How "standard" is .223 mag COAL 2.260?

S

Stats Shooter

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So I'm doing a ladder test of Hornady 75 grain BTHP with Varget. The recommended COAL is 2.260. obviously that's no where near the rifling. I'm sure Hornady recommends that due the old standard that the max COAL for all AR mags is 2.260.

However, I'm finding with pmags, my Brownell steel mags, my stag steel mags, my Ruger mags, and my mags that say USA in orange on the side will all reliably feed 2.270? In fact there is a bit of room to spare at that length but I left it there because I do not want to single shot these and some of the tips are more like 2.2715. while others are 2.268 when seating base to ogive 1.88.

Also, Lyman and hodgdon published powder quantities wayyy above hornady for the match kings compared to the hornady BTHP.
 
2.260" is the SAAMI standard. You are correct. Just keep in mind that SAAMI is a manufacturer's ANSI standards organization, not a handloader's organization. Their standards are all about how to manufacture ammunition and guns in ways that maintain cross-compatibility among various platforms. The handloader can tailor his ammunition to his particular equipment. A manufacturer of ammunition has no idea whose gun it will end up in when he ships it out, so he has to make it to work in any gun chambered for the cartridge. That's what complying with the SAAMI standards allow him to do. But that's a very different situation from the one the handloader is in. The handloader isn't required to follow the standard, though it usually makes a good starting point for one's own load development tests.

The magazines usually have a little extra room. I find that if you don't leave a little extra, some ammo will bind and not feed reliably. You discover that limit in your magazines with your COL experiments by trial and error.
 
If we look at SAAMI for the .223 Remington Cartridge the maximum C.O.A.L. is in fact 2.260". While the claim is that the 2.260" C.O.A.L. is to accommodate magazine maximum length it really matters not. What you are seeing or noticing is the same thing everyone else has noticed. That being many or dare I say most magazines out there for AR15 type rifles will easily accept cartridge overall lengths of 2.270 or well over the SAAMI specification.

Sierra has a good example with their Sierra Match King 80 grain HBBT bullet. The 69 grain MatchKing has a C.O.A.L. of 2.260" while the 80 grain MatchKing comes in at 2.550 which well exceeds the 2.260" SAAMI maximum. Sierra does go on to say the 80 grain MatchKing was fired in a 5.56 NATO chamber which will accept the longer bullet length and the bullet was never designed to be run through a magazine requiring a C.O.A.L. of 2.260 or less.

Anyway. it is not at all unusual to seat bullets exceeding 2.260" C.O.A.L. in AR15 magazines and they seat, feed and shoot just fine. SAAMI just keeps inside the 2.260" upper limit or maximum limit.

Ron
 
Develop your load the way you will be using it

If it will be used feeding from a magazine use the
2.260 to develop your load
( that will feed from most magazines, but not all
some plastic magazines require 2.250 to feed correctly )
( my ammo is at 2.260 COAL )

( Also, in the future you might acquire some magazines
that need the 2.260 to feed correctly and not the 2.270
that you have measured )

When testing your loads, check each case as fired for
signs of over pressure
Especially when you find different Maximum amounts of powder
from different sources
 
Keep in mind that industry Standards are just that, standards for the industry. They are not immutable laws of nature, they are the limits for what should work and be safe in every standard firearm commonly found in each caliber.

What YOU load to for COAL, and what YOUR individual firearm will accept could be much different.

AND, also remember that while many if not most guns give best accuracy when the bullet is "just off" the lands, rounds considerably shorter can, and often do deliver acceptable accuracy.

If you are shooting a repeater, rounds that work through the magazine and action are better than rounds that don't, unless the game is ONLY group size.

Extra long rounds that must be single loaded negate the benefits of a repeater, even though they might be more accurate. (and HOW MUCH MORE accurate is another individual firearm thing) IF, for example, if longer than SAAMI seating cuts your group from 4 inches to 1 inch, then I'd say its worth it. IF, on the other hand, if your groups go from 1" to 3/4" and you lose the ability of the repeater, is it really worth it??
 
Well I began the ladder test today. COAL avg 2.270, base to ogive 1.88. After 56 rounds all feeding flawless I will stick to that jump.

Now, here is where things have gotten interesting. I began the 75 gr BTHP ladder at 23 gr of Varget moving up in .3 gr increments. I shot 2, 4 shot groups per load. 23, 23.3 and 26.6 grains were mostly unremarkable around or above MOA. However, 23.9, 24.2, and 24.5 all posted sub moa groups with the best "worst" group of 23.9 being .76" and 24.2 being .67". The best 'best' group were also from those charges at .27 for the 24.2 grain load. 24.5 had one group just above moa and one below.
The 24.8 grain load had both groups below moa also but not as tight as 24.2.

At 24.5 and 24.8 primers begin to flatten and at 24.8 there are mild extraction marks on some cases. I'm debating on trying 25.1 which is above ANY published load I have looked at including Lyman which is the highest to find out if in my gun 24.8 is the definitive upper bound of safety given flat primers and slight extraction marks but beyond that I guess there is no point as it is probably not a charge I will use .

My next step will be 2x5 shot groups beginning at 23.9 to 24.3 in .1 grain increments to find what appears to be the true sweet spot for this bullet.

Oh btw
LC once fired brass (fire formed in this chamber from factory ammo)
CCI 450 primers
Trimmed to 1.75
Gun Ruger SR 556 Varmint 1:8 twist 20" stainless bull barrel.

I must say however that I have never had a ladder test were all charges shot so well. Normally things are wide open then tightening up , then opening back up. This bullet/powder combo never truly opens up. It can make ladder testing difficult because any slight mistake shooting can give erroneous results when things are this fine.....hence my second ladder to truly discern the sweet spot.
 
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Without suggesting overmax loading,in both .308 and .223 with 69 gr bullets
I ,too have noticed group tightening at the upper end of powder charge.(Varget)

The often repeated mantra that best accuracy will be found at lower charges is no doubt true with some combinations,but not always.

I'll tell you what you will run into with hotter loads.The.223 just does not have a lot of material strength around the primer pocket.

The price you will pay if you go hot with your .223 loads is loose primer pockets.

If you choose to pursue the warmer loads,I suggest segregate 20 pcs of brass and load them 3 or 4 times and see if the pockets get loose.

Beats finding out 500 or 1000 pcs of brass are junk.

I'll say it again,whatever fps you can squeeze out of Varget,you will get there easier with RE-15.
Seems like I heard Norma N-140 is the same powder,but I do not know that for sure.
 
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COAL

I have a one Savage 223 bolt gun that will accept 2.40 COAL in the Magazine, and chamber, and they shoot well (Hdy 75 gr HP-Not the Amax). That is NOT a 5.56 chamber, but those are longer too.
I have another Savage in 223 that will not chamber any COAL in excess of 2.26.
You can take a sized case, no primer, and slip a bullet in enough to stay. Then chamber it, and eject it. Measure it: that is the max COAL in that particular rifle.
 
Thanks HibC,
I think I will try the 25.1 grain load just because it will annoy me if I never test it. I hope it groups terribly ;) or has obvious over pressure so that I have an easier decision for this load ha-ha.

Also, when I get the load finished, I am going to buy a lot of 1k or so and separate each bullet by weigt/ogive to try and get consistent sub 1/2 -1/4 moa.

Why you ask? Because I love this $#@&!!!!

Also Marco Cali, I have cases I have modified to check the max base to ogive in every caliber I own for any new bullet.
 
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