Mk6 Meteor woes

[Dornfelderliebe]

I have problems with my newly acquired Mk6 The power is dreadfully low.
I checked the power and it was only about 6.5 fpe (450fps with superdomes). Ho hum I thought and ordered a kit from Welsh Willy.
1st stripdown revealing a broken mainspring and fitting Wills kit 450 fps again!
Put a new breech seal 460 fps
Second strip down with new piston seal and being very careful not to knick it on the deburred edges.
Still 450-460 fps.
Will wonders whether I have a continent spec. version with a small transfer port but I enlarged it VERY slightly with the same round file that I used on my MK4( too close to1/8 in for me to measure a difference) and asked me to check for a hole in the piston head. That must wait until after the Bash but I don't remember seeing one.


Does anyone have any ideas or actual figures for power on a .22 Mk6, or even general comments on the Gamo Meteors.
P.s Wills kit has worked wonders again firing cycle wise.

[Shed tuner]

should make full power easy.. you have a massive leak someplace..

[Dornfelderliebe]

Please God let it not be like an Hw35 internal leaking breech.

[edted]

Funnily enough I have the same issue.
New breech seal new piston seal average of 465 with rws superdomes. Tried several springs inc a titan and even an ox for good measure but output remains the same. Given up and resided myself to it being 7 ftlb . Don't think there is enough volume to get to the higher powers

[Dornfelderliebe]

There ought to be. I've just been out testing my MK3 &4 ready for the Bash, both breathed upon as per a previous post and both making 11 fpe the 'proper ' meteor cylinder is roughly the same diameter, what the strokes are I do not know apart from long stroking an extra 2mm.

I am not giving up on the Mk6, My back garden is short and overlooked so a slower pellet should be better for neighbourly relations.

[evert]

should make full power easy.. you have a massive leak someplace..

The Mk6?? I think you have guns mixed up, the Mk6 is a short stroke junior Gamo tube.
The Mk7 is a totally different stroy with a full length Gamo tube.

I've seen some power variations between the Mk6 tubes, but dont really remember the numbers.

[Shed tuner]

The Mk6?? I think you have guns mixed up, the Mk6 is a short stroke junior Gamo tube.
The Mk7 is a totally different stroy with a full length Gamo tube.

I've seen some power variations between the Mk6 tubes, but dont really remember the numbers.

ahhh.. then you are right. I didn't know there was a short stroke gamo version, only the long stroke version. The long stroke version is very efficient.

what is the stroke and bore of this "junior" one ? Should be easy to determine it;s potential..

[Dornfelderliebe]

Bore is 25 mm measured by ruler over (used) piston seal but I don't know about stroke.

[Dornfelderliebe]

I've just measured the stroke of the MK6 measuring the piston at cocked and fired and found it to be 60mm vs 71 mm for a MK3 This must be the reason for the low power but I don't know how to calculate it from a given volume.

Going back to the thread on the broken spring where I just used the .177 barrel to test power and got 550 = 5.5 Fpe and the thread on barrel tight spots where my superdomes drop out. I don't think the barrel has anything to do with the power

It's a very short stroke.

I forgot to mention I've took 1.5-2 mm off the Mk3 head

[Shed tuner]

60mm, 25mm bore... I think 6-7 Fp is about right. For reference an hw30 is the same bore (well 26mm) and 64mm stroke, max 8 FP in .22

[Dornfelderliebe]

Thanks John. Well done Gamo