Did my civic duty, saved a Bren from the scrap pile.

[Peter Laidler]

Great piece of technical description there Tankie. I was looking at it, pondering how it was all going to work until I read that! I agree that it's a good bit of work and the builder has kept it as close as possible as allowed. 17th Airborne has done the same with a Mk5 paratroopers Sten and Vince is about to start the same with an early Patchett. Good projects chaps

[Topfmine]

You certainly carried out your civic duty and given new life in such a grand piece. I also love the parkerizing job, just what I will be doing to my Bren when I sort out my blast cleaning facilities. How do you parkerizing the welded areas that would otherwise show up in the process, was the action re-tempered?

[Brit plumber]

With a new barrel and the gas piston/cylinder removed/closed. This would make a good UK straight pull rifle.

The spring over the original guide rod is genius. Brilliant idea.

[David TS]

With a new barrel and the gas piston/cylinder removed/closed. This would make a good UK straight pull rifle.

Making a straight pull Bren crossed my mind a LONG time ago! .

[Peter Laidler]

There MUST be a stop of some sort to prevent the breech block/piston extension and hammer part being pushed as far as the buffer plate - as happens on a standard gun. We can confirm this because the buffer plate on the standard gun is recessed to allow the raised part of the return spring rod recess (on the rear of the piston extension (the PE)......) to seat snugly into the buffer while the full surface of the PE strikes the flat surface of the buffer . Hence the name 'buffer' as it buffers the reciprocating heavy breech block and piston extension assembly(the BB&PE).

If the new hammer block on this gun reciprocates rearwards with the BB&PE the new almost 6" long hammer return spring must surely become coil bound during the last inch or so of its travel rearwards! Why............ Well, we know that when the BB&PE is fully to the rear there is/can only be about 1/2" of return spring rod protruding from the buffer. And that ain't a lot of support for a long spring!

Try it on your guns to see!

[bentwrench]

The manual of arms has indeed changed by quite a bit, firing form the closed bolt in semi-auto.

Assume the striker is cocked and the action closed and the bolt in lock up. Pulling the trigger releases the striker forward and it strikes the new firing pin. The gun fires and gas pressure begins to cycle the action. The striker spring rests on the base of recoil guide rod and its extended length remains the same as the carrier pushes the guide rod and recoil spring rearward. The front face of the new striker is shaped to seat against the back of the bolt carrier, just after unlocking the carrier now pushes the striker and guide rod to the rear until it contacts the buffer. The recoil springs push the action forward as usual, but the new sear will grab the sear notch on the bottom of the striker and hold it back, the carrier continues forward pushed by the recoil springs and guide rod, chambering a round and locking the bolt, during this time the striker spring is now compressed. The gun is again ready to fire from the closed bolt.

I don't know who first came up with this design, Project Guns in Florida builds this type of semi, and the builder of this gun has refined it some. Other designs such as those built by SMG Guns in Texas fix the receiver rigidly to the butt slide and add the striker spring in a separate tube the stock. This changes quite a bit more of the gun.

[Brit plumber]

I see, so the hammer spring remains at full length on the return spring guide until the return spring guide is forced forward by the return spring and this causes the hammer spring to begin to compress as the hammer is now on the sear. So effectively the return spring will lose some of it's power by having to compress the hammer spring. Does this mean the return spring is now stronger? Or that the cycle is now a little slower than original?

[bentwrench]

I was able to get the gun to the range yesterday. Fired standing, from the prone, off the bench and from the tripod. Ran about 100 rounds or so with no issues. I brought both MK1 barrels out with me to sight them in, as luck would have it bot barrels were on target with no adjustment of the front sight. I changed the barrels from time to time to see if it affected the point of impact, couldn't really see any difference. I was shooting at steel between 100 to 300 yards. Next time I go out I will put some groups on paper.

One thing that really surprised me was how easily the Bren is to fire from the hip. I was able to direct fire very easily at the 50 to 100 yard ranges. I imagine that as an automatic the Bren was very effective this way.

Firing from the prone using the bipod is where the gun really shines. Easy to operate the action, change magazines, find your target, and very soft recoil too... just fantastic.

[bentwrench]

You certainly carried out your civic duty and given new life in such a grand piece. I also love the parkerizing job, just what I will be doing to my Bren when I sort out my blast cleaning facilities. How do you parkerizing the welded areas that would otherwise show up in the process, was the action re-tempered?

The receiver is annealed after welding. The gun is parkerized and then painted and cured. I believe this one is Duracoat over the Parkerizing.

I see, so the hammer spring remains at full length on the return spring guide until the return spring guide is forced forward by the return spring and this causes the hammer spring to begin to compress as the hammer is now on the sear. So effectively the return spring will lose some of it's power by having to compress the hammer spring. Does this mean the return spring is now stronger? Or that the cycle is now a little slower than original?

Yes it seems to slow the action as it moves forward, but the gun has no problem chambering the next round, the striker spring is quite small compared to the recoil springs.. The action feels very smooth, actually almost fluid like. Having a MK2 butt it has the double recoil spring, don't know if that helps things out...

[csmarcher]

Question, has the piston post cross pin been welded in place, or is the piston post removable for cleaning and maintenance ?