5.56-6x45 questions

Scrypt

Scrypt

New member
First off, I'd like to thank y'all for hosting this forum and I hope I don't cause too much trouble
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I don't reload, but I'm going to start and I like to build a basic understanding before I jump into anything.

That aside:


I just purchased my first AR in 5.56- I am unsure at this time if it is indeed mil-spec; so, my first question is:

Are Core-15's M4s true 5.56?

I will probably be following .223 loads, but it would be good to know for sure.


I read that a 1:7 twist rate is good for 50-90gr bullets, though 90s won't likely fit my mag, and that in all likely hood, 62-80gr are going to be my best bet for mag fed ammo. Your thoughts on this?


With all things being ideal, what velocity should I expect from a 1:7twist 16” barrel in various grain bullets?


Loading for hunting the larger species of this rounds capabilities, I would assume the heaver grain bullets would be my choice; is this the consensus?


What is the maximum moral range for hunting out of a 16” barrel in this caliber?
Max range for target?


I may also be interested in a 6x45 conversion, would all the info pertaining to the above carry over to a 16” 6x45, save for barrel twist? (though I will probably save that for my next build- questions to follow)


Any other guidance, corrections, or recommended reading you can advise?









My next rifle will surely be 6x45 build, though, it will not likely be an AR and will probably have a 20-26” barrel. These next questions are regarding the future build.

The maximum grain recommended to fit OAL standard mag is 95gr, correct?


The twist rate recommended is 1:10?


To gain the most accuracy while maintaining higher terminal ballistics out to the furthest ranges of this round, it is my assumption that my round of choice- magazine fed, is 75-95gr out of a 24-26” 1:10 twist. Your thoughts?


With all things being ideal, what velocity should I expect from a 1:10twist 24-26” barrel in various grain bullets?


What is the maximum moral range for hunting out of a 24-26” barrel in this caliber?
Max range for target?


Any other guidance, corrections, or recommended reading you can advise?
 
Welcome to the forum....Many of your questions have been thoroughly discussed and if you will use the PM search engine on specific subjects at the top of the page, you will probably find many opinions on each...

Not to be putting you off in your quest for information, but that is the best place to start on any subject...Some of your questions/concerns can get pretty detailed and the resources to find the answers are already present...

If you check the data base and can't find the answer to a specific question, you will find a wealth of experience and knowledge among the general membership, but wide open and detailed questions need a little research on your part first..

We have a couple of lengthy topics just under the "AR" section that may answer many of your immediate concerns..
 
Your post is right on time - two weeks (it's an insider joke)
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"Mil-spec" is a cliché that is so over used that it should banned from the language - even the military language. There have been so many discussions on this, that there is a book ready to be written by just harvesting the archives of this forum.

Your new rifle, no matter who built it, takes 223 and 5.56x45 ammunition interchangeably.

There is no way to predict the velocity of your combination - too many variables.

Your issues of larger game does not say how large and what game - coyotes, wolves, antelopes, caribou?? And morals of shooting large game animals with the 223... I won't touch that with a 10 foot pole

And your target does not say what or why... but the 223/5.56 is shot at 1,000 yd targets and does well, and people have been whackin' Prairie dogs at over 1,000 yds with it, and eastern woodchucks at 500+ yds - so you should be able to have fun somehow.


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As far as bullet size for the .223. Once you get longer than the .69 or .75 grain bullets, they don't fit in the magazine, unless you seat them very deep in the cartridge. Doing that, uses up powder space and defeats the purpose. If you want to shoot the 80's and 90's with any speed, be prepared to load them single shot style in the AR. For small game up to coyote, most people use 40 to 60 grain bullets of various makes. Hornady and Serria is a good place to start looking. A lot of people think the smaller 40's won't shoot good out of a 1:7 twist. Nonsense, however the only way to comfirm in your particular rifle is to try. As far a morale shots on game. That would depend on how good of a shot you are. The .223/5.56 will take game of reasonable size as far as you can confidently hit it in the kill zone. The selection of bullet has more to do with that. Wish you luck and enjoy the process of reloading.

Tom
 
Thank you for your replies.


OldTurtle, believe me I've been reading. This post was the cumulative response of 6 months research, just to make sure I'm absorbing it all properly.


CatShooter, I had a feeling that was going to be the case
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From what I've been reading, though .223 and 5.56 are externally identical, the operating pressures are different which can(in some cases) cause adverse effects on the firearm.

As to moral game-size:distance shots, I obviously won't be shooting elephant @ 1200 even if I could shoot the grapes off a fly(obviously meant to be an extreme example; bull elk @ 300-500 though, to me, seems just a wee bit risky with a 22). White tail @ 300 seems reasonable, but what about @ 450? Caribou? I'd imagine I'd pass on that, just trying to build some reference.

