The Ruger Mini-21

Easy DIY M21 Sniper Rifle Simulation
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The M21 Designated Marksman Rifle used to be the apex predator among gun nerds truly dedicated to their craft. Images from Vietnam of filthy bush-savvy snipers crawling out of the jungle with their scoped M14 rifles made a deep impression on this young stud. When I came of age I built up one of my own.

The M21 in military service was an accurized M14 action mated to a Leatherwood Automatic Ranging Telescope (ART). This lethal combination offered accurate precision fire combined with a reliable semiautomatic action. It was also one of the sexiest military weapons ever contrived.

My M21 clone began life as a heavy barreled Springfield Armory M1A. I traded into this magnificent rifle back when I was a newlywed. The deal quite nearly cost me my young marriage, but that’s a tale for another day.

What my ad-hoc M21 really excels at is looking cool. It shoots straight enough, to be sure. However, the thing weighs as much as a vending machine and feasts upon match grade bullets. A single box of those spendy rascals costs as much as a nice meal out with the wife. It is also so pretty I almost, but not quite, regret dragging it out into the field. I needed some kind of simulator.

Back when I flew helicopters for Uncle Sam, the simulator was where we trained on the kind of stuff you couldn’t or shouldn’t do in the real $26 million helicopter. Ever wonder if a 50,000-lb. CH47D Chinook will do an inside loop or fly inverted? Yeah, me, too. The simulator claims it will. I needed something like it for my classic Vietnam-era sniper rifle.

Who am I kidding? I didn’t need anything like that. All I really need is a little food, a sturdy lean-to, a source of potable water and a loincloth. Truth be known the loincloth would be more for decorum than practicality. I built up a .223-caliber small-scale M21 just because it was so freaking awesome.


Is it, or isn’t it? Will’s homebuilt DIY Mini-21 sniper rifle is fun to shoot
and cool to boot. Sure, it’s not an exact copy but it’s close enough to
start conversations at the range!

Will sourced the inexpensive scope mount someplace
online but doesn’t remember the brand name, if it ever had one!

Raw Material

The M14 rifle was an evolutionary development of the M1 Garand that American GIs used to kick the dog snot out of the Axis during World War II. With its 20-round detachable box magazine and selective-fire action, the M14 stood poised to make George Patton’s “Greatest Battle Implement Ever Devised” into something yet greater still. However, when America subsequently went to war in some of the planet’s most fetid jungles we found the cumbersome 44″ M14 battle rifle to be a bit much.

The whole sordid mess led to the M16 and the zippy little 5.56mm cartridge soldiers use to this very day. One might think the M14 design would then be relegated to museums alongside aged 1903 Springfields and vintage Krags. However, it seems the American shooting public just couldn’t quite let go of all that sweet Parkerized steel and walnut.

Springfield Armory has built a thriving business providing American shooters with semiauto .308 M1A rifles. In 1973 Sturm Ruger introduced the most adorable miniaturized version chambered for .223. Designed by Bill Ruger and L. James Sullivan, one of the original designers of the AR15, the subsequent Mini-14 has remained reliably popular ever since. It also spawned a thriving market for aftermarket accessories. It is from this deep well we drew what we needed to build a miniaturized M21 sniper rifle.

Mini-14 rifles are ubiquitous. Walmart sold them for decades at around $400 apiece back before the woke crowd castrated the Walmart sporting goods department. I picked up my high-mileage copy at a gun show. With this beater as a foundation, it was time to wax creative.


The Mini-21 (bottom) is essentially a .223-caliber scale model of
the full-sized GI sniper rifle (top) built by Will on an M1A chassis.

The raw material: Will’s nicely aged Mini-14 was a gun show conquest.
The old-school Ramline folding stock was a nice blast from the past!


Unlike the forged receiver M14, the Mini-14 orbits around an investment-cast, heat-treated steel receiver that is plenty strong but cheaper to produce. The rifle sports a self-cleaning, fixed-piston, gas-operated action. While the Mini-14 intentionally looks a great deal like the larger M14 rifle it apes, its beating heart is actually quite different.

For starters you need to lose the original Ruger front sight. Just tap out the retaining pin and gently bump the front sight off with a hammer. Use a piece of brass or aluminum if you want to avoid marring the old part. I just hammered it loose and still didn’t leave a mark.

To complete this odd charade my Mini-14 needed a long flash suppressor, a 20-round magazine, a scope and mount and something to approximate the gas piston of the larger military rifle. An evening with Google and a credit card sourced everything easily. The M14-style flash suppressor comes from Choate Machine and Tool.

Choate is an Arkansas-based company that cut its teeth on stocks and gun accessories back in the 1980s. HK selected Choate’s side-folding stock for their MP5K Personal Defense Weapon (PDW). There are scads of aftermarket muzzle accessories for the Ruger Mini-14, but the Choate flash suppressor most closely mimics the long M14 number. There’s no bayonet lug, but Springfield Armory eschews bayonet lugs on their modern M1A rifles as well for some reason. Installation requires you drill a hole to accept a 1/8″ roll pin. A drill press is the ideal tool but I knocked mine out in a jiffy with a hand drill just to prove I could.

The fake gas cylinder is from Accu-Strut. This accessory is technically an accurizing device bolted underneath the barrel. While the Accu-Strut does improve barrel rigidity and subsequently accuracy, I picked it simply because it made my Mini-14 look more like an M14.

The stock Mini-14 has a fairly lightweight barrel. This feature contributes to the little gun’s handy portability. The longer two-clamp version of the Accu-Strut dampens the thin barrel’s harmonics for more consistent shots. The short version doesn’t help so much, but it looks great. Installation required nothing more than the included Allen wrenches and a little Lock-Tite.

A proper scope and mount complete the charade. I found the mount online and sourced a cheap Chinese CenterPoint scope from my local Walmart. Before you seasoned long-distance shooters poo-poo my cheesy imported scope, it is a surprising lot of glass for the money. It is clear whoever made the thing has actually launched a round or three downrange.

The newest versions of the Ruger Mini-14 feature a redesigned front sight assembly that does not readily interface with the Choate flash suppressor. My high-mileage gun show trade Mini-14 was fairly old, so it wasn’t a problem. However, you might want to check the Choate website for guidance if you are thinking of using a more modern Mini.


The most critical components of the Mini-21 build are the Accu-Strut
underneath the barrel and the Choate extended flash suppressor.


The resulting miniaturized M21 just drips cool. Ammo costs about half what the full-sized 7.62x51mm rounds might, and recoil is a non-event. I did get a bit nuts with the details just for aesthetic purposes, but my Mini-21 is undeniably adorable. Trigger time with the small-caliber, low-recoiling version is pure unfiltered ballistic bliss. The Mini-21 will also reliably set you apart at your local range. We grizzled gun nerds really shouldn’t care about such stuff, but, in quiet moments, we invariably do.

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