How to choose powder throw and COL?

A

ADClope

New member
Hi all,

I'm fairly new to this, and had a couple questions that I haven't really found a definitive answer to, probably because everyone has their own "preference" I'm assuming...

But I was wondering how you choose the powder measurement and the COL. My manuals give a "starting load" and a "max load" and they also give a max COL. But how do you choose the load? And how do you choose the COL as the load could be anywhere in between and the COL just needs to be < specified length.

If this is a stupid question I apologize lol, but I've been trying to figure this one out.

Thanks!
 
Start loads are there to assure good ignition of powders and make sure you don't have a squib. With some ball powders like h110 leaving too much airspace by using a light charge in the case can cause erratic ignition leading to issues. Also too light of a load in autoloaders may not cycle a slide.

Max loads in most books are taken up to or just shy of industry spec for the round. Cartridge oal is usually listed as a minimum length and by going shorter you will increase pressure. Maximum length you can go is generally limited to what the magazine will fit and what will fully chamber in the barrel. Going longer than spec if possible has usually lower pressures but also lowers velocities of a given charge.

I usually start my load process by making a dummy round of the longest I can load a bullet in my gun which is usually longer than minimum length then start in between start and max loads with my powder charge. Most accurate loads seem to be just shy of book max but only testing will tell you.
 
You'll get better answers if you give more information.

What cartridge are you loading for?

What's the purpose? Powder puff target loads, hunting loads or self defense?

The cartridge overall length (COL) is usually determined by me for my 1911 style .45 ACP by the 'plonk' test. I take the barrel off the gun and drop the cartridge in the chamber. Do a search on 'plonk' and you'll find the illustrations. Different bullets, even of the same weight, might have different profiles and might need to be seated differently.

If you don't measure your rounds against your own gun take the bullet manufacturer's recommendations. The COL is primarily to get the round to feed in your firearm without problems. Later on you can adjust the COL to fine tune the round to your firearm for accuracy and if you wind up seating the round deeper and you're at max powder charge then back off the powder charge a bit and work up again.

Changing the COL to fine tune a load is kind of an advanced procedure.

Once the COL is determined for a bullet I begin with the starting load of powder and work up from there until I get what I want as far as accuracy and velocity go. I mostly target shoot so I usually stop well short of the max powder loads.

Once again, start with the bullet manufacturer's recommendation for the particular bullet your using, adjust it if needed so the round feeds ok in your gun then start with low powder charges and work up to what you want.

If you do a search on COL you can get a lot of information on it here in this forum and my advice would be to take any posts by 'Unclenick' to heart as being very good advice.

Good luck.
 
A good strategy

Here is a good strategy to get you started. This will get you an accurate load, if an accurate load is possible with your powder/bullet combo.

Once you get your cases prepped and ready:

1:Take an already fired case and one of your new bullets. Color one entire side of the bullet with a sharpie. Then, put a bullet barely in the case and put it in the chamber. Slowly close the bolt all the way. Then pull the case and bullet out and see how far the bullet was pushed into the case.... Measure the overall length with the bullet pushed into the case as far as it was pushed in when you chambered it.. the sharpie helps you see the marks.
This will tell you the maximum overall length using that bullet in your gun.
2: pick a powder charge below the middle or near the minimum from your manual, at the manuals suggested COAL and load 5 rounds. Then do 5 rounds with a COAL about .02" longer....Then 5 rounds .02 longer than the last set until you get to about .020 from the Maximum you found your chamber to be. Also, be sure and check to see if each round will chamber before moving on to a longer COAL.

The above will tell you what seating depth is most accurate. Keep in mind, if you want to load from a magazine, you may be limited in how long you can seat the bullet. Also, the most accurate seating depth will usually be the most accurate across all amounts of powder.

3. Once you have settled on a seating depth, then do a ladder test for the most accurate amount of powder. I usually start at the minimum recommended by the manual. I then increase the powder by 0.7% and shoot another 5shot group...And repeat until I start seeing pressure signs and then stop.

4: I then take the most accurate load from step 3 and load up 5 rounds 2/10 of a grain below that, 1/10 of a grain below, 1/10 above and 2/10 above to see the exact range of the accuracy node.

Sometimes I use my chronograph at step 3, but I always use it during step 4.

You may also want to document the point of impact of each group during step 4 to see how much 1/10 of a grain changes where the bullet hits in the event the weather is cold or warn.

5: Admire your extremely accurate load, politely brag about it and enjoy the felling of superiority over factory ammo shooters.

6: Begin load development with a different bullet, or for a different gun.

