Good afternoon everyone and welcome back to TFB’s Silencer Saturday brought to you by Yankee Hill Machine, manufacturers of the new YHM R45 Multi-Host Suppressor. Last week we tested the Dead Air Mojave 9 modular silencer. This week we return to my favorite 300BLK weapon systems – the SIG MCX SPEAR-LT and the SIG SLH and SLX suppressors to test POI shift between models. Let’s take a look.

More SIG @ TFB:

• SILENCER SATURDAY: Why, Hello SIG MCX And 300 Blackout Subs
• SILENCER SATURDAY #269: First Shots – The SIG MCX-SPEAR And SLH SLX Suppressors
• SILENCER SATURDAY #215: SIG Sauer SLH300TI & SLH762 Suppressors
• SILENCER SATURDAY #213: Blizzard! SIG Sauer SLH Suppressor Preview

Firearms, suppressors, and ammo used in this review:

• SIG SLH300TI-QD – 300BLK – Titanium – 8.8″
• SIG SLH762-QD – 7.62 NATO – Inconel – 7.4″
• SIG SLX762C-QD – 7.62 NATO – Inconel – 5.2″ (Compact)
• SIG MCX-SPEAR LT SBR (Pistol)- 300BLK – 9″ –
• SIG Marksman Subsonic 300BLK Ammo – 220gr – OTM

Magazines:

• DURAMAG Aluminum 5.56/300BLK – OD Green

SILENCER SATURDAY #302: POI Testing With SIG SLH And SLX Suppressors

If you are anything like me, it’s a rare event to shoot an unsuppressed rifle. It is simply uncivilized. However, in that rare instance where length actually matters, you may decide that removing the suppressor to gain five or more inches of clearance on a personal defense weapon is worth it. But it would be nice to know if or how the point of impact (POI) changes, requiring a point of aim (POA) adjustment. With three SIG Sauer Clutch-Lok 7.62 suppressors in house, I thought I’d use my favorite 300BLK gun to take the test a little further.

Point of aim is the place where your reticle or sights overlays on a point on the target. Typically this would be the reticle placed in the center of the target or bullseye, but it can be anywhere that you decide to… aim. Point of impact is the spot on the target where the bullet makes terminal contact. If your rifle is perfectly zeroed for the distance, ammunition, and other variables, the POI will occur at the POA. This is the basics behind zeroing a rifle – pick a distance with a specific load and make POA=POI. From there, with a little calculation, you can determine the POI at other distances based on the trajectory of the bullet.

This is one of my “go to” rifles that is setup for a 50 yard zero using Barnes VOR-TX 110gr ammunition. With a 50 yard zero on a 9” barrel my carry ammo has a nearly flat trajectory between 25-150 yards. Meaning that within this range, I wouldn’t need to adjust my POA to maintain the same POI*. I use StrelokPro to calculate bullet drop and other variables, but all distances should be confirmed with actual shots on target. Also, at close range, rifle shots will have an offset – the height of the optic or sights – that will need compensation. For example, a head shot at five yards with a 50 yard zero will have a hold-over offset of 1.5” or the height from the bore to the reticle in the optic. Below is one of the StrelokPro rifle/ammo profiles for the Barnes 110gr VOR-TX and a 9” barrel.

* For defensive purposes, ~2.9” change is within the “stop-the-threat” range.

Today, I wanted to shoot quietly, and I’ve found that the SIG 300BLK 220gr is one of the most accurate rounds for the 1:5 twist MCX barrel. Because this rifle is zeroed for 110gr rounds, my POA will be a few inches higher to keep the 220gr round near the center of the target.

Because my eyes are old and I’m using an unmagnified optic, today’s shots were all taken from the 33 yard line.

Let’s take a look at the numbers.

SIG SLX and SIG SLH Specifications:

SIG Sauer SLH762-QD

• Manufacturer’s Page: https://www.sigsauer.com/slh-suppressor.html
• Caliber:7.62 NATO
• Material: Inconel
• Diameter: 1.67 in (42 mm)
• Length: 7.49 in (190 mm)
• Weight: 1.32 lbs (21.1 oz)
• Attachement: Clutch-Lok QD

SIG Sauer SLX762C-QD

• Manufacturer’s Page: https://www.sigsauer.com/slx-suppressor.html
• Caliber:7.62 NATO
• Material: Inconel
• Diameter: 1.67 in (42 mm)
• Length: 5.2 in (190 mm)
• Weight: 12.6 oz
• Attachement: Clutch-Lok QD

SIG Sauer SLH300TI-QD

• Manufacturer’s Page: https://www.sigsauer.com/slh-suppressor.html
• Caliber: 300BLK
• Material: Titanium
• Diameter: 1.67 in (42 mm)
• Length: 8.8 in (190 mm)
• Weight: 1.0 lbs (16 oz)
• Attachement: Clutch-Lok QD

My MCX SPEAR-LT is equipped with the SIG Sauer SLH762-QD 99% of the time, so we are going to test this POA/POI first.

Holding at the 12 o’clock position on the target, the POI was about two inches above center. I probably should have re-zeroed for todays testing to put the first rounds in the center of the target.

Removing the suppressor, the POI seemed basically unchanged.

Next up is the Compact SIG Sauer SLX762C-QD suppressor.

Again, the POI/POA remains basically unchanged.

Next we have the SIG Sauer SLH300TI-QD 300BLK specific suppressor.

The POI kept the same elevation, but shifted about two inches left.

I removed the suppressor and reinstalled it by tightening it as much as possible. The POI may have lost a little elevation but remained about two inches to the left.

Lastly, I reinstalled the SIG Sauer SLH762-QD and fired three more rounds, confirming the original POA/POI test at the beginning of the test.

I am impressed that the unsuppressed, SLH762, and SLX762 with the Clutch-lok mounts basically kept the same POA/POI. The SLH300, not unsurprisingly, must have a slightly different internal geometry that pushes the SIG 220gr ammo slightly left.

The internal geometry of suppressors can have an effect on bullet trajectory which may change POA/POI. It good practice to know how your suppressors can change the POI for certain rifles in case you decide to shoot unsuppressed or even change suppressors altogether. This is especially important for defensive weapons that will require accurate shots at varying distances and for hunting rifles. Confirm your zeros with the ammo, optic, and suppressor you intend to use at a range and at the necessary distances. Don’t wait for the zombie apocalypse or worse, that one shot on a monster elk, to wonder if your POA/POI is where it should be.

Have a great week. Be safe, have fun, and we’ll see you back here next weekend for another Silencer Saturday.

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