Does anyone know why my FX M4 . 22 shoots the first 3 or 4 low-power shots, for example, at 880 fps, and then evens out at 920 fps? I use 18.13 grain JSB. Thanks for your answers.
FX Help Fx m4
- Thread starter alcuerna
- Start date
If you search the topic you will find a couple very long threads on the subject. Supposedly FX is working or has worked out a fix for the issue. However I haven’t heard of them offering any parts yet. There is someone on eBay selling plenum orings made from a different material that are supposed to help. Here is the link to them.
FX Impact M4 - M3 Accu Shot Plenum o rings New Design | eBay
Tired of Inconsistent shot counts? does your Fx impact M3 or M4 have inconsistent cold shot issues? does it take 5-10 shots before getting consistent Fps? New Compound Fx Impact M3-M4 Valve Rod Orings Gives You Consistent Shot Counts we did the homework now install and enjoy.
www.ebay.com
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I've never experienced reg creep with my guns but one thing I've learned about a lot of airguns in general is if you fill their bottle or air tube to its maximum psi the 1st couple or 3 shots might be "off". Most guns have a "comfort zone" where they shoot most efficiently & consistently. Once I started filling only to the apex of that "comfort zone" & NOT the MAX fill pressure those squirrely 1st few shots disappeared. For example, my FX Boss max fill is 250 bar but if I fill to 235-240 bar I don't get those errant shots.
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This is the only good fix. I can vouch for Mubhaur.
Im using his part now for over a year and no troubles. No slow shots.
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Go to Ebay and look up MUDPRO1 he has all of parts needed. He found the perfect o-rings made diamond polished valve rod and the re-engineered the front of the plenum to perform better. He also has a channel on Youtube
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In my opinion Mubhaur his part is the perfect replacement.
You dont need a diamond polished valve rod. The part he makes, presses the oring in a 90 degree position so it cant clamp on the valve rod. Just like an mk1 impact had.
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mudpro1 makes a cnc machined plenum with a thumb screw that is flat vs a nut sticking up the tube is also the correct length mubhaus is .130 longer.
i know i bought both if you want i have mubhaus plenum on Ebay for sale, like mudpro1 said, not all these guns need them as he is finding other issues like 20-25 bad valve rods that come bent at the crimp causing the little Oring tend to wobble and get wedged into the seat and stick ,,a new valve rod and o rings fixed that one no plenum needed, his valve rods don't need lube is the whole advantage ,its carbide coated then polished on a wet diamond wheel
his plenum has 2 peek bushings inside one on each side that act as a guide and touches no aluminum like the original does.
potato patato one made in USA one made in Pakistan they both work little different in design
mudpro1 also filed for 2 patens for his Orings and Plenum 3 or 4 weeks ago, Huban had contacted him about his plenum people who make regulators
so, he filed for paten.
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Must regulated rifles have that problem.
Just very few regulated PCP's shoot first shot without that problem.
Indeed is something to keep in mind for hunting purposes. My big game PCP rifle is a Wolverine HP .30 Cal NON REGULATED. Precisely to have perfect accuracy on the first shot.
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if valve rods are bent from the factory you should claim warranty.
I never had a bent valve rod from FX. Only thing that I had was the slow shot.
Mubhaur his part is maybe indeed a bit longer, but that doesnt harm the performance.
The flaw with FX is simple, its the oring that clamps on the valve rod, if the oring cannot clamp its solved.
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let me just say this.
since this gun was released, it has the same issue as the M3 does with warming up.
I've seen and witnessed mudpro1 Jig that replicates, an impact being fired.
it is not a cheap set up i will say that it takes all the guess work out of the equation.
it's an actual complete fx plenum and fx rear block, he machined a block that attaches to the plenum tube as it does the original gun.
it uses a linear solenoid that he controls the pulse width which releases the hammer to replicate the shot as if you pulled the trigger.
there are 2 photocells one gets data from the Oring one gets data on the valve rod air pressure is also recorded and temperature.
let me just say it's a work of art i wanted to take a picture of it but he would not allow it i tried.
he can tell you how much drag an Oring is causing on the valve rod it shows on the graph
heat also comes into effect and running lower reg pressures slow the rod down action down causing more heat which he thinks is a problem
for the sub 10 guns.
he started playing with higher reg pressures 160-170 as is snaps the valve open very quickly short hi burst of air
has found less heat on the o ring and valve rod using higher reg pressures like he said the quicker the air travels through the gun
the cooler the air which cools the Oring and valve rod which also helps with friction,
so as far as bent valve rods yes, he has several that are bent where they crimp the threads if you roll it on a flat surface, you will see the end wobble.
he made a short clip and posted on YouTube after he found several new guns coming with them inside. not all but I'd say a dozen or so far.
he has them in a pixie Stix container lol. it causes the valve rod to jam like a press fit. i know i had one in my new 30 Cal M4 he just fixed it.
i know 110% after what i seen MUDPRO1 is the one who did the homework and research had new Orings made and you cannot buy them online
unless you buy them directly from him period. nobody else has them why do you think he filed for a paten weeks ago
he has shown me some of his emails with people saying it's just the pur90 Oring he laughs and says ok then go buy that Oring.
when your gun acts up don't say i didn't tell you so.
it's if the Oring cannot clamp its solved?
plenum length being .130 longer sure does affect the gun unless you have a longer valve rod measure your C1 i bet it's at 5 to 5.25mm
i have Muhars for sale on Ebay
if you want to fix your consistency 100% you will need mudpro1 new Orings you can come up with whatever you decide in my opinion.
i have 3 impacts and after mudpro1 installed His new Orings and one valve rod in all 3 guns i am back in love with all 3 of my impacts as they perform flawless now especially with the reg at 160-170 bar.
my closing to this
mudpro1 is not a young guy he is 60 to 63 yrs of age takes his work very seriously at the same time acts like kid in a candy store when he finds something.
was in the B&M Drag racing circuit for 25 yrs has been building drag engines for 35+ yrs
flow Benches Bridgeport's etc heavenly man cave.
now he is retired he found a new niche and just happens to be the FX air guns.
i said what got you into these he said he wanted a bb gun for pesting did some reading and all started with a Umarex Notos
he said after that he got bit.
that's all folks.
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Im not going to fight or argue this online, but let me say this.
I have his part now for over a year, I never experienced a slow shot ever again. Not even when stored more then a month due the winter temperatures.
My Impact shoots super consistent, not any problem at all. See picture. Even first shot is dead on.
Mudpro1 for sure did his homework, and might be cheaper to buy thats for sure.
Im still not 100% convinced about just changing few orings, as the original part has it flaws. See below
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no arguing here i just stated my finds and facts and my opinion that's all,, we all have different outlooks and opinions
that's what makes the world go round.
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