TargetTalk

The pressure regulator of my MG1 has gone bad. Some other owners have experienced similar problems, apparently:

Silvershooter wrote: The Matchguns MGH 1 is supposed to have the best regulator of any PCP AP.

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Jcortiz wrote:Well if its the mg1e then you will find an allen screw on the lower part of the trigger guard card holder(the black part were is located the on/off switch. Remove that screw and you will find a silver cap with 2 holes ,unscrew it and take care because you will find a washer spring, dont miss the order of the washers as they act like a spring on tension. There you will find oring 1032 (4.5x2mm). Now you will find a valve cap 1030, uncrew it and you will find gasket 1034. Both the oring and the gasket can be ordered to matchguns. Stefano its always fast answering emails and fast shipping the orders.

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I have noticed variable pellet velocity, and random changes of impact, for some time from my about 10 years old MG1. Some shots were merely "duds", - pellets impacting at bottom of target. The air cylinders of this gun have no pressure gauge, but there is a red analog pressure indicator "pointer" visible through an inspection window at the lower part of the "subframe". I noticed alternating position of the "pointer" from shot to shot.

I removed the "subframe", and noticed the smal "cap" at the center of the regulator bottom cap (bottom cap with two holes) would be seated at different depths below surface, from shot to shot. By pushing at this small "central small cap"" with at plastic stick, the cap would became positioned less deep below surface, and hence let more air into the regulator, I think, and the pellet would then achieve normal velocity. But I would have push this cap aboauat every second shot. Boring.

By unscewing the air cylinder until some air escapes (evacuating air from regulator), and then retighten the air cylinder, normal pellet velocity was experienced again. To follow this procedure about every second shot? Not in the long run, no.

I asked the Matchguns company if spare regulator (or parts) was available, but they said I had to bring thh gun to the Matchguns company for "regulator revision". That is in my opinion not practically feasible, from my country, considering the paperwork and trouble involved.

Could the valve assembly (positioned at top of frame, just under barrel) be involved in these problems, too?
The MG1 is a lovely gun, and it has served me quite well for many years. I hope I`ll get the problem cured.


Would appreciate any help.

Hi there.
You are right the Matchguns has the best possible pressure regulator. My MGH1 and those of my fellow shooters which I have seen testing have a velocity variation of 0.1-0.2 meter/second! Mine is even better, as often on 15 shots I get no decimal variation for most of them ( with the cheapest diabolos!).
With my MGH1 the pressure regulator is external and you can easily remove it for maintenance (I never needed in 3 years). Are you sure that it is not the same in older models?

therider wrote: You are right the Matchguns has the best possible pressure regulator.

Well, that was the opinion of mr. "Silvershooter ", not me. He was considering the regulator of the MG1H (hybrid), - mine is and older MG1 with mech. trigger. Of all airguns I have owned, the regulator of this Matchguns MG1was the only one to ever let me down....

therider wrote: With my MGH1 the pressure regulator is external and you can easily remove it for maintenance (I never needed in 3 years). Are you sure that it is not the same in older models?

The regulator of my MG1 is incorporated in the guns frame, not "external". It is not easily removed, regrettably.

northpaw you can open the regulator of your mg1 and see if there is a visible worn o-ring. the exploded diagram of the manual has the sizes and location. just be careful with the stack of the spring discs. make a copy of their arrangement so you can be sure when you reassemble everything. also check how much the reg screw cap protrudes. after reassembly make sure it is in the same position or you will alter its output pressure

Thanks for Your reply, "ghostrip". I plan to make å wrench to fit into the two holes at the endcap of the regulator, to be able to torque it open.

One of the two air sylinders that came with the MG1 is leaking badly. It`s more than 10 years old, and it has no pressure gauge. I`ll use a vice and wooden blocks, and wrap duct tape around the sylinder. I`ll apply moderate heat (this is an anodized cylinder) to the endcap w/valve assembly, with a heat gun.

I`ll keep you posted.

northpaw i wouldnt try to repair the cylinder myself. if it leaking that bad and assuming you fix the regulator it is best to buy a new one either from matchguns directly or from a local importer. also i think (but i am not sure) that the SAM K-series cylinders fit the MG1.

Some proceedings:
Endcap w/valve assembly removed from cylinder today. (With assistance of personel at a qualified instrument workshop).
Just fixed the ducttape wrapped cylinder in a vice, applied torque with hand, (ho heat gun used), and the endcap came loose with moderate effort. The thread of the cap was lubricated with a yellowish grease, some chunks/slugs of this grease visible inside the sylinder too. The O-ring of cap was inspected, and found to be OK. The leak I had experienced was from the end "pin"-valve, btw.

