Basic instruction - Reloading and Trajectory

[jkushner1]

I don't reload, I have some one load for me for IPSC, IDPA and Steel. He is a Bullet maker (all hard lead allow - and they are very hard - you cant scratch the lead with your fingernail). His latest load for me was for IPSC's production class which was a 9mm in 147 grain LRN, 3.3 grains Titegroup - its flyng at about 900 fps, is super accurate and recoil is truly minimal.

HERE'S MY QUESTION THE CYBERSPACE RELOADING EXPERTS HERE:
In reloading, how do you maipulate or what affects trajectory. Can someone provide me with basic knowledge, i.e. lead vs. jacketed, lighter vs. heavier bullet weight, lighter vs. heavier powder charge, etc. to make a bullet fly higher, flatter or lower.

Thank in advance for any advice provided.

TY
Jon

[Johnny Guest]

Forgive me if this is too basic - - I don't want to seem as if I'm "talking down" to you, but I'm not sure of your background. You list several handguns and some competition background, so I bet you know most of this stuff.

Trajectory is the path the bullet takes in flight. ALL bullets describe an arc, from the time they leave the muzzle until they come to rest. The shape of the arc is dependant on several things- - barrel position (usually determined by the shooter and the sights,) bullet design and weight, and velocity.

Skipping some of the VERY basic stuff - - Let's say your 9mm pistol, shooting your 147 gr 900 fps load is sighted in for 25 yards. The bullet will strike about an inch high at 15 yards, hit point of aim at 25, be maybe four inches low at 50, and around 15 inches low at 100 yards.

If you use the same pistol and bullet, but boosted the velocity by 100 fs, with the same 25 yard sight-in, your trajectory would flatten out a bit - -
15 yards + 3/4", 25 yards 0, 50 yards -3, and perhaps -12 at 100.

The drop is constant, but gravity has a lesser time on which to take effect.

To alter the trajectory much more, you need more velocity, with means either a different cartridge, or, staying with the 9x19mm, reducing the bullet weight. Let's skip right to one of the more rapid loads, the 115 gr. JHP +P Remington load, MV 1250. This really flattens things out - - Approximately-
15 yards +1/2, 25 yds 0, and around -6 at 100.

All of the above figures are approximations, interpolations from the Remington ammo site, and some of it is from memory. Actual measurements will vary somewhat - - This is all for the purpose of illustration.

Generally speaking, trajectory as a function of powder charge has to do with, with a given bullet weight, more powder = more velocity = flatter trajectory. I hasten to add, that extra velocity also increases the recoil, both felt and actual.

As to lead vs. jacketed bullets - - IN GENERAL, given a jacketed bullet and a lead bullet of equal weights, the same weight of powder will fling the lead bullet noticibly faster, in the low-to-mid ranges of bullet weight and velocity. This has to do with the greater friction of the harder bullet exterior. I see this mosly in the .45 ACP loads. Above a certain point, usually around 1000 fps, you begin needing the jacketed bullet to prevent rapid barrel fouling and to ensure proper function in an autoloader. Because we usually keep lead bullet velocities down, this means that a jacketed bullet of decent horsepower generally has a flatter trajectory than a lead bullet of equal weight.

Bullet weight - - So far, we've concentrated on keeping the same bullet weight and altering the velocity. By extension, if you increase bullet weight, maintaining the same powder charge, the velocity will normally be somewhat lower. If you increase powder charge in order to drive the heavier bullet at the same speed as the lighter, you are increasing pressures on the cartridge case and the gun, not to mention increasing the recoil.

Has any of this answered any of your questions? Clarified any points? Or have I only further muddied the waters for you?

Best,
Johnny

[OLD LOADER]

[OLD LOADER]

Johnny! 147gr 9mm's, That must be a truck comming out of that barrel.

BE OF GOOD CHEER

[Johnny Guest]

OLD LOADER - -
Yeah, the 147 seems pretty heavy compared to the "Standard" 9x19 bullet weights, the 116 and 124 numbers, and there have been a pretty good number of 88 to 105 loads as well.

