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SIG SAUER Sound of Silence
February 2017
Gerhard Schroeder

What happens when we hang a weight at the end of a rifle barrel? More to the point, attaching a suppressor that is 9.3 inches long, has a diameter of 1.75 inches and weighs 1.1 pounds such a can has got to mess with barrel harmonics. What about balance of the rifle, accuracy, any shift in point of impact and especially shootability under field conditions?

Well, I got the means of exploring some of those issues. Because after more than eight months, ATF finally sent its approval, and I wasted no time to pick up my SIG SAUER SRD762 TI silencer, as they refer to it. From here on Ill call it the SIG Can, or simply Can. That is basically all it is. Except, behind this Can is a well thought out design. SIG SAUER received awards for it. Their Can has no outer tube, is made from Titanium parts welded together. This maximizes internal volume and surface area while minimizing weight.

Suppressors work by robbing the hot and high pressure gases exiting a barrel of much of their energy. This takes place by a more gradual pressure reduction and by cooling those gases. Instead of instantly discharging those high pressure gases to ambient, a pressure differential of thousands of pounds per square inch (psi), which is basically a controlled explosion, a suppressor like a muffler channels those gases through several compartments. The result is a more gradual pressure reduction. Simultaneously, there is significant cooling going on. That Can gets too hot to handle in just a few shots from calibers in .308 Win class, for example. Heating of the Can appears proportional to the powder quantity in the ammunition. The Can barely warmed when used with subsonic loads of a 300 Whisper, where less than ten grains of powder do the accelerating.

To say it up front, whatever else this SIG Can may do, it does make shooting very quiet. That is especially the case with subsonic ammunition. There are no decibel measurements. To say it scientifically, I know guys who can fart louder. While waiting for the ATF approval I had done some planning, and my friend Ron some machining. Add to that rifles from Steve. The first step for each rifle was a fit check. That is, attaching the Can via its 5/8-24 threads and then looking down the bore to confirm that it was indeed in (near) perfect alignment, meaning that a fired projectile would not touch any of the 20 compartments inside the Can.

Next step: go out and shoot (through) the darn thing. I did this an hour before our annual Turkey Shoot. First up, of course, was a 300 Whisper (the cartridge design stolen by some big company and re-named as 300 AAC or Blackout). The 300 Whisper was created to operate quietly with subsonic loads. And this SIG Can make it so. Next up was Tikka T3 in .243 Win. No Can will eliminate the supersonic crack when the fired projectile departs faster than the speed of sound. Shooting without ear protection I could hear with how much violence 80 grains of Sierra smack a steel plate some hundred and twenty paces away. Cool! And while the supersonic crack is loud and annoying, the noise level is no longer damaging to our ears.

Nice! Too bad such healthy and environmentally friendly technology requires a $200 tax stamp and 8 month waiting period. May Trump trump that.

So much for the acoustics. All cans also have a positive effect on recoil. The Sig Can is not as efficient as a dedicated muzzle brake. Still, adding that 1.1 pounds and streaming the gases out slower changes recoil from a punch-like impact to a friendlier and lesser shove.

The first day of more serious testing, meaning shooting from the bench, happened to be accompanied with strong and cold wind. That alone resulted in one data point: the wind was strong enough that with Can installed, the rifles on the sand bags wiggled slightly more than without. The crosshairs, at 10X or more power, noticeably moved around more. Similarly, trying to aim offhand in windy conditions was more difficult with the Can added to a barrel.

Then I opted for a structural test, simply because the opportunity was there. Steve had a new 24 barrel for his TC Encore. He had ordered it with 5/8-24 threads. The Can also aligned just fine with this .338 WinMag barrel. And since the holes in the SIG Can appeared to be right at 10mm, meaning a .40 S&W bullet would fit, I told Steve to touch one off if he wanted to. He did. And a fat smile came over his face. Because for the first time his .338 WinMag did not punish him. The next couple of shots actually grouped OK. He ordered a muzzle brake after that. And the SIG Can showed no signs of distress.

Getting into details, here are my observations:

.300 Whisper / aka AAC or Blackout
The Ruger American came with 16 barrel, threaded muzzle, and a trigger that sucks. Allow a quick side note. Apparently many Ruger owners realized that the triggers in the American are just too heavy. Timney to the rescue! Mine went on backorder, since the demand was huge. But then it arrived, and all is better now.

