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Mad Max MP5 bolt

11K views 34 replies 13 participants last post by  madmaxbolthead 
#1 · (Edited)
#12 ·
Roller delayed blowback firearms are most definitely not the same as a simple blowback design like an UZI, Colt SMG, etc.

So I don't think it's completely correct to say that the MP5 is a "blowback" design. HK has always described it as delayed roller locking blowback system (DRLBS) which to me distinguishes it from a basic blowback design.

I was thinking along SMG lines. Thanks for those examples.
 
#13 ·
"Roller delayed" is a modification of the term "blowback", but it is definitely blowback. The chamber opens itself and starts doing that immediately after ignition - that's what blowback is. The word "locked" is a misnomer - rollers don't "lock" the chamber any more than the gas piston in a P7 does. The rollers just make the transmission of blowback forces more complicated. But the action is "locked" for no amount of time - the chamber begins to open immediately and in direct proportion to chamber pressure.

Locked breech firearms do not begin to open the breech until something external has happened - like the gas piston hitting the bolt carrier or the slide retracting until the barrel is cammed down.
 
#14 ·
I disagree. It's not an adjective. It's part of the system's name. Literally the single thing that makes it special.

"Roller delayed" is a core component of the operating system. It can't be divorced from the term "blowback" when talking about HK's design.

This is where I disagree with you. The statement that 'the MP5 is a blowback firearm' is to me, technically incorrect. At best an oversimplification that I am sure HK engineers would also not accept. HK has never described their guns using the word blowback, without the full nature of their operating system (Roller Delayed).


Blowback is an operating system design. Roller-delayed-blowback is a completely different one.

We can see it differently and still be friends.
 
#15 · (Edited)
"Blowback" isn't an operating system design, it is a general category. What you would like to call "blowback" is actually "Straight (or Simple) Blowback". Open bolt subguns are actually "Advanced Primer Ignition" Blowback. Roller Delayed Blowback, Gas Delayed Blowback, Lever Delayed Blowback, Rotating Barrel Blowback, Off Axis Blowback. They are all the subtypes of the general category of blowback operation.

If we were talking USPs you could call them "recoil operated", but they are also a particular type of recoil operation - Tilt Barrel as opposed to Tilting Block, Roller Locked, Rotating Bolt or Rotating Barrel.


It doesn't matter if the English translation of German terminology makes it sound like it is a locked breech firearm. It isn't.



Why does it matter? Because the behavior of all blowback firearms are similar. All are primary extractors, which is why it is important to understand that what they use the extractors for is different than secondary extraction firearms like gas or recoil operation.
 
#16 ·
I never said it was a locked breech design. You are arguing against what HK has called it.

I see calling the MP5 a "blowback" firearm to be a gross oversimplification.

"Roller Delayed Blowback."

Which two of those three words make the MP5 and all the other G3 descendants remarkable?

I could say "Roller Delayed" and most would immediately associate that with an HK.

You say "blowback," and nobody knows what you mean.

We should describe a gun like the MP5's operating system with its full name. Because it's a unique and wildly successful design in the bloodline of small arms development.

Unless you truly feel that all the different sub-categories you mentioned are so indistinguishable from each other that everyone understands them to be essentially the same.

I miss G3Kurz.
 
#17 · (Edited)
The point I was making was that all blowback firearms are primary extractors, and none of them suffer from "failures to extract". You're getting wrapped up in the specifics of HK's variation and missing the point I was making that it shares that characteristic with all blowback firearms.

So if you want to avoid "gross oversimplification", you're going to have to stop reading the word "blowback" as a specific system - it isn't one. "Blowback" is a basic category and "Simple Blowback" and "Roller Delayed Blowback" are the specific types.

I didn't make a "gross oversimplification" because what I said was completely accurate as applied to every kind of blowback firearm. Of the two people that replied, NoScoE30 understood me and you are the only person who didn't "know what mean". I made a statement that applied just as much to an MP5 as any other blowback firearm and your objection doesn't change that at all.

The MP5 isn't a blowback firearm.
This is 100% incorrect.

G3Kurz understands these distinctions perfectly well.
 
#20 ·
I do see how you are using levels to justify calling large portions of very different guns' operating systems by the same oversimplified word. It makes sense to think of them that way.

That said, what you are calling a "subcategory" is actually a very different overall system of operation per each of the examples you listed.

Your "Straight Blowback" or open bolt "Advanced Primer Ignition" are so dramatically different technically from roller delayed that they should be called what they are.

You see this as an issue of definition. I see it as more one of context and specificity.

Nobody ever refers to the roller delayed blowback using only the word "blowback."

Any more than you'd walk up to an ice cream stand and say "I'd like a frozen dairy dessert please."

It's technically not incorrect to do so, but is there more to it than that? Yeah, there kinda is.
 
#22 · (Edited)
I do see how you are using levels to justify calling large portions of very different guns' operating systems by the same oversimplified word. It makes sense to think of them that way.

That said, what you are calling a "subcategory" is actually a very different overall system of operation per each of the examples you listed.

Your "Straight Blowback" or open bolt "Advanced Primer Ignition" are so dramatically different technically from roller delayed that they should be called what they are.

You see this as an issue of definition. I see it as more one of context and specificity.
And what is the "context and specificity"? Extraction.

What is the same between all blowback firearms? Extraction.


It would be one thing if we were talking about some other aspect of firearm operation aside from extraction, but primary extraction is the #1 thing that makes all blowback firearms the same. So you are making a distinction without a point.

