9mm +P with Silhouette

A

alzo

Inactive
I usually use 5.4gr of N340 with a Zero 125gr JHP, COL=1.112. This load gives me 1145fps from a 3.8 inch barrel. I don't like to exceed published load data.

I was trying to work up a comparable load with Silhouette, and was disappointed that the velocities I achieved were on low side. Are my results typical of what can be expected with Silhouette in this application?:

5.1gr 1001 fps
5.3gr 1046 fps
5.5gr 1068 fps
5.7gr 1086 fps


I'm also not sure what the real max charge is for Silhouette. The only 124/125gr JHP data Ramshot lists is for the Sierra bullet and tops out at 5.5gr. Sierra's data for the same bullet with Silhouette goes up to 6.1gr.
 
+P is about pressure, not velocity.
5.1 grains of Silhouette is over max for a 125 jacketed according to Ramshot(Western or Accurate) out of a 4" 1 in 10" barrel. The later data matters for velocity. Not seeing any 125 grain Silhouette data that comes close to 1145fps. Burn rate may be too fast.
 
+P is about pressure, not velocity.
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Well stated.

Burn rate may be too fast.
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I'm thinking the same too.

I don't load with Silhouette (or N-340 for that matter). But I have always had the impression that it is designed and suited for low-flash applications with short barreled compact carry-type pistols. So it not delivering the same velocities as N340 comes as no surprise to me.

The two propellants are rather different animals.
 
Ramshot has updated their load data to include 9mm+P. Here is the link:

http://blog.westernpowders.com/wp-content/uploads/2014/01/LoadGuide-9mmParabellum+P-update1-28-14.pdf


As an aside....what is the point of +P pressures, if not to gain some additional velocity ?

The reason I was surprised is that there are plenty of folks posting that Silhouette is one of the best powders for "high end" 9mm loads. I don't think a 125gr bullet at 1100 fps is a "high end" load, so I am surprised if that's all that Silhouette can deliver. Maybe those other folks are loading well beyond the manufacturer's suggested maximum charges.
 
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what is the point of +P pressures, if not to gain some additional velocity ?
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The +P designation is meant, to some degree, to let folks know they are getting a high pressure round that might not be suitable for some guns.
Velocity isn't the concern, just the pressure.
And the +P designation on a box of ammo probably increases sales, even if there's no great increase in velocity or effect on the expected target.
Besides, how many people who buy ammo will actually run their rounds through a chronograph?
It would be interesting to do a test on it.
Give someone two batches of ammo, both with the exact same loads, but one marked +P, and see if they think the +P seems more powerful.
Bet they do.
 
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I find two burn rate charts where Silhouette is faster than N340, and two where it is slower. I'm guessing your lot is slower and the bullet is too easy to push down the tube so it isn't burning all that well. I'd go back to a starting load and try a magnum primer to see if that helps get it burning any better. The SD on the chrono will tell you if the magnum primer made ignition more or less consistent. You want whichever is more consistent.
 
what is the point of +P pressures, if not to gain some additional velocity?
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g.willikers covered it 96.23%.

I'll cover the remaining 3.77%. :p

To answer as directly as I can: For the average person at a retail gun store, looking for a stout defense-level round (for their modern firearm), maximum velocity is exactly the point of +P.

But this is the handloading section of TFL; and we're handloaders. This is the place where we know the "P" in "+P" means "pressure." And as handloaders, we know that high pressure doesn't necessarily translate to high velocity.

The tendency to use +P as a function of velocity is one of my pet peeves. +P is supposed to be a function of pressure; although I admit that the guy a couple paragraphs above at his LGS is wading through the muddy waters of semantics. That seems to suit the ammo manufactures just fine. And so it is.

But here, we should be talking about pressure. Case in point:

Last week, I chronographed a 38 Special round: Berry's 158gn PFP, under 5.5gn Unique. (Gun = S&W M67, 4" bbl) The round had a hardy report (for 38 Special) and tripped the chrono at 971 f/s. I'm sure this round achieved +P level pressures (kind of caught me by surprise; shame on me for not doing a proper workup). Using, say 2400, I could have pushed that Berry's 158 to 971 f/s without achieving +P pressures. And going the other way, had I attempted to push that Berry's 158 to 971 f/s using Bullseye, the pressure probably would have exceeded 357 Magnum levels; and may have damaged the firearm.

