Tuning Smaller caliber for FX Impact M3 .35 cal

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falconhover

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Apr 18, 2021
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GA, United States
Hey guys,

So I have a fx impact m3 .35 cal to be shipped soon to hunt wild hogs with but still like to hunt small game. So I ordered .25 cal barrel kit. I’ve seen where this can now be done easily and double checked with FX that this can still be done with M3. They affirmed but mentioned that I would not be able to adjust speed down much. So sounds like I will be limited to slugs more vs pellets that require lower speeds or at least heavier grain? I don’t like the idea of being limited with the new quick tune system. Anybody have experience with results of lower calibers and .35 cal impact?



thanks!
 
From my discussions with FX on converting a Lower caliber M3 to the 35, the stock as factory delivered 35 cal has 2 additional weighted washers added to the hammer to get the power up enough. 

So to convert the 35 to a lower caliber and to reduce speed to a more acceptable adjustable range you would need to remove said washers

Much like the 25 cal and 30 cal Maverick have 2 different hammer weights... 25 cal is 11 gram and 30 is a 13 gram IIRC
 
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If FX gave you the information I would go by what they say. The .35, as smokeonbro55 has stated, has some different internals to push the heavier pellets/slugs.

I have the M3 in .35 and will be doing the same thing as I have 500mm, 600mm and 700mm barrels in .22 and .600mm in .25. I'll start with the numbers for the factory tune and work from there to see what numbers I get. 
I would start with factory tune for the M3 and work from there...
 
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Ok, I just converted over to .25 and did what Ernest Rowe did and got similar results with the M3. I left the regs alone and just used the macro wheel and the valve adjuster and was able to to shoot the FX hybrids from 1058fps down to 685fps. The range is significant and you will be able to fine tune for your specific pellet/slug. 
I have a bunch of the hybrids so I'll start with those and move my way up to the NSA's/Varmint Knockers. Trial and error are the keys to tuning, especially when the M3 has so much room for change.
 
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Thanks for the responses guys! So UA told me that .35 cal converted with just .25 cal barrel and pin probe would be smokin even for a 33 grain pellet but smaller hole on barrel with dual hole transfer port might help. I mentioned Ermest’s video and he said that his impact is not stock and highly modified which makes things look a lot easier. I had also asked same question to fx and they said that I can buy internals to convert. But I don’t want to break down gun every time I switch. But I am conflicted now with ram2jeep’s results. Leaning more towards keeping my .25 cal impact mk2 and adding .35 cal to my arsenal and just have have both 
 
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I'm not sure if you already have the barrel kit or not but trial and error. I wasn't looking for much reduction in speed but as soon as I started adjusting the valve, turning in, it was exactly like Ernest Rowe's. Be exactly I mean the speeds decreased from the 1050's down to 685fps. Keeping all things the same except for the valve and utilization of the macro wheel. Turning the macro to number 1 with the valve screwed in dropped the speed significantly. 
I own a MK2 as well but don't like the idea of being limited to keeping my M3 only a .35 when it should be able to change calibers.

Also to note that you were told Ernest M2 in .357 was modified and that makes it easier for him but then why would he put out a series of videos showing and explaining the process for us to change calibers too; he went through all the calibers as well.
 
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Put it this way, I will more than likely sell my M2 now because of how easy it was and the power differential. The .35 basically comes with all the modifications you need to shoot heavy slugs or pellets, not that the lower calibers can't but you need to add the slug kit to reach maximum power: power doesn't equate to accuracy.

It's funny though because even in the FX literature it states to reach the ft/lbs, even in the .35, you need the power kit but I have yet to see one for the .35. I could be reading it incorrectly but it's in there. My .35 reached and passed the ft/lbs but accuracy at 100yds was not great with maximum speeds so I need to lower the fps to tighten up the groups for hunting. 
 
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Been through this and it took quite a bit of back and forth with the dealer and FX Tech Support. I have a .35 that was converted to .22 by the dealer. While it could shoot the smaller caliber at any intended velocity, it did not have any adjustability at the micro or macro adjusters. We tried using the .22 Sniper stronger valve return spring, but still. not reasonable adjustability. Eventually I pulled apart the hammer assembly and found a few differences of note. The hammerseat and hammer are different as the hammerseat has the Delrin attached vs the hammer, but don't worry about that. For me the key was that the spring was extra tensioned with two spacers. With those in place I couldn't get the hammer pre-load low enough to do anything other than a massive whack to the hammer assembly. So, try pulling those out and I bet you'll be able to use other calibers, It's not identical to what the factory specs would be given the hammer and hammerseat differences, but it works fine. I also haven't been able to try this with the lighter valve return spring, so you may need to turn in your valve adjuster. Hope this helps. 
 
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wyfly said:
HI folks,

I'm looking for any updates from folks who have reduced their .35 down to .25. Still working well?

Did you make the spring and rubber ball mod to the valve adjuster like Ernest Rowe suggests? Where did you get the ball?

Anyone change the hammer spring or spacers? Or just the pellet pusher?
Click to expand...
Bumping this post, as I am considering doing the same; buying a 35 and converting to 25
 
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wyfly said:
HI folks,

I'm looking for any updates from folks who have reduced their .35 down to .25. Still working well?

Did you make the spring and rubber ball mod to the valve adjuster like Ernest Rowe suggests? Where did you get the ball?

Anyone change the hammer spring or spacers? Or just the pellet pusher?
Click to expand...
You can buy metric rubber balls from McMaster Carr. That ball is either 4.5 or 4.75mm. Huma includes that rubber ball in their valve spring kit
 
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I went down from the .35 but to .30 and kept everything as it was. The .30 is moving but fps does go down with valve adjuster and the power wheel does lower fps as well. I’m still shooting the 49gr Zan slugs at 1040 fps and love it.
I left the internals as is because we never know when FX will finally bring to us what we have been waiting for.
 
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