FX liners, non-choked?

[DougH.]

Just wondering if any body has attempted in utilizing a 700mm liner with the choked end cut off to 600mm and recrowned to shoot slugs. I have heard that slugs prefer non-choked barrels. I have been toying with the idea in my head to sacrifice a $100 liner and test it with a slightly larger diameter (.219?). Idk, just throwing ideas out there. I feel that the choke hinders the fps and requires a hotter tune for the required speed for slugs (in conjunction with more contact area between the slug and barrel, of course). I would love to know any of your thoughts on this. Does anyone think it’s viable to try? I know fx liners are not consistent diameter throughout the entire length. That’s why I suggested maybe a .219. Very curious about any opinions out there.

 

[jps2486]

Tempting idea. I've slugged a few of my liners and found that the pellet or slug as it is pushed through from the breech to the muzzle goes through sections that are loose and tighter, then gets real tight as you go through the choke area. Cutting off 100 mm puts you in that area, so I'm not sure how well it will work. With slugs, at least, you can get them in diameter variations, so it might be a good experiment. Are you willing to write off a $109 liner if it doesn't work?

 

[DougH.]

I think it would be worth it for the sake of science. The only thing is, I only own a WK MKIII compact as of now. My only option would be to sacrifice a 600mm cut to 500. But to answer your question, yes I would do it. This a thought I had while I had my Impact MKII, which I no longer have.

 

[qball]

question I have is what are you trying to achieve? I have great luck with many heavy liners so not sure what improvement are you trying to get.

If you want to try it then go for it but are you not able to get good accuracy now? it could be tune or other issues.

 

[DesertSilver]

That's exactly what I've been thinking about doing. I don't like choked barrels for slugs and feel the only reason they did it is for the lazy slug shooter who didn't want to slug their barrel. Plus if you think about it, FX hybrids would not be affected by a choke.

 

[bigHUN]

I think the choke ( in FX liners) have a function, even for slugs. All of my Superior Heavies (5.5 and 6.35) that were marketed as slug liners have a suprisingly heavy choke.
If I remember correctly one of my STX-A has a lightest choke and that was a pellet liner.
Instead of cutting off the choke I would try resizing first.
For tight spots inside liners ... I polished them very very much, and also I did a firelap on one and I cannot realy feel a difference now when slugging. Butter smooth.

 

[DougH.]

question I have is what are you trying to achieve? I have great luck with many heavy liners so not sure what improvement are you trying to get.

If you want to try it then go for it but are you not able to get good accuracy now? it could be tune or other issues.

I’m just curious to see if a lighter tune would be achievable without the restriction of a choked barrel. The accuracy of course may or may not be affected. That’s a gimme. Thanks for your thoughts.

 

[MEC17670]

Guys, remember, the engineers over at FX Sweden aren't sitting on their hands. They have done most all of the experiments you're thinking of doing .

 

[jbravo103]

Tempting idea. I've slugged a few of my liners and found that the pellet or slug as it is pushed through from the breech to the muzzle goes through sections that are loose and tighter, then gets real tight as you go through the choke area. Cutting off 100 mm puts you in that area, so I'm not sure how well it will work. With slugs, at least, you can get them in diameter variations, so it might be a good experiment. Are you willing to write off a $109 liner if it doesn't work?

Both my .25 700mm slug liners exhibit similar characteristics when pushing a slug through. Snug for the first 20-30% of the liner then loose until I get to the choke, which is very tight.

• 1:18 STX Superior Slug
• 1:16 STX Slug

So far I’ve had the best luck shooting the H&N Heavy slugs ( both 0.249 and 0.250) Javelins (0.250) are terrible - shotgun groups and major fouling.

 

[qball]

I think the choke ( in FX liners) have a function, even for slugs. All of my Superior Heavies (5.5 and 6.35) that were marketed as slug liners have a suprisingly heavy choke.
If I remember correctly one of my STX-A has a lightest choke and that was a pellet liner.
Instead of cutting off the choke I would try resizing first.
For tight spots inside liners ... I polished them very very much, and also I did a firelap on one and I cannot realy feel a difference now when slugging. Butter smooth.

I’m lazy so I polished the choke only, no lapping/just polish. Does it give me better accuracy or speed increase? Not really, I’m just hoping it would foul up less.

 

[sobdiver]

Lot's of good info on this video, I'd give it a watch before doing any cutting:

 

[Revoman]

bigHun
Would you mind explaining how you polished the tight spots out in a PM please?
Thanks!
Mike

 

[Nico5999]

Many, MANY match grade rimfire and centerfire barrels are choked. I don't think it's true that slugs necessarily prefer a choked barrel.

Sizing the slug to the groove diameter is the most important thing from what I've found. Slugging the barrel, etc. The choke allows for variation in slug size within a given diameter and "incorrect" slug sizes to be corrected before exiting the barrel.

