Home Forums Hunting & Shooting AR and Tactical Rifles PTR-91 (H&K 91 Clone) At The Range

The AR-180 was a cool gun. Better that the AR-15, IMO.

That concerns me too. I remember my HK93 spitting out deeply striped spent cases, and my PTR just barely shows sign of the fluting on the spent cases.

Early CETME prototypes (and some early machine guns) used lubricated cases to aid extraction. A bit of Imperial Die Wax aids extraction in the early PTR barrels with shallow fluting, or when using commercial (thinner) brass in a roller delayed action designed for military (thicker) brass. Last I heard PTR's current fluting is closer to spec than some of their earlier barrels.

You have to be real careful with lubricating cartridge cases that are fed into a chamber to be fired. You have to be absolutely certain that said lube doesn't leave ANY residue whatsoever or you can have a buildup and BIG pressure spikes. This was identified around 1906 with match rifles (read Hatcher's Notebook). At first it will actually reduce chamber pressure, but after some buildup, pressure will spike.

It certainly could have been / should have been. It lacked the development of the AR15 so it always came in last in tests. When tested against the AR15/M16 the 15/16 was a rather mature design, and the 180 in its infancy. There was nothing wrong with the design, which is quite evident by all the direct copies of it today (SA80, SAR80, XM8, G36, etc), but it never got the opportunity to work out the issues related to materials and manufacturing. In tests it was always parts breakage that stopped the 180, nothing related to the design. Same thing happened to the M16 (and pretty much every other major military rifle ever built, with the possible exception of the M1 Carbine).

The 180 showed a lot of promise, but it was killed by legislation that said essentially that no non-US Military small arms can be sold to foreign militaries. This killed the market for innovation if you ask me.

But they didn't want anyone complicating NATO supply lines. In the 1960's I guess it made some sense. The thinking back then was that we'd be going to blows with Russia sooner or later.

Yep. I bought mine since they deepened the flutes, but it's still shallow compared to my old HK91.

Yep, true.

PS About fifteen or so years ago, my girlfriend and I were house guests of a very wealthy man and his family. He was not only extremely wealthy, but he was a survivalist. He and his family owned a mountain top mansion in Oregon.

Unbelievable compound/estate home. He had a helicopter and heliport on the property. He had a collection of vintage Corvettes in a huge garage. All sorts of live in help. I think he owned the whole mountain, because his was the only house on it, with a single private road going up the mountain to his compound on the top plateau. Electronic security gate at the bottom.

Believe me, I know it sounds like I'm writing fiction, but I'm not embellishing. This guy happened to go to the same Church as my girlfriend at the time.

Anyway, we go into his home and we're talking about guns, and tactical carbines. He goes over to a wall and flips a switch. A panel in the wall slides open and there's a row of ten or fifteen AR-180s. Then we went down to the basement level where he had a bomb shelter/safe room. More guns, cases of ammo, box after box (fifteen or twenty) of brand new Beretta 92s. Food, water, etc..

Relating the story, I know it sounds like a fourteen year old kid made it all up, but I can't help it. It's the God's honest truth, with details as accurate as I can remember. That was one weird experience. Pretty cool, though. I'll never forget the sight of all those AR-180s lined up in a hidden wall compartment.

Chamber pressure or bolt thrust spike? Roller delayed blow back firearms don't have the same issues with case head separation as locked breech firearms, well they do have issues but for different reasons. Does Hatcher's Notebook blame the spike on oil in chamber or oil in barrel?

Here is a quote about MG's using lubricated brass-

The machinegun is unusual because it is the only successful military machine gun working on the delayed blowback system before H&K systems at 1950.
The Schwarzlose Machine Gun M1907 was an extremely simple mechanism compared to other famous designs like Maxims. It was easy to make and proved reliable. The designer had managed to solve the problem with a delayed blowback system. The problem is that the breech starts moving backwards immediately as the cartridge is fired. The gas pressure is still very high and the walls of the cartridge case are expanded towards the chamber, which will cause very high friction. At the same time the extractor starts pulling out the empty cartridge case. The problem was solved by using very strong recoil springs and recoil parts together with a very short barrel. When the bullet left the barrel the pressure dropped while the kinetic energy of the recoil parts continued to pull out the empty cartridge case and reload the gun. The Schwarzlose machine gun has a device for oiling each cartridge to ease the reloading cycle. On each stroke oil was squirted into the firing chamber to lubricate the incoming cartridge case.

