Is .223 - 55 gr FMJ-BT OK For AR-15 & M4

brycealbright · February 23, 2015, 03:29 PM

The reason I ask, is that the Hornady Reloading Book does not have this bullet listed in their Service Rifle Data section. It is listed in the .223 reloading section. Thanks in advance.

oldpapps · February 23, 2015, 05:39 PM

Anything that will chamber and fire in a .223 chamber/throating will do the same in a a 5.56 chamber with no problems. Your biggest problem would be projectile weights versus twist rates and the 55 grain range is usable with most, well I use it.

Load with care,

OSOK

sevt_chevelle · February 23, 2015, 06:48 PM

It will work just fine. Am guessing why its not listed in the service rifle section because maybe that would push it into 5.56 pressure range and Hornady doesn't want to provide such load data.

If you want a 55 fmj load at 5.56 ranges Accurate provides load info on their website.

rg1 · February 23, 2015, 08:17 PM

55 FMJ's are probably the most used bullet weight for reloading AR-15's and Hornady's 55 FMJ is the most recommended 55 FMJ. Their 55 FMJ is possibly the most accurate, affordable, and consistent FMJ bullet. Why Hornady doesn't test their 55 grain bullets in AR's for their manual is hard to understand. They keep copying previous data from one edition to the next and it's always in a 26" bolt action rifle. Plus their data isn't realistic for the AR-15. Laziness and to please the lawyers maybe? For loading Hornady 55 FMJ's the only useful information is their minimum recommended overall length at 2.200" which in an AR can be extended out to 2.230". Aggravates me when a manual keeps copying the same 10 year old or so data into their next new manual especially with the popularity of the AR-15 platform. My advice is to consult the powder company manual for up to date data especially Hodgdon's data. Don't disregard any data source, just compare as many sources as you can.

Bart B. · February 24, 2015, 11:44 AM

What's the spec'd average peak pressure difference for both CUP and PSI systems on both cartridges?

What's the proof load pressures for each?

brycealbright · February 24, 2015, 05:24 PM

Appreciate everyone's help, will be back later with the psi and cup info.

mboylan · February 24, 2015, 10:03 PM

You are aware that 556 and 223 are dimensionally the exact same cartridge? The difference is pressure and the chamber it is fired in. 223 tops out at 50,000 CUP and 556 at around 60,000 CUP.

Are you asking for load data at 556 pressures?

brycealbright · February 24, 2015, 10:38 PM

I'm getting ready to reload 1,000 rounds, and was concerned about the 55 grn bullets not being listed in the Hornady Reloading Book's Service Rifle Data Section. One of the above threads talks about Hornady not providing reliable information on this and other topics. Now I'm wondering who does provide reliable information for the reloader.

bacardisteve · February 24, 2015, 10:43 PM

As mentioned above the hornady reloading book leaves a lot to be desired and I have found that for most cartridges the max published load is rather conservative.

mboylan · February 24, 2015, 10:53 PM

Ramshot provides data at 556 pressures. Most 556 military ammo gets 55,000 - 56,000. CUP in a 556 chamber.

Load data is built with the cartridge dimensions and equipment listed. You may get higher or lower pressures with your chamber and ammo. Start low and work up.

February 23, 2015, 03:29 PM	#1
brycealbright Member Join Date: October 12, 2014 Posts: 28	Is .223 - 55 gr FMJ-BT OK For AR-15 & M4 The reason I ask, is that the Hornady Reloading Book does not have this bullet listed in their Service Rifle Data section. It is listed in the .223 reloading section. Thanks in advance. __________________ "A 45 Makes All Men Equal"

February 24, 2015, 11:44 AM	#5
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	What's the spec'd average peak pressure difference for both CUP and PSI systems on both cartridges? What's the proof load pressures for each? Last edited by Bart B.; February 24, 2015 at 11:55 AM.

February 24, 2015, 05:24 PM	#6
brycealbright Member Join Date: October 12, 2014 Posts: 28	Thanks For The Information Appreciate everyone's help, will be back later with the psi and cup info. __________________ "A 45 Makes All Men Equal"

February 24, 2015, 10:03 PM	#7
mboylan Senior Member Join Date: March 31, 2011 Posts: 120	You are aware that 556 and 223 are dimensionally the exact same cartridge? The difference is pressure and the chamber it is fired in. 223 tops out at 50,000 CUP and 556 at around 60,000 CUP. Are you asking for load data at 556 pressures? Last edited by mboylan; February 24, 2015 at 10:10 PM.

February 24, 2015, 10:38 PM	#8
brycealbright Member Join Date: October 12, 2014 Posts: 28	Just Making Sure That The 55 grn Is Suitable For The AR-15 & M4 I'm getting ready to reload 1,000 rounds, and was concerned about the 55 grn bullets not being listed in the Hornady Reloading Book's Service Rifle Data Section. One of the above threads talks about Hornady not providing reliable information on this and other topics. Now I'm wondering who does provide reliable information for the reloader. __________________ "A 45 Makes All Men Equal"

February 23, 2015, 05:39 PM	#2
oldpapps Senior Member Join Date: September 22, 2011 Location: Middle America Posts: 518	Anything that will chamber and fire in a .223 chamber/throating will do the same in a a 5.56 chamber with no problems. Your biggest problem would be projectile weights versus twist rates and the 55 grain range is usable with most, well I use it. Load with care, OSOK

February 23, 2015, 06:48 PM	#3
sevt_chevelle Senior Member Join Date: April 13, 2013 Posts: 324	It will work just fine. Am guessing why its not listed in the service rifle section because maybe that would push it into 5.56 pressure range and Hornady doesn't want to provide such load data. If you want a 55 fmj load at 5.56 ranges Accurate provides load info on their website.

February 23, 2015, 08:17 PM	#4
rg1 Senior Member Join Date: November 6, 2001 Posts: 1,125	55 FMJ's are probably the most used bullet weight for reloading AR-15's and Hornady's 55 FMJ is the most recommended 55 FMJ. Their 55 FMJ is possibly the most accurate, affordable, and consistent FMJ bullet. Why Hornady doesn't test their 55 grain bullets in AR's for their manual is hard to understand. They keep copying previous data from one edition to the next and it's always in a 26" bolt action rifle. Plus their data isn't realistic for the AR-15. Laziness and to please the lawyers maybe? For loading Hornady 55 FMJ's the only useful information is their minimum recommended overall length at 2.200" which in an AR can be extended out to 2.230". Aggravates me when a manual keeps copying the same 10 year old or so data into their next new manual especially with the popularity of the AR-15 platform. My advice is to consult the powder company manual for up to date data especially Hodgdon's data. Don't disregard any data source, just compare as many sources as you can.

February 24, 2015, 10:43 PM	#9
bacardisteve Senior Member Join Date: September 5, 2006 Location: West virginia Posts: 653	As mentioned above the hornady reloading book leaves a lot to be desired and I have found that for most cartridges the max published load is rather conservative. __________________ Kill em all and let God sort em out! USAF

February 24, 2015, 10:53 PM	#10
mboylan Senior Member Join Date: March 31, 2011 Posts: 120	Ramshot provides data at 556 pressures. Most 556 military ammo gets 55,000 - 56,000. CUP in a 556 chamber. Load data is built with the cartridge dimensions and equipment listed. You may get higher or lower pressures with your chamber and ammo. Start low and work up.