Why do you think HK discontinued delayed blowback action?

[Guest bigbuck_tn]

Ok. Here is another one. I don't see how this one could turn into a flame war but you never know.

Why do you think HK discontinued their roller locking action? From an engineering perspective it seems very innovative. No gas system to worry with, no primary extraction problems (with gas float), simple to manufacture. No rotating bolt. Simple mechanism.

So why did they discontinue it?

Bonus question. Why is the HK system which actually intentionally vents combustion gases directly into the action and chamber considered and seems to be so reliable, while the AR Direct Impingement system which only vents gases into the BC and has some leakage into the chamber when the bolt retracts is considered filthy and needs to have a piston?

(By the way, pistons don't keep all combustion byproducts out of the action, some are almost as bad as the AR)

Okay, let's open the debate.

[Guest gcrookston]

The G3 came from the same generation as the FNFAL and the M14 and shared at least one fault with rifles of that era: weight. Even the 33 is heavier than most of its contempories. The G36 has proven itself a great battle rifle, but falls short in a market that is dominated by the AR type. Then comes the 416, a concept driven primarily by the question: "How can we sell the most rifles?" HK looks to see where it can sell the most, maximize the profit and produce a market acceptable product. The 50 year old design doesn't live up to expectations.

They have not abandoned the rollerblock design entirely. They currently continue to mfg. the MSG90, PSg1 and MP5.

As for the bonus question, I'll leave that to the engineers. The HK design is a filthy weapon and runs like a clock. I've never had a failure with an AR type, gas impingement rifle due to fouling. Recent field tests of the current design and the piston driven design didn't show much of a difference between the two and I believe these results have contributed in the continued delay in switching over.

[Marswolf]

What gcrookston said.

H&K basically just said they weren't going to make more G3s because it was an old design.

Getting a definitive answer from H&K is pretty much impossible. Their view is that they make excellent weapons. You can buy them or you can go buy a girly-man gun.

[Guest sling]

You can buy them or you can go buy a girly-man gun.

But its true!

[Marswolf]

But its true!

Actually, I think that is pretty much true.

[Guest gcrookston]

Yes, HK is famous for Teutonic charm. But it's hard to build something not enough people are buying. Their fans are limited, but fierce. Those that really want these rifles to be built already have them or dream of they day they can afford one. If the demand were truly there the folks at PTR would be cleaning up, as they are building the identical rifle on original HK tooling and selling them for 1/2 of what a good clean original will bring. Sentimentality doesn't get far in free market economies.

[Guest bigbuck_tn]

I figured it was probably because of the cost and critical machining involved.

With a piston gun you just have to get the piston "close" and then the locking lugs have to be machined correctly.

I would imagine that with roller locked design you have to get the locking blocks, the recesses in the receiver, the chamber flutes all within a fairly tight tolerance to get it all working in sync. Plus the design was stamped steel and welding which is alot more expensive that just insert molding around a steel frame. They have to make a profit somewhere.

I have never owned or disassembled a roller locked action so I don't really know what all looks critical. What other ideas are out there?

As to the bonus question, does the HK have a rotating bolt that locks into a barrel extension or does it just have a bolt head? If it doesn't lock into an extension with a rotating bolt like an AR and relys totally on the roller locks to hold the rifle in battery that would mean the fouling building up in the chamber would have less of an effect I would think since there was only one degree of freedom in the locking blocks instead of 2 like in a rotating bolt head.

[Guest gcrookston]

Bigbuck, there are not that many critical machining processes, probably fewer than an AR. Aside from the bolt and trigger mechanisms, there are few moving parts. The design is fairly straight forward. There is no operating rod, hence the mess. Gas directly impacts against the bolt. The bolt is a two piece, non-rotating design with two roller cams which engage camming surfaces in recesses of the barrel extension / trunion. Graduated roller cams are manufactured to adjust for different tolerances (handy to have as a gun ages -- also for assembly of new weapons). Stampings are generally cheaper and faster to produce than millings or castings

The following is stolen from wikipedia, who stole in from HKPro, who stole it from Ian Hogg...

The two-piece bolt assembly consists of a breech (bolt head) and bolt carrier. The bolt is locked in battery by two sliding cylindrical rollers that engage locking recesses in the barrel extension. The breech is unlocked when both rollers are compressed inward against camming surfaces driven by the rearward pressure of the expanding exhaust gases upon the bolt head. As the rollers move inward recoil energy is transferred to the locking piece and bolt carrier which begin to withdraw while the bolt head remains locked in battery. As the bolt carrier clears the rollers the bolt head is unlocked and begins to recoil backwards at a velocity lower than that of the bolt carrier. The bolt also features an anti-bounce mechanism that prevents the bolt from bouncing off the barrel chamber’s surface. The spring-powered claw extractor is also contained inside the bolt while the lever ejector is located inside the trigger housing (actuated by the recoiling bolt).

http://www.bimbel.de/artikel/artikel-12.html

Edited April 18, 2008 by gcrookston

[Guest bigbuck_tn]

Bigbuck, there are not that many critical machining processes, probably fewer than an AR. Aside from the bolt and trigger mechanisms, there are few moving parts. The design is fairly straight forward. There is no operating rod, hence the mess. Gas directly impacts against the bolt. The bolt is a two piece, non-rotating design with two roller cams which engage camming surfaces in recesses of the barrel extension / trunion. Graduated roller cams are manufactured to adjust for different tolerances (handy to have as a gun ages -- also for assembly of new weapons). Stampings are generally cheaper and faster to produce than millings or castings

http://www.bimbel.de/artikel/artikel-12.html

Das ist Goot.

