How consistent should COL be? 9mm, LCT press, 4 die set with FCD

[ddc]

Hello,

I have a question concerning COL.

I’m a raw beginner loading my first rounds (9mm) on a Lee Classic Turret Press with the Pro Auto Disk and Safety Primer Feed options.

I’m using the Lee 4 die carbide set with the FCD. I’ve set up the dies using Lee’s instructions.

I loaded 10 rounds and am seeing what to my mind seems to be quite a variation in COL.

Powder: WSF
Primer: CCI 500
Bullet: Montana Gold 124 FMJ
Brass: Once fired Federal American Eagle that was loaded with 124 FMJ.

I set the COL using a dummy round with only brass and bullet, no primer, no powder.

Target COL was 1.135

Using a Frankford Arsenal digital caliper my dummy round mikes to 1.135 about half the time and 1.1345 the other half.

I’m using the .46 Auto Disk cavity and threw about 20 test loads before things settled down to 4.9 grains.

The COL for each of the 10 rounds is as follows:
round COL
1 1.133
2 1.131
3 1.1385
4 1.1335
5 1.132
6 1.1365
7 1.1395
8 1.1375
9 1.138
10 1.136

(Note that the number of the round in the list is not intended to indicate the order in which it was loaded; I didn’t record that data.)

I tried running the rounds with the longer COL’s back through the sizing and FCD dies and the COL does not change.

Also: I checked the primers and they all appear to be flush with the base.

What do guy’s think? Are those numbers to be expected or ?

Thanks!
Don.

 

[1KPerDay]

Nothing to worry about. If they pass the plunk test, and they feed reliably, that should be your primary concern.

 

[GT1]

Differences in the tolerances of bullet manufacture. The ogive varies, and your seater die typically pushes against the ogive, not the very tip of the projectile.

It is a common occurrence and a somewhat common question here, you are good to go as 1kper says..

I have the exact same set up and see differences as you mentioned. Montana Gold are good bullets and as consistent as any and better than most. They are all I use for pistol fmj.

 

[ArchAngelCD]

All the COAL numbers you listed were only 6 thousands of an inch apart. Do you know how very small a difference that is? Since most presses have some flex to them, especially a turret press, you will get those very small variations. It's impossible to pull the lever on the press with the same exact pressure each and every time. Good question to ask but your numbers are nothing to worry about.

Welcome to reloading Don...

 

[GJSchulze]

Gee, I wish my OAL tolerances were that good

I load my 9mm to the same length and have had no problem in several thousand rounds.

 

[Walkalong]

Using a Frankford Arsenal digital caliper my dummy round mikes to 1.135 about half the time and 1.1345 the other half.

It is not designed to read to the nearest .0001. (It rounds to the nearest .0005) You can mostly ignore the last digit.

A .005 spread on 9MM rounds is all I am expecting with my reloads. The better the seater stem fits the bullet and the more consistent the bullet noses are the better this spread will be.

 

[ddc]

Yes, I believe they "plunk" quite well.

Thanks to all for the feedback. It is greatly appreciated. Being an engineer (that may be part of the problem, lol) I know there is a difference between good data and noise but being a new reloader as well I don't yet have a feel for where to draw the line. Your feedback is quite helpful.

(And thanks for the "welcome to reloading")

 

[kimbernut]

As noted above

As noted above you are well within my range of .010" . Note particularly if you use waxy lubed cast lead bullets but in all cases really. Even though once settled in to the right COAL check every now and then for build up on the seat die that could begin seating bullets deeper. Rem. match 148 gr. LHBWC comes to mind particularly since it is extremely messy but extremely accurate as well. With them I clean my seat die and crimp die about every 300-500 rounds on the Dillon 550.

 

[RandyP]

Every now and then I 'test' the OAL of each round in a box of factory made ammo with my handy-dandy Harbor freight digital caliper. The results are informative and lead me to not fret too much about the consistency to the 3rd decimal point of MY reloads.

 

[Beretta96]

Every now and then I 'test' the OAL of each round in a box of factory made ammo with my handy-dandy Harbor freight digital caliper. The results are informative and lead me to not fret too much about the consistency to the 3rd decimal point of MY reloads.

This has been my experience as well.

 

[Markm87]

Nothing to worry about. If they pass the plunk test, and they feed reliably, that should be your primary concern.

Agreed. I don't have any idea what the rash of OAL obsession is on all the gun forums lately.

Measuring that obsessively will only drive you nuts and waste your time.

 

[Mr. Farknocker]

Your die should be seating the bullet on the ogive, not the bullet tip. It may or may not depending on the type of bullet you are using and the profile of the bullet seating stem. Measuring COL consistency using the tip of the bullet will give you a greater range of readings then measuring from ogive due to manufacturing tolerances. I would only measure COL from the tip of a bullet when attempting to determine whether the round will load properly in the magazine. Measure the ogive with tools made for that purpose if you want to know whether your die is seating the bullet consistently. If your die is set up properly and seats on the ogive, you will find that the COL (based on the ogive) is more consistent than what your current readings show.

The attached picture is for a rifle round but is still appropriate to illustrate the above.

 

[Walkalong]

That is an outstanding photo illustration of the difference between OAL variation and base to ogive variation. Most excellent.