I believe the 147 was a compromise weight, between the 158 gr .38 fmj bullet and the 124 fmj, when the US (Navy??) went to special procurement of some suppressed S&W Model 39 pistols. They were said to be for UDT/SEAL use in the rather specialized role of sentry removal and guard dog silencing. (Hence the name, "Hush Puppy" for the project. ) Most conventional weight 9mm loads are well above sonic velocity, hence the heavier bullets for subsonic effect while still retaining some impact.

Interestingly, some of the earlier non-military sub sonic loads were developed for SWAT and TAC Team use in suppressed SMGs - - MP5, Colt AR, MACs, and S&W M76 types, perhaps others. , worked pretty well in the SMGs, and .

Trouble was, the velocity of these specialized loads, with JHP bullets was apparently pretty carefully tuned to remain below speed-of-sound from the somewhat longer barrels. They would generally expand when so launched. When some personnel began using them in their sidearms, though, it became obvious that they would NOT open up when fired from the shorter barrels. Too bad - - Oh, well, still a decent flat-point-bullet effect, but it disappointed many.

When you think about it, though - - The standard subsonic JHP OR FMJ, or the custom load that jkushner1 uses - - 147 at about 900, up to +/- 100 - - This is very similar to a normal +P .38 Special load of 158 at about 900 to 950 from a service revolver. The 158 LSWCHP+P round has been doing yeoman duty for more than 20 years now . . .

Best,
Johnny

[OLD LOADER]

I,m sorry johnny you got me on that one,thats why I'm here. In 45+ yrs
of loading I still have a lot yet to learn.Thats why we are given 2 ears &
2 eyes & ONE mouth.

BE OF GOOD CHEER

[Johnny Guest]

I haven't "got you" at all - - Just pointing out another way of looking at it.

Another loader of decades standing, huh? You've got me by several years, sir. I'm not quite to forty years.

A mild coincidence, too - - My first on-my-own handloading experience was loading 9x19mm with heavy bullets. Years before, I had watched my uncle load a few rounds for his then-wildcat .22-250,

In about 1966, I'd bought a Smith Model 39, and was spending all my spare money on $2.00 a box surplus Winchester SMG ammo. I got a C-H press and some 9mm dies and various components. The nearby shop in Fort Worth was kind of short on knowledgeable loading advice, and, really, not many loaded 9mm back then. The Lyman catalog listed the 358311 bullet in two weights - - 125 and 158 gr. When my order arrived, the jobber had sent the far more common 158 mould blocks. This, by the way, is the classic LRN bullet for .38 Special, so I can see why they'd have the heavier one in stock. Heck, I didn't know the difference.

I'd been around when a friend's father had cast some .45 ACP wadcutters, so I scrounged some lead and cast a bunch of bullets. I mean, over A HUNDRED! Lubricated them with a Lyman Kake Kutter and used a push-through sizing die in the press. Opened a brand new can of Unique ($2.50 plus tax) and used a dipper to charge the cases. It was a suggested starting load for the 125 gr. bullet, but WAY too much powder for the 158. It was pretty brisk for that alloy framed autoloader . . . Don't know how I kept from straining something. I soon got a Pacific scale, though.

For some reason, it was hard to find 124 FMJ bullets, so, in another ignorantly-ahead-of-my-time move, I reasoned that SOMETHING lighter than the 158 bullets would be better, so I bought a box of the old Speer half-jacketed 146 gr hollow points. Same powder charge. Hey, what's .002" excess diameter? Actually, they shot pretty well, all things considered.

Finally found a shop that kept 116 FMJ bullets in stock, and my 9mm loading went better after that.

Ah, the folly of youth . . . .

Best,
Johnny

[jkushner1]

Excellent insights presented in laymen language, so that the shooter who doesn't reload but wants to understand the different dynamics of powder charge, bullet weight, bullet material could be well enlightened - mission accomplished, with honors.
Thank you.