Roller delayed is really good. It's ability to tolerate less consistent ammo (especially with regard to powder burn rate) is often overlooked. It shares this idea with recoil operated actions - the entire time the bullet is the in barrel is dwell time, so pressures and burn rates at some certain position partway down the barrel doesn't matter the way it does in gas operated systems. The inconsistency in powder found with early self loading actions is a part of why recoil operation was more prevalent than gas operated systems, despite the systems themselves being "discovered" at around the same time.
That is a good point. But in exchange you are much depend from a state of those surfaces - between rollers and leaps and spring between rollers. That probably main reason why roller delay is not spread wider.
@@vladimirpecherskiy1910 the sort of tolerances and precision required in a roller delay action aren't any more demanding than those found in AR, SCAR, AK, etc actions. I think the big drawback to roller delay is on the manufacturing complexity itself (you can't just crank out bolts from a bar-fed lathe like with AR bolts), not so much a question of tolerances.
@@IvanPrintsGuns And that is where lever delayed blowback comes in. Lever delayed blowback is simpler and can work just fine in relatively lower tolerances. However lever delayed blowback requires a reinforced strong steel plate where the lever can rotate around.
I'm glad you got in the 5.56 roller delayed systems. For whatever reason I was always under the impression that roller delayed outside of 9mm was snappier, glad to see it's all smoove 😎
Most HK91s are "overgassed", meaning there's more than enough energy being transferred to the locking mechanism to operate, even under adverse conditions. Most HK91s are *also* set up for "light ball" 7.62x51 NATO ammo, meaning 147gr. So they tend to have rather snappy recoil inpulses, because under typical civilian range conditions there's a good deal of energy left over. Add 168gr ammo, the most common civilian load in the US, into the mix, and you get a *lot* more leftover energy, which is probably part of why HK91s got their reputation for kicking like mules (the other being that AR15s don't actually recoil 😜). The solution to the one is to develop good shooting fundanentals of stance, shoulder weld, etc. The other us, if you're planning on feeding your HK a steady diet of "heavy ball" ammo, is to swap the factory bolt key for a H&K #17 bolt key, which reduces the efficiency of the locking mechanism so that it eats more of the energy...and doesn't punch your shoulder as hard. Interestingly enough, I'm pretty sure the PSG-1s came with #17 bolt keys installed from the factory, because they were intended for use with heavy match ammo.
@@christopherreed4723 Here it seems like they had more of a problem with the overly aggressive bolt return rather than the impact from the bolt going back even with being overgassed. Maybe these guns would be better served with lightened bolts and more aggressive locking angles instead.
I will say that our Danish military G3s has given many a soldier a black eye. In Bosnia we tried swapping firearms with the Ukrainians; the first one tried the G3/M75 and nobody else wanted to :-D
Excellent video, I think a lot of gun-tubers write off roller delayed because you can't bang on the trigger like you would a paintball gun. Your explanation on recoil is one of the best I've seen, and fits exactly to what I've experienced with my PTR-91 - You can't really fight it, you've just got to ride with it.
I'm 55 yrs old. IMHO, this vid was THE best demonstration of 'roller delayed' firearms I've ever seen... AS WELL AS the best use of 'spousal abuse' as a teaching aid! In all fairness, Henry really was asking for it... *smirk 😏
It will be a financial failure again. Nobody wants that garbage except H&K fan boi's. This is America and it's Stoner Country. Eugene Stoner's AR-15 Weapon's System is popular and the best system on the market. It's been the best since 1959 and 65 years later it's truly America's favorite Weapons System and 5.56x45 NATO is the most popular Rifle Round in America.
What a criminally underrated video and channel. This channel should have millions of subs. Educational resources like these are amazing. That’s the best explanation of a roller-delayed mechanism (as assisted by Henry’s lovely wife) ever. Incredible engineering by HK too.