 

[GJSchulze]

Agreed. I don't have any idea what the rash of OAL obsession is on all the gun forums lately

Like me, there a lot of new reloaders, maybe because of the ammo shortage. Without a special tool there is no way to measure to the ogive and new reloaders, especially pistol, won't have this tool. You read forums and books where people are saying that their bullet seating is within .001" and wonder why your own is an order of magnitude larger. Being an engineer I find some claims of small tolerances (including primer depth) to be a bit unbelievable, but then I don't have the experience (been reloading two years) to know for sure. I've read books, magazines, and forums and while they all mention measuring to the ogive, I don't have a way to measure it.

It wasn't until I've heard enough people say not to worry about it and realize from experience that the only dangerous OAL is going too short. A too long one might not feed correctly, but unless you're loading your own SD rounds, not dangerous. I hear certain shooters saying that OAL makes a difference in accuracy, but then you realize that these are benchrest shooters and that if you're not that kind of shooter, it won't make a difference.

So let me ask this, will .01" spread of OAL make a difference in accuracy with a handgun, say at 15 or 20 yards? 9mm if that affects it.

 

[TheCracker]

Nothing to worry about at all. Just manufacturing deviation esp if the longer ones don't seat any farther down after you tried.

As already mentioned as long as they pass the plunk test and don't stick in your chamber your are GTG

 

[herrwalther]

Looking in my reloading book I see all my loads I have ever done have been within 0.01 or 1 hundredths of an inch spread among batches. Never have had any feed or reliability problems with that much OAL leeway. My die seating consistency has gotten quite better and generally seat +/- 3 thousandths most of the time.

 

[TheCracker]

Btw, try loading soft point rifle loads! They can be all over the place as the noses can be dented or formed differently.

 

[Mr. Farknocker]

Dagnabit! Haven't figured out how to do a reply and quote on this forum yet!

In answer to GJ's post about having special tools, all you need to verify consistent COL in handloads is a bullet comparator for the bullet you are attempting to reload. For example, you can buy an inexpensive PTG Bullet Comparator that measures a variety of calibers....

http://www.midwayusa.com/product/365474/ptg-bullet-comparator-17-20-22-27-30-33-calibers

Seen below...

Or you can be cheap like me and make one yourself for pennies on the dollar by taking a nut and by drilling the right size hole through one side like how I did.....See below.

The comparator measures the COL on the ogive and not bullet tip.


I have to admit that my knowledge about reloading pistol rounds lags behind my knowledge about reloading rifle rounds (and that ain't sayin' much!) but I think the principles are similar and still applicable to pistol rounds.

From what I know, you measure COL to make sure your rounds properly fit and load from the magazine. In a semi-auto handgun or rifle, the COL is important since the bullet must fit properly in a magazine and load properly when the slide extracts a spent case and strips a fresh round from the magazine and moves it into battery. COL is critical in a bolt action rifle only if you intend to use the magazine. Otherwise, a round that exceeds the recommended COL may be inserted into the chamber by hand.

As far as COL's affect on accuracy, I can only say that there is a lot of data which shows that with rifles, accuracy is affected by the COL and in particular, the distance between the bullet and lands of the barrel. It is not uncommon for shooters to achive greater accuracy by seating the bullet a certain distance from the lands (e.g., .001 to .002"). I would imagine that the same principle applies to handguns to varying degrees dependent upon the handgun itself.

 

[ArchAngelCD]

That is an outstanding photo illustration of the difference between OAL variation and base to ogive variation. Most excellent.

I was thinking the same thing as I looked at your post. Thank you, it is excellent alright!

 

[GJSchulze]

inexpensive PTG Bullet Comparator

According to the description you put the cartridge into the appropriate hole, bullet first, and measure from the opposite face to the head. There are two sizes and they seem to be for rifles. The largest caliber is .338. My question is how to you keep the cartridge straight i.e., perpendicular to the side you are using? I can see a bullet easily fitting at different angles which would make the measurements vary. Pistol bullets generally have a much higher diameter to length ratio than rifle bullets.

 

[RussellC]

Dagnabit! Haven't figured out how to do a reply and quote on this forum yet!

Its easy...to reply, hit "reply" then type. To Quote, click the little quote deal in the lower right. When your typing space appears, you must check the box on "Quote message in reply?" or it will not appear. You will notice that the original posters message will start and end with quote info. You can delete whatever you dont want to quote by editing within the quote info...

Russellc

 

[Mr. Farknocker]

My question is how to you keep the cartridge straight i.e., perpendicular to the side you are using? I can see a bullet easily fitting at different angles which would make the measurements vary. Pistol bullets generally have a much higher diameter to length ratio than rifle bullets.

There are two flat surfaces that square the loaded round to the comparator and the comparator to the loaded round. The round is squared to the comparator when the rim of the round lays flat against the edge of the caliper arm. The comparator is squared to the round when its side lays flat against the other caliper arm.

 

[Walkalong]

Care must be taken, but it's not that hard to do.

No harder than squaring up this button to check shoulder position.

 

[dagger dog]

Drop the 4th digit !

 

[jerkface11]

Buy a box of factory ammo. Measure their COAL and you'll see how good yours are.