Acceptable COAL Variance for .223 Rem?

R

Rangerrich99

New member
Okay, let me start by saying that I've only been reloading for 12 months now (in fact, 11 months 2 weeks), so this is probably a dumb newbie question, so bear with me here.

I reloaded a couple hundred (250) .223 rem last night and after measuring them I found that about 40 rounds measured an average of 0.004 inches shorter than 2.260 inches, with the extreme variance for 8 rounds being 0.008 inches short, or put another way, those 8 measured 2.252 inches. I found this surprising, especially as no cartridge measured longer than 2.262, or just .002 inches longer than the recommended 2.260 inches. My question is should I be concerned, or is there a variable I'm overlooking here?

Details:

Cases: FC
Trim Length: 1.750 +/- 0.003, average variance - 0.00176
Bullet type: Nosler 60 gr. boat tail/ballistic tip Varmint

I'm don't think powder brand/type should matter, but just in case, I'm using 23.3 gr./ IMR 8208 XBR. Judging from the height of the powder in the case and the length of the bullet I'm guessing that compression is minimal.

I know that what we're talking about here is about 1/20th of an inch, I just would like to know if there's something obvious I'm unaware of here or if this is just normal when reloading.

Thanks in advance for your replies.


P.S. Just thought of this: could it be the variance in bullet length or variance in length of the ballistic tip?

P.P.S. All primers were checked for seating depth, all are slightly recessed into the primer pocket.
 
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If you are measuring to the tip, that is pretty solid consistency especially considering that you could be a thou or two off just from not having the round perfectly square in your calipers.

If you are measuring to the ogive, you likely have some occasional buildup or dirt in your die or just a little out of spec round.

Either way, a few thousandths isn't going to make any significant difference.
 
I measured from the tip (meplat?); I wouldn't know the first thing about how to measure from the ogive.

I actually just did a quick search on how to measure to the ogive, which I'll probably attempt later, but the authors of the articles I just skimmed all say that even ogive shape/length can vary from bullet to bullet from the same manufacturer/lot, so it seems that I may not be able to get more consistent than about 1/20th-1/25th of an inch.
 
The 2.260 that you can't exceed is ONLY so that the rounds will fit into a magazine. You can go longer and you can go shorter. If you have a fast twist, you are absolutely going to be a lot longer if 77-80 or 82 gr target rounds.

Use the Hornady OAL gauge to see where your round hits the lands. Where it does, you will see the marks on the bullet. You will need their dummy bullet that screws into the gauge also. Seat deeper about .003 from the lands and that will be your starting seating reading. Take ten shots with the same exact powder and load. Seat deeper another .003, ten shots. Again and again and again, each time going .003 deeper. Obviously, set this up with your seating die and go to the range with 50-70 or so rounds. Your best grouping with exactly the same load and powder will tell you what the best seating depth for YOUR rifle. Make sure you use the same brass for all shots.

READ A RELOADING MANUAL- Lyman's 49th is suggested. A few of the others with very familiar names are pretty useless on the tutorials and very long on reloading data for their own bullets.

You will know that you are too long when you are using undue force to chamber a round. Bullet is hitting the lands nice and good and you are inscribing the lands onto the bullet. Not good and may very well damage your chamber or yourself.
 
@Fotheringill - Thank you for your advice. At present I don't have an OAL gauge, but I probably will put that one the X-Mas list.

Also, I have Lyman's manual and a couple others, though I admit that I haven't read any of them cover to cover. So I have to admit that I don't remember reading anything that said I had to have an OAL gauge. Maybe during X-Mas during my three day vacation I'll get a chance to read Lyman's more carefully.

As my recipe sits so far I average around 1 MOA 5 shot groups at 200 yds, but with some significant outliers (2-4 inches outside the rest of the group) on every outing to the range (thankfully not every group), which in all likelihood is operator error, as I'm not the best rifleman. I've been working on my trigger control, but I have good days and just as many bad days.

Part of my reason for my OP was the thought that perhaps the variance in COAL that I noticed might be the cause of some of those strays. Again, it's probably just my inconsistencies on the trigger, but just by asking you guys I can probably save myself countless hours at the reloading bench and at the range trying to figure it out on my own.

I use this recipe for prairie dogs, at an average range of over 250 yds, out of an essentially stock AR (aftermarket trigger and a Mag-Pul fixed stock), so consistent small groups are absolutely necessary.

Anyway, thanks again guys, I'm learning a lot here.
 
You're doing good, measuring off the meplat will always give you those kind of inconsistencies, and with the Hornady guage you may still show a few thou +/-. But that is probably not causing your "outliers". There are way too many things to go into in a short reply that can cause those, like bright sunbeams, planet alignment, spider farts, cat sneezes, and general luck of the draw.

Don't get me wrong, there are a LOT of ways to tweak your ammunition, and this board is a good place to do some research, but sometimes it's the rifle, (never the shooter :D )

You'll get it. :D
 
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