:: Stonycreek Armory Suomi/MAC installation directions ::

These basic directions will inform you on how to install the new Suomi kit to your M11/9 or M11A1 .380 Submachine gun.
More detailed instructions are available with firearm safety, trouble shooting and maintanance.
This Patent pending, ATF approved accessory is not a firearm and therefore needs no paperwork for transfer or installation.
Many options are available now and more will soon be released.
Please completely read these instructions before you began.
if these directions seem out of your skill level have a gunsmith preform the installation for you. Modified or damaged parts are not returnable.

#1) BE SURE YOUR FIREARM IS EMPTY WITH NO MAGAZINE INSERTED AND NO ROUND IN THE CHAMBER!!
it is wise not to have any ammo in the area during this time. Safety first!

#2) Your firearm must be in good working order with a fresh, well maintained sear. The sear is the trigger part that catches the bolt and also releases the bolt when the trigger is pulled. if you are not sure what shape your sear is in email us before installation or see a local gunsmith for inspection and possible replacement.

#3) Remove your receivers pin that attaches the upper to the lower. Lift off the upper and put your original upper and bolt assembly away. you will not be using this upper or bolt with the suomi kit.

#4) IMPORTANT: inspect your sear for wear. The sear should have a nice edge and no rounding of the contact point should be present. The sear should rise above the side of your receiver at least the distance of the edge of a penny, .060"
This is important as you need the height to properly capture the bolt.
Purchase and install a new sear if it shows any wear.

(It is highly recommended to purchase the new Stonycreek Monster sear if you have not already received one)

Caution: installation of this kit on a firearm with worn, misaligned or poorly maintained sear will void warranty and may be dangerous!

#5) You must remove your trip lever to use this Suomi kit. Your firearm will now be full-auto only but will run great. The trip lever is a 1" long flat steel plate with two holes in it and a round "hook" like rear end that is held inside your trigger group by the selector switch.
lift up the spring holding the selector switch and slide out the switch. The thin trip plate will now be able to be removed.
Store your trip lever and selector switch for re installation later when not using the Suomi kit.
Use the steel pin and clip provided with your kit to reassemble the trigger group.

#6) Align the new Stonycreek Suomi magwell extension to your lower receiver.
Be sure the two set screws are not tightened too low as this will block the alignment. a hex wrench is included.
insert the receiver pin. if this does not go in easily be sure the set screws are loose and there is no welds blocking the perfect alignment.
Lightly snug the two set screws as just to remove any movement between the new extension and the lower receiver. a drop of "lock-tite" on the set screws threads will help keep these in place.
Warning: Over tightening of the set screws may make the upper receiver difficult to install and cause functioning problems.

(2 Set screw locations in RED)

#7) Slide the new Stonycreek Suomi bolt into the new upper receiver after adding a few drops of high quality gun oil to all four sides. insert it so the bolt face is pointed toward the front of the upper.We recommend not oiling the sear or sear notch on the bolt. a clean, dry, un-oily sear and bolt notch will reduce the chances of a run away bolt.

insert one of the two include nylon 2" long blocks over the rods and spring. This single block must be used at all times as it keeps the spring from over collapsing and damaging the rear plate.

This set up will offer a R.O.F. from 550 to 625

The second block is added to the first block to raise the R.O.F. up to 835 to 865

The addition of a Stonycreek Rate accelerator with the first two blocks will raise the R.O.F. to 1,000 to 1,300+

Place the recoil spring over the guide rod. add a few drops of oil to this as well. The guide rod is the longer of the two rods.

Place the upper, with bolt inserted, with its barrel against the work table.
insert the guide rod assembly into the bolt. There will be increasing spring pressure as you press this assembly down until the rear plate is just about even with the rear of the upper receiver.
While holding the plate in the upper receiver with one hand place you lower receivers back end over the plate and catch the spring loaded bolt assembly as you slowly release the plate.
Align the front of the lower extension with the hole in the front of the upper receiver. The machining of these parts is so exact that you must have the holes perfectly aligned to install the pin. a very light tapping of the pin with plastic hammer may be necessary.

#8) Pull the charging knob back and check for smooth easy action. There should be no binding of the bolt or knob.
Be sure the sear catches the bolt firmly and is released with correct amount of trigger pressure. A too light trigger pull may be dangerous.

>>VERY IMPORTANT!! The first few times you use the new kit be sure to only place 5-10 rounds in each magazine until the internals of the new kit are broken in throughly. Then un-assemble, clean, re-oil, re-assemble.

The bolts spring may not seem like it has enough energy to strip the rounds out of a full magazine at first until properly broken in, but through rigorous testing the spring was found to be correctly built.

use only powdered graphite to lube the coffin mags.

#9) NEVER, EVER INSTALL A LOADED MAGAZINE INTO THIS FIREARM UNLESS YOU ARE AT THE FIRING LINE WITH THE FIREARM POINTED IN A SAFE DIRECTION!!

Caution: As with ANY open bolt submachine gun there is always the possibility of a run-away firearm. Remember if this or any firearm continues to fire after the trigger has been released don't panic, keep the firearm pointed down range and maintain control over the firearm until the magazine empties. Do not shoot the firearm until the problem has been corrected.