1912 some changes were made to the feed system and this change was called M1907/12. It had a straight top receiver and a simplified oil pad system instead of the pump mechanism. http://www.gotavapen.se/gota/artiklar/utv_ksp58/ksp14/schwarzlose.htm

also-

Modern high-pressure blowback systems such as the HK G3 incorporate fluted chambers to facilitate extraction. Lacking fluted chambers, previous toggle-locked firearms required cases lubricated with wax (Pedersen) or oil (Schwarzlose).
http://wecsog.blogspot.com/2013/02/blowback-autoloader-design.html

The rival to the Garand rifle was a rifle designed by Pedersen. Look up the 276 Pedersen cartridge sometime. The Pedersen rifle required waxed cartridges for reliable extraction. The Germans solved the extraction issues by having a fluted chamber in their rifle. Simple and elegant...

I'm sure lubricated cartridges were lubricated with a lubricant appropriate to the design. My warning is about lubing cartridges yourself in an un-scientific manner. Just pointing out there can be some issues. Personally, that's not something I'd be willing to do with a thousand dollar rifle. I'm just not very adventurous with high pressure cartridges.

PURE SPECULATION ON MY PART...

My recollection from when I had my Sig Stgw 57 (PE 57) was that Sig and H&K chamber fluting was actually hammer forged into the barrel on manufacture. Headspace on both rifles is done at the bolt/roller end, so they can produce finished & chambered barrels. I think this is why the fluting on the Sig & H&K barrels was so much deeper; they could do it without stressing the barrel.

Speculation on my part, but I tend to think the PTR barrels have their chamber fluting pressed into the barrel after chambering, and that's why it's so shallow.

I would think that chamber fluting could be done via EDM. In fact, I would think making the entire barrel by EDM would be THE way to go. But I'm far from an expert on EDM, maybe there are issues that prevent them from doing so.

I know S&W makes all their revolver barrels by EDM.

Jimmy, I have one as well. Mine actually has a picatinny rail on top so it's easy to mount an optic. I seem to remember getting about 1.5" with some reloads & an optic but didn't like what it did to my brass. I bought some surplus for blasting and decided to use it as a fun gun. A buddy of mine has the HK91 and warned me not to use steel cased ammo but when I inquired about it to PTR, they said steel runs great in their rifles.

Its a high quality 91 clone in my opinion.

Back in the 1920"s at the US Army Springfield Armory, John Garand competed his semi auto rifle design against one by a man named Pederson. The Pederson rifle required waxed cartridges for reliable extraction. That is a reason why the M1 Garand was adopted.
CETME/H&K solved that issue by fluting the rifle chamber for the G3 for reliable extraction. Apparently Mr Pederson had not considered that solution

When I was just 21 I was at the range with some serious military gun collectors, when a guy walks up with a nearly mint condition Pederson in .30-06. First, I had never even seen one in the flesh. 20 minutes later, I got to put 5 rounds through it. I don't recall any mention of lubricated cartridges, but I don't recall what I had for lunch yesterday either.

What I do recall was that the entire rifle was Carbonia type blued and made with impeccable quality. Few military rifles are "beautiful" but this one was certainly a looker. And the first half of the barrel had very deep spiral fluting, which just pushed the cool factor over the top.

I fired just 5 rounds, and I have to tell you, seeing that toggle pop up in your face freaked me out a whole lot the first round. And freaked me out a bit less for the other 4; but freaked me out nonetheless. It's one of the coolest guns I've ever shot. I just couldn't believe the guy was shooting the thing. I've never seen another in the flesh, and his was nearly mint condition. I also wasn't aware that any were made in .30-06 but I suspected they had.

On that same day I also got to shoot a Johnson 1941 Light Machinegun...that was a very impressive Squad Auto.

chrome lined barrel or no?

www.atdesigner.com/ptr91/techinfo.html

This PTR tech page says not chrome lined. I have not seen any chromed PTR or G3 military barrels, but that doesn't mean they don;t exist.

A Pederson rifle in 30/06?
The original Garand versus Pederson semiautomatics were both chambered for the 276 Pederson cartridge. The Garand was selected but Army Chief Gen. Douglas MacArthur refused the adoption any rifle that used any cartridge other than the 30/06. So John Garand redesigned his rifle for the 30/06.
As far as I know the Pederson rifle was strictly a 276 Pederson cartridge chambered rifle.

in a military type rifle a bare steel barrel in a humid environment can get you killed. My Bad let me rephrase that...if your having to shoot zombie's in the rain and dirt a bare steel chamber might rust and prevent extraction....