FX Impact M3 .30 Huma Dual Hole + Slug/Pellet Probe less FPS?

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Er1ckNL

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Nov 28, 2021
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Ov, Netherlands
So last weekend I installed the Huma Air dual hole transfer port + pellet&slug probe, in hopes to get a little FPS improvement. In a .30 cal I wasn't expecting huge gains, but certainly not less FPS.

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Before installation I took 9 shots to compare later:

1: 842
2: 840
3: 837
4: 842
5: 835
6: 840
7: 837
8: 844
9: 842

Today I took a few quick shots, to see if there was any difference:

1: 828
2: 835
3: 830
4: 828

Shooting the same JSB 50.15 grain pellets before and after, but this was certainly not what I was expecting.

The macro is at 16, micro 3.5, valve just over the 4th line, reg pressure at 110 bar. Now I was hoping the Huma set was giving me a little extra FPS and work my way up from there. Always took JSB pellets as my baseline tune, I do have some JSB Knockout slugs laying around.

Should I adjust the valve and up the reg pressure from 110bar as the Huma parts will get more efficient that way? Not sure where to go from here or why I've gotten less FPS.
 
NorCalFrank said:
Was ambient temps and other local weather conditions the same for both tests? Headwind? I've found, at least in my area, just moving 10 miles, or a few hours from the morning to the afternoon can make a big difference in velocity.
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Small difference, both rainy days. Maybe a 3-4 Celsius temperature difference. Shooting into a wood stack, but last Saturday was more windy.
 
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The Huma dual hole will start shining at higher pressures. Your running very low regulator pressure at 110 bar with a fairly low velocity so you might not notice a huge difference if any. The better flow may have even changed the pressure pulse timing of your gun slightly. This may be the reason for the slight velocity drop. At higher reg pressures like 150-180 bar, the dual port really shines.
 
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This actually not uncommon. I have had the same thing happen in my Crown MK II, where a .30 cal barrel with a dual port was slower than an otherwise identical barrel with the regular round FX port. In particular, the .30 cal suffers from this and it is often not seen with the smaller calibers. In fact i have never seen it with the .22
FX actually claimed at one point that there is no need for a dual hole in the .30 cal. However my experience aligns well with what rappert says above. At higher pressures the dual hole setup starts to shine.
 
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Airgunmann said:
Only thing I can think of maybe transfer port was part way covered or not lined up correctly idk
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What do you mean not lined up correctly? The barrel is all the way in, can only be done one way as it falls into the notch on the back. With the original transfer port I could see a small silver line at the end of the barrel. Also you own a .30 cal?
rappert said:
The Huma dual hole will start shining at higher pressures. Your running very low regulator pressure at 110 bar with a fairly low velocity so you might not notice a huge difference if any. The better flow may have even changed the pressure pulse timing of your gun slightly. This may be the reason for the slight velocity drop. At higher reg pressures like 150-180 bar, the dual port really shines.
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Will start to play with the gun more, perhaps a little bit with the valve, but 150-180 bar on the second reg, holy! You get like 30 shots out of a tank? :D
 
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rappert said:
Yup, you don't get a lot of shots. But you can get 1070 - 1110 fps with 44.5 gr. slugs with the right set-up using the Huma. Great for coyotes.
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Impressive numbers. No coyotes around here, just small game like rabbits. My goal for now is at least 950 fps with 50.15 gr pellets/slugs (jsb pellets/knockouts). Increasing the 2nd reg from 110 to 130-150 means I need to adjust the 1st regulator as well I guess. Not sure where I got the numbers from, but the 1st regulator has to be 30-40bars higher than the 2nd regulator right?

Lets just say I were to increase the 2nd regulator from 110 to 150 bar, how many shots you reckon I got before I need to refill? Got a big 7L heavy scuba tank which is quite a pain to carry around in the field. Maybe I need to invest in a smaller carbon fiber tank.
 
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Airgunmann said:
Nope 25 cal some times they don't line up correctly my friends is a 30 cal and gets about a magazine full out of a tank
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You mean the pellet/slug line up in the barrel? Or the actual transfer port.

Took some photos as comparison:

Huma Air Dual Hole installed, you see a small silver line:

IMG_0802.jpg


Original FX (My dads FX M3 .30). bigger silver line:

IMG_0801.jpg


As if the Huma Dual sits back deeper, but when looking at the actual probe insert (bronze transfer port), they are both equal.
 
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Airgunmann said:
I was talking about the hole in the barrel lining up with the hole in the probe it would doesn't happen all that often but once in a while it does
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I see what you mean now. Loaded up a pellet from the magazine and took the barrel out to see how it fits:

IMG_0838.jpeg




IMG_0835.jpeg


IMG_0834.jpeg


Looks like it's properly pushed in.

Still haven't had time to tune the gun yet, dark early and lots of rain during the weekends.
 
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So it has been a few weeks, weeks with rain and freezing outside. Had a day off today. Ok weather is still cold.. F it, lets play around with the M3 .30 cal!! (Been searching this forum for al sorts of topics during the past 2 weeks on this subject. dual hole, pellet probe, pin probe etc etc.). Been struggling with it quite a bit.

Long story:

Before:

So before I installed the huma dual hole transfer port v2 + pellet/slug probe I was netting around ~840ish FPS. This was the second reg at 105-110 bar. Valve over 4 lines. JSB 50.15gr Pellets.

