Stoneycreek Armory Upper




Review of the Stoneycreek Armory Suomi upper for the M11/9

Submitted by MAC10 Talk Member Vegas SMG




I recently came across a unique opportunity to acquire a little used Stoneycreek Armory Suomi upper from a friend. I'd previously had some limited trigger time on one of the first SCA uppers ever shipped at one of our local subgun matches. Although I wasn't favorably impressed due to several malfunctions that day, this was a great chance for me to obtain one for my collection without the long wait. Given that many people had pre-paid and then waited for their uppers for over a year without delivery, I was delighted to have this opportunity to accept delivery of a SCA Suomi upper immediately.


My Initial Impressions.

The first thing one notices is the excellent fit and finish of the SCA Suomi upper. The welds are uniformly good to very good. The long sight radius coupled with the supplied H&K style sights are far superior to factory M11/9 sights. As with most after market M11/9 uppers these days, a standard weaver rail that runs the entire length on the top of the upper receiver. It's a very useful feature for attaching optics if the user chooses to move in that direction.

The removable magwell presents all manner of possibilities! SCA has delivered a 9mm Suomi upper for .380 MACs, and that's no small feat. The possibility exists of swapping out the magwell, bolt and barrel and having a .45 upper for your previously one caliber M11/9 so it would accept grease gun mags. Is this the pathway to a .223 caliber conversion using a TASK style op-rod? It's a very interesting topic for discussion!

I'm a tall man at 6'3" and have the reach to match. I think the distance to this upper's forward grip will present difficulties for some smaller people to comfortably shoot with the Suomi drum. The short distance from the fore-grip to the drum forces your hand outward and around the drum into an uncomfortable position which gives the shooter less control of the weapon.

The cocking knob is located very close to the muzzle. It should have a return spring since firing a side cocking upper with the cocking knob retracted can cause misfires if it's not manually returned to the it's forward position. This location makes for a long reach and some shooters will need to remove the gun from their shoulder to cock the bolt. This detail may only matter to those who would consider using this upper in subgun matches where reshouldering the weapon and re-acquiring a sight picture can cost you valuable time. If the upper is equipped with a SCA Tri Rail Adapter and K-grip, any rotation past a 60 degree angle  will make the cocking knob difficult to grasp due to a clearance problem.

Relocating the optional SCA "Tri-Rail" system to allow for a 60+ degree grip still gives the upper less than optimal ergonomics IMHO. A couple of shooters who tested this upper actually like the grip in this position. After some experimentation, I found I liked the K-grip in the traditional 90 degree angle in spite of the issue of the drum being in the way of a good elbows tucked in stance. I can work with it over time.

This upper is long! I've shot this upper with my CAC-9 suppressor in place, but doing so makes for a long reach with your supporting hand. A typical MAC type suppressor with course 3/4 X 10 threads requires you to hold on to the can while shooting to prevent baffle strikes, and the OAL of the SCA Suomi package presents a challenge. The upper seemed to suppress well probably due to the slow ROF.

The magazine release feels un-natural and is located in an awkward position on the upper. Common sense and experience with other weapons says to push the lever towards the magazine while grasping not to pull the release lever rearwards while trying to remove the drum or magazine. This is a difficult task to accomplish with one hand and tight fitting magazines. None of the magazines or drums I had would drop free without fitting and insertion into the magwell was difficult. It took almost 3 hands to remove the 36 round magazines due to their tight fit in the mag well, but a quick pass of the Dremel on the Suomi magazine pads took care of that problem in no time. Even with the guides in the magwell, magazines have to be carefully aligned to the magazine well slots to be inserted making magazine changes slow. The forward placement of the mag well and the distance between it and the pistol grip make control of the weapon during any mag change very awkward.

In my particular gun, the stock M-11/9 sear is unsafe to use with the upper. I could lightly hit the side of the receiver with the palm of my hand and get the racked bolt to easily release. The SCA Monster Sear is a must with the Suomi upper! The Monster Sear is somewhat difficult to install as it interferes with the sear/selector pin retaining spring during installation. The OEM sear spring does not fit in the hole provided in the Monster Sear. It appeared the previous owner tried to drill it out slightly larger to accommodate the factory sear spring, but could not fully cut through the hardened steel with his drill bit. I've noticed SCA now offers sear springs on their web site. Perhaps those springs will fit the Monster Sear or the sear itself has been modified to accept the OEM spring. I can only comment directly on my experience.