Nobody ever refers to the roller delayed blowback using only the word "blowback."
I did, because it was reasonable in context. If you don't understand that blowback extraction is all the same, you won't understand why it is reasonable to compare a Beretta 950 and an MP5.
 
#21 ·
If you boys are done waxing intellectual about the finer semantic points of firearms design, perhaps we can just agree that when you look down at your feet at the range and see a 9mm casing scored black with chamber flutes you think "somebody cool must have been here".
 
#26 · (Edited)
Short range report with the MAD (Moore Advanced Dynamics) Max MP5 Bolt:

Lock Cylinder Hardware accessory
Drawing Illustration Cutting tool Art


- Price: $299.
- Installed in Omega OMR-9 (MP5 clone) to cure persistent failures to eject (FTEs).
- Bolt gap with this bolt remained same as original bolt.
- Genuine Heckler and Koch 10 round MP5 magazine used in testing (Calfornia compliant).
- The MAD bolt has an extractor spring under the extractor claw, with a pin holding the extractor in place. I believe this results in (1) a firmer extractor grip and (2) less overtensioning of the extractor spring. In contrast, the original bolt has the extractor spring above the extractor claw.
- Per the manufacturer, the extractor spring change interval is 15,000 rounds. They don't yet sell spare springs, but I hope they will do so in the future.

RESULTS
- 20 rounds Winchester 9mm +P NATO brass ammo: 3 FTEs (spent casings stuck in chamber, preventing chambering of next round).
- 50 rounds Blazer 9mm brass 115 grain: Perfect shooting-ejecting-cycling.
- 50 rounds Geco 9mm brass 115 grain: Perfect shooting-ejecting-cycling.
- 40 rounds Fiocci 9mm brass 115 grain: Perfect shooting-ejecting-cycling.
- 20 rounds Remington 9mm brass 124 grain: Perfect shooting-ejecting-cycling.

- Aside from the Winchester NATO 9mm +P ammo, all the other ammo functioned 100%. This bolt looks very promising from my small sample of 180 rounds.

- In contrast, with the original bolt, my OMR-9 was having several FTEs per box with all the above ammo, except the Remington 124 grain, which had a FTE rate of 1 per 300.

- With this new MAD bolt, some ammo now felt "underpowered" (i.e. I was able to perceive longer cycle times from round to round). The Geco and Fiocchi felt underpowered while the Blazer and Remington "felt right" (cycling was quicker, stronger, with more pulse). I was not able to get this perception with the original bolt. The Remmy 124 grain felt the best. Regardless of how the ammo "felt" to me, the Blazer, Remington, Geco, and Fiocchi ammo all worked well.

- I am a little leery of running steel case ammo (e.g. Wolf) because I don't know if would be safe for the bolt. I will shoot only brass rounds for now.

- For a more complete test, I will running 500 rounds of Aguila 9mm 124 grain brass ammo soon. If I can get 500 rounds of this (or any other 9mm ammo) to fire with no problems, I will officially declare the MAD Max Bolt to be a winner. Will post results of this test.

- I think we have a real game changer here. I am hoping that, with the right ammo, my Omega OMR-9 can attain Glock-like reliability.

Ammunition Gun accessory Bullet
 
#27 ·
Were the +P FTEs in the first 20 rounds fired? I have to wonder if your new ability to feel the "underpowered" ammo is due to the new bolt head dragging a bit, which might also explain the FTEs. That could be a tiny dimensional issue, or simple new parts that haven't burnished in yet.

The new extractor design is certainly unique. It looks unlikely, but clearly it works and uses a more flexible spring design.
 
#29 ·
That sounds like a chamber issue, meaning the win ammo doesn't like the chamber or vice versa. Next time if you clean the gun thoroughly (chamber) and try again, start with ammo it liked, then bring in the winchester turds. If you get the same behavior, it's the ammo.

As far as the feel being different, I wonder if the new bolt weighs more. Adding mass might explain that.
 
#31 · (Edited)
SECOND RANGE REPORT - MAD MP5 BOLT

- I went back to the range today with my Omega OMR-9 rifle with the MAD (Moore Advanced Dynamics) MP5 bolt. I used Aguila 9mm 124 grain brass ammo, which was recommended to me by Wade Bailey of Top Notch Accessories, the manufacturer of the Omega line of MP5 clones.

- I had been bedeviled by failures to eject spent casings with an Omega OMR-9 with the original bolt. I was on the verge of returning the gun, as I was so unhappy with it. Then, this MAD bolt came out, so I purchased it to see if I can get this gun working.

- I am happy to say that all 500 rounds I shot performed FLAWLESSLY. Not one jam or failure to eject. Previously, I could not get past 300 rounds without a failure to eject, which then got progressively worse. Now, with his new bolt, every round, from the first to last, shot perfectly.

- If you are thinking about getting one of these to fix ejection issues on your MP5 or MP5 clone, do it. I highly recommend it. After months of trying different ammo, magazines, extractor springs, and post-two warranty repairs, I finally have a fully functioning MP5 clone.

- At $299, it's a $100-$150 dollars more than a comparable US made complete MP5 bolt, but well worth the extra money due to its reliability. It's also $200 cheaper than a genuine HK MP5 bolt, but probably more reliable.

Material property Font Technology Electronic device
 
#34 ·
Issah...good to hear.

I just bought one. And I will shoot the hell out of it FA on multiple sear hosts.
I'm hopeful.

I'm sick of replacing extractor springs. I shoot a lot and replace them a lot. It's a nuisance and is the point of failure for the roller locks.
Glad to see it finally addressed.
 
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