Need help with a Bofors 40mm breach.

[Jon Bradshaw]

Anyone have a good working knowledge of the bofors 40mm? I have one that is a bit rusted and I can't get it to move/ function.
It has spent the last 2 months in a barrel of diesel and that helped but the main breach block is stuck hard in the open position. I have an operators manual on it and can't identify any parts that would account for it to be stuck.
I have removed the barrel and pushed the barrel safety pin back to make sure it is not locking it open.
I have freed up the trip ejectors and they are not catching the breach block.
I have tried hitting it, using a bit of heat to warm it up and even tried willing it to work...... but it has defeated me thus far.
The only thing I can see from the manual is that the inner sears are simply stuck with rust.... I can't see where the best place to tap on them is and have tried gentle tapping on everything I can see to try to get it to move.
I would also love to borrow some of the take down tools for a day to remove the parts that are free and give more access to the rest. The coil spring is still on it and that will be hard to remove without the proper tools.
If there is someone in my area (Edmonton, Alberta) I can meet with you in the next few days.

[Brad Deckard]

That breech looks ok, you have to knock the sear out first which will release the spring and release the cams. Then the breech will drop out the bottom. , it may need a tap.. You dont need any special tools to remove the coil spring. But DO NOT attempt to dismantle the spring housing as its under tension.

You will need a crow bar for a lever and a drift and a hammer.. But if your wacking it like hell your doing something wrong..

I will get some photos on here to help you.
Brad

[Brad Deckard]

http://www.mapleleafup.net/forums/at...1&d=1515068147

[Brad Deckard]

The long bit is the sear, it is pushed into the spring, but it glides through the cams as well.
It needs to be pulled out . The manual does say it can get stuck a bit, I jemmy can be used to get it going.
I would suggest gently tapping the thin end in the middle of the circular spring housing to start it off.

Also at the other end of the sear is a small wheel which should rotate.( my bottom left photo.. in the bottom left of picture.. in the other photo im holding the wheel). this is separate to the removal of the breech but is like a little wheel which rolls over the side cover. Just for info.

When the cam is drawn out the sears will fall out of the bottom, as will the breech. It is relevant when replacing the breech if its cocked or not. If it isnt cocked there is a way of doing it. But replacement of the breech if its fired off is difficult. But get it out first and we can worry about getting it back in then.

(I have to add that my Bofors guns are all deactivated and certified by the London Proof House, and have the certificates and proof stamps on the cannons. Here in the UK we cannot own live bofors guns)

Brad

[Brad Deckard]

Your top left photo is the extractor removal bolt. If you unscrew it the extractor can be removed. You mentioned the barrel safety pin.. If the barrel is screwed in then this pin is not going to affect the removal of the breech.. If the barrel is out ( which yours is) then be sure you have disengaged this safety plunger. It will stop the breech removal. I am assuming you have disengaged it as you mentioned the barrel safety pin.
It mentions that in the manual.
Brad

[Brad Deckard]

If I have miss understood you and it is simply stuck.. and wont budge, this is the little sear on the bottom of the breech which hold the pin back.. it could be in the wrong place and need pushing over to release the firing pin..

[Jon Bradshaw]

After looking at your pictures and reading your comments I went out and tried again. I was trying to hit the shaft towards the spring instead of away from it. Beyond that I applied more force to the cam shaft and it did come out but with some serious resistance. This breach has not functioned in over 30 years that I know of and who knows how long before that.
The cams and the breach block are still rusted solid in place and I can not see any way to apply adequate force to them if they are stuck as solid as the cam shaft.

[pekelney]

I have found both of the these manuals helpful, esp. when you can disassemble in the order suggested:

https://maritime.org/doc/boforstm252/index.htm
https://maritime.org/doc/boforstm/index.htm

The illustrations are better in the Navy manual:
https://maritime.org/doc/bofors40mm/index.htm

rich