OK, let's shoot this thing!

Test ammo was Fiocchi 124 grain, Winchester 115 grain packaged in 50 round boxes, and Winchester White Box 115 grain of the 100 round value pack variety. The later is what SCA has mentioned as being used and tested on their web site with their Beta upper. Even with the hotter Fiocchi ammo at 1250 FPS, the upper sometimes cycled erratically unlike my other subguns using this same ammo. This is probably from the bolt rubbing on the feeding devices and was observed when using drums, 36 round stick magazines, and 50 round coffin magazines.

The single sear catch on the M11/9 doesn't lend itself to a light trigger pull, but the Suomi trigger pull feels very heavy. Despite this, singles were fairly easy to pull. With the upper being designed as full auto only, they need to be easy and the user won't be disappointed.

I thought perhaps the larger bolt and it's weight was "stacking" against the sear and resulted in the heaver pull. I weighed the SWD M11/9 factory OEM bolt and the SCA Suomi bolt. The factory / OEM M-11/9 bolt weight was 13.1 ounces while the Stoneycreek Armory Suomi bolt weighed 15.1 ounces. A difference of only two ounces. Clearly the extra bolt weight wasn't responsible.

Occasionally, spent brass would be caught in the ejection port between the bolt and the ejection port opening - a seemingly common issue in speaking with other SCA owners. Once again, this problem may have been caused by the bolt rubbing on the magazines. This is disconcerting as the upper is specifically designed around the Suomi drum and magazines and one should expect the upper to run properly with the unmodified factory feeding devices it was designed to use. While observing ejection patterns, I noticed an occasional empty round dribble out of the ejection port, while the other brass was nicely ejecting two to three feet. This could be one of several problems. A problem with poor extractor design, lack of a polished chamber or perhaps a too light recoil spring.

The drum as supplied by Stoneycreek with the upper has a very pronounced lateral movement which I suspect caused a couple of failure to fires resulting with a live round striped and chambered, bolt down and a light primer strike. I suspect this may have been due in part to my supporting hand on the fore grip pushing on the drum and causing additional bolt rub. Three other Suomi drums exhibited this same side to side play when inserted. Not once was the extractor able to remove the unfired round from the chamber when the bolt was retracted to clear the malfunction. I suspect a weak extractor spring or poor extractor design may be to blame.

Clearing jams with this upper is extremely slow. Any failures to fire with the afore mentioned bolt down on a dented primer never resulted in the unfired round being extracted - not once! Clearing this type of jam in an open bolt gun is painfully slow. Remove the drum or magazine, rack the bolt, hold the gun upwards, shake vigorously until the offending round drops free from the chamber. I chose to fire the round and it always lit on the second hit. After the chamber is clear, carefully realign the drum in the mag well, insert, and resume shooting.

The disconnector has a nasty habit of slipping off the Monster Sear engagement surface. The Suomi upper had to be completely removed from the lower receiver and the engagement surfaces manually reset prior to the SCA upper being reinstalled to continue firing. This phenomenon occurred on two separate occasions, once with a suppressor installed.

I previously noted there's nowhere to comfortably put your front hand when using the Suomi drums. The stick mags are a different story. The upper was easy to hold by the magazine when the 36 round stick mags are used. I dislike holding and firing a gun while gripping the mag. It is a recipe for failures to fed if the mag is moved with your grip while firing the weapon. Factor in a potential KB where much of the explosive force is expelled through the mag / magwell and I don't think holding a subgun by the magazine is a good idea if there's an alternative. In my experience with the SCA upper, the single feed drums are more reliable than the 36 round, double feed stick magazines. The coffin mags, like the drums and 36 round Suomi stick mags need to have material removed from the rear and feed lips to be reliable. The Suomi coffin mags are difficult to load but manual unloading reveals they're as smooth as butter. Unfortunately, I couldn't get more than about three rounds to feed before the gun had a typical bolt down on a live round jam. I need to grind and file on the coffin mags for additional bolt clearance due to the swelling that occurs when these are loaded to capacity. Once adjusted, these will afford the SCA Suomi owner plenty of clearance for the forward grip as opposed to using the drum, and allow for attaching two coffin mags together for a total of 100 rounds on board.

