My .308/7.62mm fullauto conversion- Plug & Play Success!!

[TactAdv]

Finally got around to looking at doing a .308 conversion for my '42 Daimler Mk II fullauto gun.

I've been picking up the various bits over the last year, finally got interested enough to put it all together,,,,litterally as it turns out. ;-))

I've been reading with much interest the various posts of doing the .308 conversions.....with all the ups and downs, so I now feel kind of sheepish to report to you all that, for my original gun at least, this turned out to be a "plug & play" exercise........not sure what to feel about that bit of luck but I'll report on my affair here.....

My receiver/gun as I said, and have posted several pictures around other posts herein, is a factory original condition Daimler Mk II from 1942, so that may/may not have turned out to be an important data point in this....

I am using one of the long-ago imported "South African"/DENEL/Lyttleton Eng. 7.62mm barrels that were new made for the SADF conversions there. Many of you seemingly have the same barrels.

I had been holding off on this project because, stupid me, I never really looked at the damn barrel carefully when it came in except to note the R1/FAL flash hider they used, which I think is a nice visual change for the BREn. Then one of you pointed out here that these barrels are markedly differently constructed in the that the barrel shank end is cut back, and chambered accordingly, to permit use of the standard .303 bolt with horns. I had been thinking I'd need to machine the barrel base for the normal .303 bolt, machine in the ramp to accommodate the feed horns a la the .303 barrels. That was a major discovery.... ;-))

In this particular combination of receiver & S.A. 7.62mm barrel, I was very lucky I think in that the combination breached up tight on the first try, and the bolt locked perfectly, with both the currently installed barrel lock and bolt locking shoulder. With that bit of luck, I checked the head-spacing and was in luck again. I swapped in a S.A. 7.62mm extractor into the normal .303 bolt it had in there, and that was it.

I am using unmodified Bulgy ZB-39 mags. I have read a lot here about using them for various things but wanted to try them first as-is. They took the full 25rds no problems. I was also lucky in that they locked in perfectly with the Mk II mag catch I had installed......

I decided to try some Russian "Brown Bear" steel case .308 I have lots of. See pictures below. The whole thing went together Plug & Play style.......I fired 160rds in various semi-auto and fullauto shooting, with only a couple of things to note.

As JoeH here pointed out, occasionally, I had the last round fail to get picked up out of the magazine. It was an intermittent thing, maybe 20% of the time. Interestingly, when that happened, leaving that single round in there, the gun would fire it if cocked again.

No failure to chamber or fire at any time, other than as above for the last round. I tried both gas port position #1 & #2. Both ran it fine, though #2 seemed, with this .308, to run more smoothly and I am guessing at about 600RPM or so.......I'll think about as I shoot it further. So far, so good.

Here are some pictures; I'll get live fire video next time out.
-TomH

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[browningautorifle]

We did one once using an 8mm Inglis. All we did was changed barrel(plus the minor fitting), checked headspace and carried on. Shot like yours does...used the same mag and bolt too...

[Joe H]

Tom,

I'm green with envy. FA Bren in the US.

Joe

[Lee Enfield]

[QUOTE=browningautorifle;334679]We did one once using an 8mm Inglis. All we did was changed barrel(plus the minor fitting), checked headspace and carried on. Shot like yours does...used the same mag and bolt too...[/QUOTE]

I assume you mean "...used the 8mm Mauser magazine and bolt too..." ?

[browningautorifle]

used the same mag and bolt too...

Like I said, used the same mag and bolt too...the ones in the gun. And, they worked fine.

[Peter Laidler]

Must have had an extractor change surely! I have just used a .303 BB assembly in an L4 gun (not the same I agree....) with a slightly dinged/distorted drill round (to replicate it having been fired and tight in the chamber) and the 7.62 drill round just moves to the rear a couple of mm's, then upwards slightly and slips off the extractor. It's not exactly comparing like with like but the mechanics of it are the same.

The trouble with a converted gun WITHOUT the magazine well stop inserts is that before long the gun feed lips will tear away. Or maybe this only occurs with those guns that use L1A1/FN type magazines that sit slightly deeper in order for the BB feed horns to make better contact with the smaller base rim diameter of the 7.62 cartridge

[browningautorifle]

Must have had an extractor change surely!

It was an 8mm gun boys, the 8mm extractor...and little square mag...he didn't have any 7.62 extractors so I know we didn't change it.

[AmEngRifles]

Must have had an extractor change surely! I have just used a .303 BB assembly in an L4 gun (not the same I agree....) with a slightly dinged/distorted drill round (to replicate it having been fired and tight in the chamber) and the 7.62 drill round just moves to the rear a couple of mm's, then upwards slightly and slips off the extractor. It's not exactly comparing like with like but the mechanics of it are the same.

"The trouble with a converted gun WITHOUT the magazine well stop inserts is that before long the gun feed lips will tear away. Or maybe this only occurs with those guns that use L1A1/FN type magazines that sit slightly deeper in order for the BB feed horns to make better contact with the smaller base rim diameter of the 7.62 cartridge

"


I am understanding just a little more each time comments are made... As I slowly become aware of the nuances of the Bren, I can see that the L4 mag did need to be seated deeper, as you say Peter, because of the smaller rim face. Then along came the gouged magazine follower, causing the feed horns to be abbreviated as well. One begets the other, begets the other. Kinda Biblical. lol.

Not having spent much time researching South African conversions, what did they do for mags? Was it the FAL Metric style? And at some point, what was modified about the mag well to allow the FAL mags to fit and lock?

In these mentioned conversions, a non-7.62 mag is being utilized, but that is ok for range work. I know the SA Military Brens must have had a more thorough solution.

[Joe H]

AER,

I had a similar fitting problem with the Semi Bren & the ZB39 Mag. My MKI which was made from an IO kit and has a spec mag well and worked with an unmodified ZB39 mag. Locked in perfectly.

My MkII was made from a MGS kit and had a "loose" mag well. Worked with a .303 mag but the ZB39 could slip out as you experienced with your semi Bren.

My fix is pictured below. A shim soft soldered int between the ribs of the lower rear of the mag.

I also found that removing the follower guide (pictured) from the mag allowed more rds. in the ZB39 mag.

Here is some info. I found about the SA Conversion:

www.nutria.co.za - View topic - South African Bren gun

Joe

[AmEngRifles]

Thank you Joe, will read and digest.

Oh to locate a coveted Mag release, ejector conversion unit...

Do any drawings exist?

The obvious question, does the front of a .303 mag well accommodate the small triangle lock tab on the FAL mag? I sure it locates, but is that small bit of meatl enough to keep that mag in place securely?

Form that article Joe, it does sound like the SA conversion was somewhat suspect and relegated to other duties besides front line. Good read though. Thank you.

I may try brazing a small piece of metal to the fronts of the ZB mags. Try one at least. See if that is enough to have a more positive lock.