The piston system is much better.

​

 

The roller delayed blowback system is dependant on the pressure exerted on the boltface to hold the bolt in battery. The more pressure on the boltface, the more pressure to hold the rollers in their semi-circular shaped recesses on the barrel extension until pressures drop to a safe level and the rollers can retract into their recesses. Although the bolt system is slightly more complicated, there is no gas system whatsoever. A different version of the roller delayed system was proven in ww2 with the MG42 light machine gun and later modified for the Cetme/G3. Since then it's been used in everything from sniper rifles(PSG-1)to submachineguns(MP5). Whether it has an advantage over more conventional gas piston systems with a rotating or tipping bolt system is hard to say, since both have more than proven themselves both on and off the battlefield.

 

Depends on the specific design, there are excellent and crappy examples of both.
The roller system is simple and effective, but IMO more susceptible to fouling than a good piston design, but the piston design has to operate with fouling in mind since it essentially runs dirtier.
I suspect some roller delayed systems could be superfluous as the Blish system was in the Thompson.

 

The roller systems theoretically have less parts, and thus are simpler to manufacture and maintain.

However....they are more prone to fouling.

 

The major difference is the way empty gets extracted. What happens after the round is fired is the pressure expands the brass and makes it “stick” to the chamber walls: bad time to extract. Bullet leaves the barrel, pressure drops, elastic brass contracts back: good time to extract. The way a (well timed) gas system works, bullet leaves the barrel, case contracts and only then the bolt starts extracting the case. There’s no pressure at this point, the bolt is driven only by the inertia of the carrier. Happy extraction.

Roller delayed blowback has the same inherent drawback as all blowback systems have- extraction starts almost immediately as the bullet leaves the case neck. The pressure is high, the case is “glued” to the chamber, the extraction is violent and abrupt. You have to use additional means to ease the extraction. Generally it means to A) lubricate the cartridges or B) cut the flutes into the chamber as invented by the Italian designer Agnelli at the turn of the last century. Flutes allow gasses to flow around the case and equalize the pressure. The case is floated out on a film of hot gasses.

In practical terms this system still produces harsh felt recoil and, unlike the gas system, cannot be easily adjusted for different ammo, battlefield conditions and comfort. I also don’t think it’s nearly as safe. On a plus side it runs cooler and a quick-change barrel is a bit easier to design. The last one is irrelevant to a civilian. What is relevant to a civilian is that flutes chew up brass. Roller delay however works great in weapons too weak to employ gas system.

For whatever reason G3 family gained momentum, I suspect it had to do more with marketing, cost and the refusal of Belgians to license FAL out to certain nations. Another popular rifle that uses more direct Kiraly set-up is French FAMAS, decent gun by all accounts but probably owes its existence to the fact that French are, well, French and have to be different.

Subguns aside I don’t think we will ever see another delayed blowback rifle hitting the world market.

A different version of the roller delayed system was proven in ww2 with the MG42 light machine gun…

MG42 was not a delayed system, it was a positively locked system. The action was not operated by the blowback but by the barrel recoiling within the receiver.

The roller delayed blowback system is dependant on the pressure exerted on the boltface to hold the bolt in battery. The more pressure on the boltface, the more pressure to hold the rollers in their semi-circular shaped recesses on the barrel extension until pressures drop to a safe level and the rollers can retract into their recesses.

I don't think this is the case. Pressure doesn't hold the rollers in recesses, the action spring does, via the inclined surfaces of the carrier. The pressure fights to dislodge them, the higher the pressure the sooner it will dislodge the rollers.

 

The roller systems theoretically have less parts, and thus are simpler to manufacture and maintain.

However....they are more prone to fouling.

Don’t know about that. Gas system needs piston slide and bolt, roller delay needs bolt, carrier and rollers. 2:3. Roller delayed gun may be easier to manufacture but not due to the minimally required number of separate components.

 

Delayed blowback is an older system that has been surpassed by more modern pistol driven designs. Even HK stopped using the design with the G36 rifle. The piston system keeps the chamber cleaner and cooler, and is also more reliable.

