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+P to compensate for short barrel??

7K views 16 replies 16 participants last post by  gunfan 
#1 ·
I have a question for you guys who are into ballistics....

I understand bullet types, expansion, performance results of the bullet itself. But I'm not deep into the velocities, pressures, energy, etc.

Testing data often comes from a 5" barrel. Let's say you carry a 3.5" or a 4" barrel. The shorter barrel should produce less velocity (maybe 50-75 fps) and energy with the same round. So you find a bullet that has good terminal characteristics, maybe a 9mm 124 gr Gold Dot. If both rounds are using the same bullet, would a +P loading in a shorter barrel offset the reduced velocity and basically achieve the same ballistics as the standard pressure load in a 5" barrel? Would using the +P be an effective method to achieve 5" barrel standard pressure performance in the shorter barrel?

Any downsides to a +P in a short barrel?

Thanks in advance for your thoughts and insights.
 
#2 ·
I've been trying to compensate for a short barrel my entire life :rofl:

Umm... Okay, 'sorry about that...

I don't think there's any downside to +P on a snubbie as long as the gun is rated for it, and you can handle the muzzle flip. As to whether it equals a standard round in a 5" barrel, I'm not sure if that would make any difference. Is it not best to carry the most potent round that you can accurately shoot?
 
#3 ·
There is an up side to velocity. Higher pressure doesn't alway result in higher velocity. There are +P bullets that have less velocity than standard pressure bullets. 124g bullet at 850fps will give up 56 ft/lbs of energy when compared to the same bullet at 1000fps. More energy is better, but do you need it? How much more energy do you need before it has any real meaning? If you are using +P ammo in gun that is marginally designed to handle it how much will you shorten the life of the gun and how will that effect reliability. As long as the bullet is traveling with enough velocity to perform as it was designed to probably not. Say a 9MM bullet is designed to operate between 900-1200 fps as long as the bullet is still traveling at that velocity when it reaches its target it should perform. Trust me, a lot of folks are going to disagree with me and say always use +P.
 
#4 ·
Stevew makes a good point: what is "good enough" for your use? Decide that, and you're well on the way to solving your question.

For example, I'm comfortable with a .38sp cartridge in a J-frame as a pocket gun. Meaning I can carry either a .38sp or a .357mag revolver - more options.

Not every gun needs to be the biggest, baddest, longest-barrel, with ammo that has the hottest load. Figure out what your minimum is, and go from there. Sure, when I can, I carry something bigger, more powerful, or with more rounds than a .38sp J-frame - but I'm comfortable at that level, if need be. Poke around our BBTI site for more solid info about how different rounds perform in a given length of barrel.

Jim D
 
#5 ·
Any downsides to a +P in a short barrel?
Recoil... Muzzle flip...

I believe Stevew's post raises a good question. It's the simple concept of diminishing returns, and it's something everybody should ask themselves.

I've also noticed that polygonal rifling in pistols seem to speed things up a touch over the traditional rifling pistols. Just a thought.
 
#6 ·
As others have noted, opinions are endless on ammo selection. . .but isn't that part of the fun?

I read a lot but shoot a lot less, and therefore claim no particular expertise. With that caveat, I'll state that I like to carry 200g LSWC-K loaded to standard pressures, which gives 718fps from my D.S. I figure that gives me penetration (6 water-filled milk jugs with energy left to bury itself to the shoulder in a 2x12) & a full-caliber hole, which is what I personally want to optimize.

My personal concern about penetration is the desire to have a bullet that gives me full confidence for side-angle shots against opponents scrambling for cover, intervening raised arms, huge assailants, heavy clothing, etc.

I give up something in accuracy, until/unless I get a higher front sight somehow & someday. It's an accurate enough load, it just shoots high--IIRC, about +6" at 7-10 yds. So, a center mass hold equates to chest area hit--OK by me.

