My takes on the new "Slug Power Kit" for the Impact

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biohazardman

biohazardman

Member
Jul 3, 2019
5,451
280
Herriman, UT United States
Well so after my screw ups;

https://www.airgunnation.com/topic/well-looks-like-i-wont-be-shooting-my-impact-for-awhile/

https://www.airgunnation.com/topic/fx-slug-power-kit-not-for-gen1-impacts/

I finally got the kit completely installed and decided to test it in the basement since the range is closed down cuz of all the fires and fire danger. So, I set up my Chronograph, put the gun on my shooting table, loaded up a magazine with NSA 36.2 .25 slugs and sat down to test this thing out. I pulled the cocking lever back and managed to get it halfway forward before there was a problem. The lever locked up. Pulled it back again and the magazine indexed so I pulled out the magazine, shoved the lever forward the slug slid in without a problem.

After a couple minutes of whats up I figured out that the thin part of the probe was allowing the magazine to index before the thicker part of the probe was in the magazine. So just a simple adjustment to make the pin shorter was all that was needed to get the gun to function correctly. However this adjustment meant that my new power kit would not even push the slug as far forward as the stock unit.

Pic shown with the adjustment necessary to get the magazine to function as compared to a modified stock unit.



So with that figured out I went ahead and chronied the gun and without any adjustments, the reg still set at at 125bar, it was 4fps shy of the 1000fps plus I got before the mod so acceptable for sure.

But lets remember I have not even tried to tune the gun yet. I have already ported the barrel and probe, drilled the valve body, cut the valve spring, added a hammer weight/spacer and installed a polish plenum to the gun prior to the install. So I was not expecting much.

Now the likely pluses for those that already have heavily modified guns;

I am pretty sure this mod will be great when using the gun in a single shot configuration as the magazine will no longer be a problem. So adjusting the depth of the seating of the projectile will definitely have an impact on accuracy and possibly a slight increase in fps as well.

Another plus especially for Gen1 owners is one now has easy access to the valve spring so many more tuning options are now available that were not before the slug kit install.

For those who have near stock guns;

You can expect velocity increases across the board and likely accuracy increases in single shot mode.

So there went a few Chinese corona-virus and smoke filled days of fun anyway. At least I was entertained for a bit so what is next.? 



So I think I will see about stiffening up this barrel a little even though it has not given me much of a problem as yet.




 
Yep. Same problem here. I had many jam until I figured it was too long. So I shorter it to cycle the mag. Now it cycle ok but it does make it shorter than stock. My impact already have the PP and huma duel TP. It was shooting about 950 without the fx slug kit. With the slug kit I got around 960. About 10 fps increase. Not the 50 to 80 fps its advertising lol. Don't believe in advertising. You will be disappointed. 
 
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This slug kit you guys are discussing is made for the guns with the new Power Plenum. I didn’t know until I went to install it. I ended up just trying the pin probe. The spacers, spring and ball that are included are specifically for that gun with the power plenum’s internal parts. If you mark and set the seating depth precisely with a sharpie, based on the original probe, you won’t have any of the feeding issues, at least I didn’t. You also need to keep in mind that the estimated gains are from a stock gun. If you already have a hammer weight, modified transfer port, spacers, springs, etc...The gains you see will obviously be less than estimated.

Have a good one. 

Stoti
 
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I think that a next possible gain comes from enlarging the valve seal hole from 6.5 to 7.2. but the Valve poppet is only 7.5 that may need to go to next up 8.0.

The rear block also the valve housing port is 7.2, without tweaking with that just enlarge the 6.5.

I cannot proof yet because nobody have parts to sell me, but some of you folks may have tried it?
 
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BigHun 
There is a topic started from member Edosan and is calling “Fx impact mods for more FPS/FPE. I think you know it because you have post in this topic before a week . You just need to read it from the begging ( if you already heave read it my apologies)

https://www.airgunnation.com/topic/fx-impact-mods-for-more-fpe/ 

Too many members of this forum made the mode you are mentioning and they shared their knowledge with us and we learn a lot .
Opening the valve seat diameter is one of the most important modes to gain speed . The first generation vs was (if I remember correct ) 5.5 mm and we started opening them at 6.3 up to 7.1 mm. Even at 6.3 the gain in speed was big .
The big secret here is to try to keep as much possible smaller the valve rod poppet seal. Right now my valve seat is 7mm and the valve poppet Seal I use is 7.55 .