Very interesting. I still want to take one apart myself but oing through the pictures with your explanation of operation was very informative.

But it begs the question even more to me now. Why stop making it? It seems to be much more robust system in comparison to lots of other designs. No op rod, no piston, no worry about lockup in an extension. Looking at the rollers on the bolt it seems to me that would be very hard to get enough material in to jam the gun.

I agree about the stamping/welding as opposed to casting/forging/machining but progressive die stamping can get rather expensive too especially compared to an injection molded frame with metal inserts ala the G36.

Maybe that was the reason?

Any ideas?

[Marswolf]

But it begs the question even more to me now. Why stop making it?

Keine neuen Geld

[Guest gcrookston]

...und unzulängliche Verkäufe

[Guest m14man]

Keine neuen Geld

no news money, thats what the translator said.

[Paletiger13]

I think HK are a bunch of jerk asses. IMHO, just came from HKPro.com and I am tired of looking at HKs. Overpriced greedy(military contract asses) non-civilian freindly unlike FN. My money is going to other manufactures until they change their marketing plans. Sorry to sound negative but when you spend $4,000.00 to make a G36K clone(SL8K) then you would understand I guess.

[Guest gcrookston]

Don't know much about clones, tiger. Really don't know much beyond their steel rifles. The only pistol of their's I was ever attracted to was the Socom, which I quickly traded for a tactical... But I do love their steel rifles and have owned several dozen over the decades. Especially like the 93... I lost my interest in 91's a few years ago and have since sold them all with no intentions of acquiring more (though I'm always on the lookout for a value priced 93).

Edited April 19, 2008 by gcrookston

[Guest bigbuck_tn]

Wow. SWEET.

Will you adopt me so I can come and live at your house?

Why did you decide to get rid of the 91's?

I have never even seen a '93 in person. Only in pictures. And you have some nice ones although isn't that a 91 in the second pic and 2nd from the top in the 3rd pic?

[Guest gcrookston]

Don't get me wrong, I like the 91's for what they are, a great battle rifle. But they can never be made beyond battlefield accurate (2moa), without throwing a lot of money at them, due to the fact that the receiver deforms during firing (normal). The 93 doesn't have that problem as it shoots the much lighter 5.56. Picking the right 93, one can put together a sub-moa rifle by installing the minimal factory parts (Psg1 trigger pack). Also, the 93 was the first HK and first ugly black rifle I ever purchased...

The one pictured above in some of the pics is the first I'm speaking of. It has the common 1:12 twist rate and will put 52 gr match on target @ 0.75MOA consistantly.

Here's another 91 I once owned:

Edited April 19, 2008 by gcrookston

[Guest gcrookston]

But to get back on topic. The reason HK quit building them was because not enough people were buying them. Hard to build something that can't be sold. They moved on to other products.

There are 2 kinds of HK91 and 93 buyers, those that have them and want more and those that wish they had them and can't afford them, and they are a small minority of gun buyers.

It's up to you, Bigbuck, to cross that line and step up and buy a PTR.

[Guest bigbuck_tn]

But to get back on topic. The reason HK quit building them was because not enough people were buying them. Hard to build something that can't be sold. They moved on to other products.

There are 2 kinds of HK91 and 93 buyers, those that have them and want more and those that wish they had them and can't afford them, and they are a small minority of gun buyers.

It's up to you, Bigbuck, to cross that line and step up and buy a PTR.

Although I have never actually fired one, I have picked them up and admired them. However, I have fired an M1A and I really, really liked that one. If I am ever in the market for a battle rifle I will probably be pulling a M1A (or like design) off the rack.

I just posted this topic one day after my 2 hrs of mowing where I had been thinking about different gun designs and it occured to me that based on my limited knowledge of them they should have been better sellers.

I figured I could post here and find someone to talk to about them.

Thanks for the information.

[Guest gcrookston]

If I am ever in the market for a battle rifle I will probably be pulling a M1A (or like design) off the rack.

And you are a member of the primary reason there are no more new HK91s or 93s.

You just answered your own question.

Edited April 19, 2008 by gcrookston

[Guest 5Legion]

[quote name=

It's up to you, Bigbuck, to cross that line and step up and buy a PTR.[/quote]

I always admired the 91s as a kid (too much SOF magazine I guess) ... I bought a PTR-91K last year. It has exceeded all my expectations. Some say fit & finish is nicer than the real 91s. Not sure about that, but it is a nice shooter with all ammo. Truth is, I don't shoot it much now, as .308 is not cheap, but I do take it out of the safe and fondle it every couple of weeks!

5L