? length of round diff .223/62 vrs 5.56/55

[Bravo Whiskey]

I think I understand the diff between .223 vrs 5.56 but this threw me a curve ball.
I stood a Privipar 5.56/55 next to an A.E. .223/62 and was confused that the privi was longer. I would have thought that the 62grain round would be longer. With regards to the brass it appears almost the same but the bullet on the 55grain round tops out a heavy1/8' taller.
I think the brass is very close , just slightly diff "necking".
If the 62 grain bullet is longer does this mean that the velocity is less do to less propellant?
I am trying to understand all the smaller details so any help would be great.
TIA,
BW

[Lycanthrope]

Too may variables.

Considering the same powder, seating deeper will cause increased pressure....as will a heavier bullet. Of course, seating longer and closer to the lands can also increase pressure (but you can load beyond mag length in 5.56 and still not touch the lands).

5.56 brass can also have decreased volume/powder capacity due to thicker webbing at the base designed to handle the hotter pressures that 5.56 can be loaded to.

Don't get me started on different powder burn rates and barrel lengths.......

Lycanaskmoredetailedquestionsthrope

[smitty56]

In my opinion, you should consider 5.56 and .223 brass the same. (SEE EDIT below)
For reloading ammunition, there are many different types of bullets that are of different materials, lengths, weights, bases, and tips. When you look in the Lyman 49th book of reloading it tells you many recipes for different calibers. What bullet, what primer, what powder, what powder amount (high to low), and the OAL (over all length) for the that finished round. If you add in the concept of a marksman fine tuning a load for a particular rifle? He will tweak up and down to find what particular powder amount groups his shots best. Additionally, the amount the bullet is either pressed into the case or held out of the case (OAL) affects how his bolt action rifle shoots that load. Semi autos in a magazine require a good crimp where as accuracy loads in a bolt action don't.

Edit after Mr. Lycanthrope's comments....
I absolutely do stand corrected that not all brass is the same. In my comment that I treat all brass the same, let me clarify some details. For the majority of 223/556 ammo that I reload, I do treat the .223/556 brass all the same but DO load at a lower level than maximum. (about 80% of the low to high range) That covers me for variations in case volume. This ammo is for general purpose AR shooting. However, with loads for accuracy, and mainly in a bolt action .223, I choose all the same brass and at as close as possible to the same weight for each case. (self made match ammo) Those rounds go into plastic cartridge boxes where each reloaded round is documented and the empty case placed back into the box. The general purpose AR loaded rounds simply go into 50 caliber ammo cans.

I think I understand the diff between .223 vrs 5.56 but this threw me a curve ball.
I stood a Privipar 5.56/55 next to an A.E. .223/62 and was confused that the privi was longer. I would have thought that the 62grain round would be longer. With regards to the brass it appears almost the same but the bullet on the 55grain round tops out a heavy1/8' taller.
I think the brass is very close , just slightly diff "necking".
If the 62 grain bullet is longer does this mean that the velocity is less do to less propellant?
I am trying to understand all the smaller details so any help would be great.
TIA,
BW

[Lycanthrope]

In my opinion, you should consider 5.56 and .223 brass the same.
.

Externally, they are the same. Internally, there can be a variance of half a grain of powder. That changes loads considerably and can be a very bad thing if you are already at max loadings.

Most (but not all) rifles shoot tightest when then are loaded long. In an AR, that usually is limited by magazine length unless you want to single feed rounds (and CMP shooters will do that at longer ranges).

Lycanbecarefulthrope

[Hawk]

I can attest to brass differences between .223 and 5.56. I've loaded Lake City brass (5.56) with 24 gns of H335 and 60 gn heads and Remington 223 brass with 24 gns of H335 and 60 gn heads both to the same OAL. The LC load is much hotter do to internal case dimensions. The report gets peoples attention, and my primers get flattened pretty badly with the LC load. I've since drop to 23 gns when I use the LC brass. I've never crono'd either, but I should.

[Rundownfid]

As to the original posters original queston. This is just a guess, but it makes sense that the 60 gr is fatter, not in max caliber but thicker in the nose area. That would mean the ogive is more round than the 55 (more pointed). Perhaps the 60 gr is slightly shorter due to its contacting the lands closer to the tip?

[Lycanthrope]

As to the original posters original queston. This is just a guess, but it makes sense that the 60 gr is fatter, not in max caliber but thicker in the nose area. That would mean the ogive is more round than the 55 (more pointed). Perhaps the 60 gr is slightly shorter due to its contacting the lands closer to the tip?

Doubtful in a spire point configuration. Even 5gr makes a difference in a diameter as thin as .224.

I wager they are just seated deeper and likely are running a totally different powder than the 55gr loads.

Lycannotallbrandsloadthesamelengththrope

[Bravo Whiskey]

Hey Guys,
Thanks for all the info. I now realize there are countless options. I ASSumed that a bullet would always be seated @ the same depth with in the shell and if was longer due to weight and or design that it would naturally be longer out to the limits of the chamber. I am starting to work on my groups and midrange shooting and checking out what factory ammo works best.
I have been saving my brass and I will try to seperate 5.56 from .223.
I have been only trying to buy 5.56 but found some AE .223/62 so I wanted to give it a try. This is all being shot out of an AR w/ 1:7 16"
One thing for sure is I need some learn'in before I start to reload.
Great Info
BW

[jrm]

I think I understand the diff between .223 vrs 5.56 but this threw me a curve ball.
I stood a Privipar 5.56/55 next to an A.E. .223/62 and was confused that the privi was longer. I would have thought that the 62grain round would be longer. With regards to the brass it appears almost the same but the bullet on the 55grain round tops out a heavy1/8' taller.
I think the brass is very close , just slightly diff "necking".
If the 62 grain bullet is longer does this mean that the velocity is less do to less propellant?
I am trying to understand all the smaller details so any help would be great.
TIA,
BW

Velocity is less do to weight of bullet, Look at loading book, see a certain name powder in a caliber. Then look what happens when the weight of the bullet gets heavier. That same powder gets less as bullet gets heavier.
As others mention different powders call for different AOL (over all lengths) this has to do with the powders burn rate and pressure of. Theoredically your 1/7 twist would stabalize a heavier bullet. I load 75gn bullets for my Colt 20" barrel with 1/7 twist H-Bar. Im sure you knew that, just wanted to add after you posted what your rifles twist and barrel where. Another general rule of thumb is the lighter the bullet the faster burning type powder is used. Heavier bullets uses slower burning powders. Best bet is to load as data says, and try to pick load as to oal to fit in magazine After about 75gns, depending on bullet, they get to long for magazine, and wont feed. Take care.