I was shooting NSA 26.8, 29.5, H&N 30, and 34 out to 100yds But gun was harsh. didn't sound good and was max out. Would like to try all with this tune. Sometimes lower speeds have great accuracy.
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FX FX IMPACT M4 SNIPER PELLETS & SLUGS .25 cal
- Thread starter Irish shooter
- Start date
Congrats on your new Impact, they can be some amazing fun. I have a 700mm Impact MK2 in 25Cal that I use for slugs. It is fully built and pushes Nielsen 34.9g slugs about 990-1005fps currently. Most people will find that you really end up setting up your rig for either slugs or pellets, not both. Especially at the long ranges you are after, even if you were to find a tune/pellet/slug combo that shot well together your zeros will be wildly different.
Some observations on your pellet tune not doing well past 50 yds. Pellets of all design have an inherent maximum fps before they start doing erratic things during flight. They can suddenly veer off to one side or spiral like they are trying to win your local Air Show. And this issue can really start to show up past 40-60yds. For example my M3 Impact Compact is tuned to launch 22Cal Hades at about 1020fps for pesting. It shoots tiny groups out to 50-55yds then the groups open up like crazy. FPS is only one aspect to consider with pellets, the air charge can disrupt pellet flight as well. If you dont have a well balanced tune you can push the pellet off course right out of the muzzle, even at lower speeds.
For slugs I have been loving Nielsens in 4 different Cals in many different pcps and barrels. If I were you, I would tune my Impact to stack 34g Pellets at 850-880fps. You should be able to do some good pesting out to about 100yds with those. Then I would try some lighter slugs with the same tune, something in the 26-30g range. That way you can push the slugs faster without messing with your pellet tune. You will really have to dial in your drops and zeros to have any chance of switching quickly between the two, but it can be done. One last note, dont be discouraged or disappointed if you cant find a good slug combo or cant reach as far as you want. A 200yds Slug pesting pcp is a unicorn, not the norm. Most people will see 2-4moa with slugs, especially past 100yds.
Some observations on your pellet tune not doing well past 50 yds. Pellets of all design have an inherent maximum fps before they start doing erratic things during flight. They can suddenly veer off to one side or spiral like they are trying to win your local Air Show. And this issue can really start to show up past 40-60yds. For example my M3 Impact Compact is tuned to launch 22Cal Hades at about 1020fps for pesting. It shoots tiny groups out to 50-55yds then the groups open up like crazy. FPS is only one aspect to consider with pellets, the air charge can disrupt pellet flight as well. If you dont have a well balanced tune you can push the pellet off course right out of the muzzle, even at lower speeds.
For slugs I have been loving Nielsens in 4 different Cals in many different pcps and barrels. If I were you, I would tune my Impact to stack 34g Pellets at 850-880fps. You should be able to do some good pesting out to about 100yds with those. Then I would try some lighter slugs with the same tune, something in the 26-30g range. That way you can push the slugs faster without messing with your pellet tune. You will really have to dial in your drops and zeros to have any chance of switching quickly between the two, but it can be done. One last note, dont be discouraged or disappointed if you cant find a good slug combo or cant reach as far as you want. A 200yds Slug pesting pcp is a unicorn, not the norm. Most people will see 2-4moa with slugs, especially past 100yds.
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A very informative post thanks for this. I think for me I would like to shoot between 70 and 100 yards. Closer than this I don’t think works for me on flat open fields trying to get close enough to birds etc. I will have to push the heavy liner before I shoot slugs will order this asap. Will also upgrade my hammer while I’m at it I think.
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If you try the lighter slugs you probably dont need the heavy liner, and I doubt any pellets will shoot decently through one anyway.
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Maybe but not necessarily. The faster twist will over spin pellets, and might over spin the really light slugs. Extra rpm isnt really solely a bad thing; but when there are projectile defects they will spiral. Virtually all pellets and even slugs have plenty of defects so they will be more sensitive to over rpm compared to a jacketed powder burner. The speed you push a projectile also contributes to rpm.
I would at least try the light slugs in your standard liner before buying a heavy version. My M3 Impact does really well with light slugs and pellets at the same tune with a standard liner. We have tested several 22Cals and have had similar results across the board. Now if you want to only shoot 34g and heavier slugs, you will need to try the faster heavy liner. My MK2 is on the fence, and I am probably going to go back to a standard liner in the future since my setup really likes the mid-weight slugs. I have a bunch of the H&N Heavies in 42g I think that I was planning to use with the heavy liner but lucked out with the Nielsens. It can be very time consuming and costly to find a tune and slug that will perform well in your pcp, and many people never get there. So when mine settled in I opted to leave things alone and buy a used Impact for a pellet rig.
