BSA Meteor MK7 fettle

[Backgardenplinker]

@flyboy1950 has leant me this one to have a look at improving its firing cycle. Cheers for that mate, it will be an interesting little project

Heres it is. I thought it was a mk7! but a ZE prefix serial number is a mk6 from 1993-present. Id guess this ones from 2014 from the serial. Mk7 meteors have a QF prefix apprently.

Its quite different to the older BSAs i own. Its a Gamo rifle in essence. Theres plastic pieces here and there but it seems nicely made and finished.

I am informed its shooting 10.4 with superdomes. I can confirm it is more or less doing that.

5 shots over my chrono..

Plan is to strip it down soon but for now i did a quick test of the open sights on target.

10 meters rested to adjust sights. The fibre optic offerings are in my opinion pretty good. Bright and precise to aim.

First 5 shots at bottom of this target and raising the rears up..

And cut a playing card 2nd shot..

Hobby pellets used. Seems to shoot straight enough. Im sure with some practice it would group tighter. Trigger isnt too bad, its certainly on par if not better than the triggers on my old BSAs!

Lastly heres a video clip of the firing cycle. Fair to say its slammy/harsh/buzzy. Hopefully it can be tamed so a pellet stays put on top.

View attachment 768575

Thanks for reading

 

[Backgardenplinker]

Upon more research it is indeed a mk7. No idea on the serial numbers.

Started stripping it down so will update again soon

 

[Backgardenplinker]

Strip down part 1

Yes, i took so many pics and have so much to waffle on about it wont fit in 1 post

Sights.

Rear fixes with a single screw and locating pin to breach receiver holes.

Front sight..

View attachment 769006

The post is on a dovetail with single screw beneath.

The stock.

It is fixed in the standard way but uses star head bolts or posi drive whatever they are called.

No washers on fore end fixings but bolts are knurled to grip.

The front bolt in trigger guard is a wood screw and smaller size head. Could have left it in but i didnt know.

Rear is the same size head as fore end bolts and holds the action.

Bit more fiddly than usual but stock off.

Look at action.

This rod is interesting. Beartrap part connecting trigger to cocking lever.

Barrel seems held by a single bolt. Again star head.

On other side theres a kind of fixed nut

On the cocking lever theres a small plastic horseshoe kind of shaped thing. Anti galling measure?

Inside the stock is another piece of plastic the lever runs on.

Peek through the cocking slot. Not your usual spring guide. It looks very thin but thats because its not exactly round.

Plastic end cap fell off on its own and reveals the pin holding trigger block in place.

Gamo trigger. Im always happy when a trigger is in 1 piece as a unit. I will only be touching the bear trap part here.

Part 2 to follow

 

[chouchin66]

Strip down part 1

Yes, i took so many pics and have so much to waffle on about it wont fit in 1 post

Sights.

Rear fixes with a single screw and locating pin to breach receiver holes.

View attachment 768982


Front sight..

View attachment 769006

The post is on a dovetail with single screw beneath.

View attachment 769007

The stock.

It is fixed in the standard way but uses star head bolts or posi drive whatever they are called.

View attachment 769008

No washers on fore end fixings but bolts are knurled to grip.

View attachment 769009

The front bolt in trigger guard is a wood screw and smaller size head. Could have left it in but i didnt know.

View attachment 769010

Rear is the same size head as fore end bolts and holds the action.

View attachment 769011

Bit more fiddly than usual but stock off.

View attachment 769012

Look at action.

This rod is interesting. Beartrap part connecting trigger to cocking lever.

View attachment 769014View attachment 769013

Barrel seems held by a single bolt. Again star head.

View attachment 769015
On other side theres a kind of fixed nut

View attachment 769016

On the cocking lever theres a small plastic horseshoe kind of shaped thing. Anti galling measure?

View attachment 769017

Inside the stock is another piece of plastic the lever runs on.