Installed the Huma TP + Probe and netted ~830ish FPS, which is a loss right? Also JSB 50.15gr Pellets. Makes no sense.. bigger and more efficient transfer port + pellet/slug probe.

Thinking process:

As mentioned in this topic by @cosmic @Airgunmann @rappert. What am I doing wrong, is the probe not lining up correctly.. can the pellets be pushed in further with a adjustable pin probe... Is the air more efficient, do I get blowback and need to up the second regulator for the huma to do its work..

Tinkering:

Ok so Jan 4th I had my huma TP+Probe installed, went from ~840 (original TP + Probe) to ~828 FPS with JSB Pellets 50.15gr.

Jan 21th I decided to adjust the 2nd regulator from 105-110 bar to 120bar, numbers increased to ~856-860 FPS.

Lets increase the second regulator to 130bar I thought. It went straight back to 830 FPS. Lets fill the tank back up to 250 bar to make sure all regulators are ok, and not shooting below regulator pressure. Let it cool down for a few minutes. Nope, still 830 - 835 FPS. Really confused.. hammer spring?

Thinking process again...

Re-watching the huma dual hole v2 + probe installation over and over with different video's. Did I install the liner the other way around? Am I missing an o-ring etc.

Today 9th/10th of Feb:

So after reading a lot, watching youtube vids on the FX impact's. I decided I wanted a pin probe to F around. Did some browsing on Huma-Air.com, might as well throw in a Carbon Sleeve for my liner. Picked the items up during lunch break from Huma-Air (Huma-Air located near the company I work at). Explained my situation that my M3 .30 cal shoots lower speeds. He was kinda confused why it was shooting lower speeds... He showed me some items like a better hammer spring + weights. Huma-Air is a very nice company btw!

Today the 10th:

Ok I took your advices! Lets start over, take the barrel apart, take out the probe etc.

As you take out the liner, it has three o-rings:

oring.png


When I took my liner out the first time, it had three as well. Spaced them around before putting it back. This time it only contained two...

Took a compressor and blew out the remaining o-ring.. well.. looked like a flat tire.. pieces or rubber everywhere. Looked like pieces of plastic.

oring2.png

Closest google image I could find. But was worse than that.

Installed my Carbon Fiber Sleeve for the liner, so I didn't need the three o-rings anymore.

Next step was marking the probe on how it sits on the transfer port:

IMG_0934.jpg


Pellet was already loaded before I took out the barrel and probe, couldn't even push in the probe further. So this was not the problem (can even see the sharpie markings.) Huma Dual Hole + Pellet/Slug probe fits perfectly!

Also tried the Huma Pin Probe, but that is too short for JSB pellets in .30 cal, that would have left the pellet skirt sitting semi naked in the transfer port.

Must have been the liner o-ring that got stuck/lost somewhere the last time.. still amazed on how this could happen. When you push back in the liner, the o-rings rather get pushed upwards.

Re-assemble results:

2nd reg at 125-130bar:
Micro 4
Valve: 4.5
Power wheel at max: 16

JSB Pellets 50.15GR:
898-900 FPS

JSB Kockouts 50.15GR:
895-900 FPS

NSA SLUGS 43.8GR:
930-946 FPS

I will take off the air pressure tomorrow and set the second regulator back at 105-110bar, build back up from there. If I still have the will, I will try the huma pin probe on the NSA slugs, my M3 really seems to like those! With the NSA flat base I think the Huma Pin Probe will give them an extra 10-15FPS!

Also I don't want to shoot pellets at 900fps, much lower than that, but was my measure point from the start. Will have to turn down the Power wheel, kinda want a hybrid pellet/slug shooter for now.

Sorry for the long story, wanted to share, might help other people.

TL;DR:

Liner o-ring got stuck, gave negative results in FX impact M3 .30 700MM. After assembling huma air dual transfer port + pellet/slug probe.
 
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Airgunmann said:
Might want to try the pellets at 900 fps some people are finding 870 to 920 fps give good accuracy on certain guns
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You might be right, .30 cal is a whole different beast. I also own a Walther Reign M2 L .25. Just comparing the pellets .25 vs .30 in JSB Pellet/Hades/Knockouts have a whole different depth to them. Even the skirts are different in design. What I've learned is that you can't compare .22, .25 and .30, not even mentioning .35! While .30 is not rare, .25 is more common, you simply find more information on the .25.

JSB 50.15gr pellets and JSB Kockout Slugs 50.15gr do seem to get the same FPS (same skirt), not sure about accuracy, as I don't have the range at the moment. But they almost lift my capable .22 LR pellet trap!

With your, and others I've learned a lot during the last couple of weeks! Thank you for that. I'm not quite done yet with my M3 .30 cal.

Will update my findings, even though it's weeks from now!

IMG_0935.jpg
 
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Took off the air bottle, dry fired. Let the gun bleed dry. Turned the second regulator all the way back, turned it back up towards 100bar. Was 110 bar from the factory.

844-860 fps with 50.15gr pellets, so yes the huma parts did actually improve my FPS with less bar on the second regulator. 900 fps with NSA's 43.8gr's. So I actually gained at less bar, 100 vs 110.
 
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