If you cant get Nielsens where you are, the FX Hybrids--H&N--Zan slugs are some other proven high performers available in light-mid weights.
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I have purchased the following slugs to try on my m4 soon:
- .25 ZAN Projectiles Air Rifle Slugs / Pellets - 28gr,
- .25 ZAN Projectiles Air Rifle Slugs / Pellets - 26.5gr,
- .25 H&N Grizzly Slugs 31gr
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Just read your post , very interesting you obviously know your stuff ,I will be back out to try my Fx M4 sniper in FAC /.25 soon .I was getting tight groups with 34g JSB pellets at 850 fps /50yds tried to increase fps and messed it all up .I will try once again I have reg now set at 120bar , macro 8 and micro 3 .
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After reading the useful information regarding settings /pellets and slug alternatives and barrel liners ,can anyone tell me why the superior liner STX supplied with the fx impact M4 /.25 FAC has a pellet port and a slug port machined into the breach /brass inserted end of the barrel if you require a dedicated slug liner in order to successfully use slugs .
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98% of my shooting Prairie dogs is with slugs. Impact M4 & Wildcat M3. Both Compacts. With short barrel not sure if 1:16 slug barrel would make much difference. I haven’t experienced any problems shooting slugs. Most of which is within 100 yards.
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its to my knowledge an understanding fx Hybrid slugs are designed to use in the superior stx liner
i am waiting on my m4 i also purchased 26g fx hybrids and Neilson's 26g slugs
I'm thinking once you go to a heavier slug is when you need to change to the heavier barrel and faster twist.
i will be shooting out to 50-75yds and will let you guys know how it goes.
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Have just worked out you are also on the M4 Facebook group.
Was out last night looking for a tune for NSA slugs in my M4. I’ve got the 26.8 gn slugs. Ended up with 120 on the reg, 16 macro, I think it’s 3.5 on the micro and valve set just on 4. Getting 960 fps and for a 5 shot group at 50m 4 shots inside .800 of an inch and the 5th shot another .500 inch away.
Showing promise but need to go and test again for repeatability and hopefully for improvement. This was with pellet port engaged not the slug port as I’m not sold on how much benefit it will get. Might test that out once I’ve got this tune sorted out.
Shot count looks to be around 75-80 per fill on the current setup.
Hope that helps.
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Plan on doing some shooting today
As ups should be here by 10 am
Sounds like your close
I have the same slugs and some hybrid 26g
Well see how it goes
From what I been reading the slug port is good for
Another 15 -20 fps vs the.pellet port
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Thanks for the input I will have a go today to get some where close to where I need to be .
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I’m hoping I can get away without using the slug port and keep it in a fashion that hopefully will allow a power wheel decrease to find a good pellet tune as well.
Not sure if it’s possible though but time will tell.
Ive ordered some more NSA and some ZAN slugs in the 26.8 ish weight range for more testing. Just not sure when I’ll be able to get back out to test as weather looks pretty bad over the next week or so.
That being said I’d be comfortable chest shooting rabbits with the NSA tune as it is so a clear weather gap might see me hunting rather than testing.
Will see.
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I think you should try the slug port. Just one screw to loosen. I’m also shooting JSB Diabolo 33.95’s along with NSA 29.
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I have just found a sweat spot with the JSB heavy’s in 34grain it’s 880fps and at 50yds it was down to 1/2” groups ,tried the zan 33g and the H& N grizzly on the same settings and they were running at 900fps point of impact out slightly .I think you could dial down on macro to get away with 26grain slugs as the ,26grain hades were pushing out 920fps maybe not much in it .I kind of think it would just be better to find a pellet or slug they like and stick with it and dial in for hold over at various ranges using a ballistic app .
i found I had to run the fx at 125bar reg pressure to get the 34grain JSB to 880 fps ,16macro,4.5micro and about 4.5 on valve.Yes maybe need to try slug port
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Good to know. Thanks.
Will see how I go next time the wind is quiet enough to rule it out. I’ve ordered some more ZAN and NSA to do some proper testing. FX Hybrids might be off the table as supply here has dried up. That being said Hybrids are like 2.5x the price of equivalent NSA or ZAN.
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Yes ,it certainly is a learning curve and I noticed my reg pressure when I got home was 130bar once it had settled .Maybe the lighter slugs is the way to go and hopefully if we get a sweat spot for the 34grain JSB heavy’s the settings will accommodate those lighter slugs .
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