View attachment 769018

Peek through the cocking slot. Not your usual spring guide. It looks very thin but thats because its not exactly round.

View attachment 769020

Plastic end cap fell off on its own and reveals the pin holding trigger block in place.

View attachment 768997

Gamo trigger. Im always happy when a trigger is in 1 piece as a unit. I will only be touching the bear trap part here.

View attachment 769021

Part 2 to follow

Holy smokes, way diffo to an 880, plastic breech ?

 

[Backgardenplinker]

Holy smokes, way diffo to an 880, plastic breech ?

Yes it is plastic chris. A new one on me. Guess thats the modern way its heading on some lower end break barrels now.

It does seem to work fine and of solid enough construction. Ill write up part 2 of the strip down now which shows it a little better.

 

[chouchin66]

Yes it is plastic chris. A new one on me. Guess thats the modern way its heading on some lower end break barrels now.

It does seem to work fine and of solid enough construction. Ill write up part 2 of the strip down now which shows it a little better.

My rifle that lists on some of the same parts ( on a schematic) is a ' 98 model, so guess that's the difference...

 

[Backgardenplinker]

Strip down part 2.

Removing barrel.

The breach is held by the main bolt. I expected some washers and shims but none there.

The cocking lever.

Quick note. That small plastic horseshoe part to keep lever clear of the cylinder. Theres 2 cut outs for it to sit in

At this point i had a head scratch. The lever isnt free of the slot as its held by the beartrap rod thing.

After some prodding and inspecting i worked out the rod wouldnt come out.

The side of the trigger rhe rod attaches to is a sliding plate under spring tension.

That spring needs to come off. I covered it best i could with a zip lock bag and worked the spring end off the tab with needle nose pliers.

Pics for reference. The other end of the spring locates on the tab on inside od the white plate.

I think that is goimg to be fiddly to refit!

Anyhow the rod part now was free to remove in full.

Job done.

A little look closer over breach.

Seal is around the transfer port. Detent chisel and latch are metal.

Removing internals.

An unknown quantity of spring, it went in the sash clamp compressor.

I used a plastic block to press against end block inside tube diameter.

Add tension to clamp, retaining pin only needed a prod.

Unwind till spring preload is slack.

Remembered to measure preload. 37.6mm.

 

[Backgardenplinker]

Strip down part.3

Ok. 3 posts needed

Removing internals.

With pin out of trigger block the rest of internals are accessible. Here is the spring guide. I dont know what that shape is but its that odd ridged design like on smk underlevers. Its integrated to the trigger block.

Mainspring.

Yes, thats a solid very heavy steel top hat fitted!

Not the worst finished ends to be fair.

I think this top hat explains quite allot of the shot cycle.

Piston.

Came out fairly easily.

So obviously no latch rod. Latches on the skirt. feels a good modest weight. Glad seal is ok.

A 25mm piston. Nice

Theres room for a sleeve with this spring.

Spring specs for reference.

Further inspection of the spring guide..

There is a thick spacer and metal washer thst form the base for spring to sit. End of the guide forms the end of the trigger block. It has a hole for the retaining pin also.

That concludes the strip down. I will update soon. Cleaning and some thinking to do and then onto changing the internal setup

 

[Backgardenplinker]

Tinkering begins this afternoon.

Ive found a spring of near identical dimensions to the original but a little longer.

So both can be used to experiment. My plan is to do away with the steel top hat. In reality that is there for weight not spring support in a piston without a latch rod.

Sleeving the piston.

To address spring support, reduce tolerances and as a by product, add 'some' weight back to piston.

Cleaned the piston up and selected a steel coffee can.

Ill let pictures do the talking..

Its a little short but should be fine. A washer holds it all in tidy so spring end can unload. I can add a slip washer also.

Spring guide.

The factory guide is a bit of an issue. Usually its simple to modify or drop a new guide in but not really the case on this one.

