.223 55gr FMJBT, H322, 16.5" Bbl, and a Chronograph

[Shawn Dodson]

I took the day off work yesterday to hit the shooting range to chronograph a few .223 loads I'd worked up using H322.

I use H322 because I want to use one propellant between .223 and 6.8.

Way back in July 2007, before I relocated from Washington state to Florida, I chronographed Federal XM193 55gr FMJBT and Winchester Q3131 55gr FMJBT from one of my M4s. Five shot measurements of each showed an average velocity of 3083fps for XM193 and 3118fps for the Q3131.

Over the past 6-8 months I've built (among other things) a new reloading bench and I've finally gotten back into reloading. My Speer #12 manual shows a max charge of 24.5gr H322 for 55gr to achieve a velocity of 3158 from a 22" bbl. My Hornady 7th Edition manual shows a max charge of 23.1gr for 55gr to achieve 3100 fps from a 26" bbl. (I wasn't having any luck in my search for H322 loads that would allow me to reproduce XM193 and Q3131 velocities.)

Working up loads and shooting them from my M4 named "Fat Bob" (16.5" 1:7 bbl) (because "Skinny Bob" was clean and "Fat Bob" wasn't) the following charges produced the following average velocities:

22.1gr - 2576fps
23.1gr - 2730fps
24.1gr - 2839fps
24.5gr - 2910fps
24.8gr - 2943fps
25.1gr - 2989fps
25.4gr - 3052fps
25.7gr - 3068fps
26.0gr - 3100fps

My goal was to find a load with H322 that achieved between 3000 - 3100 fps from my M4s and then use that as my "standard 55gr load." At this point I'm probably gonna load up a few at 25.5gr H322 and call it good.

Cheers!

 

[Runningman]

Dam the accuracy, full speed ahead?

I tried working with H322 years ago in the 223. For me it only tended to group well at around staring loads (lower velocity) for a given bullet weight. I would try to crank it up and group size would open up fast to unacceptable levels.

 

[Shawn Dodson]

Yeah, I haven't shot any groups yet but a max of 3 MOA with iron sights is plenty adequate for my needs (consistent head shots on an IPSC target at 200 yds).

I'll follow-up and post my accuracy results here.

 

[243winxb]

Another reloader dumping powder and watching the chronograph, plus only 2 1/2grs over Hodgdons maximum. Hope it don't end up like this.

[/URL][/IMG]

[/URL][/IMG]

 

[mongoose33]

Dam the accuracy, full speed ahead?

I tried working with H322 years ago in the 223. For me it only tended to group well at around staring loads (lower velocity) for a given bullet weight. I would try to crank it up and group size would open up fast to unacceptable levels.

I've moved away from H322 in my .223 rounds for the same reason. Chrono's well, doesn't seem all that accurate. 748 is better, and it meters better than H322.

 

[ants]

Curious question...

Original post:
My Speer #12 manual shows a max charge of 24.5gr H322 for 55gr to achieve a velocity of 3158 from a 22" bbl.
My Hornady 7th Edition manual shows a max charge of 23.1gr for 55gr to achieve 3100 fps from a 26" bbl.

22.1gr - 2576fps
23.1gr - 2730fps
24.1gr - 2839fps
24.5gr - 2910fps
24.8gr - 2943fps
25.1gr - 2989fps
25.4gr - 3052fps
25.7gr - 3068fps
26.0gr - 3100fps

I'm not bashing you, Shawn, just asking a reasonable question.
If your manuals showed lower max loads, why did you test all the way out to 26 grains?
Also, why settle on a load clearly exceeding max?

These questions are asked in the best spirit. Some reloaders have a rational reason for exceeding maximum. Others don't. I think it's important to ask.

Thanks, Shawn.

 

[HOWARD J]

I went away from H322 when it went to $26 a #
Bye-Bye..........................................

 

[Shawn Dodson]

If your manuals showed lower max loads, why did you test all the way out to 26 grains?
Also, why settle on a load clearly exceeding max?

