Firing pin and block are VERY stuck

[AmEngRifles]

Raptor,

Yes, I recognize that gun as it was on Gun Broker and I had inquired about it. Of course John Stemple was well known for this S&W Model 76 copies. But the person who had the gun listed, replied that John had only built ONE Bren semi auto!? Something I guess he wanted to try late in life. R.I.P. Obviously, John knew firearms, but he may have not been completely up to date with all that makes these semi autos run properly. They can be frustrating. He passed in 2007, so it has been over 13 years of continued (somewhat) development.

Yes, your bolt is worn. The last time I saw a bolt with this much primer erosion was on an AR-180 I owned that ran a bunch of reloads that had loose primers, hence the gas cutting in that circular pattern around the firing pin. And in case you do not know, Bren firing pin faces are rectangular (sort of) like a Glock firing pin (NOT interchangeable). But if the bolt still head spaces, I would work with it. Don't grind or polish the rear, or the face of the bolt, as those areas help establish head space. The gas cut ring should not hurt too much, unless your primers are backing out and hanging up on the circular groove. My AR-180 ran find with a bolt like that.

Certain parts for these semi auto are very hard to come by. At the present time, I only know of Historic Arms and Kiwi who are still making the guns in any form of series. They may be a source to get a replacement striker? Your design is very similar to the Historic Arms internals. Len (of Historic Arms) removes the buffer plate at the back of the trigger frame and uses the large diameter striker spring as Stemple did in this gun. The firing pin has an extension welded to the rear so the striker can impart force upon it, but the forward part of the firing pin is normal Bren, and those are still available. Look up a normal Bren firing pin and you will see the difference in the two. The semi has the long tail welded on.

It may be possible to "rebuild" your striker, by having some areas built up with weld, filing to shape and size and having it heat treated. The striker "head" or portion that contacts the rear of the firing pin appears to be battered. That should possibly be built up and squared off? There is a wonderful striker set up by "Mighty Lime", but not sure he makes them any more? Mighty used to be on here and at WeaponsGuild. My only problem with the Mighty Lime set up was within a Project Guns Bren. It would touch off the commercial ammo fine, but seem to be a tad light to touch off the harder primers on surplus military ammo. I ended up going back to the original striker (closer in design to yours) and worked with the spring tensions in both the striker spring and the return spring areas. It is a bit of a trial and error to get them balance right and then that is dependent on the gas setting you have the barrel set to.

Welcome to the world of Brens. If you ship it back to the guys (Stemples son) hopefully they have enough extra parts to get it cleaned up and running properly. I hope they themselves are aware of the intricasies of the semi auto Bren. They can be frustrating at times. All the best.

By the way, I suspect if you pull on the firing pin from the rear, with a pair of channel locks to get a good grip, and having the firing pin retaining pin backed out, ready to let the firing pin pass by, it would probably come out. Give it a twisting motion as you work it back. You either have a bound up, kinked firing pin spring or a bit of debris that has gotten into the firing pin channel and is binding things together.

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