Tuning Looking for feedback from folks using FX Impact MK2 Compact .25 to shoot slugs

[pkita99]

Hello,

Recently tuned a newly purchased FX Impact Compact in .25 and getting single hole groups with both JSB Kings 25gr and King Heavy MK2 34gr at 50 yards. Decided to try the FX Hybrid slugs. Just wanted to see how they would shoot without doing much to the gun besides turning the hammer wheel. At max hammer setting was able to get them flying right at 900 ft/s but the groups at 50 yards were just terrible and all over the place (like 3 inch groups) . When I purchased the FX Impact Compact from Utah Airguns I was told that it already came with the superior barrel so supposedly should handle the FX Hybrids better. Do I need to push them at high speeds to for the groups to tighten up or is the 500mm barrel just to short to shoot them effectively? 

Anyways just looking for feedback from the forum from the people shooting hybrids or other slugs from the Impact Compacts and what accuracy they are getting. 

Thanks,

Paul

 

[Nathan]

I can tell you that I had them shooting decent in the mid-940s (600mm). Once I tweaked the reg up and got them going around 955 FPS, they started stacking like pellets at 90 yards. Try leaving your valve wide open (just past fourth line).

 

[Jayman07770]

I got decent groups with the hybrids around 950fps on the Maverick compact. Going faster just opened up the group with the tune I had. My Impact compact barrel kit will be in this week so I’ll start test that rifle too. 

 

[Hobbyman2007]

What size did you buy? If the slugs aren’t the right size for your barrel they simply won’t shoot well. 

 

[Vetmx]

My Impact 600mm shot them great at 885fps at 90b and I finally achieved the same accuracy at 937fps at 115b. It’s not necessarily about speed with these guns that determines accuracy. It’s about delivering the exact amount of air. If you have your VLA turned in just far enough to see a change in your velocity, shoot groups and turn it in 1/8 of a turn at a time. Watch how your groups change at each setting because they will. If you want to shoot hybrids to their full potential, you better have a ton of them for testing. I wanted a 925fps+ tune for my gun and I went through 400 slugs. Weather conditions still haven’t let me test at 100 with this setting so even though I’m one hole at 30 and a ragged hole at 50yrds, my 100 could still be junk. That means a slight reg change and back to shooting a ton of slugs again. How committed are you to shooting them is what you have to ask yourself and your wallet.

 

[pkita99]

Thanks to everyone for the feedback. 

I got decent groups with the hybrids around 950fps on the Maverick compact. Going faster just opened up the group with the tune I had. My Impact compact barrel kit will be in this week so I’ll start test that rifle too.

Ya I was suspecting i was shooting them a bit too slow. Will try to get the reg up to get them flying faster. 

 

[pkita99]

What size did you buy? If the slugs aren’t the right size for your barrel they simply won’t shoot well.

The rifle is .25 cal and I got the .25 cal FX hybrid slugs. They should be the right size.

 

[Vetmx]

Thanks to everyone for the feedback. 

I got decent groups with the hybrids around 950fps on the Maverick compact. Going faster just opened up the group with the tune I had. My Impact compact barrel kit will be in this week so I’ll start test that rifle too.

Ya I was suspecting i was shooting them a bit too slow. Will try to get the reg up to get them flying faster. 

They will shoot at 885fps, trust me. So your 900 isn’t too slow. You just have to put in the work.

 

[RALPHK]

My new impact with the 700 Superior barrel doesn’t like the hybrids at any speed I have tried yet, but it likes the NSA 33.5 in the low to mid 900’s. 
One thing I have found is that most slugs have a ton of lead flashing that if not washed off and lubed will leave this crap in the barrel and hurts accuracy.

Furthest squirrel to date was 184 yards sitting in my truck over the mirror, my favorite shooting position.

 

[qball]

Forget pricey hybrids, if you got superior liner then try 29grain NSA, cheaper, shoots better, cleaned and lubed on top of that so you don’t have to clean your barrel at all. Also you don’t need 900fps, try 800FPS and up you will be pleasantly surprised. Thanks to the high BC the drop is only around 1mil or 2-3 inches at 100 yards compared to 900fps.



because you got shorter barrel you probably want to set your reg at 140-150 and close your valve to just below 3 lines. you want to valve close before the slug leaves the barrel so a hot but short burst of air works the best. It will be quieter and more accurate, again don’t chase just speed. 





