Question for the "experts"

Lefty Dick

Lefty Dick

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I see it all the time, why do you guys insist on posting your COL for a cartridge?
If the "experts" would care to note no two production rifles are the same even consecutive serial #'s will have marked differences in the leade.
Therefore quoting COL is meaningless, since every rifles throat dimensions will be different.
I'll shut up now, just doing a bit of venting.
Rant off.
 
COL is not meaningless. If you shorten the COL you'll increase pressure and possibly blow up your firearm. Lenghten COL and there could be less velocity. There is also a max COL if you're shoooting out of a mag fed firearm. It can't be too long or you might have problems feeding. I am no expert but I haven't blown up a firearm yet.
 
Lefty #### said:
...why do you guys insist on posting your COL for a cartridge?
.... no two production rifles are the same even consecutive serial #'s will have marked differences in the leade.
Click to expand...
You answered your own question in your post ;)
 
Case in point, two custom 338-06s one on a M-700,the other on a pre 64 M-70. The Remington is going to be able eat a lot more Varget than the Winchester,because there is good chance the gunsmith throated to the mag length.So one safe load pops primers in the other rifle,COL matters.
 
it is a moot point if one starts well below a maximum charge and works up slowly, using a chronograph and keeping an eye on case stretch, primer appearance, extraction etc. If you start at the proper COL for your rifle and work up, your buddies COL matters little

I personally never really bother to post mine.
​
 
todbartell said:
it is a moot point if one starts well below a maximum charge and works up slowly, using a chronograph and keeping an eye on case stretch, primer appearance, extraction etc. If you start at the proper COL for your rifle and work up, your buddies COL matters little

I personally never really bother to post mine.

​
Click to expand...
True. Why post any load data at all? What is safe in your gun is not always safe in the next.

So. I(f I was posting my load for my gun with my charge weight, I might include my COL.

None of it means anything at the post stage for your gun.:D
 
for my first post, lets start off argueing:)

hi all, I have never understood or found a need for the COL measurement system...
firstly, what good is COL measured from the physical tip, isnt the only important length is the bearing surface wear as the rifling would start from?

case in point, if your using a falling block action with a weatherby chamber, the bullet tip to headstamp measurement is absolutly meaningless, as there would be 3/8" from the lands minimum. So the COL has little or nothing to do with pressures, primers and the like, it really only has to do with feeding and magazine constraints, which in all respects, is a pointless measurement.(no pun intended) as this OAL would have to be determined by arms brand name not ammo manufacturers

granted, If you assumed that all the reloading bullets that came out of the box had the exact same dimensions, and you were to add the distance from the tip to the 'jam length marks', that would be somewhat useful, but a comparator should still be tool of choice..
maybe Im way off, but thats nothing new
 
varmitr said:
hi all, I have never understood or found a need for the COL measurement system...
firstly, what good is COL measured from the physical tip, isnt the only important length is the bearing surface wear as the rifling would start from?

case in point, if your using a falling block action with a weatherby chamber, the bullet tip to headstamp measurement is absolutly meaningless, as there would be 3/8" from the lands minimum. So the COL has little or nothing to do with pressures, primers and the like, it really only has to do with feeding and magazine constraints, which in all respects, is a pointless measurement.(no pun intended) as this OAL would have to be determined by arms brand name not ammo manufacturers

granted, If you assumed that all the reloading bullets that came out of the box had the exact same dimensions, and you were to add the distance from the tip to the 'jam length marks', that would be somewhat useful, but a comparator should still be tool of choice..
maybe Im way off, but thats nothing new
Click to expand...

Very true but you still need a starting point! :)
Not every-one is a very experienced reloader!

When using my manuals I tend to pick the one that is using the same bullet I am, if I can, it saves time!
For instance if I know my rifle like .020 extra length to the lands, as long as the manual is using the same bullet I can usually just add the extra to the COL! :)
 
varmitr said:
firstly, what good is COL measured from the physical tip, isnt the only important length is the bearing surface wear as the rifling would start from?
Click to expand...

OAL also matters because if you seat a bullet deeper, you are in effect reducing the internal capacity of the cartridge which will in turn increases pressure.
 
MiG25 said:
OAL also matters because if you seat a bullet deeper, you are in effect reducing the internal capacity of the cartridge which will in turn increases pressure.
Click to expand...