The "pin-valve" assembly was easily removed with an Allen wrench.

The "pin-valve"-assembly consisted of 4 parts (from rear to front):

- a short threaded Allen-wrench-compatible cylinder, with a 3 mm diameter airchannel.
- a 10 mm long, 5 mm diameter coiled spring
- a 5 mm diameter, 4 mm long stubby cylinder of orange-brownich hard plastics, - deformed and cracked, - some minor loose parts of same dropped out at removal (!)
- a 7 mm long, 2 mm diameter flanged "valve needle"

The culprit appeared to be the cracked stubby bit of "plastics". The flanged end of the needlevalve rests against this bit of plastics, under spring tension. No O-ring visible in the valve-assembly.


Remember I experienced the first signs of regulator-trouble just as one of the aircylinders started to leak badly. Could a minor part of the plastics "valve-seat" have found its way to the interior of the guns regulator, interferings with its operation? Just my 5 cents...

I`ll get in tuch with the Matchguns company,- hope they will be able to ship spare parts for the aircylinder.

Within a few days I will (try to) dismantle the pressure regulator.

northpaw it would be great if you can post any photos :) hope you fix your mg1

Northpaw. My regulator backed out so far that it started leaking. I removed the counter weight and pushed the pin in the center back in. When I did this I tore the oring.The oring is easily available2x5x9.Replaced the o ring. The leak stopped. I used a pair of snap ring pliers to get the threaded plug out. When I removed the threaded plug the series of washers fell out. The are conical washers that act as a spring to push that piston back up. This operated the red flag air pressure indicator. I got the conical washer out of sequence. I didn't pay any attention to their order. Now the red flag indicator doesn't work. Do you know the order of the conical washers???
As far as the air tanks. There is a small valve in the end of the end cap. It is like a valve in a car. I think over time it gets bent. New end caps are available from Stefano at match guns. They are 50 euros each. I put mine in a lathe to get the end cap off. Email steffano at match guns. He will help you. HTH.

PFribley wrote: I got the conical washer out of sequence. I didn't pay any attention to their order. Now the red flag indicator doesn't work. Do you know the order of the conical washers???

I`ll try to help you out with that one.. I plan to observe the stacking order of washers at dismantling.

PFribley wrote: As far as the air tanks. There is a small valve in the end of the end cap. It is like a valve in a car.

Been there...I my case the small yellowish bit of "plastics" below the needle-valve had developed cracks, and a couple of small pieces had fallen off.
This small stubby part of "plastics", has a tray-formed shallow depression at one end, and this acts as a seat, for the flanged inward end of the needle-valve, as you noted.

Edit: Got the "two-holes" regulator endcap rotated one half turn, not much effort needed, just a proper tool. Will soon dismantle the regulator, with the outmost of care...

I tried to make a new spacer. It is some phenolic substance. Found some tubing near the same diameter as the spacer. Measured the length. Filled the tubing with jb weld. Didn't work.LOL.Thats when I ordered new end caps from match guns. We are lucky on this issue. We don't have a pressure gauge as another leak source.

I tried to make a little new spacer for the end cap. It seems to be some phenolic substance. Didn't work still leaked. That's when I figured that the small valve must be bent. That's when I ordered new end caps. One nice thing. We don't have a pressure gauge as another leak source. My air tanks were 14 yeas old. They should last at least that amount of time before they need replaced.

My gun is of same age as yours. No pressure gauge at cylinder end.
Did you have to order a new endcap with all internal parts? The "spacer" (valve seat) not available as a separate spare part?
50 euros for a new endcap? Think I may get a new cylinder for 120 euros.

The end cap comes complete. MG won't sell the individual parts. Steffano is very professional. You can pay with paypal. I got two end caps with shipping for 120 euros. Shipped to the USA. It was a very easy transaction. Grease up the threads when you screw it back together. I used a cresent to put mine back together. Even held it with my hand. Have you fixed the pressure regulator yet??? Good luck.

PFribley wrote: ↑Thu Mar 09, 2017 9:18 am Have you fixed the pressure regulator yet??? Good luck.

I´ll start working on this problem in the near future. Have the endcap unscrewed about 1/2 turn....

