questions about roller delayed blowback

[M995]

I heard that 5.56mm roller delayed blowback guns like the HK33 will generally have broken parts before 10,000 rounds during endurance testing. Does anyone know what the MRBF is for the G3?

Also, does anyone know if roller locked recoil operated weapons like the MG42 are more durable than roller delayed blowback guns? I know they are completely different operating systems but they both have rollers on their bolts. From my understanding, roller locked recoil operated weapons do not suffer from the Roller delayed blowback system's sensitivity to ammunition because the rollers in the MG42 are used to lock the breach rather than using rollers to delay the opening of the breach like the G3. I'm wondering if the rollers and other parts on the MG42 would last more than 10K rounds in an endurance test? Also, does anyone know the MRBF for the MG3?

[Shattered Mind]

I've lost more parts than I've broken. I've also worn more parts than broke outright... and ALL my HKs and clones have WAY over 10K rounds through them.

We have listed spare parts you should have in your toolbox countless times.

[M995]

I've lost more parts than I've broken. I've also worn more parts than broke outright... and ALL my HKs and clones have WAY over 10K rounds through them.

We have listed spare parts you should have in your toolbox countless times.

G3 kurz said 5.56mm roller delayed blowback guns would have broken parts by the time it got to 10K during ENDURANCE TESTING. I'm not sure how much the guns would last in casual shooting.

[Blitzkrieg]

I have heard Glocks are junk too.. both are BS

[TGS]

I have heard Glocks are junk too.. both are BS

You know that G3Kurz worked for HK, and he's not exactly an HK hater, right? I wouldn't toss away his mention of breakages by 10,000 rounds just because. He has a lot of inside experience with the design of these weapons, putting them through the ringer, and getting agencies to buy them. I think he just might know something.

[Spitfyr]

What exactly is the question? Are we talking about all roller-locked HK's, or specific models? You mention a 5.56 HK33, then you move on to the .308 version G3. Of course we also have 9mm and .40 cal, not to mention 7.62 x 39 variants now. Of course each model could have dramatically different pressures and different impulses on the bolt face and thus different stresses on the rollers. With that in mind, it sure seems like 9mm guns will run much longer without failing than a 5.56 or .308, right? I hear of roller retainers breaking, but I've never heard of a roller breaking...and if a retainer did break, the gun will continue functioning with a broken retainer. In fact, some people don't even use retainers, they just set the rollers in the BH and stuff it in the receiver. Am I missing something here?

[Shattered Mind]

G3 kurz said 5.56mm roller delayed blowback guns would have broken parts by the time it got to 10K during ENDURANCE TESTING. I'm not sure how much the guns would last in casual shooting.

What do you consider ENDURANCE TESTING? 99% of my shooting is at MG shoots... which generally involves 1K or more per caliber, per firearm, per day.

3 day shoot, figure 3K per gun. Then figure I go to at least 5-6 shoots per year, not counting informal weekend blasting with friends and range trips "just because". Now add in that I've been doing this since 1989 and I really have stopped buying guns back in 1994... minus the clones that started up in '99.

[TGS]

What is endurance testing can vary between who's doing it, and I don't know what HK's specifications for their testing was, but 1000 per day/18,000 rounds per year is most certainly nowhere near what could be considered endurance testing. Remember that 1000 rounds is about a basic loadout for a machinegun crew in most NATO countries.

So, I wouldn't be surprised if your experience is different than a gun put through the meat-grinder.

[G3Kurz]

You know that G3Kurz worked for HK, and he's not exactly an HK hater, right? I wouldn't toss away his mention of breakages by 10,000 rounds just because. He has a lot of inside experience with the design of these weapons, putting them through the ringer, and getting agencies to buy them. I think he just might know something.

I know many things. The source of this info came from the test we conducted with the DEA in the 1990s on the HK53 which lead to its eventual adoption. However few were purchased @ 40 on that contract by the DEA. We were required to fire 4 weapons to 10,000 rounds each using M193. The tests had to be completed in less than 4 8-hour days. Our 4 man HK team did all the firing. Cleaning and lube was done after every 1000 rounds as I recall. In the end after firing 40,000 rounds (10,000 per day) in semi, short bursts and full auto there were only two broken parts across all 4 guns. Both as you might have guessed were locking roller holders - the old plate style. We did not remove or clean under the extractors - ever. Interestingly one broken end piece of one locking roller holder managed to find its way between the chamber face and the bolt face and causing a failure to fire on that round. We found it still stuck to the face of the chamber and though initially it was thought to be a blown and crushed primer but the color was wrong. It was removed and the gun finished the test with no other issues without a locking roller holder in place.
The German tech there with 35+ years with HK had never seen that happen.

We also successfully completed a similar test with the MP5 with similiar results. Once again the DEA purchased very few from that contract (they were loaded up with Colt carbines and SMG's from the previous contract) but other agencies (BATF, BOP) "piggybacked" the DEA contract and purchased the entire contract amount.

We were not so lucky with the Benelli M1 Super 90 which failed a BRUTAL 9000 round per gun (3000 slugs, 3000 OO, 3000 #9) fired by 4 shooters over a three day period. Shoulders that were meat tenderized by the end of that test and we were 90% home when the last stoppage failed us!

You'll be interested to know that the Indian govt just ordered 16,000 new MP5A3's from Oberndorf. That gun lives on strong even today.

G3Kurz

[M995]

+1 on TGS's comments.

G3 kurz has witnessed many side by side endurance tests involving roller delayed blowback guns so I would definitely listen to what he has to say about them b/c he has a lot of technical experience with roller delayed blowback guns.