrid .22 slug  needs 1 in 21.5" for 900 FPS and 1 in 19.5" for 1150 FPS.

I have no clue .. none of my sources seem to know either (FX is being fairly hush-hush about them, they might still be figuring that out).

The Hybrid 22 cal ammo has been (very) accurate at 900 (780-940fps FWIW) using several other rifles that I tested them with. Those bbls were primarily choked LW and CZ with 1:16, 1:17.5. They seem to be preferred with all of my rifles over the 20.2 & 24.8gr NSAs, but no where near as good as those 25gr H&N Slug HPs.

[Bunyboyz]

Guys are getting the heavy superior barrel

They are listed in Krale shop

17.5 for heavy superior in .25 if post I read guy knew what he was doing.  He did have photos

Fx impact owners Facebook group

[UnderPressure]

Guys are getting the heavy superior barrel

They are listed in Krale shop

17.5 for heavy superior in .25 if post I read guy knew what he was doing.  He did have photos

Fx impact owners Facebook group

So twist is increasing.

[Nvreloader]

Sbak
I would be greatly interested in your Sentry build, especially the Flat Wire SSG etc,
photo or two would be a great help, I am leaning very hard in the same direction,
only in the 172/224 cal in the Sentry, as I have several bbl's (RF/CF) that I could use.

I am interested in HEAVY weight pellets and Lite weight slugs, I believe that the Sentry 705 models can work very well,
as they are very well built in the plenum tube and valve areas, and with the 8lb hammer spring that can be changed out
to a Flat wire Hammer spring with more options etc.

I am planning on running a lite weight hammer, to get away from the 746 gr OEM hammer weight etc.

I am waiting on Knives reply to my PM, before I take the next step...............

Thanks,
Don

Ive never worked with the air force rifles, but from what ive seen they should be plenty capable of maxing out the .224 platform. I used a prototype xisico senty, cause im cheap. Although, i really enjoyed this gun i would not suggest it for a high energy build. It is limited in hammer energy by design. I have it maxed out in hammer weight and travel and it is still pretty hard to cock.

I was able to get a little over 900 fps maxed out @ 3000 psi with the 56 gr lee. .22 porting minus .10 probe (.203 equivalent). From 3000 psi to 2500 gave a tune of 850-870-850 for i think 6 shots on 240cc of air. It has since been detuned for 20 shots @ 65FPE with the NOE WFN

The .224 is a very underappreciated caliber, mine shoots pretty much everything fantastically
Appreciate it, i should have added, 24in barrel, peek poppet, flat wire spring ssg, and i did experiment with valve springs. My experience has only been with "QB" stiffness springs and less, but the valve spring has zero effect on shot curve. YMMV

[UnderPressure]

Guys are getting the heavy superior barrel

They are listed in Krale shop

17.5 for heavy superior in .25 if post I read guy knew what he was doing.  He did have photos

Fx impact owners Facebook group

Any mention of .177 superior liners (both standard and heavy)?

[luge007]

So, here is a pic of the actual slugs that came out of my Lee "Bator" mold.  These were setup to be propelled by powder, so disregard the gas checks on these, the air powered ones will not have checks.  As you can see they are very cylindrical and have a rounded nose, very dissimilar to the diagram and pic previously posted.  I can attempt to take accurate measurements and post them if that is helpful for further advise, but they are .545" long.  They have a huge meplat for their diameter, so I am considering modifying the mold to hollow point them.  The HP process will make them lighter for easier 'propelling', and hopefully dump all their energy on impact.  Could also use them non-hp for penetration.

I am leaning towards a 1:12 twist for these projectiles.

Thanks for all the input so far, keep it coming,
M