I feel like the good physics way to explain the difference in recoil is that recoil is produced by two things: The force of impulse produced by the bullet, and the mass of the reciprocating parts. Both the AR and roller delayed guns will have very similar strength of recoil impulses, because their reciprocating mass is similar in weight, but the roller delayed impulse is felt over a longer duration, which is where the big perceived difference is. Blowback guns, on the other hand, have a significantly higher reciprocating mass, which is why they have greater recoil impulse.
Um, no, roller delayed is still direct blow back, but as the name suggests, it delays the unlocking using rollers. This is necessary with higher power cartridges like rifle rounds where direct blowback simply wouldn't work, hence with the delay is necessary to allow pressures to sufficiently drop. It's still the same amount of mass, just some of the energy is being used to work the rollers or other locking mechanism in similar designs.
@@tedhodge4830 What? That's incorrect, on direct blowback the mass of the bolt is much higher, so it uses inertia alone to keep the bolt closed for enough time... The bolt of a roller delayed mechanism is delayed via mechanical advantage, not mass. It uses the transfer of inertia over the rollers, not the mass of the bolt to stay closed. This is why a direct blowback of higher caliber would require extremely heavy bolts to actually contain the pressure, exacerbating the issue of higher reciprocating mass on top of adding significant weight.
@@V3RTIGO222 The energy comes from direct blowback, hence the name "roller-delayed blowback." But maybe I'm being pedantic, I hope you get the point. The gas isn't being redirected, the propellant gases being blown straight back act on the bolt to push it back. The rollers simply delay the blowback. It's literally the name of it. Obviously it's a more elegant solution than using a heavy bolt or a heavy buffer spring to slow down the blowback, that's why they designed the mechanism.
@@tedhodge4830 I'd argue that it's not technically "gas operated," as the working mechanism could be opened with any significant enough force applied to the bolthead, unlike conventional gas operated guns which are locked until the carrier has gas tapped and uses the pressure to activate the carrier which unlocks the bolt (otherwise every gun would be 'gas operated' or 'powder actuated')... specifically it's not "direct blowback" because the blowback is being redirected through the rollers and wedge... Much like how lever delay redirects the force through the lever. Direct blowback specifically has no redirection of inertia, giving no mechanical advantage to the closing mechanism. It could be considered delayed blowback, but that is also a pretty ubiquitous term that could be applied to the inertial delay of direct blowback too. So, yes, I would say you are kind of being pedantic.
12:15 longer bolt overtravel also making those guns recoil softer. More recoil energy is transfered to shooters shoulder through the spring, rather than a hard hit of the back wall of the reciever.
Hands down the best explanation I’ve seen. In the past others have kind of gotten it across but I never understood how it got the carrier moving to release the rollers. Solid work as usual
You ever going to do a video on the CETME L? I’d love to see what you can do with the LV/S variant! Yes Marcolmar is currently sold out of those but they’re getting ready to put out another very small batch of them and this time more authentic to the originals than the last batch.
After years of just giving up on understanding roller delay, and just filing it under German Space Magic.....I finally have a rudimentary grasp of the science!!! Thanks 9-Hole Reviews!!!
Thank you for this very interesting video. Physical principles are one thing, engineering and manufacturing are another one. Look at the frightening complexity of the Swiss Stgw57. The rollers must be very precisely adjusted to the trunion, and conversely. They did it successsfully but, quite literally, at a serious cost!
The STG 57 is in manufacturing terms easy to produce, its mostly flat surfaces. The Swiss of course complicated it but it's bolt group is easier to make than a HK one.
@@snowflakemelter1172 Well, just look at bloke on the range's videos with gruening & elmiger about tuning the Stgw57. This rifle is horrendously complex and its bolt is as complex as the rest of the rifle.
The roller delay mechanism and the fluted chamber makes this a surprisingly robust system for rifles, but not for pistols. My P9S will not tolerate hot loads and getting replacement bolts is like unicorns teeth. Would like to see the 9-hole review wives edition! please.
Speaking of the roller delayed guns, looks like your favorite rifle is the PSG1 sniper rifle, and Mr. Garand Thumb has posted the HK PSG1 video already, and you should do a PSG1 series of videos, once you have gotten your hands on one, and that’s you Mr. Henry Chan.