 

Delayed blowback is an older system that has been surpassed by more modern pistol driven designs. Even HK stopped using the design with the G36 rifle. The piston system keeps the chamber cleaner and cooler, and is also more reliable.

More modern piston design? Piston driven mechanism was one of the very first mechanism designed for autoloaders.

Thus far it seems to be a more efficient and reliable system than its peers, but modern? Far from it.

 

I never said the pistom system was new, just that newer designs of it have replaced the delayed blowback locking roller system in modern small arms design.

More modern piston design? Piston driven mechanism was one of the very first mechanism designed for autoloaders.

Thus far it seems to be a more efficient and reliable system than its peers, but modern? Far from it.

 

The only roller-delayed firearms I've ever had much fondness for are the P9 pistol and MP5 subgun. Once you move to rifle calibers, the recoil becomes quite a bit more than in competing designs, and for no real gain in other areas. And like others have said, they foul quickly. I've never thought of the AR-15 as a terribly "dirty" rifle, and I think the main reason is that one of my first guns was a G3 clone. Cleaning the locking recesses in the trunnion was a pain.
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At least the fouling on the delayed blowback roller lock design is only confined to the chamber and the bolt face, and that's why HK had to flute the chamber to help with extraction. Most other parts are clean.

 

The major difference is the way empty gets extracted. What happens after the round is fired is the pressure expands the brass and makes it &#8220;stick&#8221; to the chamber walls: bad time to extract. Bullet leaves the barrel, pressure drops, elastic brass contracts back: good time to extract. The way a (well timed) gas system works, bullet leaves the barrel, case contracts and only then the bolt starts extracting the case. There&#8217;s no pressure at this point, the bolt is driven only by the inertia of the carrier. Happy extraction.

Roller delayed blowback has the same inherent drawback as all blowback systems have- extraction starts almost immediately as the bullet leaves the case neck. The pressure is high, the case is &#8220;glued&#8221; to the chamber, the extraction is violent and abrupt. You have to use additional means to ease the extraction. Generally it means to A) lubricate the cartridges or B) cut the flutes into the chamber as invented by the Italian designer Agnelli at the turn of the last century. Flutes allow gasses to flow around the case and equalize the pressure. The case is floated out on a film of hot gasses.

In practical terms this system still produces harsh felt recoil and, unlike the gas system, cannot be easily adjusted for different ammo, battlefield conditions and comfort. I also don&#8217;t think it&#8217;s nearly as safe. On a plus side it runs cooler and a quick-change barrel is a bit easier to design. The last one is irrelevant to a civilian. What is relevant to a civilian is that flutes chew up brass. Roller delay however works great in weapons too weak to employ gas system.

For whatever reason G3 family gained momentum, I suspect it had to do more with marketing, cost and the refusal of Belgians to license FAL out to certain nations. Another popular rifle that uses more direct Kiraly set-up is French FAMAS, decent gun by all accounts but probably owes its existence to the fact that French are, well, French and have to be different.

Subguns aside I don&#8217;t think we will ever see another delayed blowback rifle hitting the world market.


MG42 was not a delayed system, it was a positively locked system. The action was not operated by the blowback but by the barrel recoiling within the receiver.

I don't think this is the case. Pressure doesn't hold the rollers in recesses, the action spring does, via the inclined surfaces of the carrier. The pressure fights to dislodge them, the higher the pressure the sooner it will dislodge the rollers.

Actually, it's the inclined surfaces of the firing pin shroud or "locking piece" that force the rollers into their recesses in the barrel extension. If you re-read my post, I didnt claim that the G3 system was identical to the MG42. I prefer to condense things as opposed to writing a book about the salient differences.

 

HK91/G3 has a fluted chamber, over-engineered massive parts. It is a very dirty system and had to be engineered to and can work dirty. Compared to the FAL, with a piston, it is like Frankenstein vs. Dracula. The FAL being so much cleaner in operation, and so much more refined. I do not miss cleaning my HKs. Not at all. Looking back, I regret all the time I wasted cleaning HKs. I wish I had a powerwasher back when I had them. It would have saved a lot of time.

