Overall length questions for a noob

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OK beginner reloading questions, COAL version: is it accurate that:

SHORTER overall length than a proven recipe is always a hard no due to pressure increasing, and

LONGER length than the recipe is not unsafe, up to the length that your chamber (and magazine) can reliably operate (but you'll get lower pressures).

OK so far?
Groovin' and jivin' and diggin' the skin I'm in

Lyons, CO

Re: Overall length questions for a noob

2
The short, safe answer is always stick to the oal recommended by the manufacturer for the specific bullet you're using.

A shorter oal in a small case like the 9x19 can increase pressure a lot.
A longer oal can increase pressure, if the bullet is seated out to the point where the bullet is in contact with the lands.

Rifle shooters often experiment with oal when looking for better accuracy.

Re: Overall length questions for a noob

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Experiments are the ways we learn things. You make five or ten rounds backed off this much, then this much, and so on. You look at group sizes when you shoot off the bag. Then you write it in your reloading book.

You do have a reloading book, don't you? Usually we end up with two or three books so we can cross check.

CDFingers
Crazy cat peekin' through a lace bandana
like a one-eyed Cheshire, like a diamond-eyed Jack

Re: Overall length questions for a noob

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CDFingers wrote:
You do have a reloading book, don't you? Usually we end up with two or three books so we can cross check.

CDFingers
I do have three, unfortunately my immediate powder and bullet combinations are apparently not terribly common :).

Mostly though I'm trying to learn the underlying principles in addition to following the recipes.
Groovin' and jivin' and diggin' the skin I'm in

Lyons, CO

Re: Overall length questions for a noob

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I load pistol ammo long to reduce recoil, but keep in mind that every gun is different. For example, the ammo I use for my Sig P320 is too long for my PCC with a JP barrel. The OAL from reloading books are generic enough so that you can use them for most guns. Like everyone has said, it's a process of experimentation. Start with the values from reloading books, then change one variable at a time.

(bullet shape + bullet coating + bullet weight) + powder weight + powder + OAL + crimp = perfect round for that one gun

Re: Overall length questions for a noob

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I actually contacted Barnes about this, since I had some projectiles with a cannelure that could not be crimped into without lowering the COAL by a couple thousandths. The Barnes guy said it's not a problem, and that the COAL recommended on their load data is the max. I wouldn't overdo it, but my findings have been that you can go a little shorter than COAL and be ok as long as you are working with lighter / mid loads. Also, if you're loading softpoint or cheaper projectiles in general, the projectile length can vary, so if you're measuring COAL from primer to bullet tip, you're going to have variation that can drive you nuts until you realize that it's, er, just the tip that's throwing off the measurement.
Minute Of Average

Re: Overall length questions for a noob

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Benredbeard wrote: Wed Oct 14, 2020 2:38 pm Wait so the recipe is the *max* length? Doesn't going shorter risk increasing pressure?
My understanding is that most COALs are listed as the max length for an "average" chamber (whatever that is), and it should vary from bullet to bullet since not all projectiles are the same length. So if you're getting the COAL from the data on your Lee Die Set box, that isn't going to be the same as the data from each individual bullet manufacturer. Like I said above, I called Barnes to ask this question for some of their MPG bullets and they said it's ok to go just slightly deeper to achieve a proper cannelure crimp. YMMV with different bullets, but if in doubt you can always contact the manufacturer. Every bullet Co I've contacted has been really nice, except for the guys at Buffalo Bullets, who made fun of me for living in Cali and told me to ignore all laws on non-lead projectiles... which they sell... :eh:

Again, best advice I can give (and I'm NOT a lawyer, haha) is to start with minimum loads, shoot groups, and check your primers for signs of overpressure, like flattening or severe cratering. If that's happening with minimum loads, then you may be too far under COAL.
Also, I feel like a lot of factory stuff, especially Federal green tip 5.56 is WAY higher pressure than what I make, even when I'm pushing my loads a little. Makes me wonder if I'm too conservative or if I keep getting "friday afternoon" boxes.
Crow
Minute Of Average

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