COL questions

MDS · February 13, 2009, 12:40 AM

Ok, I've learned quite a bit so far. Everyone has been very helpful and generous. And I appeciate it. Something is nagging away at me. Most all the loads I have used were at a col of 1.25 Now there are a lot of loads (combination of powder, bullet) that I'd like to try. A lot of these will be listed in my manuals at whatever col that it is. But if 1.25 functions perfectly, and they show that load as say..1.20. How do I know how to manipulate the load to my col of 1.25? Or can I? Does this make any sense?

joneb · February 13, 2009, 01:24 AM

What cartridge and weapon are you loading ? Always pay attention to the specific components of your data, always start with the Starting Load, if no start data is given then reduce the load by 10% and work up from there. Some powders such as W-296 and H-110 have load reduction restrictions, Always Read your load data CAREFULLY AND COMPLETELY.

IllinoisCoyoteHunter · February 13, 2009, 08:27 AM

Generally the max COL is there so that a round will fit in a standard sized magazine and have enough "grip" from the case neck to securely hold it. If you need to increase your COL beyond the max COL, make sure your are seating enough of the bullet into the neck (they usually say 1 caliber) AND make sure it will fit in your magazine and feed properly AND make sure you don't seat it on the lands (unless you want to...this will raise your pressure so beware). For example, I am shooting Berger VLDs and I have to load them quite a bit over the Max COL for a standard .243 round so they are seated where I want them (.020" off lands). But, I don't load them up in the mag...I single shoot 'em. Good Luck! Maybe I did not answer your question??? If you are changing components (especially bullets) you need to test out what COL works best. Just because Bullet "X" shoots great with a COL of 1.25 does not mean Bullet "Y" will also shoot well at the same COL.

dlb435 · February 13, 2009, 09:26 AM

Good question. There are three parts to an answer.
1. The depth the bullet is seated to makes a differance to the pressure built up as the round discharges. In small pistol rounds this can be very critical. I load 9mm and there isn't much room for error. What makes the differance is the weight of the bullet, the charge, how far the back side of the bullet is seated and the bullet material.(lead, copper jacket ect.) With round nose bullets this is fairly easy.
2. Will the loaded round fead in the gun? Let's say the book calls for 1.25. You should never go shorter. 1.25 feeds fine, but you test to 1.35 and that works well too. Now you have a little wiggle room. Keep in mind that by making the COL a little longer, you have probably cut the pressure and velocity of the round. That's OK if the round works for you. It's not OK to go shorter.
3. Finally, there is bullet shape. Just because a 1.35 round nose will work does not mean that a jacketed hollow point will work at 1.35. Most bullet makers publish load data for their bullets. Stick to that data if you can. Here again you can make some dummy rounds to test COL and find out if you can get the round to work at a little longer COL than listed. That gives you a little room for error when relaoding. There are also issues with seating dies. Just because your die seats perfectly with one bullet shape does not mean it will give good results with an other. You'll have to test to find out. Some seating dies even come with different shaped seating stems for different shaped bullets. Compare the new bullet geometry to your old bullets. Is that back face going to be set at the same distance or further back? You'll need a good micrometer for this, we're talking a few thousand's on an inch.

Finally, what is your motivation for changing your loads? If you got 1000 bullets free, that's a good reason to go ahead. If your pistol hunting and working up a good hog killer, that's great. If you're trying to get a good self defense round STOP right now. There are just too many leagal issues with that. Just use commercial rounds.

SL1 · February 13, 2009, 09:38 AM

MDS,

The answers you received above seem to have missed the point that apparently you are talking about a semiautomatic pistol cartridge. I am basing that on the COL being only 1.25".

There are a LOT of considerations associted with COL when you consider ALL types of cartridges in ALL types of firearms. When you narrow it down to one cartridge in one firearm, you won't be overwhelmed with irrelevant info or mislead with info not applicable to YOUR situation. SO, you would be wise to provide more info in your post, and WE should pay more attention to what info you do provide.

Guessing from your COL = 1.25", I am ASSUMING that you are talking about something like the .45 ACP or 38 Super cartridges. The thing that will most affect your loading is that rather small changes in COL for such cartridges produces a relatively large relative change in the space for the powder inside the case. That will SUBSTANTIALLY change the peak pressure. I spent a little longer than I wanted to looking for a quote for the 9mm cartridge in Speer Manual #14 that shows how big a 0.1" COL change can be in pressure, but could not find it quickly. So, take my word for it, it can easily be too big to ignore.