As you mentioned before If you start these experiments is good to have in stock at least a second spare part . Me I reach to have 7 valve houses ( all with different modes) and 5 rear blocks . 
If this conversation was happening one month ago in my holidays honestly I could send you from one piece because I can see you can not find in the market but now is impossible . I am working for years far out of my country and nobody has access to my guns and my spare parts back to my home.

You can read this topic I post above and you can find all the possible modes. 

The biggest gain from all this mod journey is not only the power. Is the confidence you gain with your gun after you have disassembled it 100 times !!!
Personally I learn everything for my impact from this forum even before I receive my gun . Theoretically everything seems to be easy with so many informations. In action from day one I got crazy . I could not seal my brand new gun for weeks ......but after I learn by the hard way I am able to fix my impact in the field up to the trunk of my car no matter what is the leak or the problem .

As Ernest mentioned lately in his last post in this topic we catch already the power limits ( I am shooting .30 cal 65 gr nsa at 1040 FPS!!!) we need to run after accuracy and harmonics of the gun.

Sorry for the long post if I highjacked a little bit this topic . 


Best regards

Christos 

 
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More woes with the Impact! I did not like the feel when I chambered a round into the barrel. It felt like something was catching just a bit. So I pulled my new probe and put the original back in last night. 

When I got up this morning I aired the gun up, loaded up the magazine and fired a few shots over the chrony. They came out at 356- 400fps!! Whatsupwidthat? Then my chrony went into error mode on me and I found the battery was dead so figured it was just a chrony problem. Even with the new battery the chrony gave me the same numbers though so not a good thing. The gun was shooting in the thousand plus fps the night before. The last thing I did to the gun was to reinstall the old probe. It took me a few minutes before I decided to pull the barrel out, to see if there was something blocking the port, but it would not budge no matter how hard I pulled on it. So I screwed the front adapter that holds the moderator on to the shroud and barrel on put a crescent wrench on it and hammered on the side of the wrench. I saw the barrel move the tiniest bit so I kept on hammering on it until the barrel finally broke loose and I was able to pull it out by hand. I heard something fall onto the table and found a piece of lead that had been stuck in the barrel. I didn't really know what it was until I turned the gun over and the better part of a sheared off slug tumbled out onto the table.

The new probe did not keep the slug centered while moving over the slightly enlarged oval port and somehow a slug went into the port and got pressed into it. I was unlucky enough to change the probe at that exact time so I had a hard time understanding what went on. Good thing that the NSA slugs are fairly soft lead cuz it sheared pretty easy all things considered.

Edit; Installing a dual port barrel transfer port would solve the jamming issue.

Anyway velocity is back up to normal again and it is doubtful I will put the adjustable pin probe back in the gun. So all that the Slug Power Kit did for me was allow me to pull the valve spring from the inside to the outside of the gun. Which really is a pretty big thing, as now I can easily change out valve springs for tuning purposes, so in the end it was well worth the time and trouble. So I wasted a few more hours on the gun and posting about it. Kept me out of the smoke and away from the China virus it did. ;^)






 
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Well so after my screw ups;

https://www.airgunnation.com/topic/well-looks-like-i-wont-be-shooting-my-impact-for-awhile/

https://www.airgunnation.com/topic/fx-slug-power-kit-not-for-gen1-impacts/

I finally got the kit completely installed and decided to test it in the basement since the range is closed down cuz of all the fires and fire danger. So, I set up my Chronograph, put the gun on my shooting table, loaded up a magazine with NSA 36.2 .25 slugs and sat down to test this thing out. I pulled the cocking lever back and managed to get it halfway forward before there was a problem. The lever locked up. Pulled it back again and the magazine indexed so I pulled out the magazine, shoved the lever forward the slug slid in without a problem.