EDIT: I ran the stability calculator with the wrong twist rate, the superior liner with twist rate of 1:23 would need minimum speed of around 880FPS to START to get good accuracy. 

 

[Vetmx]

I have sized quite a few slugs starting at .254, .253, .252 and .250 with not so impressive results. The only slug that showed promise right out of the box besides the Hybrids is like qball said is the NSA 29gr. If you want your starting point with the 29gr slug to be over 900fps, your 25gr pellet speed will have to be in the 970’s.

 

[Keyman62421]

Yep, the NSA 29 better than hybrid but it's been too cold to really test them correctly. I'm not pumping them fast enough.

 

[qball]

Yep, the NSA 29 better than hybrid but it's been too cold to really test them correctly. I'm not pumping them fast enough.

Assuming you got superior barrel which as 1:23 in .25 barrels, what speed and what group sizes are you getting with the 29grain? According to the stability factor calculator based on the information I have on the barrel and the 29 grain slugs you need to shoot them at minimum 850FPS to have the minimum stability factor of 1.5. However we all know we don't get 100% of FX's advertised twist rate because of the smooth lands, most likely 880 or 900 is where you will start to see good accuracy, just my theoretical guesstimate. 



I need to correct my first post because I ran the calculator in error with my superior heavy's twist rate not superior OP has. The 29 grain might not be the best slug for OP with 500mm barrel because the minimum speed of 880FPS the superior barrel needs to shoot the 29 grain. Definitely give the 26 grain a try with superior starting around 880-900FPS range. I don't have the twist rate for the 500mm superior, in the past the .25 barrels all had the same twist rate so I'm assuming the same twist rate of 1/23 for all .25 superior barrel. Can someone bust out the marker and tape measure in case I plug in the wrong info into the calculators again?




With superior heavy's 1/18 twist rate in theory I can shoot them even below 600fps and still have a stable or accurate bullet. This I can attest to because I've gotten sub 1 inch group at just below 800fps before when messing around with the power dial. 

 

[pkita99]

Yep, the NSA 29 better than hybrid but it's been too cold to really test them correctly. I'm not pumping them fast enough.

Assuming you got superior barrel which as 1:23 in .25 barrels, what speed and what group sizes are you getting with the 29grain? According to the stability factor calculator based on the information I have on the barrel and the 29 grain slugs you need to shoot them at minimum 850FPS to have the minimum stability factor of 1.5. However we all know we don't get 100% of FX's advertised twist rate because of the smooth lands, most likely 880 or 900 is where you will start to see good accuracy, just my theoretical guesstimate. 



I need to correct my first post because I ran the calculator in error with my superior heavy's twist rate not superior OP has. The 29 grain might not be the best slug for OP with 500mm barrel because the minimum speed of 880FPS the superior barrel needs to shoot the 29 grain. Definitely give the 26 grain a try with superior starting around 880-900FPS range. I don't have the twist rate for the 500mm superior, in the past the .25 barrels all had the same twist rate so I'm assuming the same twist rate of 1/23 for all .25 superior barrel. Can someone bust out the marker and tape measure in case I plug in the wrong info into the calculators again?




With superior heavy's 1/18 twist rate in theory I can shoot them even below 600fps and still have a stable or accurate bullet. This I can attest to because I've gotten sub 1 inch group at just below 800fps before when messing around with the power dial.

Thank you for this info. Very interesting. What stability factor calculator are you using if I may ask? I wasn't even aware there was something like that available. 

 

[qball]

Yep, the NSA 29 better than hybrid but it's been too cold to really test them correctly. I'm not pumping them fast enough.

Assuming you got superior barrel which as 1:23 in .25 barrels, what speed and what group sizes are you getting with the 29grain? According to the stability factor calculator based on the information I have on the barrel and the 29 grain slugs you need to shoot them at minimum 850FPS to have the minimum stability factor of 1.5. However we all know we don't get 100% of FX's advertised twist rate because of the smooth lands, most likely 880 or 900 is where you will start to see good accuracy, just my theoretical guesstimate. 



