For questions relating to specific aspects of the 76 / 760 please go to the appropriate pages.
For FUNCTIONING PROBLEMS, please go to our trouble shooting page:
76 / 760 Troubleshooting.
For MAGAZINE PROBLEMS, please go to our magazine page:
76 / 760 Magazine Problems.
For INSPECTION & EXAMINATION, please go to our inspection page:
76 / 760 Inspection.
PREFACE:
While questions regarding these firearms are many and varied, the following questions are the ones most
frequently asked. Individual experiences can and do vary, as do invividual 76s / 760s, and we understand that
you may not agree with the answers given to a particular question. The answers are, however, based on
our experiences in making parts for, diagnosing problems with, and trying to keep this series of firearms
functioning properly.
If we err, it will be on the side of caution. Remember, just because something CAN
be done doesn't mean that it SHOULD be done.
What spare parts should I keep for my 76 / 760?
Please go to our spare parts page:76 / 760 Spare Parts.
Why won't my 76 / 760 run using "ABC" factory ammunition but my buddy's gun loves the stuff?
First of all, The Smith 76s and MK 760s are FINICKY! What works well in one can be poison in
another. The only way to tell if your 76 / 760 likes or dislikes a particular brand / load is to actually
try a box or 2 in your own firearm. If this means custom loads or your own reloads, go for it. For testing
in our shop, we use Winchester® White Box 115 grain ammunition as our test "standard". This is simply
because it is available nationwide. Note here that even this is not 100%. There are some 76s / 760s that
don't care for WWB. One final note, try going to a load
using a 125 grain bullet instead of the 115 grain. We have found that the heavier bullet can make a difference.
Why do my magazines fit my 76 just fine but my buddy's magazines won't even go into my gun?
True Smith & Wesson manufactured 76s are quite uniform in the magazine well area. After Smith sold
the manufacturing rights to the 76, they had no control over any changes the new owners made. Adding to
the issue is that rights were subsequently divided between the two original purchasers. Manufacturing
plants were relocated and new workers were hired. Each time a change took place it seems as if (to us at
least) the tolerances in the magazine well area loosened up. Magazine fit is critical in any subgun and
seems to be especially so in this one.
Why does the stock on my 76 wobble so badly?
Quite simply it is the design of the folding stock, more specifically the design of the top hinge / latch plate,
the way in which this plate mounts to the receiver, and the way in which it locks the stock. The top plate has
a groove .590 wide by .136 deep and slides into a slot in the mounting block welded to the rear of the receiver.
A parallel slot .590 wide by .150 deep holds the stock in either the folded or open position by the top stock arm
dropping into this slot. Due to manufacturing tolerances, these parts are not a precise fit, that is, they
wobble. Adding to the issue is that only one bolt holds everything together. The design has no adjustment for
wear so loosness becomes worse with each folding of the stock.
Can a wobbly stock be tightened up?
Short of a complete re-design of the stock hinge / lock system, or installation of an aftermarket stock adapter
assembly, not really. Other than a tack welding of the top plate to its receiver mounting block and adding a
screw through the top stock loop to tighten it to the top plate, what you have is pretty much what you get.
You have to be able to remove the grip in order to remove the trigger group for cleaning or possible repair.
We can assure you that the trigger group gets plenty dirty from powder residue and should be periodically
removed, cleaned, and lightly lubricated.
In FULL AUTO, I can fire a couple of bursts but then the next shot is one round SEMI. What's up?
You have just been introduced to one of the idiosyncracies of the 76 / 760 trigger mechanism.
There is no positive disconnect in the 76 / 760 trigger mechanism. SEMI fire requires the trigger bar
to drop free of the sear from forward movement as it rotates the sear downward to release the bolt. Once
the trigger bar drops free, the sear will rotate upward under pressure from the sear spring to intercept the
bolt. FULL auto fire occurs when the trigger bar is prevented from dropping free of the sear by the selector.
In the FULL auto position, when the trigger is pulled and the trigger bar moves forward, the nose of the trigger
bar still partilly disengages from its notch in the sear as it rotates the sear downard to release the bolt.