These are just suggestions, obviously you can do all or none of it but those steps will usually get you to find an accurate load. If you don't find one following those steps (at least MOA or better), then it may be that your gun doesn't like the bullet you have chosen or the powder.

You can make sure that your gun likes particular bullet by shooting a box of factory ammo with the bullet you intend to try and see how it shoots. If the factory ammo shoots at least 1.5 moa or better, it's likely you can get a sub MOA load with that bullet.

I hope this helps.
 
"My manuals give a "starting load" and a "max load" and they also give a max COL. But how do you choose the load?"

Most data manuals give information about working up loads and doing accuracy testing. Lots of useful information within the covers of those manuals besides the load data.
 
I choose COL based on what is the longest that will pass the plunk test in my tightest chambered pistol for a particular style/brand/weight of bullet. (Brand can make a difference, even in the same style/weight bullet.) Then I work up a load based on data from my reloading manuals.
 
I always load up a slew of rounds (maybe 5 each) of different powder weights, starting at the min load and going up to the max (or just below). I go up in .5 grain increments to start.

Then go to the range and work you way up, inspecting each round of shots for pressure signs, and measuring your groups. As soon as you see any pressure signs, stop. This will give you a good idea of pressure, and where to start your load development with a powder charge that your gun prefers.
 
Have you read up on reloading methods and procedures (like working up from starting loads); or did you just dive in head-first, buy some equipment and components, and start looking at load data?

Hornady, Lyman, Sierra, Nosler, Barnes, and nearly every other printed reloading manual will guide you through the reloading process and have answers to your questions.

"Start low and work up" is one of the most basic reloading rules.
 
I agree it is an issue as many manuals do not describe how to work up a load.

And it really is the same both pistol and rifle, for powder. In never saw COAL change things in a pistol. Also pistol is much harder to see a difference (you have to be a good pistol shot to do so, not an easy skill)

So, this is how I have settled on it.

I look at the manual and see what their low is.

Rifle: I take a sized case, put the bullet of my choice in it and have it COAL much longer than the recommended.

I gently close the bot and hit a resistance, do an eye ball of how far out, and adjust the searing die and repeat.

Once I have it fully closing and maybe a bit stuck in the lands, I take that back .015 and try a full solid closure. If good I load up the first rounds to the COAL (though I change that to an OGIVE reading)

I then pick a load that is a bit above the very lowest and maybe a bit below the highest start low.

For rifle I then load 10 or 15 of each of that, increase it by 3/10, load another 10 or 15 until I have 50. The very low ones I go with 10 as that is not usually the low accurate one.

I am looking for the best looking consistent pattern groups.

If I find one, then I will adjust the OGVIE OAL out a bit Longer)

Shoot 5. If I get something decent looking I adjust the next load to that.

When done I assess and see if any of them were really good.

If they are and some look promising then I load a box of 50 up at 3/10 below and on and 3/10 above and work with COAL while shooting.

If I am getting 3 and 4 shot groups with one or two odd ones I don['t discount it, it may be me shooting poorly a couple of times. Always the fun part figuring that out.

If nothing looks good I do another test round moving them up to Maximum in 3/10. There should be a node up there that is good.

Good is relative, nice even 1 inch pattern is good, it may not get any better than that. If it doesn't, then that power bullet combo is off the list for that gun.

The Hornady bullet COAL gauge is not bad but I have found it is under by a fair amount so have gone to the resized case and bullet approach.
 
Cartridge oal is usually listed as a minimum length
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This is incorrect.

What is listed in many manuals is the MAX overall length with bullet.

NOT THE MINIMUM. With most rounds, there is no standard minimum.

The Max COAL (Cartridge OverAll Length aka loaded length with bullet) is the longest length that should reliably work (feed) through the action of all common firearms in that caliber.

it is also a number you may, or may not reach. This is simply because some bullets are shorter than others.

There's a lot more to it, and as a beginner, don't worry about setting your bullets "just off the lands", focus on making ammo that will feed through the action reliably, first, and try various accuracy tricks later, IF you need to.
 
. Amp 44:........ There's a lot more to it, and as a beginner, don't worry about setting your bullets "just off the lands", focus on making ammo that will feed through the action reliably, first, and try various accuracy tricks later, IF you need to.
Click to expand...

This is good advice. The simple solution is to seat your bullets to the COAL listed in the manual, try and chamber the first round you make, if it feeds from the mag , the bolt closed, and it extracts, then stick with it.....If the bolt will not close, then try seating the bullet deeper and make sure the shoulder didn't get pushed out.

When I first started reloading, I didn't screw around with seating off the land....I just adjusted powder and loaded to the COAL in the manual and I made some very accurate ammo.
 
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