IMPORTANT: it is your responsibility to instruct anyone using your open bolt firearm of this and all safety procedures.

#10) Only use factory fresh FMJ 9mm ammo. Do not use reloaded, re manufactured or aluminum cased ammo as this may be dangerous and will void your one year Stonycreek warranty.
Using Steel cased ammo is not recomended

Remember your trigger is not a throttle or speed control device, it is an on/off switch so completely squeeze the trigger and then completely release the trigger. not half way.
incorrect trigger use will cause premature wear on your sear and bolt notch.

TIP: After pulling the charging knob back to cock the firearm push it forwards to seat it all the way up front.
This will re leave the bolt assemble of some drag on the first stroke of the bolt and will greatly improve first round reliability! Thanks to Craig V. for pointing this tip out to us.

Stonycreek Armory, its owner or employees will not be held liable for any injuries or death to persons or any other damage to property from the use, installation or handling of this product.By assembling this kit you are accepting all responsibility.See our "disclaimers" page for more details.

::STONYCREEK ARMORY'S BOLT ASSEMBLY DIRECTIONS::

NEVER, EVER INSTALL A LOADED MAGAZINE INTO THIS FIREARM UNLESS YOU ARE AT THE FIRING LINE WITH THE FIREARM POINTED IN A SAFE DIRECTION!!

The second method is a bit tougher to learn but works great to speed up the magazine changes.

You leave your trigger hand on the pistol grip while you will use your forward hand to grip the magazine.

Push backwards against the mag release lever with the side of your thumb and drop the mag into that same hand. a little practice and this will be the fastest way to change mags in competion.

::Direction on how to raise the sear up for safer functioning::

Here is a little something you can work on that will allow the sear to be raised up slightly. This will be good for your safer normal operation with your OEM set up and the suomi kit operation.
By fileing this area of the trigger it allows the disconnector to rise up a bit there by raising the sear up.


if you file app. .050" - .060" off this area on the trigger the sear will rise app. .020"

while the sear is still in place and all pins are correctly install just slide the disconector off the sear and see if it does indeed pop up a bit.
if it does rise them the trigger mod will work in your case as the trigger mod is basisacly releasing the disconector a bit.
if there is no movement them the problem lies on the fork end of your sear.

Caution: Some customers mentioned that after preforming this operation the safety button would not to engage properly.
My own personal experence was fine but please test out the safeties functioning after the fileing is done.

The very first lot of Suomi kits we shipped out had a small issue. A few folks mentioned that the shell were ejecting to late causing the shell to get caught between the bolt and the rear of the ejection port. sometimes slightly bending the back of ports opening.

By trimming the right front leg of the bolt you will allow more room for the shell to travel out before being hit by the bolts leg on its way back. This can easily be ground by using a angled grinder or sanding wheel. Hold the bolt in vise, be sure to protect the bolts finish with a piece of card board, then remove the angled part of the right front leg. finish up by hand fileing or sanding for a nice smooth finish.

If you have one of the very first lots of bolts we sent out with the front leg needing modification you may always sent the bolt back here to us for reworking at no charge.

All new bolts sent out have the needed modifications.

Some Swedish K/ Suomi drums, coffin or stick mags may require some fitting to function 100% here are a few tips. Remember to file or dremal just small amounts at a time and then clean and test fit.

The key is to just file where the bolt is making contact.

Then you may file a 45 degree on the TOP of the mag catch to allow easier insertion.

a sharp 90 degree on the bottom of the catch to make the mag stay in place better and more fileing will allow the mag to sit lower in the magwell if the bolt is making contact with the feed lips.
After inserting mag into magwell pull down on the mag to seat it as low as possible in the magwell.

Here are a few pictures.

MAC Barrel removal and installation directions:

To remove barrel. Be sure firearm in unloaded.
Remove upper from lower receiver.
Hold upper in bench vise by the barrels trunnion, this is the very thick steel block that the barrel is screwed into.
DO NOT hold the upper by its body or damage will result!
Press out barrels roll pin using blunt end punch.
Unscrew barrel in normal counter clock wise direction.
This may be done with channel lock type plyers or 2 - 3/4x10TPI nuts tightened against eachother on the threaded barrel.
Lock-tite was used in the original installation so this may be on very tightly!
We have had barrels that were so tight that the upper was actually destroyed trying to remove them.

To install new barrel.

Be sure threads are clean and free of old lock-tite or oil.
add a few drops of high temp lock-tite to barrels threads.
Screw in barrel snuggly until the flange is tight against the front of the receiver with no gap visible.
On 10" or 16" barrels there is a wrench flat point in the middle of the barrel for tightening.
Run a drill through the roll pins hole to remove the threads that block the roll pins insertion.
use a drill that is just slightly smaller than the hole.
A drill press is recommended for proper straight drilling.
Clean out any metal chips.
Press in roll pin.

( If this is out of your skill level or you dont have proper tools we can remove and install barrels for you at nominal fee)