If the trigger is only partially released, the sear will still rise to intercept the bolt but the trigger bar
will not fully reposition itself back into it's notch in the sear and on the next pull of the trigger, the nose
of the trigger bar will slip out of the sear notch usually firing a single round.
To permit the trigger bar to reseat fully in the sear notch, all pressure must be released from the trigger.
When I'm in SEMI, why does my gun sometimes fire a 2 or 3 shot burst?
Like the question above, this is another of the idiosyncracies of the 76 / 760 trigger mechanism.
Again, there is no positive disconnect in the 76 / 760 trigger mechanism. SEMI fire requires the trigger bar
to drop free of the sear from forward movement as it rotates the sear downward to release the bolt. Once
the trigger bar drops free, the sear will rotate upward under pressure from the sear spring to intercept the
bolt. If the trigger is short stroked or "milked" (usually in an attempt to shoot a tight group in SEMI),
the trigger bar is not moving far enough forward to complerely disconnect from it's notch in the sear. This
holds the sear down a fraction of a second longer permitting a second or second & third shot. Recoil and / or
the shooter's reaction to recoil pulls the trigger the rest of the way back. The nose of the trigger bar drops
free from its notch in the sear, the sear rises and intercepts the bolt.
To permit the trigger bar to fully drop free of it's notch in the sear and give semi auto fire, a firm pull
all the way back is required of the trigger.
Can I convert my 76 / 760 to shoot cheaper ammo like 7.62 x 25 or 9mm Largo?
The short answer is NO. The long answer is still NO but is somewhat more ... ah ... "colorful".
The Smith 76 was designed around one specific cartridge - the 9mm Luger. More specifically, the 9mm Luger
as loaded in the United States as a commercial sporting pistol round. Remember, the Smith 76 came about during
the Viet Nam war and there was no official 9mm military round in use by the United States Military.
See the next question for a more detailed explanation.
If you absolutely must have a different cartridge, the .30 Luger round works nicely. Besides, how many people
do you know who even have a firearm chambered in .30 Luger, let alone a submachine gun?
Other SMGs have been sucessfully converted to different cartridges. Why can't I convert my 76?
Compare the design features of the Smith 76 to 2 other 9mm Luger SMGs - the Swedish K and the STEn. All are
unlocked blowback designs, about the same physical size, and originally designed for the 9 x 19 Luger cartridge.
|
Smith 76 |
Swedish "K" |
STEn Mk2 |
| Bolt size: |
1-1/8" OD x 7-1/8". Has 3/4" ID x 4" deep hollow for recoil spring. |
1-3/8" OD x 6-1/8". Recoil spring fits over spigot. |
1-3/8" OD x 5-3/4". Recoil spring fits over spigot. |
Bolt weight:
(includes handle) |
553 +/- grams |
753 +/- grams |
642 +/- grams |
Bolt travel:
(on firing, how far the bolt can move rearward before hitting end of receiver) |
4" |
5-1/8" |
5-5/8" |
Cyclic rate:
(published data) |
750 rpm +/- |
600 rpm +/- |
550 rpm +/- |
| End closure: |
5/16" dia vertical pin through 1/8" receiver walls.
OK for 9mm Luger. |
3 - .177" diameter pins engaging half-moon notches in 1/16" receiver walls.
OK for 9mm Luger but weak.
Last "K" model added top & bottom hooks outside receiver. |
180° fit of stock lug in end ring top groove. "T" stud or hook at bottom.
Strongest of the 3. |
| Suitable for Conversion: |
NO |
NO |
Within reason, yes. |
In plain point of engineering fact, the 76 / 760 just doesn't have enough design reserve to make it a viable
candidate for conversion to any other cartridge packing more punch than the 9mm Luger. Doing so will simply
beat the weapon to death, quite possibly in short order. We are sure that somewhere, someone, has converted to
7.62 x 25, 9mm Largo, .40 S&W, or whatever. It is our humble opinion that to do so is to invite disaster and
we want NO part of it. Once again, just because something CAN be done doesn't mean that it
SHOULD be done.