 

HK91/G3 has a fluted chamber, over-engineered massive parts. It is a very dirty system and had to be engineered to and can work dirty. Compared to the FAL, with a piston, it is like Frankenstein vs. Dracula. The FAL being so much cleaner in operation, and so much more refined. I do not miss cleaning my HKs. Not at all. Looking back, I regret all the time I wasted cleaning HKs. I wish I had a powerwasher back when I had them. It would have saved a lot of time.

The fluted chamber allows the pressure on both sides of the case to equalize, which reduces case expansion into the chamber walls and eases extraction by effectively "floating" the case. I dont see the FAL as being "more refined" by any stretch of the imagination. Realizing how crucial positive extraction is in a weapon designed for battle is why it has a fluted chamber. Another example is the HK P7 pistol, which can reliably extract with the extractor damaged or even missing! The FAL's action didnt give birth to an entire family of weapons from sniper rifles to sub-guns! The FAL's tipping bolt and piston system was designed WAY before the FAL was ever thought of. Not to take away from it, but there's absolutely nothing original about the design. Pull apart an SKS or Tokarev rifle and you'll see the same "guts". And even those rifles werent the first to use that action. Saive took the tipping bolt and piston system and enclosed them within a much heavier receiver and placed the spring and rod in the butt.....and that's about it.

 

The FAL's action didnt give birth to an entire family of weapons from sniper rifles to sub-guns! ... Pull apart an SKS or Tokarev rifle and you'll see the same "guts". And even those rifles werent the first to use that action. Saive took the tipping bolt and piston system and enclosed them within a much heavier receiver and placed the spring and rod in the butt.....and that's about it.

Actually, the FAL DID give birth to a whole family from belt-feds to subguns. The FN-MAG (M-240) is a FAL action at heart. Check out the Brazilian Imbel MD-2 5.56mm assault rifle and MD2-A1 9mm submachine gun, both FAL-based.

For the record, the FAL was derived from the Browning Automatic Rifle. Saive flipped the action upside-down, and redesigned the receiver to reduce weight and machining time.

Each type of action has it's pros and cons. Use what you personally prefer.

 

Actually, it's the inclined surfaces of the firing pin shroud or "locking piece" that force the rollers into their recesses in the barrel extension

In delayed (retarded, to be technically correct) blowback guns inclined surfaces are but a leverage agency, by themselves they don’t hold anything. The force of the action spring is what holds the rollers in place and while sometimes it is assisted in this role by the inertia of the carrier (or steering piece or bolt body or whatever) it’s never assisted by the pressure as you claimed. That’s chiefly what I’ve been trying to say: pressure, no matter how high, at no point works to hold the rollers in place; it always tries to dislodge them. We’re not talking Blish here.

If you re-read my post, I didnt claim that the G3 system was identical to the MG42

No, you said they are different versions of the same thing called “roller delayed system”. MG42 isn’t. Would you call piston-operated Sig 530 “roller-delayed”?

I prefer to condense things as opposed to writing a book about the salient differences.

I wouldn’t question your personal discount of the major differences. I’m not addressing things you omitted; I’m addressing things you stated and were, IMHO, wrong about.

 

Fluted chamber in a roller retarded rifle/ machine gun is not an additional layer of performance like it was in Russian pre-war designed 7.62 SHKAS aircraft machine gun. In G3 it’s necessity. It’s not there to make things “work better” it’s there to make things “work”. Even with it the felt recoil of G3 is harsher than of any of the gas guns in the similar size/weight envelope.

Roller retarded blowback was certainly unique when it was first proposed by Dr. Maier albeit as the side effect of an unrelated study. But roller lock itself was used in several “between-the-wars” era designs and has roots in Friberg system patented even before Maxim was invented. Friberg system was used, among others, by Degtyaryov on his machine guns pretty much exclusively.

By the time WW2 started there was very little radically new in the world of self loading firearms no matter how you slice it.

 

The fluted chamber allows the pressure on both sides of the case to equalize, which reduces case expansion into the chamber walls and eases extraction by effectively "floating" the case.

Nobody uses the fluted chamber because their actions don't need it.

I dont see the FAL as being "more refined" by any stretch of the imagination.