Target=paper for fun. Though I want to load for hunting, I will mostly shoot for practice and will shoot the loads that I will carry. Can people really get out to 1000 consistently with a 16”?!


MGYSGT, do all 75grains load to mag length when seated to spec?

Do you know what max bullet length I should be lookin' for? (I'll get my micrometer out soon enough and check my mags)

Are there some 77-80's that might fit without being seated too deep?

It seems most loads are 2.28” OAL, a few 60-70s are 2.3~. I see one 80gr Sierra MatchKing HPBT OAL as 2.28, so I'm assuming it's that most 80s-90s won't fit mags seated to spec but some will? (unless this load data is wrong; it's not manufactures)
 
Quote:MGYSGT, do all 75grains load to mag length when seated to spec.....I tried loading some 75gr A-Max Hornady rounds and had to seat them way down in the case to the point that after the first five rounds, I abandoned the effort...That was with a 1/7 twist M4 carbine...I've since kept my .223 ARs at a 1/9 twist...

All of my AR mags are 2.26" at a max. and I tend to reload mine just shy of that length, depending on the bullet configuration..Soft points don't seem to potentially hang up or rub as much as some ballistic tips, but the ballistic tips seem to be slightly more accurate..

I have seen some benchrest shooters using 80 and 90 gr rounds shooting 600 yards with decent accuracy, considering that the shooter was having trouble reading the wind flags, but the rounds blew into a decent group...With some of my 55 and 60gr rounds, I've been able to knock off Prairie Dogs past 400 yards with a 16" barrel on a pretty consistent basis and my shooting leaves something to be desired at times...
 
Although possibly not the best bullet for your personal application(s), the Sierra 77 grain SMK (.224") is designed to be seated to magazine length. It should stabilize in a 1:9" twist, so you'll be good to go in a 1:7" twist.
 
Just measured my mags- 2.275 at the shortest. They open up right before and right after.

"
.223 Loading Data for Sierra's
77 grain HPBT MatchKing

Test Specifications
Firearms used: Colt AR-15A2 HBAR
BBL Length/Twist; 20"/1x7"

Test Components
Cases: Remington
Trim-to Length: 1.750"
Primers: Remington 7 1/2

.224" 77 GR. MatchKing HPBT
Cartridge OAL: 2.260"
"
-http://www.sierrabullets.com/index.cfm?section=techservice&page=xring&volume=6&issue=3

They're not for hunting, but it's encouraging- I'll have to give some a try then; seems their 80s are .057" too long for my mags.

Would that difference in seat depth really contribute much to loss of velocity?

Barnes TTSX 62gr look promising.
 
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.224

Nosler
CC:
77gr-.973
CC HPBT:
77gr-.98
80gr-1.065


Hornady
BTHP Match/Moly:
75gr-.98


Sierra
MatchKing:
77gr-.994
80gr-1.066


Barnes
BT Match:
85gr-1.068

None of these are hunting rounds though.



These are

Speer
Semispitzer SP:
70gr-.808

Sierra
GameKing:
65gr-.852

Barnes
TTSX:
62gr-.981
TSX:
70gr-1.036
 
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Originally Posted By: Scrypt

"From what I've been reading, though .223 and 5.56 are externally identical, the operating pressures are different which can(in some cases) cause adverse effects on the firearm."



Also, a myth - the military measures pressures from a different point and they take the headspace from a different datum line.

The actual pressure in both is the same (within loading tolerances).. mid 55's


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Originally Posted By: CatShooterYour post is right on time - two weeks (it's an insider joke)
tt2.gif


"Mil-spec" is a cliché that is so over used that it should banned from the language - even the military language. There have been so many discussions on this, that there is a book ready to be written by just harvesting the archives of this forum.

Your new rifle, no matter who built it, takes 223 and 5.56x45 ammunition interchangeably.

There is no way to predict the velocity of your combination - too many variables.

Your issues of larger game does not say how large and what game - coyotes, wolves, antelopes, caribou?? And morals of shooting large game animals with the 223... I won't touch that with a 10 foot pole

And your target does not say what or why... but the 223/5.56 is shot at 1,000 yd targets and does well, and people have been whackin' Prairie dogs at over 1,000 yds with it, and eastern woodchucks at 500+ yds - so you should be able to have fun somehow.


.

Not according to DPMS.

Quote:17. Is there a difference between 5.56mm and .223 Rem?


Despite external dimensions being identical, military 5.56mm ammunition is a higher pressure round than commercial .223. To accommodate this, 5.56 barrels have a longer throat. The bullet doesn't engage the rifling until slightly further down the barrel. You can shoot 223 ammo from a 5.56 barrel, but 5.56 ammo in a .223 barrel could lead to high pressure failures, and higher wear on the rifle. The advantage of a .223-barrel, when paired with quality .223 ammunition, often offers greater accuracy.

http://www.dpmsinc.com/Frequently-Asked_ep_55-1.html
 
Quote:Quote:17. Is there a difference between 5.56mm and .223 Rem?


