AAR: 223 Rem for Mammoth Sniper

Immediately after deciding to shoot the 2019 Mammoth Sniper Challenge, Bronson and I had a quick chat about our roles.  We were building him a new 6XC rifle and I assumed he’d want to shoot it.  “So, you wanna be Primary shooter?”  Bronson said it didn’t matter to him but sure, he’d take the Primary role.

This competition is a team event.  In each team there is a “Primary” and a “Secondary” shooter.  Primary will have targets out to 1200 yards and Secondary will have targets to 800.  Primary can shoot up to a 300WM without any other caliber restrictions.  Secondary has to shoot a .308 Win or .223 Rem caliber rifle.  I had a .223 Rem trainer we built in the shop about a year before and I’d been wanting an excuse to use it at a match.  Here was my chance!

Before continuing, if you want to know more about this particular and unique event, read this AAR first.  It is a physically demanding match like no other.  The teams have timed ruck marches every day and have to camp outdoors all three days.  You carry everything you need.

I’ve shot various chassis systems for a long time and like to try pretty much everything that comes out.  I’ve run the Masterpiece Arms (MPA) “Comp” chassis on a couple rifles for awhile now and I can’t find a single thing I either don’t like or would change about the system.  I personally feel it is THE best chassis system on the market and proved a great choice for an event like Mammoth.

The barreled action on the rifle is one of our branded receivers made for us by Stiller’s Precision.  The barrel is a Brux “AO Varmint” contour, 1:8 twist that we finished at 22″ and chambered with our 223 CLE (Compass Lake Engineering) spec reamer.  If you aren’t familiar with the CLE chamber, it is similar to a Wylde in that I can safely shoot SAAMI and NATO spec ammo.  And it HAMMERS!  I went 1:8 twist so I could still shoot 55-grain M193 when I’m just playing around at the range but also load the 80.5 grain Bergers and Sierra 77 SMKs.

I’ve always liked this barrel contour.  It is modeled after Rock Creek’s “Sendero” contour, which is a medium contour slightly heavier than a Remington Varmint.  It is ideal for PRS/NRL type events IMHO because it isn’t too heavy and it certainly isn’t light.  It is the contour we put on our TMR and MARS rifles.  You can easily shoot 10+ round groups even with a suppressor without the groups opening up or the barrel starting to string.  And for this event I’d need something that was “just right” on the weight.

For the trigger I’m using a Timney Calvin Elite set at 1.5#.  I’ve used other triggers and haven’t found one I like better.  It is consistent and has kept adjustment on all my rifles even when abused.

Sitting on top is a Nightforce 7-35 ATACR in NF Ultralite rings.

As a team event, communication is critical.  Bronson and I would benefit from using suppressors because in the open fields we wouldn’t need our ear protection if we were shooting suppressed rifles.  The suppressors also help protect us from the concussion a muzzle brake can impart on the shooter (or nearby teammate!) even when shooting next to buildings or other objects that will divert that blast and noise.

I picked the Rugged Suppressor’s “Razor” silencer for my rifle. 

The Razor is a quick-detach suppressor that weighs less than a pound, is only 6.4″ long yet reduces the sound level of my rifle to well below 140 dB.  It mounts to a muzzle brake that is timed to my rifle.  I can quickly remove the suppressor and re-attach in seconds without changing POI (Point of Impact) or anything else adversely.  That was important to me for Mammoth because after each stage I did remove the suppressor from the rifle to get the rifle lower in my Eberlestock pack.  The rifle carried better that way on the timed ruck marches.  The suppressor isn’t much longer than a 10-round magazine but it was still nice to remove it to get that rifle shorter.

The ammo became the next concern.  I needed better accuracy than factory ammo offers so at this point I turned to my friend (and co-worker!) Jonathan O’Neal. 

Jonathan spent over 22 years in the Army National Guard mostly as a Crew Chief on Blackhawks.  When not flying around hanging out the side of the helicopter he spent about seven years shooting Service Rifle for the All Guard Team.  He is a High Master in Mid-Range, Master in Long-Range, Distinguished Rifleman and has been loading his own ammo since he was five years old (yeah, no kidding!).  I knew to get my rifle shooting to the best of its ability there was no better person on the planet that could help than my friend Jonathan.

First question was, “Hey, man.  I’m gonna shoot Mammoth as Secondary with Bronson on Primary.  Would you shoot a .308 Win or .223?”

With no hesitation he answered, “Absolutely .223 all day long.  I’d throw Bergers around 2900 fps.”

Since there is a caliber restriction for the Secondary shooter, using a .223 caliber rifle saved a LOT of weight in the ammo we’d need to carry.  Remember, this match has timed ruck marches and we were having to carry EVERYTHING needed for three days.  The .223 would also have much less recoil which would allow me to stay on target easier for spotting impact and follow up shots.

So, I brought the rifle into the shop and a day later Jonathan had the load mostly figured out with the exception of seating depth.  He handed me three boxes of rounds to go test to see which shot best.  Only difference was seating.  All three loads shot 5-shot groups under .3″ with one group slightly better than the others right at .24″.  We named that one the winner.

Load was 23.8 grains of H4895 under a Berger 80.5 grain Fullbore bullet seated .010 off the lands, which in my rifle put the COAL at 2.375.  Lakecity 1x fired brass and a CCI 450 primer completed things.

The COAL required us to shave out a little bit in the front of my Accurate Magazine 10-round mags.  Always remember to check mag length for your cartridges and test feeding too!  This all worked great for me.

Next up, bipod…

I have several different bipods but for a match like this I prefer the Atlas.  It has the ability to put the legs into 45-degree positions and is fast to adjust.  I run mine with the Hawk Hill Talon feet which are great for every surface we might encounter at the match….mud, sand, rock, wood, etc.  

I am running the RRS clamp head so that on my MPA chassis I can take advantage of the ARCA rail cut into the bottom of the chassis.  This lets me easily and quickly remove the bipod or slide it forward or rearward.  This was hugely beneficial on a couple stages where I needed the rifle to be stable on a short surface area.  Getting the bipod close to the magazine well allowed me to accomplish that.  This particular mount also lets me attached the bipod to standard Picatinny rails.

Scope choice is easy for me, the Nightforce ATACR.  This one is a 7-35 with MOAR reticle.  Even in the pouring rain all Friday I had no problems with clarity, resolution or definition.  The capped windage knob and ZeroStop elevation turret protected me from having something accidentally come out of adjustment with all the repeated in and out of that Eberlestock bag plus the banging around on rucks.  

Just completing this event is an accomplishment.  Thanks Matt Sprouse Photography for this awesome pic he took of me and Bronson on our first rainy stage Friday morning.

Below is a picture of the First Place and Second Place finishing teams’ rifles.  Bronson and I came in Second behind our friends Andy and Steve by two points.  All of us were running MPA chassis systems.  Coincidence????  

All of us were running suppressors.  Three of the four rifles are wearing Nightforce optics.

Interesting that we had similar equipment ideas.

The only thing I’ll change next year is the suppressor.  Next year I’ll be shooting the new Radiant762.  In the “short” configuration it is only 5.1″ long and weighs a mere 9.4 oz!

The Mammoth Sniper Challenge is a unique event for sure.  It is tough on the competitors and really demanding on their gear.  If you want to be successful at this or similar events, you need gear that won’t fail in the most adverse conditions.  Hope to see you at Mammoth 2020!