You asked how to adjust the charge when you change COL from the loading date that you have. There are 3 approaches. One is to drop back 10% and work-up the charge for the new COL. The second is to use water in fired cases and a scale to measure internal volume, find the POWDER SPACE volumes left for each COL with the bullet you are using, and use the space ratio to compute the new COL charge weight from the data for the old COL. The third is to use a program like QuickLOAD to do these computations the easy way, having to know only the bullet length and weight, total case capacity in water, COL and charge weight in the data, and new COL (and, of course, what powder and cartridge we are talking about).

You really should learn method #2, so that you understand what is going on. I don't have time to write it out here right now, but I have before, so it is in the archives somewhere. There are some tricks to getting it prcise that are worth knowing for small cases, but they take some time to write-down.

You will probably prefer method #3. Even if you don't have QuickLOAD, you could get one of us on this forum to use the program for you to make powder adjustments. But, you will have to provide the data for us to do that.

And, finally, remember that your COL needs to provide enough grip on the bullet with the case to securely hold the bullet. If it doesn't, then the bullet will set-back upon chambering and the COL will not be what we figured in the calcs when the cartridge is actually fired - so the pressure will be higher.

SL1

MDS · February 13, 2009, 09:32 PM

I always seem to forget those pesky little details. (like what cal.) Yes I was talking about .45ACP. Again I got very detailed knowledge passed on to me. Thank you. I'm going to investigate using water like you described. I've never heard of that. Thanks again. Mike

amamnn · February 14, 2009, 12:12 AM

I've found that it's useful to go with the bullet maker's COAL in .45 acp or really any other handgun load. They generally know how long their bullets are.........................

The only time fooling with seating depth did me any good was when I had to seat soem Nosler competitions deeper to fix a feeding from the magazine problem in my older Gold Cup. Going back to C/Ts was the real fix for that problem.

Mark whiz · February 14, 2009, 07:50 PM

Personally, I would use the load data's COL listed for a bullet as a starting point. You may have to adjust that (within allowable spec) to make sure the rounds feed well. You can adjust the COL some after you're statisfied with a specific powder load to see if you can improve accuracy - especially with rifle rounds.

Nnobby45 · February 14, 2009, 08:57 PM

Of the many thousands of .45ACP's I've loaded and shot, I've never trimmed a case. Pistol cases GET SHORTER as they are fired and reloaded (just the opposite of what happens with rifle cases). Few new factory cases headspace on the case mouth, anyway, since they're held by the extractor.

Your COL may be important for proper feeding in your pistol, but that's not the case's function. It's how deep the bullet is seated.

A very simple test:

Remove barrel from pistol and use it as a gage. Size your cases as they are (no trimming). If they drop below flush with the barrel hood (and I'm sure they will), they are not too long and do not need to be trimmed.

It means they are traveling much farther into the chamber to bottom out on the case mouth than they ever will with the round, held by the extractor during firing.

Loading pistol rounds is time consuming enough without unnecessarily adding a lot more time. If you must find out for yourself, trim a bunch and load them, and compare function and accuracy with those that aren't trimmed.

I'll bet you wouldn't see the difference in accuracy if you used different brands of range brass when compared to ammo loaded with brand new factory cases.

James R. Burke · February 24, 2009, 12:40 PM

Almost always if you change bullets your c.o.l. is also going to change because of the differnt profile (shape) of the bullet. For example I have a 30-06 that I have five differnt loads, and bullets for. The c.o.l. is a little differnt for all of them. Keep it safe, and have fun.