Big difference between the triggers on the AR15 and HK33, especially if you are running a Geissele trigger on the AR. I would like to see a HK33 with a tuned trigger run against the AR15. I have shot AR10s, M14s, FALs, 308 Galils and HK91s. To me the HK91 has the most recoil. I put a heavy buffer in the 91 because of that.
I love the roller delay. Really nice with such a versataile system that can do anything from pistol cartridges up to extremely pressured sniper shots. Also really like how all the moving parts of the mechanism are located behind the barrel.
Loving the videos lately. I still love the practical accuracy but these range vids are cool. Any pistol accuracy videos lol go out to 150yrds or something….
Par of the problem with comparisons is that roller delay guns are almost all decades old HK designs. I think a truly modern roller delay rifle would be a serious competitor in the rifle market, it's just that innovation is focused on AR15 and AR18 derivatives almost exclusively.
I have owned an HK91 and its clones since 1979. I have also shot M14, M1, M16 (and M16A2) and a smattering of AR-15's plus a myriad of other semi auto and full auto firearms. Although I felt roller delayed recoil as different to the others, I have never been able to pin it down or adequately able to explain it...and I feel stupid for not being able to until now. Thanks.
Nice visualization with the billiard balls. Another way of explaining how the angles of locking pieces work that I like to use is by describing their extremes: A zero degree locking piece would have two surfaces parallel to the bore that keep the rollers in the outward position. This effectively makes it a true "locking" piece since no rearward force is imparted to the locking piece and no amount of recoil can get the rollers to go in. (Transmitting recoil/rearwards force to the locking piece is how a roller delayed system gets the bolt carrier group to move.) On the other hand, a 180 deg. locking piece would have surfaces perpendicular to the bore, and thus push forward on the rollers instead of outwards. Since these surfaces don't push out on the rollers at all, the rollers can move freely and transmit 100% of the recoil to the locking piece instead of the trunnion, effectively making the gun a simple direct blowback. Roller delay is therefore a system in which the locking piece wedges the rollers into their recesses inside the trunnion at an angle somewhere between 0 and 180 degrees. This angle determines how the recoil is split between the trunnion and the locking piece/bolt carrier, and consequently the amount of delay. The lower the angle, the closer the system is to acting as completely locked. The higher the angle, the closer the system comes to acting as a direct blowback.
oh thats really good, i'll have to copy this explanation to myself. I was actually in the process of writing a script to explain why exchanging locking pieces will have an effect on bolt carrier speed
The best overall Roller-Delayed Action overview on the interboobs. Thanks! Also, Josh needs to, err, adjust his pants. You know. The Package. The horror, the horror...
I wonder if it would be possible to introduce a dwell time on roller delayed (HK) or lever delayed (FAMAS) weapons. The benefits would be a bigger time to pressure to go down, thus easing extraction. Another benefit would be less carbon deposit on the interior of the gun, making them as clean as external piston guns. A side effect is a reduced rate of fire, beneficial for controlled full auto fire and making ammo lasting a little longer for each magazine.
Well - given that the angle on the locking wedge is what determines the delay? Maybe? If I remember my geometry of momentum correctly then increasing the angle on the locking wedge would increase the amount of force needed to move it.
Its a balanced system, if you increase the time the rollers are locked then you get weak cycling and ejection , if you decrease it you get violent extraction and high cyclic rate, a balance has to be found in the middle.
No, they are designed to achieve the exact ratio of delay, in the case of the HK system it's 1:3, meaning that for every mm the bolt face travels, the bolt tail moves 3 mm. Any more delay and it won't extract enough momentum from the cartridge to extract the casing and any quicker will result in a premature extraction. The only adjustment that can be made to the bolt is changing the bolt weight, there are HK rifles variants that have slots to insert or remove a set of bolt weights.
I've seen Ian's description of roller delay & understand the concept. Being a Fudd & a handloader I generally disliked roller delay because it usually required fluted or ringed chambers to further delay bolt retraction & prevent case head separation. Your demonstration better displayed the tactical advantages of roller delay. Those wiley Heinies! It was unusual to see you fellows wearing jackets in Texas. Temp drop down to 70F?