Of course I sacrifice expansion almost totally, and I'm not as comfortable with that. Clearly, modern HP technology does a lot towards retaining adequate penetration, with expansion, usually even through heavy clothing test media. However, some problems exist in that regard, or else Hornady would not be making a splash with Critical Defense ammo. It's selling point? Guaranteed expansion through heavy clothing. Obviously, a lot of potential customers have that concern.

With all of that said, I will grant three more things:
1. I'd be comfortable with almost any brand-name ammo, but last choices would be 110g standard pressure loads, WC, and LRN. The former lack penetration; the latter lacks wound channel characteristics.

2. Even if some of a cylinderful of HPs failed to expand, odds are that some would expand, and the rest would at least penetrate about like LRN, give or take. By NO MEANS do some expansion failures equate to "this ammo is junk."

3. The 200g loads I use are reloads. I'm not trying to re-start that debate here, although I do enjoy reading knowledgeable participants' arguments on the topic! :)

Stay safe.
 
#7 ·
I'ld use the + P.
 
#8 ·
Thanks, guys. I'm not really a power junkie. I'm not really looking for a +P for the sake of shooting +P. I think we'd all agree there is a loss of performance when going from a 5" to a 3.5" barrel. I'm really wondering if switching to +p will recover some of that performance; so that shooting a +p in a 3.5" will approximate the performance of a standard load in a 5".
 
#11 ·
Ballistics by the inch

Caliber is key. This is more true in Short Bbl guns. Bigger hole means less need for expansion. I am a big fan of the 357 MAGNUM as the best self defense round ever produced but that is in a service size (4'-6') Revolver. It is NOT true in snubs. The muzzle flash and blast are disproportionate in a snub, you simply lose too much.
40 or 45 sub compact is a better choice if concealable stopping power is your goal. Throwing big chunks of lead is always a good strategy!
 
#13 ·
+P Short Barrel

I have both Speer Gold Dot +P and Corbon +P for my Colt Agent and both give a smart bit of recoil but muzzle flash is very low compared to the Federal Hydro's I used a couple of years ago. There are alot of improved bullet and powder combinations on the market now that have changed the market on what is best and functions best. You just have to find the right combination in a world of ammo shortages.
 
#14 ·
As politely as I can say this, the 'short barrel ammo' label is pretty much a marketing device.

Take a look at the information on the website, "Ballistics by the Inch". You'll find by looking at the information that the loads that go fastest in the longer barrels still go fastest in the shorter barrels. (There may be one or two exceptions and I wonder about those.)

Short barrels do flash more. Fact of life. Some powders are treated to lower muzzle flash, but they will flash less in a longer barrel as well. Nor does 'less flash' equal 'more velocity'.

Oh, did you notice lighter bullets tend to lose more velocity in short barrels than heavier bullets?

The (Rebel)Rabbi said something very important. Short barrels limit velocity in all circumstances. The other way to gain 'energy on target' is to throw a bigger lead slug. A larger caliber, heavier bullet is better than a smaller, lighter bullet if the velocities are nearly the same.

And, in all cases, shot placement. The second one starts to substitute technology for ability, one begins to lose.
 
#15 ·
As politely as I can say this, the 'short barrel ammo' label is pretty much a marketing device.

Oh, did you notice lighter bullets tend to lose more velocity in short barrels than heavier bullets?

The (Rebel)Rabbi said something very important. Short barrels limit velocity in all circumstances. The other way to gain 'energy on target' is to throw a bigger lead slug.
________________________________________________
I shoot either 125gr. or 158gr. in my long barrel .357's. Because I agree that to gain "energy on target" is to throw a bigger lead slug, and the heavier bullets lose less velocity from a short barrel, I'd shoot the 158gr. whether it be a .38spl. or a .357 from a snubby. :yup::
 
#16 ·
If you're only comparing a 3.5" - 4" barrel and about 50 fps difference, I wouldn't worry about it as that is within the normal shot to shot differences in the same barrel.

If your really concerned, get/borrow a chrony ($70) and see if there any significant differences btwn 4" and 5" with normal, +P, and short barrel ammo - 10 shots each. Don't forget to tell us what you found - indiv shots, mean vel, std dev. TIA.
 
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