You have to be an HK nerd to appreciate the true faithfulness of PTR’s designs. For example, PTR 91 rifles from its GI series are dead ringers for the old-school Bundeswehr-issue G3 service rifle. Also, consider the PTR 32–a homage to a rare 7.62x39mm roller-lock rifle intended as a leave-behind in case of communist invasion of West Germany. Then you have the lines of the much-awaited PTR 63, a rifle that owes much to the short-lived HK G41. Like the PTR 63, the G41 also fed from AR magazines.
PTR Industries likes to do its homework, which is unsurprising. PTR began business using surplus HK-licensed tooling. It’s one of the reasons it remains a leading US manufacturer of roller-lock firearms.
The K3P is modeled after a shortened G3 variant known as the G3K, short-barreled, select-fire .308 rifle. Using HK’s nomenclature, the “K” stands for kurz or “short”. G3Ks are also known as G3KA3s. The “A3” suffix acknowledges its collapsible stock.
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As a large-format pistol, the PTR K3P lacks a stock, instead having a non-rotating sling swivel stud mounted in what looks like the stub of an AR buffer tube.
With recent changes in application of the pistol brace rule, braces are once more readily available. The PTR K3P’s backplate/adapter can receive a buffer tube style brace with some minor modification (where it’s legal to do so).
G3 Genesis
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The 7.62 NATO G3 battle rifle was the result of continued development by Mauser engineers who left unfinished business in the ruins of post-WWII Germany. G3 development continued from the abruptly-stopped roller-locked Sturmgewehr. These prototypes were made from stamped sheet metal instead of millings. This facilitated production and cut costs down.
The Sturmgewehr 44, 45 and their progeny relied on a roller-delayed blowback system that didn’t technically lock into the breech the way other rotating-bolt designs do. Instead, the roller-lock system uses spinning cylindrical rollers that keep the action closed long enough for pressure to drop. Once pressure drops, the rollers kick out of the way and the action cycles. German MG-34 and MG-42 machine guns worked off this system. After WW2, the roller-lock concept had more than proven itself.
The earliest versions of the G3 were first adopted by the Spanish and were known as CETMEs. It didn’t take long for the West German Bundeswehr to issue the rifle and replace its G1 FALs. The Germans dubbed it the G3 and these models had more refined rear sights and a couple other features. The G3 proper went on to become one of the classic battle rifles, adopted by countries all over the world.
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A British Special Operations Favorite
The G3 found its way to northern Ireland during “The Troubles.” The SAS and the affiliated 14-Company intelligence unit, aka “The Det,” often found themselves operating undercover in areas where both British military and terrorists frequently set up impromptu road blocks. The Special Air Service was not impressed with the performance they saw against cars from their 9 mm and 5.56 NATO HKs. On the other hand, they liked the power of their 7.62 NATO G3s. However, full-size battle rifles aren’t exactly ideal to maneuver around vehicles. At the SAS’s request, Heckler & Koch developed the G3K, a story confirmed for me by HK’s resident historian James Williamson.
Any keen eye will note minor variations between the PTR K3P and the original G3K. The K3P’s cocking tube endcap is plain. Its flash hider is similar but missing the retention clip. Its front sight base is also missing the vestigial HK grenade ring. The trigger pack is the common polymer “Navy” style, which was actually used on the later HK guns.
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Sight-wise, the rear sight drum is different from the uber-rare one found on factory G3Ks. While the welded-on Picatinny rail from PTR isn’t “correct” but is a godsend if you plan on, you know, actually shooting it.
The left-side safety is thumb-operated, and the trigger breaks at 9-pounds, ½ ounce on my Lyman digital scale, with the same roll you’d expect.
Manual Of Arms
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The K3P’s manual of arms is simple: while many people tout grasping the front of a rifle’s forend as an innovation from three-gun competition, the technique goes back at least as far as the G3. Doing so allows one to quickly grasp the forward-mounted cocking lever located behind the front sight.
