Need some help getting consistent COL.

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colken

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Been trying to work up a load for my .223.
Problem is getting the same COL.

I am using Hornady 53 grn Vmax.
Win 748. Cases all full length resized and trimmed the same.
Got the Hornady Bullet comparator kit.
Measured all the bullets to see if the distance from ogive to the base are the same.
They are not. Differences of up to and over .011". This translates to a difference in COL.

Tried this:
Took 3 random bullets.
Bullets measured with the comparator and then with the same case for all and my rifle to get the max COL for my gun. Bullets seated long and jammed into the lands by closing the bolt.

Bullet [.3865] [.388] [.3945]
COL 1.9445 1.946 1.952
COL 1.945 1.9475 1.955
CO 1.947 1.9475 1.955
COL 1.944 1.948 1.955

Where do I go from here to get the most consistent COL.

Looking to eliminate as many variables as I can to improve group size.

Thanks in advance.

colken.
 
I did not notice you mentioned what press you have., For me, .003 (OAL)max variance is acceptable for my Dillon 550, But using my BULLET comparator and measuring from the Ogive then .001 is my allowance for variance.
 
What seating die are you using? If it seats off the meplet and you are measuring off the ogive, then thats one more source of variation.
 
This variability was driving me nuts with my Sinclair precision seater. Turned out to be that my primers were not seating below the base.

Paid a little more attention to seating the primers and I'm at +/- 0.001 inches these days.
 
colken said:
Been trying to work up a load for my .223.
Problem is getting the same COL.

I am using Hornady 53 grn Vmax.
Win 748. Cases all full length resized and trimmed the same.
Got the Hornady Bullet comparator kit.
Measured all the bullets to see if the distance from ogive to the base are the same.
They are not. Differences of up to and over .011". This translates to a difference in COL.

Tried this:
Took 3 random bullets.
Bullets measured with the comparator and then with the same case for all and my rifle to get the max COL for my gun. Bullets seated long and jammed into the lands by closing the bolt.

Bullet [.3865] [.388] [.3945]
COL 1.9445 1.946 1.952
COL 1.945 1.9475 1.955
CO 1.947 1.9475 1.955
COL 1.944 1.948 1.955

Where do I go from here to get the most consistent COL.

Looking to eliminate as many variables as I can to improve group size.

Thanks in advance.

colken.
Click to expand...

colken said:
Been trying to work up a load for my .223.
Problem is getting the same COL.

I am using Hornady 53 grn Vmax.
Win 748. Cases all full length resized and trimmed the same.
Got the Hornady Bullet comparator kit.
Measured all the bullets to see if the distance from ogive to the base are the same.
They are not. Differences of up to and over .011". This translates to a difference in COL.

Tried this:
Took 3 random bullets.
Bullets measured with the comparator and then with the same case for all and my rifle to get the max COL for my gun. Bullets seated long and jammed into the lands by closing the bolt.

Bullet [.3865] [.388] [.3945]
COL 1.9445 1.946 1.952
COL 1.945 1.9475 1.955
CO 1.947 1.9475 1.955
COL 1.944 1.948 1.955

Where do I go from here to get the most consistent COL.

Looking to eliminate as many variables as I can to improve group size.

Thanks in advance.

colken.
Click to expand...

Here goes more info.
RCBS Rockchucker single stage.
RCBS 223 Rem 2 die set # 11101 dated 13.
All primers seated below base.
Loaded some this morning did some measuring.

Hornady manual calls for COL 2.240".
Measured the bullet in my comparator. Rezeroed caliper for each measurment.
Seated and measured each cart. to 2.240" COL base to tip.
Could not rely on just setting the seater and going for it.
I made sure each round was seated to 2.240"

I know tips will vary so not too reliable, tips do not bottom out in seater plug.
Then measured with comparator on calipers.

First number bullet measured in comparator, second COL with comparator.

.395. 1.802
.3945 1.805
.3945 1.8025
.3945 1.803
.394 1.805
.393 1.8045
.3935 1.804
.3935 1.805
.3935 1.8045
.394 1.8045
.3935 1.8045
.3935 1.804
.394 1.803
.3935 1.802

max .003" difference.

Off to the range to try them out.

Thanks again.
colken.
 
I honestly can't decipher half of what OP is saying. Maybe I'm just dense this morning.

Bullets measured with the comparator and then with the same case for all and my rifle to get the max COL for my gun. Bullets seated long and jammed into the lands by closing the bolt.
Click to expand...

Wat.

OP, here's the problem: COL (COAL) is measured from the base of the case to the tip of the bullet. Bullets tend to vary in their length from the ogive, which is the important part, to the tip. (They also vary a bit from base to ogive, depending on the quality of the manufacture, but when you measure from base to tip you are getting a larger variance because ).

Especially for hollow points, spire points or polymer tipped bullets, this makes measuring from cartridge base to the tip of the bullet a bit of a weird thing to be doing, and I honestly don't know why load manuals don't also include CBTO (Cartridge Base to Ogive) so people like you with a bullet comparator can ignore the COL number.

