Replacing that awful BSA breech pin with a bolt?

[TonyL]

Fully agree, Al.

[evert]

I'll throw in an unpopular experience now:

My rescue Mercury has a quite large fork to barrel block gap, and when squeezed by the bolt,
the forks only contacts the breech block at the front.

Several of my Supersports have very good breech block to fork fit, and have less play than the mentioned Mercury.
And they have been tight for many shots (three of them have seen a lot of use) with proper lubrication and sensible use.

Of course the Meteor is not as durable, but I have one that sees a lot of use and has stayed good for a long time.
But with the number of airguns I have there's a limit to how much use a single rifle sees

[TonyL]

Yes, I'd always wondered about the possibility of the scenario you describe on your rescue Mercury, evert. I guess the solution would be to employ shims as well as the bolt to keep those jaws parallel?

[evert]

Yes, I'd always wondered about the possibility of the scenario you describe on your rescue Mercury, evert. I guess the solution would be to employ shims as well as the bolt to keep those jaws parallel?

Either shims, or squeezing the forks AND then expanding them slightly in front.
I've done the expand/squeeze combination with great success on a couple Supersports, but you have to be careful.
What you want to achieve is better contact all the way along the breech block.

[greenwayjames]

Its also worth thinking about why the breech jaws have a tendency to open after often little use. By breaking the barrel and pulling it down as vertically as possible there is less likelihood of barrel wobble especially with the BSA positive vertical lock up.
IMHO when the jaws are spread it is because the barrel is continually pulled down at an angle to cock the rifle as most folk do.
See for yourself by putting a few shots through your breakbarrel

[TonyL]

Absolutely. Agree. But then employing an arrangement that demands such attention to correct technique to avoid issues is a huge risk. Especially when, as others have said, many less prolific "budget" rifles have a more sturdy arrangement.

[greenwayjames]

Absolutely. Agree. But then employing an arrangement that demands such attention to correct technique to avoid issues is a huge risk. Especially when, as others have said, many less prolific "budget" rifles have a more sturdy arrangement.

True but the BSA has the advantage of a superior vertical lock up.

[TonyL]

Either shims, or squeezing the forks AND then expanding them slightly in front.
I've done the expand/squeeze combination with great success on a couple Supersports, but you have to be careful.
What you want to achieve is better contact all the way along the breech block.

Yes, I think shims are the route I'd be taking. Much less faff.

[evert]

Yes, I think shims are the route I'd be taking. Much less faff.

But shims will reduce the length of the breech/fork contact area. on a well fit meteor/Supersport, the breech block contacts the forks all along its length.

Plus, on a BSA, the pin is out of center of the barrel block. The barrel is brazed or sweated on, so the breech block does not have the height to provide full contact area for the shim.. so almost half the shim will not have contact with the breech block.

[TonyL]

But shims will reduce the length of the breech/fork contact area. on a well fit meteor/Supersport, the breech block contacts the forks all along its length.

Plus, on a BSA, the pin is out of center of the barrel block. The barrel is brazed or sweated on, so the breech block does not have the height to provide full contact area for the shim.. so almost half the shim will not have contact with the breech block.

Understood. And highlighting even more shortcomings with the arrangement. The more you think about it, BSA's arrangement was far removed from the ideal.

Even those Wobblies had a fuller, more substantial, proper breech block.