Measuring Bullets for C.O.A.L

endlesscoffee · Sep 27, 2021

Hey all. I've been searching the forums and seems that I'm getting lost in the sauce of threads from 2021 to 2008. I've been reloading this year with some decent success with my 6.5 (using factory 2nd 140hpbt, it did the trick) and started to load for my .308 I just got back. I'm currently going to use up the hundreds of 168smk I have stock with once fired federal brass for the winter. I'm using a S.A.C. Seater Die and my C.O.A.L seems to be all over the place. Is it standard practice to measure and sort the bullets by length before loading to COAL?
I initially started at getting my rounds to 2.8000, but have gotten anywhere from 2.8030 to 2.7890. Is this due to the consistency of the 168SMK? If so, do I need to place my time into measuring each individual bullet and sorting them accordingly? I planned on loading to 2.8 for a load test then finding a better seating depth after.

Thanks for the help.

nn8734 · Sep 27, 2021

Forget COAL outside of ensuring they fit in the magazine. CBTO is much more important for consistency.

ogive sort your bullets prior to seating for best results

alfmoonspace · Sep 27, 2021

What kind of press are you using?

You got to use a ogive to base tool. The tips can be inconsistent of the bullet.

PinesAndProjectiles · Sep 27, 2021

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endlesscoffee · Sep 27, 2021

Hey all. Thanks for the help. Ill look at the CBTO. Just trying to work with what I've got for now. Now if measuring from the Ogive, should there be that much variation? Or is that something that will vary manufacturer to manufacturer.
Forgot to mention I am using a forester Co-ax.
SAC Seater with Forster ring
Brass is trimmed on a L.E. Wilson.
I'll get a load compare ordered I supposed. Midway is killing me these days.

nn8734 · Sep 27, 2021

If all bullets are from the same lot variance should be minimal. Also keep in mind that a minor amount of variation <.005 CBTO across a given lot of your rounds wont make any difference in terms of how they print.

spife7980 · Sep 27, 2021

endlesscoffee said:
Hey all. Thanks for the help. Ill look at the CBTO. Just trying to work with what I've got for now. Now if measuring from the Ogive, should there be that much variation? Or is that something that will vary manufacturer to manufacturer.

No, not with good bullets. OAL doesnt make a bit of difference beyond fitting in the mags but its also much more variable, past that measure on the ogive where the bullet is actually interacting with the barrel and its much more consistent.

Snuby642 · Sep 27, 2021

First of all there may be a reason they were factory seconds, looks like you found it.

I use factory seconds for 223 range plinkers all the time, fooling with them can still get me 1 1/8 groups and for my ar that it decent.

Just loaded a bunch of 168 smk's and the ogive to tip varies but ogive to base is fairly steady.
Consider their 1.2 length
"nominal " and the bto of half inch a little more reliable. The cartridge bto of 2.08 is what I go by on "2.8" length rounds.

I dont know where I got a 2.1 cbto from but it was not what it was in reality.

That's giving me 0.065 jump.

Like they said the ogive is the only good constant.

endlesscoffee · Sep 27, 2021

Snuby642 said:
First of all there may be a reason they were factory seconds, looks like you found it.

I use factory seconds for 223 range plinkers all the time, fooling with them can still get me 1 1/8 groups and for my ar that it decent.

Just loaded a bunch of 168 smk's and the ogive to tip varies but ogive to base is fairly steady.
Consider their 1.2 length
"nominal " and the bto of half inch a little more reliable. The cartridge bto of 2.08 is what I go by on "2.8" length rounds.

I dont know where I got a 2.1 cbto from but it was not what it was in reality.

That's giving me 0.065 jump.

Like they said the ogive is the only good constant.

Oh the 168s are not seconds. They're normal. The factory seconds were some I bought for 6.5 last year.

endlesscoffee · Sep 27, 2021

MinnesotaMulisha said:
Buy one of these:

All SINCLAIR INTERNATIONAL Products for Sale Online - 236 Products

Brownells has 236 SINCLAIR INTERNATIONAL products for Sale Up To 91% Off including Reloading, Tools & Cleaning, and Gear.

www.sinclairintl.com

And one of these:

Hornady Lock-N-Load Bullet Comparator Basic Set 7 Inserts

The Hornady Lock-N-Load Bullet Comparator is perfect for the reloader looking to quickly and precisely measure seating depth of loaded ammunition from...

www.midwayusa.com

And one of these:

Hornady Lock-N-Load Headspace Ga 5 Bushing Set Comparator

The Hornady Lock-N-Load Headspace Gauge is a great tool for increasing the accuracy of your loaded ammunition. The Headspace gauge measures from the...

www.midwayusa.com

Then learn how to use them. It will make your life MUCH simpler.

I'm always down to save a buck, but is there any reason to consider getting the S.A.C comparator kit over the hornady? I've been enjoying S.A.C and the seater is is great. They actually did the work on my .308.

smoothy8500 · Sep 27, 2021

look close at the open tops, they are all a little different....but not usually .014”

PinesAndProjectiles · Sep 27, 2021

endlesscoffee said:
I'm always down to save a buck, but is there any reason to consider getting the S.A.C comparator kit over the hornady? I've been enjoying S.A.C and the seater is is great. They actually did the work on my .308.