Thanks for the roller delay explanation, it was easy to understand. Does the roller delay mechanism lend itself better to suppression? In particular, addressing port pop like what happens with the AR15.
Iv'e been waiting for a Ptr Gir 101/G3 clone for over 6 month now ;) This video makes me really really keen on getting my rilfe and kit it up with all the goodies. I'm from Sweden so i start with some Håkan Spuhr parts, alot of gun lovers in Sweden has spoken/written to him and i did to ;) I love your uploads and thank you so much 👍
Explanation isn't quite right, the way to think about it is the rollers provide mechanical advantage to the carrier. For any distance the bolt head moves back the carrier has to move a lot more due to the angle of the locking piece, and the force making it move back also is reduced due to that angle. As soon as the primer is hit everything starts moving just like in a normal blowback firearm. It's the same idea as lever delayed just that instead of a lever and the relationship of the force, load, and fulcrum points it's a roller pin the angle of the locking piece.
Well, what Henry wants to say, that roller delay mechanism spread recoil impulse over longer time, then simple blow back - where all impulse transferred to a shooter when bolt hitting rear spring. Naturally in sum it is THE SAME impulse that in simple blow back - that impulse depend only from protective mass and speed and nothing else. All the difference - how it is spread in time.
Then, there are the classic SiG products: the Stg 57, the 510-4 and its 7.62 NATO sporter stablemate, the AMT. In much better times, I had both delayed-blowback platforms. The AMT, firing Mil-spec Ball, had a noticeably softer "shove" than the H&K in the same calibre and using the same ammo. The H&K would heave the brass a considerable distance. The "clip-on" case bumper is a useful bit of kit, especially for left-handers. The AMT "rolled" the brass out slightly to the rear but not with the same "enthusiasm" as the H&K. I saw one AMT (NOT mine) almost wrecked on a range, once. The bolt assembly was seized up about half-way back in its travel. The magazine was bulged and the shooter looked "surprised". When we finally got the thing apart the big clue was the fired, but not ejected case. The primer pocket was seriously enlarged and the primer "evaporated". the BIG tell was at the neck-end of the case. The neck was "feathered" forward of the nominal length. Hand-loads. NO case trimmer. The extended neck was rammed into the chamber such that it tried to extend past the chamber neck, due to this excess brass. The start of the leade squeezed this excess brass around the bullet, seriously altering the pressure curve relationship with the bullet. Lesson? . This applies to all types of operating systems and calibres / cartridges.. Use a case gauge or calipers to check overall length after full-length sizing and before filling with your pet brew.. Good, basic measuring gear is a lot cheaper than a new rifle, or face., fingers, etc.
I feel like roller-delayed is very optimal on 762x39. My PTR32 is way better out of the box than my AK with many different things to help recoil. Hoping you guys try one out some time.
This has alot to do with the amount of time the recoil gets spread out over. With the roller delay you get it more spread out than in the short amount of time a gas blowback or only piston driven blowback has. Look at it like driving a car. You drive at 30mph and you break over 5 seconds for the traffic light. Or you drive at 30mph your car into a wall and stop immediately. The experience will be different while you stopped the same ammount of energy.
So the next step up from the spread out recoil force of the roller delayed system would be a constant recoil system? I'd love for you guys to take a look at one of those!
I think its mostly subjective; but I had a 93, 91, and mp5 clones, and I do not really agree with your results. The 91 was more violent than my ar10 clone and scar 17s. The 93 was slightly more violent than most of my ar15s. But the Mp5 is the sweet spot, and recoils far nicer than my Scorpion Evo. I thought I had a roller obsession, but after owning a few and seeing what they're like to shoot, I ended up selling the 91 and 93. Turns out I just liked looking at them...
it also comes down to the locking piece and carrier speed you have. Like AKs, these things come from the factory typically with a high carrier speed ("overgassed" AKs ) You can slow the carrier speed with a different locking piece and get very acceptable reliability by changing the locking shoulders or roller sizes. I intend on diving into that if there is interest later. Essentially roller delayed is EXTREMELY robust and can handle a wider range of ammunition than gas operated firearms, however you pay for it with a more difficult adjustability. Look at the roller delayed system as a "resistance" control rather an "input control" that is typical to gas operated systems.
