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patent for an MP7 in 300blackout   General Military Discussion

Started 17/10/21 by smg762; 4577 views.
smg762

From: smg762

31/10/21

If you want the size of a SCAMP or MP9 then reverse feeding would be essential...this would rule out sabot rounds because they cant be crimped tightly enough.

The original MP7 was much smaller like an MP9. With reverse feeding you could bring it down to MK23 size.

As for th crye gun im very skeptical about reliability and even feasibility of that magazine

I disagree that 5.7 is better than 4.6. Its always been shown that 4.6 penetrates better. 5.7 often wont even defeat helmets at close range.

It would be useless against lvl3

roguetechie

From: roguetechie

31/10/21

1. Funny the original scamp was already smaller than an mp7 and didn't reverse feed, you're getting caught up on gimmicks.

2. The original mp7 wasn't much smaller I don't even know where you're getting this and am beginning to question whether you've ever held a gun at all. "Getting it down to mk23 size" isn't one of the goals because having something mk23 size is going to make it iffy to distance shoot.

3. Considering that the Russians have actually done magazines similar in concept and nature and in general your lack of education on the subject, I'm not super concerned about you being skeptical.

4. I don't care about penetrating shit unless I can generate a lethal wound behind the armor, which 4.6 can't. Your subjective opinion about "better" doesn't match reality or what we're trying to do with something like this so it can be safely discarded.

5. "Useless against Level 3": See this one is a fun one since the things I specifically suggested COULD actually get you something that would pop level 3 nij with even a tool steel penetrator inside 50 meters (which is infinitely more Level 3 penetration than anything you are advocating for).  At the same time, I'm pretty certain by cues you have given in this conversation and others that you don't know the difference between Level 3 nij and level 3a nij, and that's a problem. 

Basically everything either of us have suggested and several things not covered here will pop nij3a which is what helmets and soft armor is rated for. There's civilian 5.7 rounds that won't pop some hard nij3a like helmets but that's down to the projectile not the cartridge.

As far as "not penetrating level 3" and therefore being useless, precisely nothing you've suggested has even the barest hope of penetrating NIJ 3 plates. I have a set of NIJ 3 plates upstairs in my spare carrier that weigh a whole 3.4 pounds each and they're nothing special.

The SAPI and ESAPI plates as well as their equivalents that most militaries use are pretty much fully beyond the capability of anything in this class to punch through even at point blank. Reason being is that the SAPI plate was actually a bit beyond nij 3 in protection level offered, and the ESAPI is SOLIDLY beyond nij level 4 performance.

Truthfully penetrating NIJ level 3 like a couple of my suggestions would at closer ranges is a nice to have but only debatably necessary. There's a reason why the solutions I proposed and the direction I wanted to take this have the potential capability to do so, but I explicitly understand why I even wanted that and what it takes to do it while you don't.

You're allowing your opinions and desired feature set (which is grounded in your misunderstandings and lack of knowledge if it can be said to be grounded in anything) get In the way of actually having a decent discussion. At this point I'm just going to stop because there's nothing productive In talking to someone who refused to learn enough to discuss things.

roguetechie

From: roguetechie

31/10/21

You did say one thing that was accidentally interesting though.

Reverse feed.

Combine the Caleb Crye patent with reverse feed and you might accidentally end up with something strangely workable because then what was your round presentation spring can become a stabilizer to keep the cartridge stack properly ass up for presentation to be snagged.

Where you run into trouble is in the need to either go single feed or design something particularly clever so that it can pull cartridges from either stack...

This gets us into some weird zb-47 / erma mgd pm9 territory (the zb47 used what appeared to be triple stack single feed mags)

There's definitely some meat on this bone, even if it's very weird exotic and potentially not super practical meat.

And this is why I loved this patent in the first place. It is an alternative architecture that opens up possibilities. It shows that small arms really isn't the mature technology where only incremental and ever more costly improvements are possible.

It illustrates that there's potentially different ways to do things that may not have been practical before but could be now

smg762

From: smg762

1/11/21

I doubt reverse would work. The crye gun needs the grip at an extreme angle. Making the rounds face ass up.....what kind of grip angle would you need for that?

Frankly the best compromise is a 7.5FK with very lengthened bullets....taking the OAL to 44mm

roguetechie

From: roguetechie

1/11/21

That's not a good compromise at all.

And since we've established that you and understanding cartridge design just isn't happening that's all I'm going to say. 

It's been explained to you why the 7.5 fk isn't a good starting point, repeatedly.

nincomp

From: nincomp

1/11/21

smg762 said:

Frankly the best compromise is a 7.5FK with very lengthened bullets....taking the OAL to 44mm

This sounds much like a shortened .30 HRT.   Pretty easy to do since it starts with 6.8 SPC/ .224 Valkyrie brass.  I am not sure that sticking with a roughly .30 cal projectile is the best choice, though.

 If you have not read it already, Tony has a good article on PDW's that shows a lot of cartridges side by side (https://www.quarryhs.co.uk/PDWs.htm).  Nathaniel also did a number of good articles like this one when he worked for TFB (https://www.thefirearmblog.com/blog/2017/02/20/modern-personal-defense-weapon-calibers-004-7-5x27mm-fk-brno/).  Use TFB's search function for others.

