2.250 C.O.A.L. Puts Bullet Above Crimping Groove ?

[billt]

These are the first 10, .223's off the Dillon. As you can see the overall length is right on the money at 2.250, but the bullet is seated above the cannelure to achieve this length. The bullets are IMI 55 Gr. FMJ Boat Tails. Really nice slugs. The cases are mixed, but all are trimmed to minimum overall length of 1.750. The new Hornady 8th Edition Manual lists 1.760 as minimum case length. It also lists a C.O.A.L. (Cartridge Overall Length), at 2.200, not 2.250 with their 55 Gr. FMJ Boat Tail Mil-Spec bullet.

So here is the deal. I can bump the C.O.A.L. down to 2.200 per the Hornady manual, and that should put it right into the cannelure. I'll gain .050. That will help a lot. This really doesn't matter because I'm crimping with a Lee Factory Crimp Die, which will crimp anywhere along the bullet. It does not have to be in the crimping groove. The Lee Factory Crimp Die only exerts lateral force on the case, not longitudinal.

What I'm concerned about is will running that short of an overall length effect feeding in all of my AR-15? I normally run 2.250 and they all run like a raped ape, including my Ruger Mini 14. I'm thinking shorter won't matter, but longer would. Any of you guys run into this? My load is 25.7 grains of H-335. This is a small ball powder that flows through a measure like water. Let me know what you guys think before I yank the handle on 2,500 of these babies. They fit in all of my Bushmasters, LWRC's, Colts, Mini 14, and my Dillon case gage.

I hauled out the guns because I wanted to prove out the case gage. These things are nice, and check headspace of your finished rounds, as well as case length. They have a go / no go step ground into both sides. Really makes it nice.  Bill T.

http://www.dillonprecision.com/#/content/p/9/pid/25547/catid/3/Dillon_Rifle_Case_Gages

[billt]

Another thing I should mention is the crimping groove on these bullets is very consistent in regards to location on the bullet ogive. On the last batch of Winchester 55 Gr. FMJ's I got from Midway, the cannelure was all over the place. Some high, some low. These IMI slugs are very consistent in that regard.  Bill T.

[Pathfinder]

These are the first 10, .223's off the Dillon. As you can see the overall length is right on the money at 2.250, but the bullet is seated above the cannelure to achieve this length. The bullets are IMI 55 Gr. FMJ Boat Tails. Really nice slugs. The cases are mixed, but all are trimmed to minimum overall length of 1.750. The new Hornady 8th Edition Manual lists 1.760 as minimum case length. It also lists a C.O.A.L. (Cartridge Overall Length), at 2.200, not 2.250 with their 55 Gr. FMJ Boat Tail Mil-Spec bullet.

If Hornady says 1.760 is the minimum, why did you trim to 1.750?That may be a start of your issues.

I've seen cartridges with the cannelure visible, but not completely out of the case. I would reset them to COAL 2.200 and see if you can hide some of the cannelure. BUT - I have never reloaded .223, so take this with a huge grain of salt.

[Pecos Bill]

Bill, I wouldn't worry about the crimping groove. The IMI bullets may be set for a longer case or a shorter COL. If 2,250 works for you then use it. A quick check shows Lyman at 2.260 for a 55 Soft point and Sierra shows 2.250 for their 55 FMJ. Personally I don't crimp for my AR and have no feed or bullet set back problems.

FWIW, Pecos who expects plenty of flak for this post.

P.S. I also neck size for my Rock River and don't have any feed problems or extraction problems. (I'll get some for that.)

P.S.S. Case length is not as critical as you make out. You need to have enough neck length to hold the bullet square and tight. The critical dimension is the head space from the datem line on the case shoulder to the base. Yeah you're short but it's not critical. They'll grow back eventually.

[billt]

If Hornady says 1.760 is the minimum, why did you trim to 1.750?

Because every other loading manual I own calls out 1.750. My Giruad came set to trim at 1.750, and I saw no reason to alter it.  Bill T.

[Sponsor]

[PegLeg45]

Heck, Bill....send me a case of 'em and I'll run 'em through my Mini and get back to ya.           

[alfsauve]

Several things at play.

For accuracy sake you want the bullet out far enough so they're just off the lands of the barrel.  Not too far back and not touching the lands either.

But then if you're shooting these in a lot of guns you might have to make the COAL for the shortest of chambers.

As you shorten COAL pressure will go up because of the reduced case volume.   And visa-versa.

Personally, I'd go with what the load data says, then adjust slowly for best accuracy.

And yeah, I think H-335 is the most recommended for .223. 

[billt]

I think I'm going to bump the C.O.A.L. down to 2.200. This is going to be general purpose plinking and 200 yard steel gong ammo, not for any serious paper punching. The shorter length will be better from a feeding standpoint. Also, 5.56 MM chambers are freebored to begin with, so it is all but impossible to seat out to near the lands for accuracy.

I don't think dropping the bullet .050 is going to increase pressure as it would in a short pistol case like a 9 MM or .45 ACP. I won't be decreasing volume anywhere near as much. I think shooting it in a .223 non freebored chamber would have a greater effect. Even then I suspect the actual effect would be nil. I say this because a while back I loaded up some maximum 5.56 MM loads out of the AR-15 Service Rifle section of the new Sierra Manual, and when I shot them in my Ruger Mini 14 which has a .223 chamber, they didn't even cycle. Remington UMC factory loads were noticeably hotter, and they are .223 not 5.56 MM. Those the Mini kicked at least 15 feet.  Bill T.

[alfsauve]

All very true, BillT. 

Wasn't there a study recently (or at least an article) that really firm crimping (like curling the lip of the brass into the crimping grove - I can't spell cannelure) wasn't really necessary to hold the rounds in place?   Some crimping yes, but not excessive.

[billt]

All very true, BillT. 

Wasn't there a study recently (or at least an article) that really firm crimping (like curling the lip of the brass into the crimping grove - I can't spell cannelure) wasn't really necessary to hold the rounds in place?   Some crimping yes, but not excessive.

I've read several articles about crimping, as it can be one of the more controversial steps in the reloading process. Some swear by it, some at it. I think it is good practice in loading for semi auto rifles. Especially for .308 and above because of the possibility of bullet setback from recoil. I think the key to crimping is consistency as opposed to how much or how little.

This is the main reason I'm sold on the Lee Factory Crimp Die. It is activated by the top of the shell holder itself, and not the top of the case. It takes case length out of the equation in regards to amount of crimp that is actually applied. As I mentioned it also places zero longitudinal stress on the case itself, only lateral. It is an extremely easy and inexpensive die to buy, set up, and use. I have them in most every caliber that I load for.  Bill T.