I need to correct my first post because I ran the calculator in error with my superior heavy's twist rate not superior OP has. The 29 grain might not be the best slug for OP with 500mm barrel because the minimum speed of 880FPS the superior barrel needs to shoot the 29 grain. Definitely give the 26 grain a try with superior starting around 880-900FPS range. I don't have the twist rate for the 500mm superior, in the past the .25 barrels all had the same twist rate so I'm assuming the same twist rate of 1/23 for all .25 superior barrel. Can someone bust out the marker and tape measure in case I plug in the wrong info into the calculators again?




With superior heavy's 1/18 twist rate in theory I can shoot them even below 600fps and still have a stable or accurate bullet. This I can attest to because I've gotten sub 1 inch group at just below 800fps before when messing around with the power dial.

Thank you for this info. Very interesting. What stability factor calculator are you using if I may ask? I wasn't even aware there was something like that available.

https://bergerbullets.com/twist-rate-calculator/

all science and math have been perfected in the powder burner world, airgunners are just starting to use the wealth of knowledge PB world has that directly applies to slugs. With the stability calculator you will know where to start your tuning or whether it would even work or not. Keep in mind FX’s super smooth barrel’s twist rate is not absolute because lack of “bitting” land so I like to see minimum stability factor of 2-2.5 as my starting point.


Ideal stability factor is between 1.5 and 2 but over 2 or even 3 is fine. You MIGHT get more spin drift. 

 

[pkita99]

Yep, the NSA 29 better than hybrid but it's been too cold to really test them correctly. I'm not pumping them fast enough.

Assuming you got superior barrel which as 1:23 in .25 barrels, what speed and what group sizes are you getting with the 29grain? According to the stability factor calculator based on the information I have on the barrel and the 29 grain slugs you need to shoot them at minimum 850FPS to have the minimum stability factor of 1.5. However we all know we don't get 100% of FX's advertised twist rate because of the smooth lands, most likely 880 or 900 is where you will start to see good accuracy, just my theoretical guesstimate. 



I need to correct my first post because I ran the calculator in error with my superior heavy's twist rate not superior OP has. The 29 grain might not be the best slug for OP with 500mm barrel because the minimum speed of 880FPS the superior barrel needs to shoot the 29 grain. Definitely give the 26 grain a try with superior starting around 880-900FPS range. I don't have the twist rate for the 500mm superior, in the past the .25 barrels all had the same twist rate so I'm assuming the same twist rate of 1/23 for all .25 superior barrel. Can someone bust out the marker and tape measure in case I plug in the wrong info into the calculators again?




With superior heavy's 1/18 twist rate in theory I can shoot them even below 600fps and still have a stable or accurate bullet. This I can attest to because I've gotten sub 1 inch group at just below 800fps before when messing around with the power dial.

Thank you for this info. Very interesting. What stability factor calculator are you using if I may ask? I wasn't even aware there was something like that available.

https://bergerbullets.com/twist-rate-calculator/

all science and math have been perfected in the powder burner world, airgunners are just starting to use the wealth of knowledge PB world has that directly applies to slugs. With the stability calculator you will know where to start your tuning or whether it would even work or not. Keep in mind FX’s super smooth barrel’s twist rate is not absolute because lack of “bitting” land so I like to see minimum stability factor of 2-2.5 as my starting point.


Ideal stability factor is between 1.5 and 2 but over 2 or even 3 is fine. You MIGHT get more spin drift.

ball - thank you! will give this a go and see how it does. I just had an NSA variety slug pack come and will give them a go. 

Appreciate all the help!

 

[Cloudrider]

NSA and other Slugs come pre lubed, FX Hybrids don't. There are Ernest Rowe vids where he cleans Hybrids to remove the flashing and lubes with silicone. I don't clean but i lube with silicone and get pretty good results. Sure wish I had my sideshot mounted last week, I center punch the chest of a pigeon at 176 yards with 25 cal Hybrid leaving the muzzle at 950fps. 

 

[Mikelo123]

I chased slugs for a bit in the same gun you are BUT there is something to be said about the 33.95 JSB pellets.....They shoot like a laser and great BC. Grab a slug A liner and some MK1 33.95 and you will be even more impressed.....

For the Hybrids it took me to 940 to start to see some accuracy and at 965 accuracy peaked....Not JSB accurate but not bad either.

Also try cleaning and lubing and single loading.....Made a difference for me!