So if you are seating 10 bullets in 10 cartridges and adjusting them to some specific COL measurement on your calipers, when you go to measure the CBTO it's absolutely going to vary.

Try this instead: seat *one* bullet to a COAL that you are happy with (I use the book value for starters) and use your bullet comparator to record the CBTO length. Then zero your calipers. Seat 9 more bullets and use the bullet comparator to check the variance in CBTO from the first bullet. Unless your die is having serious issues with the bullet (or maybe your die just sucks) you should find that the variance between all seated bullets, as measured by CBTO, is very small. For fun you can measure the COL of the cartridges and see how much they vary.

Write down the CBTO you used. Use that as the parameter for your load record keeping instead of just COL.

You should give the link below a read.

Reference: Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2

PS: It's possible I've completely misread the intention of your post, in which case I apologize because I really am dense this morning.
 
There are 2 different issues at play.
1) COAL. This is only important for the rounds to fit a magazine.
Find the maximum COAL That works with your mags and that is your maximum COAL.
2) when seating your bullets with a die which has a conical seater it will seat from the ogive.
Use a comparator and OAL gauge to figure out how far from the lands you want your bullets to sit and as long as it's under your COAL length you're good to go.
 
Pr589 said:
This variability was driving me nuts with my Sinclair precision seater. Turned out to be that my primers were not seating below the base.

Paid a little more attention to seating the primers and I'm at +/- 0.001 inches these days.
Click to expand...

+1 on this. Seems like a small thing, but I've had this seemingly bugger up my COAL before.
 
HeavyTread said:
I honestly can't decipher half of what OP is saying. Maybe I'm just dense this morning.



Wat.

OP, here's the problem: COL (COAL) is measured from the base of the case to the tip of the bullet. Bullets tend to vary in their length from the ogive, which is the important part, to the tip. (They also vary a bit from base to ogive, depending on the quality of the manufacture, but when you measure from base to tip you are getting a larger variance because ).

Especially for hollow points, spire points or polymer tipped bullets, this makes measuring from cartridge base to the tip of the bullet a bit of a weird thing to be doing, and I honestly don't know why load manuals don't also include CBTO (Cartridge Base to Ogive) so people like you with a bullet comparator can ignore the COL number.

So if you are seating 10 bullets in 10 cartridges and adjusting them to some specific COL measurement on your calipers, when you go to measure the CBTO it's absolutely going to vary.

Try this instead: seat *one* bullet to a COAL that you are happy with (I use the book value for starters) and use your bullet comparator to record the CBTO length. Then zero your calipers. Seat 9 more bullets and use the bullet comparator to check the variance in CBTO from the first bullet. Unless your die is having serious issues with the bullet (or maybe your die just sucks) you should find that the variance between all seated bullets, as measured by CBTO, is very small. For fun you can measure the COL of the cartridges and see how much they vary.

Write down the CBTO you used. Use that as the parameter for your load record keeping instead of just COL.

You should give the link below a read.

Reference: Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2

PS: It's possible I've completely misread the intention of your post, in which case I apologize because I really am dense this morning.
Click to expand...
Thanks for the reply.

I will try and explian my process a little better.
In my second post with more information.
The first number is the bullet [projectile only] measured from base of bullet to ogive. Using the comparator.
Each bullet measured individually.
The second number [now using the proper reference to CBTO] is the CBTO.
I measured and seated all rounds to the base to tip measurement of 2.240".
I know that the tips will not be uniform but just to be sure I seated all to 2.240".
I hope I have explained it a little better and not added more confusion.

My question still is with all this info how do I get a more consistant bullet length?
Thanks again.
colken.
 
If you adjusted the seating die between rounds to obtain the same overall cartridge length, you went about things the wrong way. The important measurement, is the distance from the ogive to the lands.
 
colken said:
Thanks for the reply.

I will try and explian my process a little better.
In my second post with more information.
The first number is the bullet [projectile only] measured from base of bullet to ogive. Using the comparator.
Each bullet measured individually.
The second number [now using the proper reference to CBTO] is the CBTO.
I measured and seated all rounds to the base to tip measurement of 2.240".
I know that the tips will not be uniform but just to be sure I seated all to 2.240".
I hope I have explained it a little better and not added more confusion.

My question still is with all this info how do I get a more consistant bullet length?
Thanks again.
colken.
Click to expand...
In my first post I was giving reference to the varying CBTO length.
[nice to learn a new language ie CBTO.]
The first number was the bullet [projectile only] base to ogive measurement using the comparator.
The second number was my attempt to find how long I could possibly seat my bullets with out regards at this point for magazine length. CBTO using comparator.

In each instance I followed the same proceedure.
Picked 3 random bullets. Measured them in the comparator this is the number in brackets. Bullet base to ogive.
Used the same case for all measurements.
After each measurement I used my kinetic bullet puller lengthen the COAL and reinsert into rifle jamming the bullet into the lands.
Used my rifle so that the distance from bolt face to lands is the same.

Hard to understand why when using the same bullet in the same case and rifle would the CBTO vary so much.

Once again I hope this makes it easier understand my process.