So far I spent most of my suppressor time with the Whisper. As is, this rifle is too short to be a good offhand gun. Adding the SIG Can gave a more capable balance. Some may not agree, since it appears heavier than a production varmint rifle. Yet, because of the shorter barrel it also remained agile with the Can out front. Id say that if the typical bolt action rifle is to be carried via typical sling during typical hunting, then this Sig Can should be married to a barrel no longer than about 16. Anything more, and field duty may become burdensome.

It cannot be overstated that with subsonic loads the rig is a ton of fun to shoot. I love the music of ricochets. By now I have dialed this rig in. It will be rare that Ill shoot it without that suppressor; Id say the rifle was made to go with a can. When zeroed at 50 steps with 180 grain lead bullets going about 1000 fps (9.5 grains of IMR 4227), a supersonic, but by no means maximum load firing a 125 grain Sierra softpoint (17 grains of IMR4227) is approximately on all the way past 150 paces. That will be my hunting combination lead bullet in the chamber, soft points in the mag should another shot be needed.

Another complaint: this Ruger only feeds pointed bullets reliably from its 6-shot mag. Even with supersonic loads this rifle/Can combo is not unpleasant. That holds for a maximum load firing 110 grain Vmaxs. Three of those grouped into .6 at a hundred yards. But zeroed for those 180s at 50, the Vmaxs print some 8 inches high at 150. So they wont get that backup job.

There is another concern. At subsonic speeds all .30 cal bullets seem to perform like FMJs. I invested sixteen bucks into a little gadget that makes hollow points into lead bullets. Did that to some 180s, and shot two into wet newspapers. Well, 8 inches of paper and at least 12 inches of water (bottles) did not stop them, and the holes did not suggest obvious expansion. We may need to go supersonic for acceptable hunting performance on critters larger than squirrels and rabbits.

.243 Winchester
Buddy Ron threaded the muzzle of my Tikka T3 during those long 8+ months. Attaching the Can to that 22.6 barrel clearly made the rifle heavy out front. From the bench, accuracy improved with every load tested that day.

The Can also allowed me to shoot this rifle more accurately offhand. But it clearly takes more muscle to get the crosshairs on target. Once there, though, they dont move off as easily as with the naked barrel. The Can did cause a shift of impact. Heres an example.

Note that the aiming point for each of the six shots was the upper circle. The Can grouped those 70 grain TNTs several inches lower. Meaning I will have to decide if I want to zero this rifle for suppressor use.

Just because I could, I also tested the Can on a Rem 700 with a 26 heavy varmint barrel and chambered in 6XC. Same change in recoil as for the .260 Rem (see below), but no change in accuracy. That 6XC is already more accurate than I can aim it. Adding the Can made this into a ridiculous rig, both in weight and length. But I have the option. Interesting was the shift of impact. With 65 grain Bergers it was about an inch in elevation and half that in windage. Heavier bullets minimized those effects. 90 grain Bergers almost shot to the same point of impact.

.260 Remington
The Tikka CTR came from the factory with its 20 barrel threaded. Already a heavier gun due to its medium-thick barrel, adding the Can fattened it to about as much as one would want to handle offhand. Then it behaved in similar fashion to the .243. That is, groups tightened (or is it that I simply could shoot tighter groups more easily?). There was also a shift of impact, unfortunately not just in elevation, but also to the right. Here it became obvious that the weight and effects of the Can left more recoil than a dedicated muzzle brake. But it was noticeably different, namely a pleasant shove.

Weeks later I had an opportunity to shoot at about 1000 yards. At least with 123 Amax bullets, the change in the point of impact seemed not as great as the 140s had shown on paper at 100 steps. Out in the desert I wasnt about to climb to that 1000 yds spot to set up and later retrieve some big enough paper target to measure the actual difference.

.308 Winchester
Ron had also threaded the muzzle on the Mossberg MVP. With its 18.5 medium weight barrel it as well seems to invite a can. Similar to the Tikka CTR, weight and balance appear at a useful limit. For me the offhand accuracy improved, at least for a few shots. It may become too much to handle near the end of a 40-shot silhouette match, for example. Off the bench, accuracy also peaked. Never before had I been able to get a sub-inch group. With this Can it happened. MVP and Sig Sauer have made friends.

Plans are in place to attach the Sig Sauer to a .223 Rem. Maybe even a .22LR, even though nobody recommends much rimfire use with a can that could not be disassembled for cleaning. Those .22s are dirty little beasts. Then again, silence is addicting. And .308-class ammo may just burn off whatever .22s leave behind.

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