Ive never done this before but i sleeved the guide with more steel. Its a bit untidy looking but its on there solid right into the block. What i wanted was a hollow tube to fit but nothing around suitable. May go down that route or could get somthing bespoke made up i suppose.

It isnt a great fit to spring but a definate improvement. Ill take sliding with some resistance over a few mm loose.

I filed a few areas and polished the sleeve and washer as that wasnt free spinning (guide steps up in OD towards the block) Its fine now. So not pretty but im confident it will hold up without issue.

Below is first setup to try with the longer spring.

The comp tube needs deburring and cleaning next as its got some razor sharp cut outs.

 

[Nomis]

Another great write up Rob. Can't wait for the next instalment .

 

[Sello77]

Excellent and helpful article. Thank you very much for your work, photos, and comments.

 

[Backgardenplinker]

Another great write up Rob. Can't wait for the next instalment .

Thanks simon. Deburred the slots, swabbed the tube and Ive been playing around testing the rifle. No lube on internals and bear trap left off. The sleeves seem allright in there. Cocking is better.. No groaning/creaking from the spring.

After around 10 shots. Sleeves are unmarked.

With the piston weight removed it is down.

I tried the longer spring first and around 10 fpe. Pretty horrible cycle though. Oversprung perhaps.

With the original spring its down to just under 9 but feels a step in the right direction. Ill rebuild it properly lubed and with a few tweaks and go from there.

Using superdomes 8.3.. Not a very good video clip and it doesnt pass my recoil test just yet.

View attachment 769541

Excellent and helpful article. Thank you very much for your work, photos, and comments.

Many thanks mate. I always think if only one person finds it useful its worth my time posting. It also helps me to be able to go back over things

 

[nav2022]

That's a Gamo trigger block. Used in a few other rifles.
Becareful on how much power you put through them. Friend of mine put a wicked spring in his and buffed out the cylinder till it was like glass. Was doing 11fpe which sounds BS but when I chronied it, it was indeed.
It ran OK for about a month then the trigger sear and catch plate on the piston both failed, the piston catch plate was completely rounded off. I had to do the fix. I angle grinded the catch plate back flat and put a new sear in because it was beyond repair. Put the original spring back in and it was doing about 8.5fpe but was OK.

 

[Backgardenplinker]

That's a Gamo trigger block. Used in a few other rifles.
Becareful on how much power you put through them. Friend of mine put a wicked spring in his and buffed out the cylinder till it was like glass. Was doing 11fpe which sounds BS but when I chronied it, it was indeed.
It ran OK for about a month then the trigger sear and catch plate on the piston both failed, the piston catch plate was completely rounded off. I had to do the fix. I angle grinded the catch plate back flat and put a new sear in because it was beyond repair. Put the original spring back in and it was doing about 8.5fpe but was OK.

Oh Christ! I wont be pushing power here but that doesnt sound good. Is this the sear latching to the piston skirt?

 

[nav2022]

Oh Christ! I wont be pushing power here but that doesnt sound good. Is this the sear latching to the piston skirt?

Yes but his wasn't the gamo trigger block, it was an ealier Meteor.
Those trigger parts on the earlier models were available as spares, the Gamo block I've never had any experience with apart from the one in my GX40 PCP. I know that Gamo block is now in the Lightening as well as about half a dozen Gamo break barrels.
The sear that engages the latch plate on the piston is the one that fails when you go too far with power.
The B2 does exactly the same, put a stronger spring in them and their monkey metal sear disintegrates.

 

[Backgardenplinker]

Yes but his wasn't the gamo trigger block, it was an ealier Meteor.
Those trigger parts on the earlier models were available as spares, the Gamo block I've never had any experience with apart from the one in my GX40 PCP. I know that Gamo block is now in the Lightening as well as about half a dozen Gamo break barrels.
The sear that engages the latch plate on the piston is the one that fails when you go too far with power.
The B2 does exactly the same, put a stronger spring in them and their monkey metal sear disintegrates.