February 13, 2009, 09:38 AM	#5
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	He's talking about an auto-pistol cartridge. MDS, The answers you received above seem to have missed the point that apparently you are talking about a semiautomatic pistol cartridge. I am basing that on the COL being only 1.25". There are a LOT of considerations associted with COL when you consider ALL types of cartridges in ALL types of firearms. When you narrow it down to one cartridge in one firearm, you won't be overwhelmed with irrelevant info or mislead with info not applicable to YOUR situation. SO, you would be wise to provide more info in your post, and WE should pay more attention to what info you do provide. Guessing from your COL = 1.25", I am ASSUMING that you are talking about something like the .45 ACP or 38 Super cartridges. The thing that will most affect your loading is that rather small changes in COL for such cartridges produces a relatively large relative change in the space for the powder inside the case. That will SUBSTANTIALLY change the peak pressure. I spent a little longer than I wanted to looking for a quote for the 9mm cartridge in Speer Manual #14 that shows how big a 0.1" COL change can be in pressure, but could not find it quickly. So, take my word for it, it can easily be too big to ignore. You asked how to adjust the charge when you change COL from the loading date that you have. There are 3 approaches. One is to drop back 10% and work-up the charge for the new COL. The second is to use water in fired cases and a scale to measure internal volume, find the POWDER SPACE volumes left for each COL with the bullet you are using, and use the space ratio to compute the new COL charge weight from the data for the old COL. The third is to use a program like QuickLOAD to do these computations the easy way, having to know only the bullet length and weight, total case capacity in water, COL and charge weight in the data, and new COL (and, of course, what powder and cartridge we are talking about). You really should learn method #2, so that you understand what is going on. I don't have time to write it out here right now, but I have before, so it is in the archives somewhere. There are some tricks to getting it prcise that are worth knowing for small cases, but they take some time to write-down. You will probably prefer method #3. Even if you don't have QuickLOAD, you could get one of us on this forum to use the program for you to make powder adjustments. But, you will have to provide the data for us to do that. And, finally, remember that your COL needs to provide enough grip on the bullet with the case to securely hold the bullet. If it doesn't, then the bullet will set-back upon chambering and the COL will not be what we figured in the calcs when the cartridge is actually fired - so the pressure will be higher. SL1

February 14, 2009, 12:12 AM	#7
amamnn Senior Member Join Date: May 13, 2006 Location: WA, the left armpit of the USA Posts: 1,323	I've found that it's useful to go with the bullet maker's COAL in .45 acp or really any other handgun load. They generally know how long their bullets are......................... The only time fooling with seating depth did me any good was when I had to seat soem Nosler competitions deeper to fix a feeding from the magazine problem in my older Gold Cup. Going back to C/Ts was the real fix for that problem. __________________ "If the enemy is in range, so are you." - Infantry Journal Last edited by amamnn; February 14, 2009 at 12:21 AM.

February 14, 2009, 07:50 PM	#8
Mark whiz Senior Member Join Date: May 19, 2004 Location: Wabash, IN Posts: 227	Personally, I would use the load data's COL listed for a bullet as a starting point. You may have to adjust that (within allowable spec) to make sure the rounds feed well. You can adjust the COL some after you're statisfied with a specific powder load to see if you can improve accuracy - especially with rifle rounds. __________________ "Every moving thing that liveth, I give unto you as meat" (Gen 9:3) Aim small.........miss small. Trust God..........but keep your powder dry!

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February 13, 2009, 12:40 AM	#1
MDS Senior Member Join Date: September 9, 2005 Location: Ohio Posts: 492	COL questions Ok, I've learned quite a bit so far. Everyone has been very helpful and generous. And I appeciate it. Something is nagging away at me. Most all the loads I have used were at a col of 1.25 Now there are a lot of loads (combination of powder, bullet) that I'd like to try. A lot of these will be listed in my manuals at whatever col that it is. But if 1.25 functions perfectly, and they show that load as say..1.20. How do I know how to manipulate the load to my col of 1.25? Or can I? Does this make any sense?

February 13, 2009, 01:24 AM	#2
joneb Senior Member Join Date: December 10, 2005 Location: Central , OR Posts: 1,888	What cartridge and weapon are you loading ? Always pay attention to the specific components of your data, always start with the Starting Load, if no start data is given then reduce the load by 10% and work up from there. Some powders such as W-296 and H-110 have load reduction restrictions, Always Read your load data CAREFULLY AND COMPLETELY.