SMG762, at the risk of being pedantic, I think that I understand Roguetechie's frustration and will try to explain.  Please forgive me if you already know all this.  You are at a bit if disadvantage on this site since the PDW concept was extensively discussed on this forum a number of years ago.  Many here have either already come to their own conclusions or have given up on the matter.*    In short, a PDW using something like .300 Blackout or 7.5 FK made a lot more sense before body armor was commonly encountered.

The concept of a PDW is broad, so it is important to determine what exactly the weapon is intended to do, at what range, and how it is going to be carried.  If the goal is 100m or less against unarmored opponents, you can end up with a pistol that has a folding or retracting stock like the Crist PDW.   These are small enough to be worn while on duty.   To meet the portability requirement, almost all of this style of PDW have magazines inside the grip.  The main problem with the pistol-based PDW's is that they work best against opponents without body armor.   It can be argued that equipping soldiers with weapons tailored to the local threat would be useful, but that is not how the US and many other countries do things.  They prefer to reduce the inventory of weapons rather than utilize a "golf-bag approach" where the soldier could choose from numerous alternatives.  Instead, they have decided to arm against peers and near-peers who are likely to use body armor... or ignore the issue and just stick with a pistol.

Everything changes once you face an opponent wearing body armor.  Here, even dedicated AP ammo in a pistol-based PDW has a very limited effective range, if indeed, it is effective at all.   The 6.5 CBJ is indeed designed to defeat some body armor, but many people have significant doubts about the terminal effect of the small diameter penetrator.  In the end, the best hope of someone using a pistol or pistol-based PDW against an opponent wearing body armor (other than run-like-hell) is to keep firing and hope to hit some spot that is not well protected.

If you want more rifle-like performance, things get ugly fast.  Much beyond 100m, the aerodynamic efficiency of the projectile becomes more important and the length-to-diameter ratios of the bullets begin to grow.  The weapons themselves get big enough that they begin to get awkward to carry full time (the Crye hopes to be an exception to this).  Another thing that changes with "rifle-like" performance is the wounding mechanism.  Although this is less well defined, in general, with a rifle-like wound, the combination of high velocity and sufficient effective frontal area** of the projectile cause tissue stretching and tearing around the wound track.  A fragmenting bullet can cause even more damage, with the fragments cutting stretched tissue. Sometimes the rapid displacement of tissue from the temporary cavity is enough to cause a stunning effect that temporarily disables the victim.***  Although the velocity to achieve this effect varies with the effective frontal area and the location of the impact, the information that I have seen indicates that it seldom occurs with a projectile velocity much below 2000fps (600mps).   Alternatively, the damage from a "pistol-like" wound is from the hole the bullet punches during its travels.  Neighboring tissue and blood vessels are left intact.  Big hole wounding, in other words.

Once body armor penetration enters the equation, the retained "specific energy" (energy divided by frontal area) of the projectile becomes more important than total kinetic energy.    The force must be concentrated into a small area to defeat the armor before it can reach the wearer.  It is the difference between shot with an arrow and being hit by a baseball, even if both arrive with equal energy.  One penetrates the other doesn't.  This is why the reasonably high muzzle energy of the 7.5FK or .300 Blackout won't necessarily translate into good body armor penetration.  The .221 Fireball may be more effective, even though it has significantly less kinetic energy when shot from a very short barrel.  

After a projectile has succeeded in penetrated the armor, what then?  It is unlikely to retain enough velocity and energy to act "rifle-like."  It might take a lot of holes to stop the opponent.  I always come back to picturing scenes in the sci fi television show "StarGate", in which bad aliens were liberally hosed with dozens of rounds from P90's.  Wasteful, maybe, but it at least saved the Earth.

For a short-barreled weapon,  I would like to see more development put into sabotted loadings, or maybe even more exotic concepts like squeeze bore.  The idea is to maximize the base area while in the barrel to extract as much energy as possible from the propellant, then send a smaller diameter bullet downrange.  Although sabots have been around a long time, I have not seen much about accuracy.  There is little point in sending a bullet downrange if it won't hit its target. 

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  • Edited 01 November 2021 19:54  by  nincomp
smg762

From: smg762

1/11/21

Im well aquainted with penetration and i know a 300 weapon would have awful penetration compared to a CBJ or hot- rod 4.6mm

I read the PDW thread years go. My own design uses a large cartridge like the 224 boz or better, the 224 JAWS

This would be necked down to about 4.9mm, with a hefty 600ft lbs in 6 inch barrels - far better than HKs 4.6

smg762

From: smg762

1/11/21

Rogue, do you think the crye gun could be made more compact by shortening the rear reciever to almost nothing?

Instead a small slide would pop out the rear of the gun with each shot

Would this system be strong enough for rifle rounds?

roguetechie

From: roguetechie

2/11/21

Yes, you probably could do that. I don't necessarily know how safe it would be though. That's essentially what the original amt automag did as well as the mars pistol which was a beast of a pistol from the dawn of the automatic pistol era.

It's not a solution I'd be tempted to go for but there's no specific reason you couldn't do it

smg762

From: smg762

2/11/21

I was thinking in terms of a handgun that can share ammo with the rifle.

Lighten the crye gun to 1kg and usr shared mags for sidearm and long arm

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