I have never used them, but I would expect them to work just as well, but probably have a nicer fit/finish

straightshooter1 · Sep 28, 2021

endlesscoffee said:
Hey all. Thanks for the help. Ill look at the CBTO. Just trying to work with what I've got for now. Now if measuring from the Ogive, should there be that much variation? Or is that something that will vary manufacturer to manufacturer.
Forgot to mention I am using a forester Co-ax.
SAC Seater with Forster ring
Brass is trimmed on a L.E. Wilson.
I'll get a load compare ordered I supposed. Midway is killing me these days.

I shoot a lot of 168 SMK's and I always sort them into batches of within +/- .001. I used to sort them by BTO (it's not unusual to find large differences between lots). Variance in the BTO's are not as large as with OAL and that's why previous posters recommend sorting by BTO rather than OAL. Obviously, what we're all trying to do is get a consistent seating depth . . . even though COAL will vary in large part because of the bullet's OAL variances, right?

Well, when you seat a bullet, the seating stem does not go down to the ojive. So, seating depth will vary according the the distance from where the bullet fits into the seating stem to the base of the bullet. So, if one want's really consistent seating depth, one needs to use and measure from the base of the bullet to that contact point in the seating stem. I decided to do this by using a comparator insert that matches the diameter of that contact point of my seating stem to sort my bullets. As a result, I get VERY consistent seating depth.

Now, when talking about "seating depth", it's not about the jump to the lands. Since "seating depth" is what effects the internal case volume that the powder works in. The more consistent you keep the case volume with consistent powder charge and ignition, the results on paper will be better. Consistent seating depth is way more important than one's jump distance to the lands. When sorting bullets as I do, there IS a little variance in jump due to some variance in the distance from the ojive to the seating stem contact point. But that difference in jump has little effect (of course, unless one loading to touch or jam the lands). This issue on seating depth is important for those who are fine tuning their loads buy testing various seating depths in .003" increments to find a good accuracy node and just where in the node they want to be. Once it's found, one tends to keep that seating depth even as the throat erodes making for longer jumps. I did so and maintained my accuracy well under .5 MOA for over 1,200 rounds as the lands eroded over .030" in my .308 Krieger barrel.

Well, I hope this give you some insight that you might be able to use.

endlesscoffee · Sep 28, 2021

straightshooter1 said:
I shoot a lot of 168 SMK's and I always sort them into batches of +/- .001. I used to sort them by BTO (it's not unusual to find large differences between lots). Variance in the BTO's are not as large as with OAL and that's why previous posters recommend sorting by BTO rather than OAL. Obviously, what we're all trying to do is get a consistent seating depth . . . even though COAL will vary in large part because of the bullet's OAL variances, right?

Well, when you seat a bullet, the seating stem does not go down to the ojive. So, seating depth will vary according the the distance from where the bullet fits into the seating stem to the base of the bullet. So, if one want's really consistent seating depth, with one needs to measure from the base of the bullet to that contact point in the seating stem. I decided to do this by using a comparator insert that matches the diameter of that contact point of my seating stem to sort my bullets. As a result, I get VERY consistent seating depth.

Now, when talking about "seating depth", it's not about the jump to the lands. Since "seating depth" is what effects the internal case volume that the powder works in. The more consistent you keep the case volume with consistent powder charge and ignition, the results on paper will be better. Consistent seating depth is way more important than one's jump distance to the lands. When sorting bullets as I do, there IS a little variance in jump due to some variance in the distance from the ojive to the seating stem contact point. But that difference in jump has little effect (of course, unless one loading to touch or jam the lands). This issue on seating depth is important for those who are fine tuning their loads buy testing various seating depths in .003" increments to find a good accuracy node and just where in the node the want to be. Once it's found, one tends to keep that seating depth even as the throat erodes making for longer jumps. I did so and maintained my accuracy well under .5 MOA for over 1,200 rounds as the lands eroded over .030" in my .308 Krieger barrel.

Well, I hope this give you some insight that you might be able to use.

Wow. Thanks for that explanation. I think that's what I've been getting wrapped around. I noticed my die seems to seat a little lower down, but not down to the ogive. I'll give that method a try when I sort these out. Luckily they're all from the same lot.

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Measuring Bullets for C.O.A.L

endlesscoffee

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nn8734

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alfmoonspace

Melmackian

PinesAndProjectiles

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All SINCLAIR INTERNATIONAL Products for Sale Online - 236 Products

Hornady Lock-N-Load Bullet Comparator Basic Set 7 Inserts

Hornady Lock-N-Load Headspace Ga 5 Bushing Set Comparator

endlesscoffee

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Snuby642

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endlesscoffee

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endlesscoffee

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All SINCLAIR INTERNATIONAL Products for Sale Online - 236 Products

Hornady Lock-N-Load Bullet Comparator Basic Set 7 Inserts

Hornady Lock-N-Load Headspace Ga 5 Bushing Set Comparator

smoothy8500

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PinesAndProjectiles

Formerly MinnesotaMulisha

straightshooter1

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