9mm HST3 124gr +P ATK Bare Gel testing

[Symmetry]

Just like if I did a torture test by putting sand in its action or being drop in dirt mud etc. I think the +P loads would make a difference .

Been there, done that in 33 degree mud....and 115 degree Arizona sand. I think you will be hard pressed to see a difference between standard pressure 147gr and
+P loads. Most of the slide related malfunctions I have seen are with low grain weight bullets such as 115gr minus. Slide recoil consistency is better the heavier the bullet weight.

[Rich]

Ive seen dirty dry pistol start having issues then when feed +P or +P+ they went away for awhile! BTW I seen it with my Carbine as well 5.56/223rem!

If you cant except it fine



Oh btw Todd G. who was the trainer you know of who experience the same thing? wasn't his name Rich. I wouldn't mind going over his finding as well.

[Haraise]

Power factor is the same thing as momentum. Momentum is what moves the slide, effectively.

Momentum favors heavy bullets.

Power factor of HST (approximate):
124gr = 142.6
147gr = 149.1
124gr +P = 149.8

Cheap bulk 115gr = 132.3

In competitions, I believe most gun racers would adjust return spring weight for a ~17 power factor difference in load.

[ToddG]

Momentum is what moves the slide, effectively.

So the actual pressure built up in the chamber has nothing to do with it?

I know I've seen guns get sluggish or stop working with standard pressure ammo of all weights that would then run as if perfectly lubed with 124+p. Should you let your gun get that bad in the first place? No.

In competitions, I believe most gun racers would adjust return spring weight for a ~17 power factor difference in load.

Except you're now getting far, far afield of what people are talking about when discussing how to make a defensive arm work as reliably as possible with the best possible defensive ammo. And I'd be the first to say that if I believed the 147gr load was meaningfully more effective at stopping someone's ability to harm me I'd go with that as my priority and not just "theoretically more reliable in a very narrow circumstance." But instead I happen to believe the 124+p has an edge in that area so I choose it.

What's obvious from Doctor Roberts's and other tests is that both choices are supremely good for 9mm.

[Rich]

that kinda reminds me of foot pounds really doesn't tell me much

except the 124+P has a higher number. sorry

When I used a 1911 I will go to a lw spring when shooting my SWC loads then go to heavy for my SD loads
BTW I hate race guns

[Spr1]

Momentum = mass X velocity
For a given bullet weight, +P typically means more velocity.

[Haraise]

So the actual pressure built up in the chamber has nothing to do with it?

I know I've seen guns get sluggish or stop working with standard pressure ammo of all weights that would then run as if perfectly lubed with 124+p. Should you let your gun get that bad in the first place? No.



Except you're now getting far, far afield of what people are talking about when discussing how to make a defensive arm work as reliably as possible with the best possible defensive ammo. And I'd be the first to say that if I believed the 147gr load was meaningfully more effective at stopping someone's ability to harm me I'd go with that as my priority and not just "theoretically more reliable in a very narrow circumstance." But instead I happen to believe the 124+p has an edge in that area so I choose it.

What's obvious from Doctor Roberts's and other tests is that both choices are supremely good for 9mm.

I'm not quite sure if you're arguing against me here? My numbers showed that the 124 +P has more momentum. That would mean that I wouldn't be advocating the 147 for maximal reliability.

And yes, they're both effective ammo termanally, didn't say anything relating to that.

As far as chamber pressure and how it relates directly to slide velocity, I couldn't say. That'd take some back to back testing I'm not set up to do.

[ToddG]

If we were more in agreement than I realized, my apologies H.

[Haraise]

It's all good.

Now I can't stop thinking about if chamber pressure is related to reliability of function, though. Would a 115gr .38 SC at 1400fps give any different slide velocity than a 230gr .45 at 700fps? Extreme example, and my off the cuff response would be that chamber pressure isn't nearly as meaningful as energy difference between the two loads with equal momentum (I'm not confident momentum is everything and energy is nothing, which is why I phrased it as 'momentum is what moves the slide, effectively'), but it'd take some real testing to give any meaningful answer. Would need to compare equal energy and momentum to different chamber pressure, such as a hot .380 vs light 9mm, or hot 9mm vs light 9mm supercomp. .40 vs 10mm would be perfect, as well. Would the same powder/bullet in a .40 be more reliable than a 10mm, all else equal, for the sake of pressure? Can't see it, but no evidence to say no way with.

[ToddG]

I is not engineer type. At all. So I guess all I can think -- and hopefully Bill or another one of the Experienced Big Brains will think about it -- is that if there's something impeding the slide for some reason, x+y pressure will "clear" the obstruction so to speak more likely than x+0 pressure. But perhaps if the momentum is the same regardless then you're correct and pressure/speed isn't really making any difference.