Earlier this year I purchased an Ops 15th Model 5.56 sound suppressor, or silencer, to mount on a Colt 6933 (the semi-auto version of the Colt Commando R0933) AR15-pattern carbine. The Colt 6933 has an 1.5" long and .625" diameter barrel, making it legally a Short Barreled Rifle with a "skinny" or "pencil" barrel as they are often called. One of the common points of interest with many owners of 5.56 caliber suppressors and AR-pattern carbines is the point of impact, or POI, shift when comparing shooting the carbine with the suppressor to shooting it without. As such, I decided to hit the range and test out this combination.
First, I am not going to defend my groups here. It was 100 degrees at the range with no shaded shooting position and a wobbly rest. Attack the groups if you must. Also, the optic used was a Trijicon Compact ACOG model TA45R-2, which is a 1.5x magnification optic with a red triangle reticule. Regardless of group size, group centers are group centers.
Rifle & can after shooting the first groups.
Targets were 7" tall shoot-n-see.
The first pic is approximately 10 rounds of each of the following (from left to right) shot from a "rest" at 50 yards. Black Hills blue box 75 grain Prvi Partisan M193 55 grain Wolf 55 grain steel case Federal 55 grain XM193
10 shots of each type of ammo fired suppressed
The second pic is approximately 5 rounds of each fired without the
suppressor mounted. After I shot the first group of Prvi, Wolf, and XM
(you can see those groups just above each shoot-n-see on the Wolf and
XM) and noticed they weren't printing in the black, I fired 5 more
rounds of each holding the tip of the triangle at the base of the
shoot-n-see. Those are the groups you actually see on the Prvi, Wolf,
and XM targets, with the BH target being shot holding center of the
black.
5 shots of each type of ammo fired unsuppressed
While the shift does appear to be excessive, I'm not complaining about the results. This is intended
to be a suppressed weapon and to be used for hogs and home defense if
needed. For those purposes and with the chosen load I'm more than
satisfied with the results.
on had asked me to measure the distance from the front of the collar to
the front of the threads on the brake mount The collar I have was a
custom made job by ADCO for a .625" barrel. There really isn't any
taper "start", as the whole collar is just one big wedge. The collar
that is not mounted on the gun is the other collar that came with my
can when I ordered it from ADCO. I'm guessing this is the factory OPS
collar. It may, in fact, even work. When I first received the can the
custom collars wouldn't fit as they didn't drill the hole big enough
and I had to send the upper in to have the custom collars matched (not
sure why .625" isn't the same measurement here as it is there, but
whatever).
It appears that the collar I
got from ADCO is approximately 1/4" thick, and that the measurement
from the forward edge of the collar to the forward edge of the threads
is 2" even.
Ron from Ops sent me a "used" muzzle break mount to try out in lieu of
the A2 flash suppressor mount that ADCO originally sent with the can. Below is what the rifle looked like at this point.
Rifle with Leupold scope in Larue mount, bipod with A.R.M.S. throwlever mount, and new Ops muzzlebreak mount for 15th model suppressor
Rifle with Leupold scope in Larue mount, bipod with A.R.M.S. throwlever
mount, and Ops 15th model suppressor
The
difference with the muzzlebreak mount vs. the A2 flash suppressor mount was HUGE. Virtually no shift this time at 50 yards. I used a
Leupold 3-9x optic and a bi-pod this time so the groups are slightly
better (I'm not used to magnified optics and bipods, I need work). Pics
to follow, but I would call the shift virtually nil at 50 yards now.
In
other news, Black Hills 75 grain is well worth the cash. I would say it
groups half to a quarter as tight as all the others I tried.
One
note. While the brake did appear to greatly improve the POI shift with
and without the can, it is CONSIDERABLY louder, even to the shooter.
and with XM193 it is loud enough that I would not want to shoot it.
Which
creates the conundrum; the brake offers the least shift, but is
essentially useless (to me) without the can, meaning that it's only
useful with the can on. So it's usefulness is somewhat questionable
IMHO. It is supposed to better protect the baffles, however, so I
suppose it's worth it in that respect.
Again,
no apologies for my ability as a shooter. Running a magnified optic and
bipod and trying for the best possible accuracy is very new to me as
I'm generally content if I can hit a 6" steel at whatever range I'm
engaging from and do so as quickly as I can. I certainly didn't take
the time I should to try for groups in this test. I think you'll be
able to tell the potential of each ammo type, and pick out the shooter
errors. Each group was 10 shots. With all but the Barnaul, I'd call
anything outside the 10-ring a flier, and with the Black Hills I'd call
anything outside a 1" circle a flier (shooter error).
I
fired 30 shots of XM193 to get the scope on paper (scope was mounted
turned sideways, took me a couple of tries to figure out how to adjust
for that), and then 10 shots of Black Hills to get zeroed. After that I
shot the suppressed groups, Black Hills & Wolf first, then reload
(I only had two 20-round mags with me) & shoot XM193 & Prvi
Partisan, then reload and shoot Barnaul. I then let the gun cool enough
to remove the suppressor, and fired 10 rounds of XM to heat the barrel
back up, then followed the same shoot/load schedule above. Without a
temp sensor I guesstimate that the barrel was kept as close to a
constant temp as I could.
After all of this, my conclusion is that the muzzle brake mount definitely makes for less of a POI shift than the A2.
This
was my first time shooting the gun with the brake mounted but without
the can. The brake is LOUD, especially so with the XM193, even with my
Sordins on. If I was going to be shooting just milspec ammo with only the brake
on I would double-up on plugs & muffs. It was borderline painful to
shoot (and probably affected the unsuppressed XM groups because of it
to some extent). Because of this, I found an interesting conundrum; if
you want to shoot the gun both suppressed and unsuppressed and see the
least amount of POI shift, you need the brake, but shooting
unsuppressed with the brake can be borderline intolerable, making the
A2 a much better choice.
For me, I only
ever intend to shoot this particular rifle suppressed. That's in fact
the whole purpose for this particular rifle. In which case it really
doesn't matter which mount I use, except to say that the brake
allegedly both better protects the baffles and provides better sound
suppression than the A2 mount. The other school of thought would be
that even in my previous test the shift was acceptable for the range at
which an 11.5" barrel AR would be effective, so the A2 is certainly
serviceable if the user needs to have both suppressed and unsuppressed
capability. For me, I'll keep using the brake on this gun since it
stays suppressed, and I've mounted the A2 on my other 6933 just in case
I ever want to put the can on it. I'd like to try the 3-prong mount I
see on ADCO's site now, but not bad enough to pay for one.
It
does bear mentioning that the A2 mount that I received with my can
sells for $75, and the brake mount sells for $185. I am unsure if this
savings was reflected in the price I paid for the can or not, but it's
somewhat of a moot point now as Ops at least sent me out a free muzzle
break mount after seeing the initial test results.
Thanks again to Ops for all the help, and hopefully the new results are more in line with what they would expect to see.