Btw the stacking sequence of the the parts of the regulator may be seen in the pdf-diagram here:

Do a google search for the term: Libretto MG1 - MG1 E

(The diagram is from the site:
https://www.aomnikandros.gr/wp.../Match ... -MG1-E.pdf)


The parts of the regulator are # 1029 to # 1036.

northpaw wrote: ↑Sun Jan 06, 2019 8:15 am

PFribley wrote: ↑Thu Mar 09, 2017 9:18 am Have you fixed the pressure regulator yet??? Good luck.

I´ll start working on this problem in the near future. Have the endcap unscrewed about 1/2 turn....

Btw the stacking sequence of the the parts of the regulator may be seen in the pdf-diagram here:

Do a google search for the term: Libretto MG1 - MG1 E

(The diagram is from the site:
https://www.aomnikandros.gr/wp.../Match ... -MG1-E.pdf)


The parts of the regulator are # 1029 to # 1036.

Nice to see my club's site to be useful :)
Best Regards from Greece

northpaw wrote: ↑Mon Mar 06, 2017 2:02 am Thanks for Your reply, "ghostrip". I plan to make å wrench to fit into the two holes at the endcap of the regulator, to be able to torque it open.

One of the two air sylinders that came with the MG1 is leaking badly. It`s more than 10 years old, and it has no pressure gauge. I`ll use a vice and wooden blocks, and wrap duct tape around the sylinder. I`ll apply moderate heat (this is an anodized cylinder) to the endcap w/valve assembly, with a heat gun.

I`ll keep you posted.

A regular gunsmithing screwdriver will do as the middle pin that makes it look like you need a special tool actually depresses, just make sure it’s not under pressure.

PFribley wrote: I got the conical washer out of sequence. I didn't pay any attention to their order. Now the red flag indicator doesn't work. Do you know the order of the conical washers???

Apparantlly, the regulators of "therider "s MG1H (hybrid) and my older MG1 are different.

Today, I removed the valve-assembly, parts # 1009 to 1013. (Noticed part #1012, a tiny washer was missing).
The "valve pin", part # 1015, was kind of stuck in the frame. Got it out finally by knocking the gunframe lightly with a rubber hammer. Lubricated part # 1015 "valve pin" very sparingly with fingrtips. Then reasembled.

I then dismantled the pressure regulator (partly). Under the endcap there are 7 conical washers. Stacking order is easy: 1st one: convex side up, then the next one opposite (convex side down), and so on.

Removed the "center rod", which actuates the "red flag" analog pressure pointer. Then I unscrewed part # 1033 ("screw"). I was not able to remove parts # 1034, 1035,1036 (gasket, pressure valve, spring). Tried to pull lighly at the protruding rod of part # 1035 "pressure valve", but to no avail.
Reassembled the regulator.
Attached an aircylinder to the gun; - the regulator was now leaking noticeably through the two holes in the endcap of regulator.
Cocked the gun, and discharged (no pellet). The regulator then stopped leaking! And the "bang" seamed about right....

Could the problems from the beginning have been caused by a (varyably) sticking "valve pin" part # 1015? Just wondering.

I´ll bring the gun to the range and get velocity readings, to test concistency, or lack of same.

Have to add my second MG1 aircylinder is leaking now , too. My older MG1 cylinders have no pressure gauge. Have to buy a new cylinder, with pressure gauge.

I managed to fire 5 shots from my MG1 today, then the air cylinder was empty. Air was leaking audibly from the regulator. But the first 3 shots appered to have fair velocity, and they printed tight. Then the velocity dropped, and the gun printed low. I´ll disassemble the regulator again.

One pecularity: part # 1037 "inspection hole screw" (w/ o-ring)
Inspection for what? For the air-channel?

Was able to get the remaining parts of the pressure-regulator detached for inspection, by attaching a partly charged air cylinder to the frame, endcap reinstalled. Popped out easily.
By incpection there was no apparent damage to any internal part of the regulator.
I noticed a somewhat loose fit, though, to the frame-recess for the green o-ring of part asssy # 1031/1032 ("pressure pin w/o-ring").

Reinstalled, but regulator was leaking. By adjusting seat-depth (less deep) of endcap the leak was reduced.
But then the gun would not discharge any air in firing mode....

I´ll get in tuch with Matchguns to figure out how to remedy the problem(s).

Sent an email to Matchguns about the problems one week ago, got no answer. Maybe they are just too busy.
Edit mars 12: got a reply from Matchguns today.