Sometimes, but not always, trigger slap was felt to the point of being painful. I could also feel some shock transmitted in the lower receiver that felt like hard metal on metal contact. I suspect it's the extra tall Monster Sear making contact with the bolt notch when the trigger isn't fully depressed when attempting to pull singles, but I can't be sure.

Premature wear on the bolt notch was evident and this shock could also be what is causing the "egging" of the selector switch hole that's been reported on M11/9 lowers equipped with SCA Suomi uppers. I've personally heard from no less than three separate SCA owners who have confirmed egging of their selector pin axis holes when using the supplied SCA replacement sear pin in conjunction with the Monster Sear. My own measurements revealed the SCA sear pin is slightly larger at .126 than the OEM selector at .124, so I doubt the SCA pin is the problem. I believe other forces are at work in enlarging the registered lower receivers sear pin holes.

Stoneycreek Armory touts its Suomi upper as having an adjustable ROF. It's commonly called short stroking the bolt. Anytime you have the bolt on any subgun contacting the rear of the receiver or hard buffer, you have an undesirable jarring effect from transferring that shock of the bolt to the receiver thereby affecting accurate shooting. The SCA's adjustable ROF is a good thing, the method of accomplishing it is counter productive to accurate shooting in my opinion.

So what's it good for?

Many "MAC" shooters are strictly recreational shooters and don't place a high premium on reliability or accuracy. M11/9 owners who have only experienced the high ROF their factory gun provides may well forgive this upper's shortcomings for the benefit the SCA Suomi provides in reducing the ROF. For those owners, this may be the perfect accessory to engage a series of cans using full drum dumps at the local gravel pit. The attraction of readily available and inexpensive 71 round drums certainly has wide appeal. The 36 round stick mags while very well constructed and less than ten dollars each, haven't been as reliable in my own experience. Frankly, I don't see those as a big draw with an upper that can make use of inexpensive and readily available drums with almost twice that capacity. If your upper is anything like mine, expect to fit and adjust each and every mag and drum and you won't be disappointed. With properly adjusted mags and drums, some tinkering and patience, this may be a really fun accessory for those lucky enough to have one shipped to them. 

I doubt this upper will find it's way into the winner's circle in many subgun matches even in the most skilled of hands. At least not in it's current configuration. Most matches require mag changes and this upper doesn't lend itself to fast magazine changes due to the forward mag well and cocking knob location combined with the difficultly in manipulating the release lever. It's difficult to "find" the mag well under pressure and properly align the mag catch. Even with the thoughtfully provided mag funnel it's slow to reload. Jam clearing with this upper will present a very real challenge against the clock. The overall ergonomics simply aren't user friendly, especially when using drums.

Can the problems be fixed?

It's my belief the design of my SCA example could be improved by the following:

1.) Add the missing relief cuts to the upper so it clears the welds in the lower receiver like the OEM and other after market uppers. This will allow the SCA upper to sit lower into the upper receiver at the correct height.

2.) With the upper receiver lowered, you'll be able to raise the rear retaining pin hole up 0.125" on the removeable magazine block. You'll then need to remove material from bottom of block. This will allow the entire SCA upper to sit slightly lower in the registered receiver and allow for the use of an OEM sear for proper sear engagement. This will also provide the necessary clearance for the magazines so magazine adjustment should become unnecessary. .

3.) Items one and two will allow use of all OEM lower components and give the SCA lower select fire capability adding value to the design.

4.) The sear notch on the bolt, needs to be cut to 7 degrees like the OEM bolts and hardened to prevent deforming of the SCA bolt as noted on my example.

5.) Polishing the chamber and using an improved extractor may also help with the failures to extract / eject.

6.) Add a return spring to the cocking knob and consider relocation of the cocker further rearward for better ergonomics.

* The views, opinions, and experiences expressed are mine and have been formed through informal testing and evaluation. Suomi upper testing is on-going and made use of my personal SCA Suomi upper combined with my registered SWD M11/9 lower receiver and that of another tester's M11/9 registered lower. More than a half dozen seasoned subgun match shooters and other RKIs with many years on title two firearms experience had a chance to test fire, and closely examine this upper. I enlisted their opinions along with that of a noted master armorer and builder who evaluated the upper. Your own views, opinions, and experience may be different.

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Last Modified: March 12,2017