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Old November 8, 2007, 11:31 PM   #1
duboy
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Those of you with Auto Ordnance 1927A1's

Hey ya'll, so i went out on a limb and got this 1927A1 a few months back. It's been great until this last trip out to the range.

I ran about 5 full 30rnd mags through it, and on the last of the 5 mags, it fired two shots in succession (kind of like 2-rnd burst) and everything after was fine. I took it apart for some cleaning..and general inspection and noticed something funky about the firing pin. this is my first centerfire long gun, so maybe i'm just not used to it. When the bolt is held back (after the last shot is fired, or when cycling), the firing pin is protruding past the bolt face. if you release the bolt slowly you can see the firing pin go back into the bolt face so by the time a round has been stripped from the magazine, it's no longer visible. Check out the pics below.

I was trying to think of any reason why it would have fired a two round burst with only one pull of the trigger and thought this might be connected to it? what's the term...slamfire is it? i was using cci blazers instead of winchester ammo, and i know that sometimes different primer might be kind of soft and more susceptible to slamfires with floating firing pins.

Any ideas? or anyone with a AO 1927A1 experience this?

IMG_5391.jpg
IMG_5392.jpg
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Old November 8, 2007, 11:44 PM   #2
Army GI
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It's supposed to be like that

As the bolt is slamming home the cartridge it is also detonating the primer. Its a long story but an automatic weapon with a fixed firing pin chambered for relatively lower pressure handgun cartridges just works. It is in fact "slamfire" that the Thompson operates on.

ETA: my mistake I'm thinking of the M1A1 Thompson.
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Old November 9, 2007, 12:00 AM   #3
duboy
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:-D wish i had a 1928 or M1A1 that fired from open bolt. the AO 1927A1 was the best i could do for now.
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Old November 9, 2007, 12:05 AM   #4
Army GI
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Well as far as I know, the pre-war models used a hammer/firing pin system. Even the M1 had a hammer; the only model with a fixed firing pin machined into the bolt was the M1A1.

Also, I don't believe the Thompsons had floating firing pins, they were held back by springs. But these are civilian models so what I say probably doesn't really apply.
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Old November 9, 2007, 12:26 AM   #5
oldbillthundercheif
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My worthless kahr thompson would go full-auto every once in a while. Bursts of two or three at first, but it got worse (better?). I eventually sold it when they sent me a new one after four trips back to the factory and 18 months of giving me the runaround.

They fixed the full-auto problem after the second trip to the factory, but they were never able to make it reliable. It would jam in weird ways never seen before (mutilated brass powder-dumping live-round stovepipes) about every 10 rounds with every .45 load on the market.

Ugly. Does yours function normally when it is not firing multiple rounds?
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Old November 9, 2007, 12:33 AM   #6
duboy
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actually yes, i've gone through probably ....5-600 rounds since i got it and have had no problems until last trip, and it's pretty accurate too, not a tackdriver by any means, but enough to be a really fun piece to shoot.

sorry to hear you had a bad time with yours, i really do like it, i hope this isn't a sign of things to come.
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Old November 9, 2007, 10:51 AM   #7
Dirty_Harry
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Quote:
They fixed the full-auto problem
Problem???? Where is this so called problem???
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Old November 9, 2007, 10:53 AM   #8
Manedwolf
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Quote:
Quote:
They fixed the full-auto problem
Problem???? Where is this so called problem???
The problem is when someone taps you on the shoulder at a range and is wearing a BATFE jacket.
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Old November 9, 2007, 12:05 PM   #9
Hawg Haggen
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Sounds like a worn sear.
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Old November 9, 2007, 02:27 PM   #10
44 AMP
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Semi auto Thompson interior design is rather "unusual"

According to my sources, Numrich (who held the rights to Auto-Ordnance for many years) had to redesign the inside of the gun in order to pass muster with the BATF. It not only had to work(fire from the closed bolt), it had to not accept the SMG parts.