Despite external dimensions being identical, military 5.56mm ammunition is a higher pressure round than commercial .223. To accommodate this, 5.56 barrels have a longer throat. The bullet doesn't engage the rifling until slightly further down the barrel. You can shoot 223 ammo from a 5.56 barrel, but 5.56 ammo in a .223 barrel could lead to high pressure failures, and higher wear on the rifle. The advantage of a .223-barrel, when paired with quality .223 ammunition, often offers greater accuracy.

http://www.dpmsinc.com/Frequently-Asked_ep_55-1.html

This is similar to the info I read from a 3rd party, non-retail blog, which I have lost the site. What it said was, that though some manufacturers bore throats to 5.56 dimensions, sometimes they don't follow up with bit replacement as soon as they should, and it becomes necessary to bore the lands slightly.

I have no experience with this, I'm just repeating what I read.
 
Script

I am not very familiar with Core 15's so I went to their website. If the specifications they have listed are correct it appears to mostly follow the M4 Technical Data Package (ie. Mil Spec) the deviations or areas I am unsure of are noted in red.

While you may load and fire ammunition using 80 grain bullets singly these bullets are to long to be loaded to the maximum cartridge overall length of 2.260 inches that is required to fit inside a standard AR 5.56 magazine. 77 grain open tipped match bullets are the heaviest production bullets you will be able to load to mag length.



•CORE15™ Mil-Spec Forged 7075-T6 Lower Receiver, Type III Class II Hard-coat anodized finish, beveled Magwell for improved reloading speed, machined chevrons in front strap, bullet pictogram safety markings
•CORE15™ Mil-Spec Forged 7075-T6 M-4 Upper Receiver, Type III Class II Hard-coat anodized finish, M4 Feed Ramps, (1913 Picatinny rail flat top) w/ dry lube internal finish and laser engraved T-markings
•16” 4150 CMV Chrome Moly M4 Profile Chrome Lined Barrel 1:7 Twist
•Chambered in .223/5.56 x 45 mm NATO
•Direct Gas Impingement Gas System
•Gas Tube made of 304 grade Stainless Steel
•Chrome lined Stainless Steel Bolt Carrier and Bolt Carrier Key This is non standard. What type of stainless steel? standard M-16 Full auto or semi auto BCG? M16 full auto is prefeable? Are grade #8 fasteners used? Is the Carrier key properly staked?
•Magnetic Particle Inspected (MPI) Bolt Assembly Capenter 158 steel? Shot peened?
•A-2 Flash Hider
•A Frame Front Sight Base (Forged)F marked or A2? Should be F
•Optional Low Profile or Picatinny Gas Block (not shown)
•Optional back up Iron Rear Sight (not shown)
•M-4 Style Thermoset molded Polymer Hand Guards with
•Dual Heat Shields
•A-2 Pistol Grip
•CORE15™ Six Position Retractable Stock. Is the stock and buffer tube Mil Spec or Commercial? Is the castle nut properly staked? •30rd Aluminum Magazine
•CORE15™ Owner’s Manual
•Weight (unloaded): 5.2 lbs.
•Manufacturers Lifetime Warranty
 
Originally Posted By: mj36639

Not according to DPMS.

Quote:17. Is there a difference between 5.56mm and .223 Rem?


Despite external dimensions being identical, military 5.56mm ammunition is a higher pressure round than commercial .223. To accommodate this, 5.56 barrels have a longer throat. The bullet doesn't engage the rifling until slightly further down the barrel. You can shoot 223 ammo from a 5.56 barrel, but 5.56 ammo in a .223 barrel could lead to high pressure failures, and higher wear on the rifle. The advantage of a .223-barrel, when paired with quality .223 ammunition, often offers greater accuracy.

http://www.dpmsinc.com/Frequently-Asked_ep_55-1.html

Since you dragged this up, tell me something...

Just EXACTLY, what is a "high pressure failure", and what is "higher wear on the rifle".

And why hasn't the tens of millions of military 5.56 that has been fired in standard 223 rifles caused an outbreak of these problems.

Inquiring minds want to know
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"Signs of high pressure include: primers that are blown-out or flowed back into the firing pin hole, flattened primers, powder stains or signs of high-pressure jets (the last only visible under magnification). High pressure can also cause violent cycling in gas guns, high cyclic rates in auto weapons, and cases that are bulged or suffer head or neck separations (these can also be caused by other things, but primer and powder anomalies are almost always signs of unsafe pressures)"-www.weaponsman.com
 


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