After a couple minutes of whats up I figured out that the thin part of the probe was allowing the magazine to index before the thicker part of the probe was in the magazine. So just a simple adjustment to make the pin shorter was all that was needed to get the gun to function correctly. However this adjustment meant that my new power kit would not even push the slug as far forward as the stock unit.

Pic shown with the adjustment necessary to get the magazine to function as compared to a modified stock unit.



So with that figured out I went ahead and chronied the gun and without any adjustments, the reg still set at at 125bar, it was 4fps shy of the 1000fps plus I got before the mod so acceptable for sure.

But lets remember I have not even tried to tune the gun yet. I have already ported the barrel and probe, drilled the valve body, cut the valve spring, added a hammer weight/spacer and installed a polish plenum to the gun prior to the install. So I was not expecting much.

Now the likely pluses for those that already have heavily modified guns;

I am pretty sure this mod will be great when using the gun in a single shot configuration as the magazine will no longer be a problem. So adjusting the depth of the seating of the projectile will definitely have an impact on accuracy and possibly a slight increase in fps as well.

Another plus especially for Gen1 owners is one now has easy access to the valve spring so many more tuning options are now available that were not before the slug kit install.

For those who have near stock guns;

You can expect velocity increases across the board and likely accuracy increases in single shot mode.

So there went a few Chinese corona-virus and smoke filled days of fun anyway. At least I was entertained for a bit so what is next.? 



So I think I will see about stiffening up this barrel a little even though it has not given me much of a problem as yet.



Click to expand...

sorry for posting on an old thread but I just purchased an Impact, and Slug Power Kit was looking for some info and found this post. Did you ever get the pin probe issue worked out? It looks like you have the .25 sleeve on probe installed backwards. The chamfered edge should be on the probe side.
 
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FYI, the pin in the pin probe is relatively fragile. If you’re shooting larger slugs (like the .25 NSA 43.5), I’d recommend skipping the magazines and single loading your slugs. I noticed today after about 400 slugs that the pin was bent. I bent it back straight but too many bends and it’ll snap. I wonder if just the pin part of the probe is available? I’d go back to the Huma probe but the pin gives me an easy 15 FPS extra...
 
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FYI, the pin in the pin probe is relatively fragile. If you’re shooting larger slugs (like the .25 NSA 43.5), I’d recommend skipping the magazines and single loading your slugs. I noticed today after about 400 slugs that the pin was bent. I bent it back straight but too many bends and it’ll snap. I wonder if just the pin part of the probe is available? I’d go back to the Huma probe but the pin gives me an easy 15 FPS extra...
Click to expand...

I'd look at https://www.mcmaster.com/ for a harden drill rod of the same size id as your pin. Then cut to the length need to repair your probe.

https://www.mcmaster.com/drill-rods/hardened-high-speed-m42-tool-steel/
 
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I did not gain anything with mine but then again I have already done plenty of power mods before adding it. Maybe I could have added little, like you, if I had gone with the Dual port but I really did not need more at this time so I did not do it. I did use the spring though not sure how all of these latest mods will werq out as I managed to thrash my shoulders again so have not been able to shoot for a month or two now. Looking forward to it soon though.

I really think these kits were made for the stock MKII with the power plenum.
 
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I almost agree. You need the power plenum to generate the necessary power. However here are my experiences.

I had Altaros 31 grain slugs going in an MKII with power Plenum, HUMA dual TP and huma probe set at 110 bars, valve at 4 rings and hs wheel and spring set at max. Increasing the pressured did not have a significant effect on speed.

I exchanged the spring and inserted the little ball but left the huma probe. The speed went from 890 to 920 fps. (I had not installed the extra spacers and the pin probe.)

Then I installed the pin probe and got to 950 FPS. I did need to adjust the probe to prevent mis feeding but it was easy. That is a 60 fps increase without the spacers. I am thinking I will not install the spacers or at best just 1 instead of both since the rifle remains more responsive to the min/max wheel.
 
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