The resultant design is really "funky" and not what we would have gotten if the Feds had kept their noses out of it. The Semi auto tommygun has a couple of strong springs (and some other parts), where the SMG doesn't. Compared to the SMG, the semi auto is very hard to cock. The reciever is made to be about 1/4" "off" from the SMG, so the parts (bolt, etc) won't fit. SMG magazines have to be slightly modified to work in the semi auto. And the trigger pull sucks.

On the other hand, except for the heavy spongy trigger pull (which I still have not got around to fixing), my M1927A1 deluxe has been a lot of fun to shoot. A pain to hold up, but fun to shoot, and quite accurate. I have only fired a few hundred rounds through it so far (gun was used when I got it, but looked like new), and I have not yet gotten the drum mag to be reliable (only tried it 3 times so far), but with the 30 rnd sticks it has been flawless feeding, and it feeds RN, SWC, and JHP. I did suffer a broken extractor early on, but that is one of those things that can happen to any gun. Since that replacement, the gun has done well.

My gun has Kahr markings, and while I have heard some folks having bad times with theirs, mine had been ok so far. I can get a five shot one hole 25yd group, and also hit the 200yd gong (using the ladder sight).

Not a really practical working gun, but a lot of fun for those of us who can't afford or live where they allow the real SMG.

Most common comment when the gun is at the range is "wow, I didn't know they were so heavy!"
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Old November 9, 2007, 09:25 PM   #11
Dfariswheel
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The most probable cause of "doubling" in the Thompson semi-auto is a broken or jammed firing pin, or a defective or worn firing pin or sear.

Another possibility is you accidentally "bump fired' the gun.

The semi-auto has a really odd looking striker/firing pin design. If the pin is broken or fouled with some brass, it "could" stick in the forward position and "skip" over the sear to fire.

The most likely cause is a worn, chipped, or broken sear area on the firing pin, or a worn or chipped sear.
I'd be taking a good look at those two areas.

If you hold a semi-auto firearm just right as you pull the trigger, the gun will recoil, "bounce" forward, and your finger can inadvertently pull the trigger again.

Many people do this on purpose to simulate full-auto fire legally.
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Old November 11, 2007, 12:01 AM   #12
duboy
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I cleaned it up real well before my trip out today:

first, i ran 90 rounds of winchester white box through it without a hiccup

second, I put the CCI Blazers back in and the problems started, FTF, FTE, no 2rnd bursts though.

Then i switched back and ran 60 more rounds of winchester white box, no problems at all.

i'm curious if the primers for CCI Blazers are softer than for the WWB, the Blazers have a silver primer, the WWB has brass (looking). one thing is for sure, since i bought the 1927A1 i ONLY shot WWB through it, until i happened upon some Blazers, then all hell broke loose. But it sure does seem to love the WWB, and aside from the attempt to run Blazers through it today, it ran flawless. i'll pick up more WWB and do more tests. Thanks for tuning in :-)
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Old November 11, 2007, 03:57 PM   #13
44 AMP
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Blazer Aluminium or brass?

Even though it is cheaper, I have never had real good luck with Blazer ammo except in revolvers (and .22s). Generally I avoid them, being a dedicated reloader, the bredan primed Aluminium cases are specifically made to prevent reloading. I have never shot the Blazer Brass ammo, but with brass cases, it ought to be ok.

The general rule of thumb is, if one brand (or load) of ammo gives trouble in your gun, don't shoot it! Blazer in revolvers gives no trouble (at least so far, for me), but in centerfire autoloaders, it acts like crap! At least one maker has said not to shoot Blazer in their (autoloader) guns. My "Tommygun" (semi) has worked fine with everthing I have fed it, WWB, Rem-UMC, and all my reloads.

My advice is dump the Blazer, and shoot the good (or at least the fair) stuff. It costs a few pennies more, but what price is proper function worth? To me it is worth the cost difference (and since I shoot reloads, there really isn't much of a cost difference anyway).
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Old November 26, 2007, 05:03 PM   #14
duboy
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44 AMP: it was blazer brass, not alum. and yeah, i'll be sticking with WWB for the time being in my AO Tommy as it is flawless with it. Thanks for all the replies!
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