Tuning FX Impact M3 35 cal power destiny

[7Green]

81 grain Jsb's

1st reg 180 to 200 bar, Huma 2nd stage regulator, sekhmet digital gauges. 9 gram brass hammer weight, with two washers, and the new 19.26 gram hammer. This shows the combined weight of the hammer is critical. The couple 660 fps ones were me screwing with the micro and accidental double feeds. It is quite picky at max settings. I get about 3 to 3.1 max on the micro with this setup. Very consistent speeds though when set right.

134 bar 900 fps peak

140 bar 912 fps peak

145 bar 921 fps peak

150 bar 926 fps peak

156 bar 928 fps peak

168 bar 932 fps peak

174 bar 909 fps peak

 

[7Green]

2nd reg set at 164 bar yielded right at 928 to 930 fps with 81 grain Jsb's. I have some more ideas to try, but I am pretty happy with this setup now.

I would have tried the 79 grain And 93 grain NSA's in .356 and .357, but I forgot them...doh.

This setup yielded a peak of 858 fps with NSA 93 grain .357s.

 

[7Green]

For my next idea, I purchased some 3/8" diameter Tungsten inserts. Idea would be to epoxy them inside the hammer and drill a hole in them for the valve rod.

https://www.amazon.com/gp/aw/d/B0791MBL9F?ref=ppx_pt2_mob_b_prod_image

 

[7Green]

A quick little recap for anyone freshly looking at the post.



It appears you need a combined hammer weight of at least 28 grams to hit near the spec of the gun. The tip of your C1 also needs to measure 5.5mm off the of gun. 



More hammer weight may be needed to go beyond the guns spec. 

 

[ram2jeep]

thanks 7green! I just got the .35 back a few hours ago from FX service! Getting all my stuff back on it and then off to some testing this week.

Nice to have it back as squirrel season starts tomorrow!!!!

 

[7Green]

Yeah, I got tired of taking it apart and puting it together. Past couple days, I ended up just leaving the scope, scope rail, and cheek rest off of it for testing. 

I am debating if I put it back together now or try some other ideas. The Tungsten inserts are really perking my interests. I may be able to get more micro adjustment range by using them with a modified hammer. I have 3 hammers now, so I can mess around. 

An 1/8 oz of Tungsten weighs around 3.54 grams. It is very dense at around 19g/cc, so an 1/8 oz is quite small.

Question is would a 30 to 32 gram hammer open the valve at say 190 bar. 

You can see in my post that the hammer couldn't open the valve enough past the 168 bar peak and the velocity fell.

The 25.12 gram combined hammer weight from the factory yielded around 893fps at 130 to 135 bar and couldn't open the valve enough beyond it. It should be mentioned that with todays setup at that pressure range I hit right around 900 fps, as the heavier hammer is slightly more efficient I guess.

A combined weight, 28 gram hammer yielded 926 fps. 93 grain NSA's hit mid 840's fps if I recall correctly. This was in the 150 to 155 bar range before velocity dropped off.

Todays hammer weight of 29.12 grams peaked at 932 fps with 81 Jsb's, but really shined with the 93 grain NSA's, hitting 858 fps. These speeds occurred in the 165 bar range.



In summary, 4 grams of additional hammer weight yielded an addition 30 bar of pressure and around 35 to 40 fps in velocity. In theory, another 4 grams may be enough to open my Huma regulator at 190 to 200 bar. What I don't know is at what point does the weight of the hammer peak or become too much. 

 

[7Green]

@Ram2jeep: Where did you get the level that attaches to the fx scope rail?

 

[7Green]

Here are my next thoughts. Below are Tunsten spacers in various sizes. From about 5.5 grams to 14 grams. Thought is to drill out the hammer enough to recess what ever size inside and epoxy it in. Maybe I will use probed 2000 gun bedding, since I have some laying around. From there, drill out the center hole to slide on the valve rod. They fit perfect inside the hammer.



The hammer void is approx. 20mm deep inside. If I drill that portion deeper, I could set the weight deeper inside and possibly allow more range of adjustment on the micro dial. It will definately be a trial and error type of project, but it sounds promising.

 

[7Green]

If I can't drill the tungsten, due to how hard it may be; I may try and see if I can get all of the parts (hammer, hammer weight, and washers) made out of brass. I am pretty sure the parts are made of soft steel, as they are magnetic. If so, steel has a density of 7.75 to 8 g/cc. Brass has a density of around 8.4 to 8.75 g/cc. 

I am trying to develope a combined weight of 33 to 35 grams.

 

[ram2jeep]

@Ram2jeep: Where did you get the level that attaches to the fx scope rail?

That came from Utah Air my friend. I also have one from EagleVision that screws into the scope ring.

 

[7Green]

Barely a scratch. Hmm...

 

[7Green]

I have the eagle vision that screws in. That just looks cleaner.

 

[ram2jeep]

It doesn't stick out the side and is held in by the two scope rail screws in the rear.

https://utahairguns.com/airmarksman-fx-impact-scope-rail-bubble-level/

 

[7Green]

Tested the .79's Nsa's. My gun like the .357's the most. It is really accurate with the 93 grainers. Pretty much what ever I point at gets hit. I will have to try groups one day, but I know I can hit a turkey head at 50 easy. My kid was spinning a water bottle at 50 every shot. Here are some speeds for the 79 grainers and 93s

 

[7Green]

50 yards with a 93 grain Nsa and I can split the foam from a jsb tin, laying flat on the ground none the less. 

 

[7Green]

Well the 93 grain .357 Nsa's are sweet. My kid smoked a rabbit at 96 yards with them using the aforementioned setup. 

 

[ram2jeep]

You have been putting in some serious work and it is paying off. I'm glad those NSA's are performing well for you. We have some rain this morning but it's supposed to clear up this afternoon. Scott, from FX in service, tuned the .35 to shoot the JSB pellets and on the repair sheet had an average of 864fps. I'm going to see how these group at 35,50 and 75 yards. Depending on how they do will determine my next steps.

 

[ram2jeep]

50 yards with a 93 grain Nsa and I can split the foam from a jsb tin, laying flat on the ground none the less. 

That is really really good to be able to do that with the slugs!

 

[7Green]

It seems like the faster I have pushed the Nsa's the more accurate they have become. When I first started, they were hit or miss and usually a couple inch or bigger groupings at 50 yards.

I don't know if it is because of all of the rounds I have shot, which polished the barrel some or if the speed stabalizes them. What I do know is they are quite accurate. I was instructing my boy to aim at the ends of the water bottle to flip and spin it, plus it would be a harder target. He never missed at 50 yards. Then later, we see a rabbit at a ranged 96 yards. I estimate 3.5 to 4 mils drop and relay it to him. He proceeds to drill it perfectly. He is 11 by the way. 

I have no doubt the Nsa's will shoot if you find the right tune and spend some time with them.

 

[ram2jeep]

I have about 4 boxes of the 79 and 5 boxes of the 93gr. With where my tune is currently it should be no problem pushing the 79's at higher speeds. Looks like Thursday is range day as hunting season opened today here in MA!

I saw a few squirrels this morning but they were extremely cautious and kept jumping around; tomorrow is another day.

Awesome that you have your son out with you as I bring my 12 year old daughter with me when she's not in school. She has a Dream-Tac in .25 as her own rifle but she will be moving up to big bore hopefully later in the season.