11 replies to this topic

[ThompsonCrazy]

Is there a rough estimate on how many rounds a Blish lock should last?
Just bored at work........Brent

[full auto 45]

Mine has lasted so far for around 8-9 thousand rounds,maybe more. It shows almost no wear at all. It is a Savage blish lock, but I compared it to a new AOC and it looks just the same. No wear.

[ThompsonCrazy]

THANK YOU!

That is very interesting. Way more than I would have guessed for such a small, soft piece of metal under constant impact.
Brent

[Arthur Fliegenheimer]

It's sort of the same question the kid posed to the owl, "How many licks does it take to get to the center of a Tootse Roll? .....The world may never know. John T. wouldn't OK any component that could not hold up to the rigors of firing.

[mp40]

Good one Phill!.....PK, how hard is the Bronze used in the original Blish lock? what scale would you use to determine this?

[PK.]

PhilOhio: you need to go shooting more! (Nice work)

I have stayed out of this because I have no hard data to offer; empirical or otherwise. I can say that most of the Locks I have replaced have been do to their being damaged by incompletely machined WH receivers or mutilated by those trying to fit them and make them work in such receivers. I have replaced a couple that were worn to a point that it seemed prudent to set them aside.

The pre war prints call for a material of "aluminum bronze". In those days of minimal standards, that could have a broader meaning that we might like to have today, however, the composition is fairly basic and some parallels can be drawn with current standards with reasonable accuracy, I feel.

This material should have these aprox physical properties

Tinsel 94 ksi
Yield 53 ksi
Hardness Bn 183 (Rb90)

To help add relevancy, the hardness of a typical WWII receiver is apx. Bn 229 (Rb98.2 or Rc20.5) so the lock is not much softer at all.

If you ever try to file a lock you will be quite surprised at how difficult it is to cut. The aluminum bronze alloys are typically used between the steel parts of sliding machinery to enhance lowered coefficients of friction and reduce wear.

Because this is a complex part to make and the supply will dry up someday, I have 3 new locks in my personal spare parts collection, I will be surprised if I need more than one in my life time.

(Bn= Brinell hardness number; the international standard.)

[john]

A: Until it breaks in half. Even then it would probably work for a while!

Mine has over 10M and it's only a bit worn........

john

[mp40]

Thanks for the information, PK! I was guessing that a Blish lock might be pretty hard, and it looks like my guess was right!

[deerslayer]

Iowa Law (similar loophole) would let me use a 1927a5 to shoot deer with. Its one of the little ideas that occasionally floats through my mind. Especially with the overpopulation of deer around here and the party hunting laws. I know there have been times I could have probably gone through 2 drums on a deer drive. Sometimes the herds come fast and furious. My father once had a deer step on his foot during a drive.

[Bisley45]

Deer season starts the 21st in Ill. I too would like to leave the scatter gun at home and take a buzz gun, or as close as the wretched politicians will let me own in state. I'd even take one of my XXsticks appart and pop a dowel in an limit myself to 3 rounds. Only shot I got last year I had to pass on as the deer was too far away, I could have hit him but I couldn't garantee where. If I had my trusty WH or a very sick 7mm Mauser carbine also resting in my safe I would have had that buck on the dinner table, but ah beurocrats gotta detest most of them.

BB

[SecondAmend]

At the risk of causing Gen. Thompson to roll over in his grave, IMHO the reason a Blish lock lasts so long is because it doesn't do anything. If I read between the lines in "The Gun That Made The Twenties Roar" there was a lot of controversy about the need for the Blish lock but Gen. Thompson insisted on having it. As we know, the Savage people took it out for the M1 and M1A1 Thompsons.

[Kevin]

UMM... we went over this before, the back end of the M1 receiver is thicker so it can stand the impact of the unretarded bolt.