If the slug is too small (i.e. .2175 instead of .218), it can pitch and yaw and the nose will move around within the barrel. A choke can correct this. With a non-choked barrel, the slug would need to be sized perfectly (or much closer to what would be ideal). A non-choked barrel may very well vary in diameter throughout the bore as well. If it opens up towards the muzzle this effect will be exacerbated, as well as the effect of blow-by.

I think there is a reason that most manufacturers add chokes to their barrels. That being said, I am experimenting with an UNCHOKED TJ .25 liner as we speak. Results has been encouraging but time will tell. I think unchoked barrels can definitely perform well, but we need to keep in mind that there are very rarely any solutions, only tradeoffs.

YMMV.

Nico

 

[Vetmx]

I’ve been doing it over the last couple months to confirm or debunk some of my theories. Been a costly experiment but education isn’t cheap. Well I guess it’s cheap if I tell everyone what I discover. I will say that one of my theories is a choke changes everything. My hardcore slug guns are unchoked. What I’ve noticed is my choked slug shooters really don’t follow any twist rate vs speed calculations. My unchoked barrels do. My choked sluggers can shoot very well but they are too touchy. I believe guys are shooting crap fitting slugs to accommodate their choke. That crap fit at the truly most important part of the shot cycle is what makes all these guns only decent shooters according to my standards. It holds them back from being great shooters every day all the time. The reason I’m experimenting with FX liners is because they did one thing right. But they also have some significant drawbacks. One is when you chuck one up in a 4 jaw. The runout on these straws is horrible, probably why we have to play the indexing game with them. Two is they are just so thin. They are harmonic nightmares. But the one thing they did right will let me see some things without having to machine a bunch of CZ or LW barrels to fit my guns.

 

[DougH.]

I’ve been doing it over the last couple months to confirm or debunk some of my theories. Been a costly experiment but education isn’t cheap. Well I guess it’s cheap if I tell everyone what I discover. I will say that one of my theories is a choke changes everything. My hardcore slug guns are unchoked. What I’ve noticed is my choked slug shooters really don’t follow any twist rate vs speed calculations. My unchoked barrels do. My choked sluggers can shoot very well but they are too touchy. I believe guys are shooting crap fitting slugs to accommodate their choke. That crap fit at the truly most important part of the shot cycle is what makes all these guns only decent shooters according to my standards. It holds them back from being great shooters every day all the time. The reason I’m experimenting with FX liners is because they did one thing right. But they also have some significant drawbacks. One is when you chuck one up in a 4 jaw. The runout on these straws is horrible, probably why we have to play the indexing game with them. Two is they are just so thin. They are harmonic nightmares. But the one thing they did right will let me see some things without having to machine a bunch of CZ or LW barrels to fit my guns.

And what is that one thing you are referring to that they did right? Or is that a secret?

 

[qball]

Many, MANY match grade rimfire and centerfire barrels are choked. I don't think it's true that slugs necessarily prefer a choked barrel.

Sizing the slug to the groove diameter is the most important thing from what I've found. Slugging the barrel, etc. The choke allows for variation in slug size within a given diameter and "incorrect" slug sizes to be corrected before exiting the barrel.

If the slug is too small (i.e. .2175 instead of .218), it can pitch and yaw and the nose will move around within the barrel. A choke can correct this. With a non-choked barrel, the slug would need to be sized perfectly (or much closer to what would be ideal). A non-choked barrel may very well vary in diameter throughout the bore as well. If it opens up towards the muzzle this effect will be exacerbated, as well as the effect of blow-by.

I think there is a reason that most manufacturers add chokes to their barrels. That being said, I am experimenting with an UNCHOKED TJ .25 liner as we speak. Results has been encouraging but time will tell. I think unchoked barrels can definitely perform well, but we need to keep in mind that there are very rarely any solutions, only tradeoffs.

YMMV.

Nico

Choke is to accommodate tolerance issues plus less bore drag before choke. If you take out the choke then effectively the entire barrel becomes the choke.

 

[Vetmx]