Okay, I'm off my soapbox. Thanks for listening.
 
Guys, I understand the difference between pressure and velocity. I am an engineer. Nobody sat around and thought, "I wish my ammo generated more pressure." But many people sought higher velocity for various reasons, mostly to boost the terminal performance of a particular caliber. The only way to get that performance (i.e.- velocity) boost was to push the pressure envelope. Of course, if the desired velocity could be achieved by using a different powder and keeping pressure down, that is the desired option. But that option must not be too easy to realize because the majority of 124/125gr 9mm loads I see that are above 1150fps are +P loads.
 
All true and good points alzo.

In the case of 9mm, it seems the cartridge is at a place where all the ammo manufacturers are pushing the envelope these days to get max terminal performance. That means +P.

My carry piece has Speer 124gn +P's in it. I have shot Speer's non+P's, and +P's alternately. The +P's are clearly more potent; both in terms of felt recoil, and actual chronographed velocity (1048 f/s vs. 1182 f/s - 3.7" bbl).
 
So back to my original question.....if anyone has some personal experience with Silhouette and 124/125gr jacketed bullets, I'd be interested in seeing your chrono results. That would give me some real world data to compare mine with. Thanks.
 
alzo said:
The only way to get that performance (i.e.- velocity) boost was to push the pressure envelope.
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Actually that's only correct if all the loads use the same powder. If you were to load, say, an 8" .44 Magnum revolver's loads with a 240 grain bullet to maximum pressure with N310, the same bullet would get to the same velocity at a lower peak pressure with 2400 because the heavier charge weight of 2400 needed to reach that velocity makes more total gas that does a larger portion of the acceleration when the bullet is further down the barrel. This is fundamental to the principle of progressive burning vs. digressive burning and is behind the availability of different powder burn rates.

The trick here is that peak pressure and velocity do not always track. Average pressure and muzzle energy do track, though, so that if the same bullet is driven to the same velocity by two different powders, the average pressures made by the two will be the same, but the ratios of peak pressure to muzzle pressure can be different while achieving that same average. Thus, the peak pressures don't have to be the same. A lower peak pressure with a higher muzzle pressure can give you the same average as a high peak pressure combined with a low muzzle pressure does.

Bottom line, +P refers only to the peak pressure and not to the average pressure, so there is some degree of independence between it and velocity. That's why there is always excitement about new powders that achieve higher velocity inside the same peak pressure limitation, and why you have to choose the right powder to get maximum velocity.

That said, it is perfectly true that if you aren't looking to achieve maximum velocity, there is little point in loading to +P pressures unless you are simply stuck with an inappropriately fast powder for the job.
 
ALZO, did ANYTHING change, other than the powder and charge weight? Like C.O.A.L.? Brass manufacturer? Extent of crimp? Phase of the moon? The side of your head where you part your hair? (Okay, the last 2 were jokes).

I've experienced what you are describing when I switched from one relatively fast-burning powder to another.. At one point, I just consigned all the fast powders for use in .45 ACP, and used powders like Unique, Herco, AA#5, and Sr-7625 in 9mm. I don't have a good way of measuring chamber pressure, so this is supposition on my part. The slower-burning powders gave equal or slightly better velocities (by chronograph) but pressures SEEMED lower, based on slide velocity under recoil (measured by distance my brass got thrown).

After you use up the 2 powders you have, perhaps something slower burning would get you where you want to be. If muzzle flash is a major issue, I think Alliant's new BE-86 is meant to reduce that.
 
N340 will yield more FPS with the same powder charge vs Silhouette.

Here is some testing with N340 and Silhouette for reference in 9 MM using Precision delta 124 grain bullets at 1.100 OAL.

XD9, 4" barrel.
N340 5.1 grains 1090 FPS
Silhouette 5.3 grains 1083 FPS
N340 6.2 grains 1268 FPS
Silhouette 7.1 grains 1330 FPS
Silhouette 7.2 grains 1350 FPS

Silhouette is nearly the same as VV3N37, but requires slightly less powder to achieve similar results.

In my opinion, Silhouette is one of the best powders on the planet, if not the best, period, for 9 MM all around use.

Cheap, meters great, clean, low flash, high velocity. What else could you want?

VVN340, VVN350 are right up there with it, but I think Sil meters a little better and is way cheaper, so it wins.

I dont rec you load these loads, some are way over book. The 7+ loads are typical in some real high PF competitions
 
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