asi/gamo mc supermatch target rifle help please.

[T 20]

These rifles are not difficult to repair, I've done a few.

The inner piston, for 10mtr/6yd target use, once depressurised is best blanked off. ther are various ways of doing this, i usually make a solid "O" ringed version.

Velocity will/should be around 580fps with 8gn pllets & the rifle will be no harder to cock than a Walther LGR.

Out of interest Dave, what velocity do they give with the inner piston working and are there any advantages to having it ?

I only ask as the Paradigm had an inner piston backed up with belville washers.




All the best Mick

[wonky donky]

if mr wonky donky can give my any more info on that issue that will be great

They uploaded in reverse order for some reason.HERE YOU ARE MATE there are other ways of doing this of course.

Hope it helps.

Out of interest Dave, what velocity do they give with the inner piston working and are there any advantages to having it ?

I only ask as the Paradigm had an inner piston backed up with belville washers.




All the best Mick

Hi Mick, Gamo must have made a small fortune from re pressurising these pistons rather than from sales of the rifle. The idea was to make the cocking stroke just a little easier by reducing the effort required just at the hardest part of the stroke. Walther did something similar on the LGR by using Belville type washers at the rear of the piston.

The jury is still out as to the effectiveness of either of the systems, I've never really been able to detect if the strokes easier or not.

The Velocity advertised by Gamo was 585fps iirc but with their pellets which were only just over 7gns?

I've been getting 580fps plus quite constantly with the above conversion & 8gn pellets.


The argument regarding Vo with a piston that's lost pressure is very dependant on how much pressure is lost as they don't all completely depressurise. I've seen examples shooting at 520fps & others down to just over 400fps. Also don't forget the outer (main) piston seal will have some bearing on this too as will the valve seal & valve opening time.

At the end of the day there's no drama to fixing these rifles.

ATB Dave

[T 20]

Hi Mick, Gamo must have made a small fortune from re pressurising these pistons rather than from sales of the rifle. The idea was to make the cocking stroke just a little easier by reducing the effort required just at the hardest part of the stroke. Walther did something similar on the LGR by using Belville type washers at the rear of the piston.

The jury is still out as to the effectiveness of either of the systems, I've never really been able to detect if the strokes easier or not.

The Velocity advertised by Gamo was 585fps iirc but with their pellets which were only just over 7gns?

I've been getting 580fps plus quite constantly with the above conversion & 8gn pellets.


ATB Dave

Cheers for the reply, Dave.

I can understand the reasoning behind having the inner piston, I just wondered if it made any real world difference in cocking effort.

I'm wondering whether to try making a similar piston for my Mohawk when it arrives, by way of a little experiment.


Thanks again




All the best Mick

[wadcutter]

thanks wonky donkey just looked at the piston images just wondering what material you used nylon maybe,as yet cannot get my piston undone have warmed it up with a hot air gun till molten plastic drips out,the thing keeps spinning in the vice although gripped in wood and rubber,need to use a bigger vice I think with more clamping force,no access to a large lathe chuck.

[Helm]

thanks wonky donkey just looked at the piston images just wondering what material you used nylon maybe,as yet cannot get my piston undone have warmed it up with a hot air gun till molten plastic drips out,the thing keeps spinning in the vice although gripped in wood and rubber,need to use a bigger vice I think with more clamping force,no access to a large lathe chuck.

hi again not at home yet but rap the the piston with sticky clothe tape "gaffer tape " then put tgat in the wood or try a piece of leather wraped round keep tightning till it grips
cheers ian

[wadcutter]

tried using the tape seems to grip well but still wont budge, warmed it up with a blowlamp this time try again tomorrow.

[venoman]

I have an action , no stock and rear sight also there is no effort when you cock it so there must be a problem with the seals. Im up for offers if any one is interested.

[Helm]

hi all taken photos wont let me post on here but pm me your email address and ill send them to you
cheers ian

[Gwain]

Hi Ian. a newbie on here ,but have thrown caution to the wind and invested in a 126. They are a nice looking gun. Might be after a bit of help with the rebuild if your offer is still open.
Cheers,
Gwain.