Very true. Tipping bolt piston driven action ain't new when the FAL came into fruition. Nothing is really new when it comes to autoloader mechanism design.

Realizing how crucial positive extraction is in a weapon designed for battle is why it has a fluted chamber. Another example is the HK P7 pistol, which can reliably extract with the extractor damaged or even missing!

Once again, it's because the delayed blowback mechanism needed it.

The FAL's action didnt give birth to an entire family of weapons from sniper rifles to sub-guns! The FAL's tipping bolt and piston system was designed WAY before the FAL was ever thought of.

Because FN engineers realizes that scaling down or scaling up an action to fit another gun may be a cheap way to do it, but not a smart way to do it.

An 18-lbs sniper rifle chambered for 7.62 NATO? You gotta be kidding me!!! A subgun with delayed blowback action? Why? The chamber pressure on the 9mm ain't squat. Why do you think that the UMP isn't a delayed blowback action any more?

Not to take away from it, but there's absolutely nothing original about the design. Pull apart an SKS or Tokarev rifle and you'll see the same "guts". And even those rifles werent the first to use that action. Saive took the tipping bolt and piston system and enclosed them within a much heavier receiver and placed the spring and rod in the butt.....and that's about it.

Nothing is new under the sun. Every operating mechanism had been designed and tried by the 1920s.

 

Oh yeah, that famed and vaunted HK roller delayed blowback system?

Stole from the Spaniards. HK didn't even invent the the damn thing but stole from CETME.

 

Oh yeah, that famed and vaunted HK roller delayed blowback system?

Stole from the Spaniards. HK didn't even invent the the damn thing but stole from CETME.

Actually, the man that designed the "Cetme" was an employee of Mauser who fled to spain just prior to the allied occupation. A project that he started in germany was basically finished in spain. Once finished, Cetme licensed production to germany since the Belgians had thumbed their noses at germany over the G1. Dr Vorgrimlers design ironically returned home, thus nothing was "stolen" from spain.

 

In delayed (retarded, to be technically correct) blowback guns inclined surfaces are but a leverage agency, by themselves they don’t hold anything. The force of the action spring is what holds the rollers in place and while sometimes it is assisted in this role by the inertia of the carrier (or steering piece or bolt body or whatever) it’s never assisted by the pressure as you claimed. That’s chiefly what I’ve been trying to say: pressure, no matter how high, at no point works to hold the rollers in place; it always tries to dislodge them. We’re not talking Blish here.


No, you said they are different versions of the same thing called “roller delayed system”. MG42 isn’t. Would you call piston-operated Sig 530 “roller-delayed”?

I wouldn’t question your personal discount of the major differences. I’m not addressing things you omitted; I’m addressing things you stated and were, IMHO, wrong about.

I think you misunderstood what I referred to as "pressure" in my posting. I was of course referring to the mechanical pressure exerted against the rollers which holds them in their recesses, not gas pressure!

 

Oh yeah, that famed and vaunted HK roller delayed blowback system?

Stole from the Spaniards. HK didn't even invent the the damn thing but stole from CETME.

That is such an ignorant post.

 

That is such an ignorant post.

Luckily no one has to take things at face value when they can simply Google things and do their own research. There's quite a difference between opinion and fact and you're FAR more likely to get opinions represented as fact on any forum. Simply Google "Dr Vorgrimler" and you'll find out everything you'd like to know about the G3 and the prototypes that predated it. Vorgrimler is to HK as John Browning is to.....Browning!

 

Actually, the man that designed the "Cetme" was an employee of Mauser who fled to spain just prior to the allied occupation. A project that he started in germany was basically finished in spain. Once finished, Cetme licensed production to germany since the Belgians had thumbed their noses at germany over the G1. Dr Vorgrimlers design ironically returned home, thus nothing was "stolen" from spain.

Did the CETME come first or did the HK come first?

I didn't say whether or not the Germans invented it. I said HK copied it.

 

That is such an ignorant post.

Once again, read it slowllllllllllyyyyyy.

Which one came first? CETME orrrrrrr HK?

That German's version of JMB, did he invent the roller lock blowback system while working for HK?