.223 Loaded with 55gr FMJ and 24.5gr H335 Velocity?
- Thread starter chasep255
- Start date
-- Colt 1/7 20" AR--RP 7 1/2 primer--RP and WCC cases
-Hornady 55 fmj seated to 2.218-2.220"
-H 335 powder
-July 90 degrees
-Oehler 35 P at approx. 10 ft
___________
average velocities
23.2--2850fps
24----2975-3005fps
24.5---3050-3080fps
Maximum as per Hodgdon--25.3 -----3165-3195fps
These loads as mentioned are in a 1/7 Colt 20" rifle. Your loads may vary in your rifle but I wouldn't think by much and your components may cause some variation. Work up to the maximum load in your rifle with your components. But 24.5 grains with Hornady 55 fmj's and H335 should be safe. A lot of AR shooters use 25 grains and report it to be accurate. That's what I've settled on and shoot these loads in different AR's 1/9 and 1/7 twist and 16 and 20" barrels. Don't know which 55 fmj you're loading but that may make some difference too and your overall length may make a little difference. Hornady 55 fmj's have a blunter tip and overall lengths are 2.200-2.230" while sharply pointed military style 55 fmj's are most often seated to 2.250" oal.
-Hornady 55 fmj seated to 2.218-2.220"
-H 335 powder
-July 90 degrees
-Oehler 35 P at approx. 10 ft
___________
average velocities
23.2--2850fps
24----2975-3005fps
24.5---3050-3080fps
Maximum as per Hodgdon--25.3 -----3165-3195fps
These loads as mentioned are in a 1/7 Colt 20" rifle. Your loads may vary in your rifle but I wouldn't think by much and your components may cause some variation. Work up to the maximum load in your rifle with your components. But 24.5 grains with Hornady 55 fmj's and H335 should be safe. A lot of AR shooters use 25 grains and report it to be accurate. That's what I've settled on and shoot these loads in different AR's 1/9 and 1/7 twist and 16 and 20" barrels. Don't know which 55 fmj you're loading but that may make some difference too and your overall length may make a little difference. Hornady 55 fmj's have a blunter tip and overall lengths are 2.200-2.230" while sharply pointed military style 55 fmj's are most often seated to 2.250" oal.
Last edited:
Miata Mike
New member
Kind of nice to know. I have been loading at 25 grains and using a military 55 grain fmj. No signs of over pressure at all, but sounds like it is getting a bit on the hot side if some heavy brass slips through.
CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
55 gr H335 .223 has a threshold of long brass life between 29 and 30 gr.
This is much higher than published loads because the .223 was SAAMI registered at 55kpsi, but can run more than 75kpsi.
It has 10X the loose primer pocket safety margin per SAAMI registration of 270W, 6mmRem, or 22-250Rem.
55 gr H335 .223 has a threshold of long brass life between 29 and 30 gr.
This is much higher than published loads because the .223 was SAAMI registered at 55kpsi, but can run more than 75kpsi.
It has 10X the loose primer pocket safety margin per SAAMI registration of 270W, 6mmRem, or 22-250Rem.
CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
.223 started with a 52K CUP MAP from SAAMI. It was revised to 55K PSI MAP by conformal piezo transducer, in one of the more curiously wimpy conversions. I once looked through all the other SAAMI cartridges I could find that started at 52K CUP, and all are now in the range of 60K-65K PSI MAP by transducer. Average is not quite 62K PSI MAP, as I recall. I don't know what went wrong with the .223, but the European CIP has it as 430 MPa (62,366 PSI), and that's worked for them and for NATO so that's the limit I use. If you buy European made ammo, ever, so do you.
As Clark says, many guns can go higher, but throat erosion rates can increase dramatically above the mid-60's, so I elect to stay inside the CIP numbers as best I can.
.223 started with a 52K CUP MAP from SAAMI. It was revised to 55K PSI MAP by conformal piezo transducer, in one of the more curiously wimpy conversions. I once looked through all the other SAAMI cartridges I could find that started at 52K CUP, and all are now in the range of 60K-65K PSI MAP by transducer. Average is not quite 62K PSI MAP, as I recall. I don't know what went wrong with the .223, but the European CIP has it as 430 MPa (62,366 PSI), and that's worked for them and for NATO so that's the limit I use. If you buy European made ammo, ever, so do you.
As Clark says, many guns can go higher, but throat erosion rates can increase dramatically above the mid-60's, so I elect to stay inside the CIP numbers as best I can.
I just recently did a load development using H335 and 55 gr FMJBT bullets in .223. COL was 2.200”. These are the results:
23.5 gr 2762 fps
24.0 gr 2817 fps
24.5 gr 2882 fps
25.0 gr 2941 fps
25.5 gr 2977 fps
26.0 gr 3032 fps
26.5 gr 3081 fps
To my surprise the best accuracy and grouping was attained with the 23.5 gr load.
23.5 gr 2762 fps
24.0 gr 2817 fps
24.5 gr 2882 fps
25.0 gr 2941 fps
25.5 gr 2977 fps
26.0 gr 3032 fps
26.5 gr 3081 fps
To my surprise the best accuracy and grouping was attained with the 23.5 gr load.
XxBulletBendeRxX
New member
Great thread guys... thx for the info.. Im loading a few right now.. i am trying 24.3 grains of h335 with a military 55 grain fmj. i want accuracy but dont need sub moa at 100+ yards as this is just going to be blasting/plinking ammo. Ive tried the 25 grains 55 gr fmj with a oal of 2.230 and it is good vs cans and 4 ich clays at 50-80 yards, but on paper not he tightest groups. so Im lowering the charge just a little to 24.3 grains h335 to hopefully tighten it up a little more. will verify on paper, im also going to try 24.6 and 24.8 grains and see what I get... 
. ALso going to lthrow a few varget loads with 75 grainers for the 1/7 twist Adams upper, but hats irrelevent to topic just thought id share... Well, Back on the press,
XxBulletBendeRxX
. ALso going to lthrow a few varget loads with 75 grainers for the 1/7 twist Adams upper, but hats irrelevent to topic just thought id share... Well, Back on the press, XxBulletBendeRxX
XxBulletBendeRxX
New member
^^^ NOT TO MENTION ressurect this old thread... ^^^