Picked up 33.5 , 36.2 and 38.5 NSA slugs to try out in my new M3. What speed would be a good place to start with each pellet. I see a lot of information for the .22 cal and .30 cal but not much information for the .25 cal.
Tuning NSA slugs in .25 cal for FX M3
- Thread starter F-classmike
- Start date
My results are it depends on the barrel. I’ve seen 950ish good with the 33.5’s, slower with the 36.2’s, and my gun didn’t like the 38.5’s. Might need a Superior Heavy liner with the 38.5’s. My best so far has been the 34.9 grain NSA slugs at 955. I’ve had a blast tuning the Impact, the whole process for me has been around more than just speed as the gun will tell you where it’s accurate. It’s more of incrementally bringing the regulator up, balancing the hammer spring along the way to see when it needs more reg, and leave the valve open til you need to fine tune the groups.
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My M3 25 cal. may be delivered this Friday. Also have a Superior Heavy liner coming too. What barrel and barrel length do you both have?
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My M3 has the 600 mm superior liner. With the factory tune shoots JSB Exact Kings great at 890 FPS. If I switch over to NSA 36.2 without changing anything they will fly at 762 FPS. The 36.2 NSA groups are larger then the JSB pellet groups at 50 yards. I tried bringing the rear regulator up to 105 bar and got the 36.2 pellets up to 800 FPS but the groups were about 1” at 50 yards. I wanted to switch the barrel over to the larger transfer port but couldn’t slide it out . I didn’t want to damage anything so brought the regulator back down to 100 bar which is where it was when I started. The velocity and groups with the JSB pellets were the same as they were before changing settings. Most 5 shot groups at 1/2 “ or less at 50 yards with the JSB pellets. Occasionally one hole less then 1/4” wide.
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26 and 29 grain flat base will probably work the best in the superior liners even at a bit slower speed. If you want to shoot slugs then just get the superior heavy and don’t waste time and money.
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