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FX “Super” Superior Heavy Slug Liner

the question I have is did the older 1:18 liner shoot the same slugs at the same time better?
My previous 1:18 liner was just as bad. That one was also branded (laser engraved) as a STX Superior Slug liner. Before that I had a STX Superior Heavy liner (1:18) twist that shot the NSA 33.5 grain and JSB KO’s really well. Below is a 3 shot group with the KO’s at 50 yards using the old heavy liner. Now I’m kicking myself for selling that one.

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My previous 1:18 liner was just as bad. That one was also branded (laser engraved) as a STX Superior Slug liner. Before that I had a STX Superior Heavy liner (1:18) twist that shot the NSA 33.5 grain and JSB KO’s really well. Below is a 3 shot group with the KO’s at 50 yards using the old heavy liner. Now I’m kicking myself for selling that one.

View attachment 375961


Interesting, it is possible and likely you need to retune it with the liner change.
 
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I re-tune my my gun each time. General technique is to tune for around 3-4% over target velocity. For example if my target velocity is 960 fps, then I set reg such that max speed plateaus at 990 fps. Then start reducing hammer spring until around 965-970, then use the valve adjuster to trim another 5-10 fps.
 
I re-tune my my gun each time. General technique is to tune for around 3-4% over target velocity. For example if my target velocity is 960 fps, then I set reg such that max speed plateaus at 990 fps. Then start reducing hammer spring until around 965-970, then use the valve adjuster to trim another 5-10 fps.


That’s concerning, I have a 25 dynamic in order, hope my barrel will shoot ok.
 
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This can be the infamous 25 Cal issue (no rifling) faced by Steve brew.
I can understand that there could be a batch of liners that did not get manufactured correctly. But who has the good ones? I won't be able to go to the range again for at least 2 weeks. Mine came in after the day at the range.
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And is indeed the 1:16 liner.
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Let's see how it fits. If anyone is looking for one of these, High Pressure Pneumatics has several when I ordered mine. Hopefully this time it will work for me 🙏

Either that or I'll just stick with the 22 barrel. As it works.

Allen
 
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Instead of chasing specific slugs sizes available or not .... you can save yourself some life expectancy - investing into re-sizers.
I have couple liners in .25, when I index the liner @ 100 meters the worst offset is one (superior heavy) with over 10 inches oval circle around the POA, but = the most tightest groups. I have dedicated that liner for 100 meters only.
What I have seen all of my liners are doing the 50 Meters job acceptable.
And just to mention it out loud, I got an adjustable re-sizer for pellets and I know today that each of my liners are a bit different.
My next investment will be slugs re-sizer in 5 micron increments, and I can buy whatever brand and model slugs that comes to my hands.
 
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Instead of chasing specific slugs sizes available or not .... you can save yourself some life expectancy - investing into re-sizers.
I have couple liners in .25, when I index the liner @ 100 meters the worst offset is one (superior heavy) with over 10 inches oval circle around the POA, but = the most tightest groups. I have dedicated that liner for 100 meters only.
What I have seen all of my liners are doing the 50 Meters job acceptable.
And just to mention it out loud, I got an adjustable re-sizer for pellets and I know today that each of my liners are a bit different.
My next investment will be slugs re-sizer in 5 micron increments, and I can buy whatever brand and model slugs that comes to my hands.
My upcoming research topic centers around Resizing, a key aspect of my ongoing exploration. I possess the necessary expertise to construct and assess various sizers, integral to my comprehensive Barrel, Size, and Slug trilogy series. The primary objective of this project will revolve around formulating sizing charts that fall within the precise range compatible with the process capabilities of barrel manufacturers. I think we are on the same page.
 
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I have a measurable evidence (for myself and your excersise may get you to the same conclusion) that the re-sized .25x35gn MK2 and MK1 pellets have a more predictable tighter grouping, and instead of weight sorting I am doing resizing now for the entire season. Also to mention that indexing liner I did not set to "vertical" but about 3 a clock to have it more horizontal for grouping in a side wind.
 
