Is there any reason to follow COAL data for .223 in AR?

Appropriate jump off of the lands for the bullet, or mag length, whichever is the shorter of the two. Can’t think of the last time I even looked at a COAL spec in a book. I don’t crimp rifle rounds, so I don’t care about cannelures.

You seemed to understand the issue at hand and even show how sometimes you do follow while other times you don't . Most manuals COAL are suggestions but in the AR we all know 2.260 is not a suggestion . If I'm crimping my 55gr bullets then the crimp groove is centered perfect for the crimp . If I'm not crimping the 55's my COAL is 2.240-ish which leaves the crimp groove fully exposed above my case mouth .

The fact the AR has it's mag length restrictions and the long throat . Seating deeper reduces case volume/velocity and seating longer stops at 2.260 and I'm still .040+ off the lands so it's not worth the time for me . I rarely adjust seating depth to fine tune a load . It's almost always playing with the powder charge , crimp/bullet hold or primers .

To answer your specific question , there's likely just as many reason why one would want to follow the suggested COAL as there is to pick one that best works for your specific application .

Varminterror said:

Appropriate jump off of the lands for the bullet, or mag length, whichever is the shorter of the two.

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^^^This^^^

Just as long as you're not jammed into the lands, there isn't really a lot of risk in not abiding by the OAL in rifle loading data. Magazine fit and setting bullet jump to the rifling are more important to worry about.

Don't be too sure you can't hit the rifling with a magazine length bullet in an AR-15. In the past I found that a Hornady 52gr BTHP could easily be jammed into the rifling of a .223 Wylde chamber and still fit in an AR-15 magazine. I don't recall the exact OAL I ended up at, but it seemed short (2.20" maybe).

This point was recently driven home for me setting up loads for my new CZ527 in .223. A Nosler 60gr Partition has to be loaded to 2.21" in my rifle to stay out of the groves. The 55gr Nosler Varmageddon FBHP needs to be at 2.18". Yet I can seat a Sierra 65gr Gameking to 2.25" and just kiss the rifling. And I managed to leave the bullet of a 55gr FMJ dummy round stuck in the chamber throat.

So never take anything as a given that it will always work, just because it should!

^^^^ I have min spec chambers in my AR's so I have to check for bullet/land contact with every bullet. There are several reload guides that have me jamming the bullet into the lands. Always check for this every time you try a new bullet or even a lat/batch change. Don't take it for granted, bad things can happen.

CMV said:

follow the often much shorter lengths in load data

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When loading 52, 53 gr bullets. Possibly others.

There has to be enough bullet shank in the case neck to provide good neck tension. When the round chambers, the bullet should not move forward, makng a longer COL.

https://www.thehighroad.org/index.php?media/223-5-56-minimum-bullet-shank-in-contact-with-neck.1429/

Your 2.255" seated oal using Hornady 55 FMJ's would not chamber in my one .223 bolt action rifle, other's bolt actions, or some .223 chambered AR's. To touch the lands in my bolt action the maximum to touch is 2.246" oal. So your long oal may not chamber should someone want to shoot your loads. To touch the lands in two popular AR's with Hornady 55 FMJ's the oal for both is 2.370" in one and 2.390" in the other. The bullet is about falling out of the case this long. I've seen no gain in accuracy in AR's seating Hornady 55 FMJ's longer than recommended lengths so I seat them from 2.200-2.230 maximum. Plus seating some bullets long could mean neck tension is low. Seating to the cannelure should put the oal close to recommended lengths. Now sharply pointed 55 FMJ's seating to 2.250" is normal but not the blunt tipped Hornady 55 FMJ.

How critical the jump to rifling distance is varies by bullet and barrel in my experience. "Magazine" .224" bullets like the 69gr and 77gr Sierra Matchking or Nosler Custom Competition, 75gr Hornady HPBT and similar styles aren't picky about how far they are from the rifling. Whereas something like the long 80gr match bullets (single load only in an AR) I had better luck running them to .010-015" off the lands.

I'm now learning how to work with "hunting" bullets in my new CZ, but I expect they'll respond well to similar inputs. However I learned Saturday that the CZ might shoot really well with the 75gr Hornady HPBT, which may make me take a completely different approach to loading for it.

BTW, the 75gr Hornady load I have on hand isn't "worked up" for any specific rifle. It's just a max charge of Varget, a Remington 7 1/2 primer in a Lake City case with a finished OAL of 2.25" to fit in a PMag for an AR-15. A 10 shot group gave me 9 into 1.5" at 100 yards with the first shot about an inch high of the remainder. I'm writing that first shot off to the action settling into the stock after retightening the action screws.

Edited: And I'm not surprised you can't hit the lands on a Remington 700 barrel. Remingtons generally have long throats on the factory barrels.

If you're interested in a longer OAL that will fit in a magazine, do some research on the new ASC magazines. Metal body with an orange follower. Stock they can fit an OAL of 2.273, I've heard that 2.3 is not unheard of, though I have not messed with that yet. Every little bit helps.

CMV said:

Is there any reason to NOT do that and follow the often much shorter lengths in load data?

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There is no reason that a reloader should be limited to the book OAL in a 223/5.56 AR-15 as long as:
1) The bullet shank is long enough and there is sufficient neck tension for the increased OAL. (For instance, .224" Hornady 55gr SP bullets are too short for mag length seating and need to be closer to 2.200"- 2.225")
2) The reloader is not crimping.
3) The recommended book OAL for the bullet is shorter than mag length (approx 2.260"). ie - you're not knowingly trying to jam long bullets into mag length!
4) The reloader can confirm that the mag length OAL for a specific bullet isn't hitting the rifling lands. Different bullets have different ogives. For the most part, this is a no brainer since most chambers are longer than the mag length of most magazines. However, this should be confirmed due to the wide variety of 223/5.56 products. There are some rifles out there that are chambered in 223 Remington and do have short throats. Additionally, "Wylde" can vary based on the reamer. There are some light bullets that are long for their weight, like tracers and copper bullets. If there are mags that fit OAL's longer than 2.260", I could see how some combination of these may be able to jam a bullet into the lands of a specific rifle.

When I look at the overall length in the reloading manuals I am thinking that is the length that they loaded for their testing purposes. As long as I do not load shorter than that suggested length and not longer than magazine length then I should be fine. There is a natural variance in the length of bullets, especially FMJs and soft points, so I will try to set my seating die to not seat shorter that the suggested length knowing that many will be longer.

Some books list max SAAMI length, while most list what they tested at. The first thing I do with a new bullet that I have not used is determine what my MAX OAL will be for all my rifles in that caliber. I have found over the years that Sierra normally have you setting around 0.030". And I normally find the sweet spot around that length with Sierra. Other wise I back off 0.020"-0.030" and start my load development provide it fits the magazine. If not I use Magazine length. Start low and workup.

CMV said:

If bullet has a cannelure, then I load to the max length possible and still hit the cannelure.

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No need for this. Don’t need to crimp, so don’t need to bother with seating the mouth to the cannelure.

I seat all of my rifle rounds, save heavy DGR, roll crimped monsters, to wherever the lands or the mag tell me.