Thanks.
colken.
 
colken said:
In my first post I was giving reference to the varying CBTO length.
[nice to learn a new language ie CBTO.]
The first number was the bullet [projectile only] base to ogive measurement using the comparator.
The second number was my attempt to find how long I could possibly seat my bullets with out regards at this point for magazine length. CBTO using comparator.

In each instance I followed the same proceedure.
Picked 3 random bullets. Measured them in the comparator this is the number in brackets. Bullet base to ogive.
Used the same case for all measurements.
After each measurement I used my kinetic bullet puller lengthen the COAL and reinsert into rifle jamming the bullet into the lands.
Used my rifle so that the distance from bolt face to lands is the same.

Hard to understand why when using the same bullet in the same case and rifle would the CBTO vary so much.

Once again I hope this makes it easier understand my process.

Thanks.
colken.
Click to expand...

I'm still confused but, if you measure them from the cartridge base to the tip and adjusted the seating die each time to get the same overal length, you will get lots of variation.

Instead, do what I posted above: seat one single bullet in one single case to a COAL that you like (I start with the value from the book) and note the CBTO by measuring it with your bullet comparator. Mark that value down and forget about it for this batch, except that you can periodically spot check each bullet you seat (or check every bullet in this batch if you want) to make sure that the seating is consistent. When I do this with a Hornady press and Hornady die I generally get +/- 0.003" of variance or less.

Find out how those rounds shoot. Then when you come back, you can adjust seating depth up or down by aiming for a depth a few thousandths deeper or less deep than the last time you did it. Assuming you don't go over the maximum COL, you don't really care about COL at that point. CBTO is a much more important (and repeatable) measurement..
 
The most meaningless figure in all of hand loading is the COAL, cartridge over all length.
It is also the most talked about and discussed, while confusing more new reloaders than everything else in hand loading combined.
Just turn your seating die in a bit, so the bolt will close on any of your loaded cartridges and go shooting.
 
True, cartridge over all length doesn't mean much except that your cartridge has to be able to fit and feed reliably from the magazine.
Length from base of cartridge to ogive is only a measurement to confirm consistent length. Once you find out
where your bullet first touches the lands, you can then decide how much back from the lands or pushed into the lands
you want to be ( keeping in mind the cartridge still has to fit in the magazine), You can then take that cartridge
and measure the distance to a point on the ogive and then all following loads should be kept very close to that measurement.
 
There is a lot of information exchanged here but some of it is confusing to me.
I will try to explain my procedure.

1. The OAL of the cartridge is only a baseline dimension so that the loaded round fits in the magazine,
this dimension might or might not be of importance.

2. No consistency can be had if the bullets are not measured and segregated by length, base to ogive,
a tool for this purpose is required and Bullets should be batched by length. Odd ones used for foullers.

3. Chamber should be measured for base to ogive/land contact, this will establish a datum for
all your loading lengths. You will need a tool for this also. This will also show you if it is
possible for you to load a round into the magazine and kiss the rifling (usually not)
Most rifles unless custom chambered will not allow the rifling to be kissed and the
loaded round to fit the magazine unless a very stubby(low BC) bullet is used,
this is prevalent these days since manufacturers are striving to leap to the BC podium,
the higher the BC the less likely you are to fit the loaded round into your magazine, that's life.

4. Unless you are able to load a round into the magazine be prepared to single feed if the optimum
accuracy can only be had with a longer than mag length OAL. A compromise might have to be
made in both accuracy and speed to allow magazine use, don't be disappointed.

5. Deep seating to allow mag use has two downsides, less accuracy and lower powder capacity
due to deep seating bullets, sometimes we must use alternative powder burn rates to achieve
max speeds in reduced case capacities.

These are my methods and may not suit your style but they have helped me overcome some
of the problems I have encountered.
I hope this helps and didn't add to any confusion.
BB
 
^^ditto. If you do all this and still end up with wonky numbers WITH YOUR COMPARATOR, your seating stem is contacting an inconsistant surface on the bullet. 53gr. Vmax can be tricky, they are a unique bullet. Mainly because the meplat has been slimmed down and bearing surface shortened to provide room for a boattail. This is how they can provide higher BC than 60gr FB Vmax.

Best I achieved with my WILSON micrometer top seating die was +/- .003. Sold the bullets.
 
Well here we go.

First off I would like to thank all of you that have taken your time and efforts to help with my dilemma.
It seems like the more information I gave out the more confusing I MADE IT.

I guess I was trying for a simple explanation to a complex question.

The long and short of it comes down to my not knowing about CBTO.

If you check my second post [the one with more information] you will see that I was using the comparator tool to measure the base of bullet to ogive [the first numbers].
The second numbers were the CBTO using the comparator for the same bullet when seated to a COAL of 2.240".

I have since been to the range to try these out.
Can't seem to figure out how to post pictures but the grouping was good.
After getting my unit sighted in for 100 yards.
First was 3 shots into one jagged hole in a half crescent.
Second was a pretty good 3 shot one holer.
Had 2 rounds left and threw them into the second target and the group opened up some.

If I can figure out how to post the pictures I'll post them.

Thanks again for everyones help.

colken
 
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