Yes. But has anyone actually witnessed a marked increase in pressure from seating a bullet deeper? I think it may make a difference in a very small case, like a hornet or perhaps some handgun. But for most cases, how much could you really decrease capacity by reasonable decreases in COL?

I'm thinking you would need some pretty sensitive equipment to detect a change in pressure in say, a 30-378, if you seated the bullet a few thou deeper.

I have goofed around quite a bit with COL on rifle cartridges. I bought a 375H&H mag for my A-bolt in 300WM. I load 180gr ballistic tips way out to get them close to the lands. I've never really noticed a huge increase/decrese in pressure as I changed the length.

Handgun? Smallest case I load for is 38super so I can't really comment.
 
migmeister, guys
i think your off to the side a little,, to reword it...
The col SHOULD be a measurement from the point on the curve of the bullet diameter which first contacts the lands, that in effect, would be the COL, and yes, it would specific to each application.
from the rifling contact point to the headstamp, thats all...its not about compressed loads, pressures or handguns
its just terminology.
EG, If a bullet has a damaged lead tip, how would you measure the overall length now, what would you use and where would it be taken from???
bye all!
 
Well yes, to produce the most consistant ammo as far as accuracy goes, without a doubt, a comparitor would be the way to go. But for general purpose accuracy, I think unless the bullet tip is obviously mangled, measuring from the tip will suffice.

varmitr said:
migmeister, guys
i think your off to the side a little,, to reword it...
The col SHOULD be a measurement from the point on the curve of the bullet diameter which first contacts the lands, that in effect, would be the COL, and yes, it would specific to each application.
from the rifling contact point to the headstamp, thats all...its not about compressed loads, pressures or handguns
its just terminology.
EG, If a bullet has a damaged lead tip, how would you measure the overall length now, what would you use and where would it be taken from???
bye all!
Click to expand...

Remember, if you take a bullet that looks undamaged out of the box and set up your seater die, the seater die does not push on the tip for subsequent rounds.

For that matter, most hunting grade bullets have slight dimensional differences from bullet to bullet out of the same box. I guess the question is to what degree to you want to take your reloading to, are you and your rifle capable of showing these minute differences and what is the intended purpose of the ammo you are building?
 
i dunno, unless i am missing something, COL (cartridge OVERALL lenght) is the measurement to the tip of the bullet.

if a bullet had a damaged tip, i would use it for plinking loads.

COL isn't something that i worry too much about (within reason), extreme accuracy or performance isn't something i pursue when reloading.
 
your very right...
im not that finicky about my reloading, if its reasonably acceptable, im hunting!
I guess it all stems from common wording errors that dont make sense, we call deer horns, when they are antlers, magazines get mistakingly called clips, and ex-wives get called ..well..you get my point!!
where is the Leftdick guy who started this thread?? He shouldnt have started a fire and leave it unattended....:)
bye all, gotta go shovel that white crap?
The queen said so!
 
If I'm going to replicate a load, I want to know its OAL. It's just one of the variables I need to make it "the same as last time" (and that's the name of the game). Of course, results (performance of any given load) will vary from rifle to rifle. On the other hand, squeezing out every bit of performance is why hardcore rifle loonies reload. :)
 
Yes, COL was the measurement that was driving me nuts. I'd rather have seating depth measured from the bullet base to the rim of the neck. But that's a bugger to check.

A pointed round will be longer than a round nose for any given weight purely because of the way its mass is distributed. Ergo, the COL for round and conicle/pointed cannot be interchanged. So you end up requiring the COL for that exact bullet. crazy stuff.

Now, if you only had the seated depth of the bullet base, you get any bullet, mark it, seat it and calc your OAL for that bullet. Much simpler (unless you had the data for the exact bullet in your load data) and the case airspace and pressure would be the same. But then, I've never had any issues loading 9mm with different bullet types using similar COL's.
 
COL is an important starting guage for making loads. Think even about wadcutters. I know guys who seat them flush with the brass. Personally I don't hence I use more powder. So if I give buddy my load without my COL for the wadcutter he risks having problems. When I look up a load I use stated COL for the bullet type and amount of powder. Then and only then do I feel I can play around after I've tried it. I know I can use a longer COL no problem, shorter you watch for problems. I just checked my .38 load it is COL 1.295 with the wadcutter and buddy would load his at 1.135 with the amount of powder I use maybe not a big problem but if I was close to max maybe a case rupture. I would rather get a COL on any load than not!
 
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