Like the Kalashnikov and most other HK roller-locks (the FBI’s 10 mm MP5 is an exception), there’s no last round bolt hold open. You reload it like every MP5 you’ve seen in an action movie. Sweep the cocking handle to the rear and up into its locking notch, change the magazine, and slap the handle down out of its notch. It looks ridiculously cool, and the more you do it the more fluid it becomes.
Shooting the PTR K3P brings us to the R3, the oft-cursed classic HK 3-point sling. First, remember that HK is no stranger to guns without stocks. Recall that the original MP5K machine pistol didn’t have that cool little sidefolder that makes it a PDW. Instead, the gun was forced forward against the tension of the sling, which helped stabilize it. This technique also works with the K3P.
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A brace makes the K3P easier to shoot. Those who live in states where short-barreled rifles are legal, a Form 1 so you can add a buttstock will let you get those most out of it. Properly stabilized, K3P recoil is much less than you expect, and the blast is…commanding, but not for the shooter.
Sonic Boom
I had no idea until I stood next to a friend while he shot it. Wanting to be considerate, the next time I was at the range, I warned the fella shooting a suppressed .22 next to me and offered him a set of muffs to wear on top of his earplugs. He politely declined, and 20 rounds later, asked me what it was.
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“.308,” I told him.
“That’s the loudest thing I’ve ever heard.”
Rocking At The Range
I fed my K3P around 250 rounds. These consisted mostly of Magtech M80 ball ammo. I also fired DoubleTap 175-grain HPBT, Federal 168-grain OTM and Black Hills Gold 168-grain Barnes TSX Match.
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I followed the shoot/clean cycle suggested in the manual for barrel break-in the first 150 rounds or so, with two malfunctions in the first ten rounds (during which the extractor spring exited the gun). In these guns, the extractor spring consists of a simple bent wire part that can be installed without tools. They’re also a $5 part and are known weak spots on roller-locks. I recommend buying a handful. My HK armorer buddy tells me they’re a single use item. Once removed, the extractor spring should be replaced. Don’t forget that the fluted chamber must also be kept clean for reliability’s sake.
HK pattern drum sights are great—I’ve used them to around 300 yards on my 16-inch PTR 91. But on the PTR K3P, it’s hard to get a good cheek weld on that end cap, and you won’t like it when you do. It feels like taking a jab when you press the trigger. Even so, from the bench with a Ransom Rifle Master front rest and Armageddon Shmedium rear bag, I was able to put five rounds into a 1.22-inch group at 25 yards and into a 3.23-inch group at 50 yards. For CQB distances, the K3P’s accuracy is more than adequate.
Accessorizing the PTR K3P
A red-dot optic makes life easier, so I mounted my Trijicon MRO HD. With it, I managed to group as tight as 1.44 inches at 25 yards and 2.68 inches at 50–off the bench. I also registered the K3P as a legal short barreled rifle, and with the collapsible buttstock extended I managed back-to-back-to-back hits on a 6-inch steel plate at 100 yards, standing unsupported.
Candidly, one of the hardest things about the K3P was leaving it alone long enough to write it up in stock form. For this article, I added only the Trijicon MRO and a Scout Light from SureFire. I’ve used an earlier Scout on one of my AR’s, and it’s a great light, but the current Dual Fuel Scout Light Pro is more impressive in every way. Aside from its dual-fuel function or its 1,500 lumens output, I really like its adjustable low profile mount (LPM). Unlike traditional light mounts, which tend to come with a take-it-or-leave-it height, the LPM pivots on a cleat that’s either M-LOK or Picatinny rail compatible. With the K3P, the LPM allows me to tuck the Scout in nicely on the right side of the forend. A wire control kit from Magpul also helps reduce the risk of snagging from the remote switch cable.
From Hereford to Belfast, Helmand and Aynor
There are limited situations in which a shorty .308 is an ideal weapon inside your house. However, the basic formula of the K3P was created to move around inside a car and penetrate autobody steel other calibers couldn’t. Hard to imagine those G3K’s didn’t bring some semblance of comfort to those SAS troopers.
Special thanks to James Williamson, Heckler & Koch USA