I will probably use the factory spring and a small drop in power here so i hope it will be ok. All looks fine. Perhaps some high content moly smeared on the engagement surfaces also

Ive not had any experience of the gamo trigger block before either or at least working on one.

Thanks for your input

 

[Backgardenplinker]

Reassembly of the rifle.

I put it back together today. Just not overly happy with the end result. Still a bit jumpy and buzzy. Different spring and stuff to test but thats for a later post.

Putting the meteor back together is not any different to most break barrels for the most part.

Grease and insert piston in clean comp tube.

I put grease on the breach, a little under the cocking lever as a witness mark there on cylinder and on the lever foot. Dont forget the horshoe part on lever.

Seat lever foot in slot and fit the breach bolt. Barrel back on.

Grease the spring and guide...

Back in compressor.

Line up and tap in the pin .

I wasnt looking forward to the beartrap fitting. It wasnt too bad but as feared, fiddly. Start by hooking the end on the cocking lever.

Heres the spring fitted. It shows how it sits.

What i did was fit the spring end in the white plate notch and hold it as i slid the plate into position. Then manipulate the other end of spring under the black tab.

Looking from the other side too was helpful.

Completed action. Just needs end cap and stock.

Thats assembly covered. Ill have to do it all again though more tinkering and testing required

 

[flyboy1950]

Thanks Rob, a bit late to the party as I have been super busy this week. I had no idea that this was going to be such a labour for you and I do very much appreciate your efforts. The gun was purchased many years ago as it was advertised as the "Last Meteor and it was a full powered hunting rifle" and it has been waiting to be fettled, but life often gets in the way. The only thing I have done is to replace the screw that controls the length of travel for the trigger, that was a beast, as too long and the sear wouldn't engage and to short it was a hell of a long pull. Looking forward to your follow up reports. Might I suggest you put this on You Tube as there is nothing on the Mk 7 except people shooting it. Thanks again. Flyboy1950

 

[Backgardenplinker]

Thanks Rob, a bit late to the party as I have been super busy this week. I had no idea that this was going to be such a labour for you and I do very much appreciate your efforts. The gun was purchased many years ago as it was advertised as the "Last Meteor and it was a full powered hunting rifle" and it has been waiting to be fettled, but life often gets in the way. The only thing I have done is to replace the screw that controls the length of travel for the trigger, that was a beast, as too long and the sear wouldn't engage and to short it was a hell of a long pull. Looking forward to your follow up reports. Might I suggest you put this on You Tube as there is nothing on the Mk 7 except people shooting it. Thanks again. Flyboy1950

Glad you found the thread mate. I am always happy tinkering with springers in spare time. Its become as much a hobby as shooting them so no complaints from me!

Its not quite as simple a task as i anticipated. Whilst it is capable of full sub 12, getting it to shoot how id like it too at that level seems easier said than done. With a 25mm piston and relatively long stroke (i measure it 85mm but could be more if i did it wrong) it should make power and shoot well. I think 8-9ft lbs could be a sweeter spot.

I know you mentioned welsh willy, i can talk to him about a kit too. I dont see a kit for the mk7 meteor but it may be the same as a gamo model.

If it was 22 caliber it wouldn't be so lively.

Would you be happy if it was a little lower on power but well mannered? I of course will keep all original parts and can set it back up in factory trim.

I have a different spring setup im working on from my spares collection. Pretty confident this is going to offer a smoother cycle but unsure on the chrono.

Edit. The trigger mod you've done is a definate winner. Its perfectly useable and predictable.

There is very little info on this rifle on the internet so i could look into some kind of video too

 

[flyboy1950]

Thank for all your trouble Rob, would be happy at around 8 or 9 ft/lbs as long as it`s well mannered, it won't ever be used for hunting purposes (at least not whilst in my possession) I have others for that. As had been previously mentioned I would be doubtful of the trigger sear coping long term at full power.