It’s not a secret. It’s quite obvious when you understand every aspect of shooting any kind of projectile. As far as a choke robbing speed goes? Well it’s a two way street. Fast loose slug getting slowed by a choke or a tight slug dragging the full length of the barrel. Six of one, half dozen of the other. Doesn’t matter really, all we should concern ourselves with is accuracy and consistency. If we want speed and big power, that’s what gunpowder is for. I believe from a manufacturing standpoint it’s easier to choke a .25, .30 or .22 down to a certain size that works with or kinda works depending on your standards with mass production slugs. My unchoked slug guns are one trick ponies. Both have a barrel made by the same manufacturer but they each require a different diameter slug. We don’t have massive pressures to send tight projectiles like a real gun so we will always be walking a finer line. FX is just trying to give you good enough. And for some purposes, it can be. But you have to be prepared for when your gun goes off it’s nut. Keeps the revenue flowing within the industry quite well though. I had slugs from a manufacturer that shot great a couple years ago. Put that slug gun back on slugs again this year just for fun. It shot great but I ran out of slugs. Ordered more, they shot horrible. Had to go up a thousandth. We are also at the mercy of who makes our slugs. So maybe a choke helps negate that slightly if your standards aren’t super high. And super high standards with slugs could also just be plain ridiculous, not achievable, not realistic. For years I’ve planned to find out. With two of my guns, both .25’s, I’ve accepted that this is as good as it gets. Now I’m messing with my one .22. I can always put it back to a pretty darn good slugger. Just want to see if there is a stone left unturned. I did build a real LW barrel for it but it only matched what the FX barrel would do. The added weight of the real barrel was not worth it. The only advantage of the real barrel was it was less sensitive to tuning. Tired of typing.

 

[DougH.]

It’s not a secret. It’s quite obvious when you understand every aspect of shooting any kind of projectile. As far as a choke robbing speed goes? Well it’s a two way street. Fast loose slug getting slowed by a choke or a tight slug dragging the full length of the barrel. Six of one, half dozen of the other. Doesn’t matter really, all we should concern ourselves with is accuracy and consistency. If we want speed and big power, that’s what gunpowder is for. I believe from a manufacturing standpoint it’s easier to choke a .25, .30 or .22 down to a certain size that works with or kinda works depending on your standards with mass production slugs. My unchoked slug guns are one trick ponies. Both have a barrel made by the same manufacturer but they each require a different diameter slug. We don’t have massive pressures to send tight projectiles like a real gun so we will always be walking a finer line. FX is just trying to give you good enough. And for some purposes, it can be. But you have to be prepared for when your gun goes off it’s nut. Keeps the revenue flowing within the industry quite well though. I had slugs from a manufacturer that shot great a couple years ago. Put that slug gun back on slugs again this year just for fun. It shot great but I ran out of slugs. Ordered more, they shot horrible. Had to go up a thousandth. We are also at the mercy of who makes our slugs. So maybe a choke helps negate that slightly if your standards aren’t super high. And super high standards with slugs could also just be plain ridiculous, not achievable, not realistic. For years I’ve planned to find out. With two of my guns, both .25’s, I’ve accepted that this is as good as it gets. Now I’m messing with my one .22. I can always put it back to a pretty darn good slugger. Just want to see if there is a stone left unturned. I did build a real LW barrel for it but it only matched what the FX barrel would do. The added weight of the real barrel was not worth it. The only advantage of the real barrel was it was less sensitive to tuning. Tired of typing.

That’s a lot of good information. Thank you. I have moderately been down the slug rabbit hole and found it frustrating enough. This subject was just something that’s been in the back of my mind for a while and was curious what others may have found by experience. I do appreciate your time! I think I will stick to pellets. They are a lot less headache. Air rifles, although they can be configured, I don’t think they are initially designed for slugs. Too many variables, and if one of the many goes awry, then it’s back to square one.

 

[mackeral5]

Not a slug shooter, but I did cut down a 600mm STX Superior standard to 480mm, with no ill effects on accuracy.

Chopped STX Superior STD from 600mm to 480mm

I've seen this question pop up every once in a while so I wanted to share results. My liner is grafted into a bottled Marauder based gun. Originally it was tuned with the reg around 1300psi and shooting Kings around 900fps. After chopping 120mm off the muzzle velocity dropped to 850fps...

www.airgunnation.com

My 700mm STX Superior Heavy .25 had many tight/loose spots until I polished and hard waxed the bore, as I do with all of my barrels. I do not lube slugs, I know many do, but it is not my preference. Choke is still fairly tight, a slug shows little signs of rifling when pushed through the choke. In spite of this, it does pretty good with ATP Smooth 49.5gr @850fps. I doubt I will ever experiment with removing the choke from this particular liner, but I may do so with a different slug/heavy liner.

A couple of 100 yard groups from Saturday morning with 700mm STX Superior Heavy .25, lapped, polished, and waxed, ATP Smooth 49.5gr @850fps out of a Bulldog based contraption, which is regulated at 124 bar. The choke indeed lowers velocity a bit, but IMO it is largely responsible for this particular liner's accuracy.

Using the tapered lap/polish/wax regimen I rarely have a barrel (Including FX liners) that leads up in a manner which affects accuracy in a small number of shots. Most go hundreds of shots before a significant change in accuracy. But keep in mind my definition of acceptable accuracy is in the 1.5moa range, others may be much more discerning...

 

[jps2486]

My experience differs with Dubber's. After about 100-125 shots, my accuracy falls off because the choke gets fouled with lead. Maybe polishing is the wrong way to go here and we should be creating a less smooth surface in the bore of the liner. I'd like to be able to bead blast the liner bore and see what happens.