Well I’m in same boat as you with trying slugs in .30 cal. Literally shot over 800 rounds and tried various speeds and 8 different slugs and none of them were able to perform well. I got same results as you which I always had 1-2 flyers that were way off and it was frustrating. I ended up going back to the superior liner and got the hybrid slugs to shoot very well out to 100 yards and beyond. But my goal was to get the javelins to do well and utilize the higher bc that they are capable of. Once I figured out the hybrids worked well in the original liner I just settled on that. Because it’s frustrating and I just needed to enjoy the gun even though it’s not exactly what I was after.
I think at some point I’ll try the slug liner again and give it another shot, but for the time being I’m sticking with the hybrids. If your able to find something that works outside of what your looking for I suggest trying it out for a while so you can just enjoy the gun. Chasing unicorns is a lot of work!
 
I did some testing this last weekend with the new 0.25 cal, STX Slug liner (1:16 twist). The results were discouraging and unpleasant to say the least.

My FX Impact M3 is setup as follows:
  • 0.25 cal, 700mm barrel
  • STX Superior Slug liner (1:16 twist) – latest and “greatest” version
  • Carbon fiber liner sleeve
  • FX carbon fiber tensioner kit
  • Reg 1: 180 bar
  • Reg 2: 145 bar
  • Probe: Factory pellet probe
  • Transfer Port: Slug side
  • Moderator: DonnyFL Sumo (.25/.30)
I tried a variety of slugs including H&N, JSB, Patriot, NSA, and ZAN, however my main focus was on the H&N 38 grain heavies (0.249) and Patriot Javelin GEN2 36 grain (0.250). Test velocities ranged from 980 down to 880 fps.

Test groups were 5 shots each, utilizing 2 burners between each setting or projectile change. Velocity was very consistent from shot to shot as measured with my FX Pocket Chrono. Also, wind was very light…maybe 2-3 mph if any. Below are the 25-yard test groups. I didn’t see anything that really stood out as being tolerable except for the H&N slugs at 905 fps. Unfortunately, that group was not repeatable. Also, I started seeing a pattern where I would get 3-4 shots that “grouped” and then 1-2 fliers.

View attachment 375596

View attachment 375597

I took my best 25-yard groups from the H&N and Javelins and pushed things out to 100 yards. Results were quite awful and downright depressing. Below are some the targets from my 100-yard testing. You can see from the photo below I did have one exciting group in the lower right where 4 shots grouped well and then 1 flier hit 2” low. Again, I was unable to replicate this grouping.

View attachment 375598

View attachment 375599

After getting home from the range and feeling defeated I decided to the clean the liner with my Patchworm kit. The first 4 patches were extremely dirty with large amounts of lead shavings as shown below. It took another 50 patches to get the liner cleaned switching between Ballistol and Butch’s Bore Shine to get all remaining lead fouling out of the liner. Some lead particles were extremely difficult to get out and I ended up using a cooper bore brush to “scrub” the liner as the patches and chemicals would not pull them out. I suspect heavy liner fouling is what caused the fliers during testing.

View attachment 375600

So where do I go from here? Here are some ideas for next steps in approximate order.
  • Polish liner with J-B Bore Cleaning Compound and Flitz metal polish
  • Try heavier slugs such as 40, 42, 44, and 46 grain
  • “Slug” the liner to determine actual groove diameter using a micrometer, then pick a slug that is within 0.0005” to 0.001” over groove diameter as a starting point
  • Go back to the STX Standard liner
  • Sort slugs by weight and diameter for better consistency
  • Use a slug sizer
  • Wash slugs with Dawn soap and then lube them with silicon spray or Ballistol
  • Change from 0.25 caliber to 0.22 caliber and wave goodbye to the 0.25 caliber
Let me know if you have any other ideas or if I’m missing something. It’s frustrating to read comments from other AGN members about how they shoot MOA groups all day long. My experience has been just the opposite. And just for comparison, this same gun stacks 34 grain King Heavies when properly tuned with the standard liner 1:24 pellet liner.
I feel your pain and frustration, probably a few thousand .25 slugs down range between two different Impacts and can not get them to shoot. The guns are lasers with pellets, and a shotgun pattern with slugs.

Idiot me orders a 700mm tensioned barrel kit to switch over my .25compact to try and get it to shoot slugs.

Definitely not buying anymore slugs, unless I get something figured out. I have about 3500 more slugs, and I might make a switch to try .22 slugs or just stick with pellets.

I'm not too far from Cape Fear airguns "910 tuning and repair" might get desperate and let them try tuning it, definitely would if I didn't have to ship the gun.