February 13, 2009, 08:27 AM	#3
IllinoisCoyoteHunter Senior Member Join Date: December 23, 2008 Location: Southern Illinois Posts: 1,527	Generally the max COL is there so that a round will fit in a standard sized magazine and have enough "grip" from the case neck to securely hold it. If you need to increase your COL beyond the max COL, make sure your are seating enough of the bullet into the neck (they usually say 1 caliber) AND make sure it will fit in your magazine and feed properly AND make sure you don't seat it on the lands (unless you want to...this will raise your pressure so beware). For example, I am shooting Berger VLDs and I have to load them quite a bit over the Max COL for a standard .243 round so they are seated where I want them (.020" off lands). But, I don't load them up in the mag...I single shoot 'em. Good Luck! Maybe I did not answer your question??? If you are changing components (especially bullets) you need to test out what COL works best. Just because Bullet "X" shoots great with a COL of 1.25 does not mean Bullet "Y" will also shoot well at the same COL. __________________ ~~IllinoisCoyoteHunter~~ ~NRA LIFE MEMBER~ ~NRA CERTIFIED INSTRUCTOR~

February 13, 2009, 09:26 AM	#4
dlb435 Senior Member Join Date: January 26, 2009 Posts: 654	Good question. There are three parts to an answer. 1. The depth the bullet is seated to makes a differance to the pressure built up as the round discharges. In small pistol rounds this can be very critical. I load 9mm and there isn't much room for error. What makes the differance is the weight of the bullet, the charge, how far the back side of the bullet is seated and the bullet material.(lead, copper jacket ect.) With round nose bullets this is fairly easy. 2. Will the loaded round fead in the gun? Let's say the book calls for 1.25. You should never go shorter. 1.25 feeds fine, but you test to 1.35 and that works well too. Now you have a little wiggle room. Keep in mind that by making the COL a little longer, you have probably cut the pressure and velocity of the round. That's OK if the round works for you. It's not OK to go shorter. 3. Finally, there is bullet shape. Just because a 1.35 round nose will work does not mean that a jacketed hollow point will work at 1.35. Most bullet makers publish load data for their bullets. Stick to that data if you can. Here again you can make some dummy rounds to test COL and find out if you can get the round to work at a little longer COL than listed. That gives you a little room for error when relaoding. There are also issues with seating dies. Just because your die seats perfectly with one bullet shape does not mean it will give good results with an other. You'll have to test to find out. Some seating dies even come with different shaped seating stems for different shaped bullets. Compare the new bullet geometry to your old bullets. Is that back face going to be set at the same distance or further back? You'll need a good micrometer for this, we're talking a few thousand's on an inch. Finally, what is your motivation for changing your loads? If you got 1000 bullets free, that's a good reason to go ahead. If your pistol hunting and working up a good hog killer, that's great. If you're trying to get a good self defense round STOP right now. There are just too many leagal issues with that. Just use commercial rounds.

February 13, 2009, 09:32 PM	#6
MDS Senior Member Join Date: September 9, 2005 Location: Ohio Posts: 492	I always seem to forget those pesky little details. (like what cal.) Yes I was talking about .45ACP. Again I got very detailed knowledge passed on to me. Thank you. I'm going to investigate using water like you described. I've never heard of that. Thanks again. Mike

February 14, 2009, 08:57 PM	#9
Nnobby45 Senior Member Join Date: November 20, 2004 Posts: 3,150	Of the many thousands of .45ACP's I've loaded and shot, I've never trimmed a case. Pistol cases GET SHORTER as they are fired and reloaded (just the opposite of what happens with rifle cases). Few new factory cases headspace on the case mouth, anyway, since they're held by the extractor. Your COL may be important for proper feeding in your pistol, but that's not the case's function. It's how deep the bullet is seated. A very simple test: Remove barrel from pistol and use it as a gage. Size your cases as they are (no trimming). If they drop below flush with the barrel hood (and I'm sure they will), they are not too long and do not need to be trimmed. It means they are traveling much farther into the chamber to bottom out on the case mouth than they ever will with the round, held by the extractor during firing. Loading pistol rounds is time consuming enough without unnecessarily adding a lot more time. If you must find out for yourself, trim a bunch and load them, and compare function and accuracy with those that aren't trimmed. I'll bet you wouldn't see the difference in accuracy if you used different brands of range brass when compared to ammo loaded with brand new factory cases.

February 24, 2009, 12:40 PM	#10
James R. Burke Senior Member Join Date: January 3, 2009 Location: U.P. of Mich/Quinnesec Posts: 1,897	Almost always if you change bullets your c.o.l. is also going to change because of the differnt profile (shape) of the bullet. For example I have a 30-06 that I have five differnt loads, and bullets for. The c.o.l. is a little differnt for all of them. Keep it safe, and have fun.