BSA Scorpion pistol - technical info and history

[lightning22]

I owned a Venom Tuned one back in the day. I wonder what happened to that? Mach 1.5

That I would like to see... the closest I have is one with a slimtech fitted and a Colin Malloy blue.

[evert]

Thanks for all the great info everyone!
It will be interesting to see what shape the spring is in.

You might want to consider taking the next three issues of Airgun World for a historical detailed study of the BSA Scorpion pistol.

There will also be a follow up on the Shadow Carbine.

John Milewski

The wife gave me a sbuscription for AGW for christmas, so I hope to get all the articles.

[Josie & John]

John's article should be compulsory reading for anyone with even a passing interest in the marque.
Inspired by part one, I have bought two pistols recently, early and late model, both in need of a service.

That is very kind of you (and Tony) to say so.

I hope you find the next instalments of equal interest.

Kind regards,

John

[evert]

Funnily enough I read your fine article a couple of hours ago. Very enjoyable and informative. Great info on the revised piston for the .22 giving shorter stroke and taming the power.

Eagerly awaiting the next instalments.

I guess the stroke reduction was done by a different piston head?

[TonyL]

Looking at the images, evert, a different piston. To me it looks like the different slot was built in so that the trigger engages the slot at an earlier point in the stroke.

I'm sure JB or some other nice, knowledgeable person will elaborate.

[Shed tuner]

Do you use a Meteor 'O' ring, Jon? Or just a smaller one from your "stash"? Have you ever played with different piston heads on them.....ie the alloy head or an altogether different one and parachute seal?

from the "stash" Yes, I've also fitted a diana 28mm seal - have to space it out though to maintain the same stroke, as the unique trigger arrangement makes it very difficult to play with the stroke, and have the main trigger sear sitting in the right place - i.e. the piston can't come too far forwards. Not sure it;s worth the effort to be honest - I guess it could be though if you have a poor cylinder that's not true enough to seal with an o-ring.

The two different strokes were actually different pistons, same heads. The longer stroke isn't really necesary, and just makes it hard to keep under the limit. With a weaker spring, it's more prone to bounce.

[ggggr]

The .177 piston is 2mm shorter--so the stroke is 2mm longer than the .22

I tried fitting a T.Robb head and a longer stroke. The head weighs a ton and it cam with a hexagon nut that the spring wouldn't go over. The trigger was ok indexing.
However I have converted the pistol and it has a leather piston washer and I've done away with the safety-----------thus removing most of the Scorpions problems--sticking buffer washer and a safety that plays up .

[Shed tuner]

The .177 piston is 2mm shorter--so the stroke is 2mm longer than the .22

guy, have you ever seen a shorter (longer stroke) piston than the 2mm difference you describe ? I've one here that is about 5mm difference when measuring from the front of the piston to the sear engagement point? Then again, I think the engagement "slot" is moved relative to the tail too, so it may be 2mm overall length diff, but a larger difference in the stroke ?

[ggggr]

guy, have you ever seen a shorter (longer stroke) piston than the 2mm difference you describe ? I've one here that is about 5mm difference when measuring from the front of the piston to the sear engagement point? Then again, I think the engagement "slot" is moved relative to the tail too, so it may be 2mm overall length diff, but a larger difference in the stroke ?

Without stripping down various Scorpions, the only difference I have seen is the 2mm total length. I am not saying that anything else is wrong but the 2mm rings a bell for some reason. Also when you thiink about it, a thinner buffer washer will give the longer stroke.
I've fitted a couple with leather buffer washers (to avoid the sticking) and one with a a leather piston washer, as well as doing away with the safety.

[Mach 1.5]

When I was a member of the Venom Rifle & Pistol club back in the late 80's Dave & Ivan did a few Scorpion pistols for club members. Venom Tuned, Silencer and reworked HW77 front and rear sights. 22 cal only and great fun for a plink.
Mach 1.5

[TonyL]

Brilliant information from Jon and Guy up above. Very interesting; thank you.

[TonyL]

When I was a member of the Venom Rifle & Pistol club back in the late 80's Dave & Ivan did a few Scorpion pistols for club members. Venom Tuned, Silencer and reworked HW77 front and rear sights. 22 cal only and great fun for a plink.
Mach 1.5

I had never heard of the Venom Club until now, Paul. Cheers.

Just wished I had lived closer.

Those pistols sound fantastic.

[evert]

Brilliant information from Jon and Guy up above. Very interesting; thank you.

Got to agree, thanks to everyone for sharing their knowledge!

I'm just waiting for the mail to get going again after Christmas, my next Scorpion is showing up any day now!

[Shed tuner]

Without stripping down various Scorpions, the only difference I have seen is the 2mm total length. I am not saying that anything else is wrong but the 2mm rings a bell for some reason. Also when you thiink about it, a thinner buffer washer will give the longer stroke.
I've fitted a couple with leather buffer washers (to avoid the sticking) and one with a a leather piston washer, as well as doing away with the safety.

trouble I had when I went for the thinner buffer washer / longer stroke - one gun worked fine, the other, with the piston going further forwards, the main sear went up that little bit deeper into the gun as there was less piston skirt to hold it down, and it wouldn't recock - stroke put back to standard and it worked fine.

Bloody scorpion triggers

[ggggr]

trouble I had when I went for the thinner buffer washer / longer stroke - one gun worked fine, the other, with the piston going further forwards, the main sear went up that little bit deeper into the gun as there was less piston skirt to hold it down, and it wouldn't recock - stroke put back to standard and it worked fine.

Bloody scorpion triggers

Yes Jon "Bloody Scorpion triggers" . I like to think I'm pretty good as sussing them now. Most problems are the safety spring throwing the safety out of plonk, but I've had a bent little sear that I only spotted after putting next to a good one and a long sear that wouldnt cock and looked identical to one that would. As I have said on here before, I've done away with the safety on 2 Scorpions. If it is not there it cannot go wrong!