@@9HoleReviews Well put. Thank you for elaborating on that aspect of the operating system. If I would have known, I think I would have tinkered with them before giving up so easily. But since there is no gas system, It honestly didn't even cross my mind. Hopefully this information will be useful to roller owners and prevent them from selling off most of their collection like I did.
I have got to get out and shoot some roller .308 goodness. I shot a .308 S(O)CAR a few years ago and was really surprised at how light the recoil was with light ball. If the roller guns feel markedly smoother than that, Henry's 'obsession' seems quite reasonable to me.
It appears having a roller delayed rifle adds weight and significant more cost. I’ll live with snappy since that is what my budget allows. Btw, my first purchase at 18 was the H&K 91 for $425. For some reason I think my buddies that were into AR15’s from Colt paid more? So long ago.
Before the start of the video for me. I have a bias for Roller Delay. I love it. I have an MP5K-PDW clone, Cetme model C and a Cetme Model L. I love them.
@@chemistryofquestionablequa6252 I use the malcomar builds. He did improvements for reliability. It's a great gun. They say they need a break in of 500 but mine was good after 120.
Just throwing it out there; a BCM 14.5 mid with a vltor A5H4 feels more like a nudge than a punch with .223 pressure ammo such as PMC bronze and federal fusion. 5.56 winchester m193 does feel a bit punchier. I'm going to step the buffer weight down to an A5H3 out of caution for reliability reasons, but I can't imagine the sensation will change much.
so we're def not talking about how PMC vs regular ammo gives you more or less recoil. We see the same in the roller delayed guns too. The key here is that with roller delayed guns you need to just let the system work instead of "muscling" it on target like the gas operated systems. The reason being that the roller delayed systems cycle slower and spread the recoil apart more with multiple recoil impulse points.
Love to see Henry toy with one of the MCM CETME L, I feel like I’m one of the few with a 93 and a L and honestly? MCM and their CETME got 5.56 roller delayed right for a pound less weight.
Henry, seems like your full size MP5s end up with collapsing A3 style stocks, even though it looks like you’ve got a B&T folder in inventory. Do you have a preference for one over the other?
The explanation given does not seem to be talking about the mechanical disadvantage of the roller lock system. My only roller locked gun is a PTR91 that is the same as a G3. I would not imagine firing that on full auto. I have seen films of people doing so. it appears in full auto to be completely uncontrollable. But an MP5 it is controllable. So the cartridge is also very important. The angle of what you call the locking piece is very important relative to recoil. Giving it a more gradual angle and a 'milder' recoil is felt for for the G3. I would have liked to see you compare the FN FAL and M14 to the G3.
Good video, very good explanation, and well-presented. Oddly enough, and I still have no serious intention to change it, there is not even one roller-delayed firearm in my gunsafes. The one that used to be was a PTR. Oddly enough I found the recoil distinctly unpleasant and went back to .308Galil and AR10s. Sometimes different is less "better" if for no other reason besides "different." I'd rather be punched in the shoulder by a ten-year old than shoved in the chest by a college lineman.
I think your observation is quite relevant. The recoil is "different" compare to rifles using direct impingement or pistons. The amount of energy is the same but the speed that it's transferred at is different. Now it's something that people either like or dislike. In the video they talked a lot about the recoil impulse and how it differ between rifles. Personally I have pretty limited experience of different rifles. All I've used are recoil operated SMGs, H&K G3, M16 and AK-74, and the later two only once. I quite like the way the G3 recoils, but then that's just me. I can't really say I got enough experience with the others that I can really make a decent comparison. The only reason I got to play with the M16 and AK-47 was to learn how they sounded to be able to tell if those shooting were likely to be friendly or enemies.
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