FX Impact X (AMP Reg) 700mm .30 accuracy optimized FPS

935-950FPS 44gn reg 135b with my power tuned my RMAC setup. at 1015FPS 155b 1/2” @ 70y I use this speed if really windy conditions.

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Wow, Ernest... that is impressive. My Impact X has the AMP reg, but is stock with no further power mods, and won't do anywhere near that. I just did some testing yesterday, and the highest velocity I could get was around 915 fps with my reg at 150B, VSA all the way out for no limiting, and the HST adjuster fully left against the stop of the housing for MAX fps. I did find that at 50 yards, I was getting my best groups (sub-half-inch) at about an 888-890 fps average. However, I had a lot of consistency issues it seemed, then I found my HST adjuster screw was moving, and the adjuster was changing position as I shot. I'm putting some blue Loctite in the threads to dry, then I'll reinsert the screw to see if it's still adjustable, but will hold position for better consistency. I don't want to run it at a fully preloaded HST just for wear and tear reasons. I don't need, nor do I have the range (shooting distance) for too much power. I want supreme accuracy.

Well I got a chance to do some follow-up tuning based on my earlier sampling. A little Loctite Quickstix 248 applied to the threads of the HST adjuster screw seems to have solved the drifting of the HST adjustment, so consistency is better now. Hopefully it will stay consistent as shooting continues.

I have always thought the mid-860 to mid-870 fps range was the sweet-spot for the .30 cal 44.75 gr JBS pellets, but I confirmed this rifle loves the low-890 fps range. I was REALLY impressed with the extreme spread and standard deviation at the settings I tuned it to. I'm hoping the group size can be reduced a little more as the guy behind the trigger improves, but I don't think there's a lot of room for improvement in real world results where the velocity consistency is concerned. What I don't have yet is a shot count before things fall off regulator, but I'll take accuracy and consistency over shot count every time. Anyone else setting things up in the lower 890 fps range? Remember, this is an Impact X, not the Mark II.

Here are shots of the LabRadar data pages (modified for more complete documentation of the tuned settings) showing where I left it, and where measurements are take:

Loctiting the threads was straight-forward. No spring-propelled parts to look for. I missed the question before it was deleted, but the output is just the LabRadar output file, edited to contain more data. Hopefully it will work as a template for tuning work. This was the wife's rifle. Mine is still at factory settings. Definitely need a way to keep the tuned settings data straight. I'm hoping I can get similar ES & SD on mine. I also updated the template to include zeroing weather, as well as target distance. I actually set the LabRadar to clock the final velocity at 48 yards vs the full 50 yards as it was hit or miss (pun intended) as to whether it would successfully clock the pellet as it hit the target.

Yeah, it appears I nailed the consistency portion of the tune. However, if I understand the physics correctly (feel free to correct me, as I'm still learning a lot about this extremely variable and interactive process of Impact tuning), you can have two very different harmonic vibration conditions, each of which can produce the same great velocity consistency, but due to the differences in barrel oscillations, one can be noticeably better in group size than the other. This is why accuracy and tight groups are not solely dependent on a given velocity, no matter how consistent.

However, with these group sizes, I don't think it's far from about as good as it will get. If you consider a 0.5" group at 50 yards the 1-MOA standard, which the Impact is know to have the ability to easily exceed, then you reduce my group sizes a little by removing my lower than competition-level holding skill and trigger control, I think even the 10-shot group would be sub-half inch. For now, it's time to shoot this thing and see how she holds over normal use.

I think I'm going to follow a slightly different sequence of operation when I tune mine. Plus a little more testing documentation, vs just good results documentation.

If you're a quantitative technician-type personality like I am, this tuning stuff is almost as much fun and rewarding as the general shooting! A rifle to tune, a few tins of pellets, a CF bottle of air to tether to on the shooting table, a LabRadar, and some clean target sheets. All the makings of some quality time (HOURS of it) in my own little corner of the world.

The below pictures actually show the setup from my first round of tuning. For the data collected this last round and published above, I didn't use the machine rest, but shot off the bipod and rear bag, so the results would be more true to my real-world conditions.

Thanks very much for the info. I was just about to ask about target distance (I did see the V48), but I see you included that here.



The consistency thru the string of Ke across the ranges also impressive!



I don't suppose you've run the same test on Impact X .25 with JSB Exacts (25.39gns), have you? I just looked up the price of those LabRadar units, too much for me but I sure like the data!



Looks like you also may have a little more power left on HST too!

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Unfortunately, both Impact X rifles are .30 cal right now. 99% of the time, if I have something that is capable of multiple configurations, I never get around to using more than the primary configuration I purchased initially. I've usually looked at multi-configurability as a marketing tool, but this may be one place where that changes for me. I'm considering adding barrel kits here. I'd like .25 cal for the cost savings on the pellets from .30 cal, and I'd like .22 cal to see if we can try out FT competitions. I have to think in terms of what my wife will enjoy as well, since I finally got her to join me in this shooting sport. To tell you how it is... last Christmas, her gift to me was letting me get her an Impact X of her own. I figured this would help keep her involved with me and shooting. Plus, I make out here in multiple ways, so it was a wonderful "gift" for me. The only thing you have to watch out for when buying your wife or girlfriend a gun is sooner or later, they start thinking it's actually theirs. And by all means, never EVER buy BOTH your wife and girlfriend a gun... you WILL get shot with at least one of them, if not both.

As for the power left on the HST adjuster, you are correct. I specifically tried to tune for lower hammer spring striking force to reduce inherent vibration. I can't help but think it had to help, but time and experience will help me answer that question.

Hello, has anyone tried slug liner 700mm for 44 and 50 pellets ??

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I have no slug or slug liner experience, but IF i understand correctly from those who do and have posted about it, you can shoot pellets from the slug liners with reasonable accuracy, but not the other way around.