No need to tread on eggshells.

In researching and comparing various loads the recommended max loads in the manuals appear to be "lawyered" specs - meant to minimize liability with firearms of weaker design. I monitored my brass for pressure indications (primer indications, bright ring above the case web, brass extrusion) and I realize the reading pressure signs is not a science. I observed some primer flattening, bright ring, and extractor and ejector wipe marks at 25.7gr and 26.0 gr. Dial calipers showed case expansion of .003" at the web compared to sized cases and no detectable case lengthing.

I appreciate 243winxb's post. It's humbling and made me realize that I'm not loading new brass but previously fired brass which has decreased case integrity.

I load Hornady 55gr FMJBT. Running Hornady's ballistics calculator, if I load Speer's max load, 24.5gr, it'll give me 2900 fps, which translates into an additional 3/4" drop at 300 yds. I can live with that. There were zero pressure signs and the case web measured .001" increase in diameter after firing.

Thank you guys for your questions and concerns. Sometimes I can get focused on a single goal and forget about other important things.

 

[ants]

Thanks for the info, Shawn. I knew there would be reasoning behind it.
I'm glad I asked politely.

Here's what I learned from techs at the Shot Show. Most modern data seems to be "lawyered" but it's not. Better lab equipment helps them detect erratic behavior as the powder charge increases. This widens the standard deviation on each side of the curve. Rather than simply looking at max pressure, they are looking for erratic behavior as evidenced by changes in the standard deviation as the charge goes up. This often leads to different data compared to past decades. It is not instigated by changes in courtroom litigation, but by changes in lab technology. I don't know if that fits in your system, but that's what the lab techs told us.

However, that applies to commercial loads meeting SAAMI industry standard. If your AR rifle is built to 5.56x45 milspec standards, it exceeds SAAMI standards. Even if we don't have 5.56mm milspec load data available, this leads many reloaders to make sure their rifles are appropriately built, then try over-max loads in a methodical manner. You are probably in that range somewhere. Just promise yourself to be very careful and go methodically. It's always a personal choice, whether someone else likes it or not.

Pressure signs:
Primers lie. Since the same primer is used in various cartridges with both high pressure and low pressure standards, the primer often starts to flatten after it's already too late. Too bad they don't make calibrated primers.
Case head expansion: I have seen in manuals that 0.0003" per cycle is common, 0.0007" would indicate excessive pressure in most common cartridges. But it takes a micrometer that can resolve to the ten-thousandth of an inch to measure that. If our case heads are expanding 3 thousandths, we got trouble.

Accuracy:
Your choice. You decide what works for you. Nobody else can tell you what to do. I have a graduated knob on my elevation turret. My choice is to load accurate ammunition that matches the drop on the knob. Then I use the rangefinder to check target distance, and turn the knob.

 

[243winxb]

I load Hornady 55gr FMJBT. Running Hornady's ballistics calculator, if I load Speer's max load, 24.5gr, it'll give me 2900 fps, which translates into an additional 3/4" drop at 300 yds. I can live with that. There were zero pressure signs and the case web measured .001" increase in diameter after firing.

I dont want to see any case head expansion as i load for long case life and accuracy. I have read the benchrest shooter get .001" expansion and use special dies to resize the web area, but they are shooting bolt actions. When there is a case head separation, they have some protection. Not so in ARs. Ants seems to be more up on current data then i. I still go by the old Speer manual that said no measureable web expansion is wanted.

 

[Walkalong]

I have read the benchrest shooter get .001" expansion and use special dies to resize the web area

Everyone I knew shooting Benchrest were using standard sizers, often times cut with the reamer their barrel was done with, cut to use bushings for sizing the neck. We would bump the shoulder just a hair. Not really worried about bumping the shoulder back as much as not letting it get to far forward causing tough chmabering. Tere wasn't enough sizing on the body to do anything with the web of the case. Of course we weren't shooting big sloppy chambers either.