Loading 5.56 for short barrel

[0utlaw]

Fat fingers on phone sorry

[Capt. mike]

I don't know much about reloading, (I've read a lymans manual from 92, and a hood bit of the materials available here and there) but that sounds scary as Fuck from everything I've read. I think I'd have to back that shoot down a notch and work my way up to what was comfortable/effective in my gun.

the lawyers for the reloading companies make sure it does scare the fuck outta you for a reason because 10+1 might equal 50 and small fractions can increase pressure exponentially. That being said Ive found that there is usually room for improvement above most published loads. If I ever have the money to blow id like to do a "run it till it blows" to see just how far you could push loads to the point it blows the gun as they are designed to handle more than they are rated for

[Rumbler]

I don't know much about reloading, (I've read a lymans manual from 92, and a hood bit of the materials available here and there) but that sounds scary as Fuck from everything I've read. I think I'd have to back that shoot down a notch and work my way up to what was comfortable/effective in my gun.

Your approach is reasonable. I won't recommend doing anything else.

But as one who has a preference for and a reputation of pushing projectiles far beyond "book" standards, I'll share the process I use to get there. Do not for one millisecond perceive the following as a recommended procedure, or as safe.

I'll take a load from a book, and try to validate it against other sources (other books). Look at the chamber pressure numbers (there is no direct correlation between PSI and CUP!) and compare them to the published ratings for the barrel, and often action of the firearm, I want to load for.

I'll base my starting load on pressure, not powder volume. If a "max listed load" is near the pressure rating for the barrel/action I'll use the listed load as a starting point. If the listed load is not near the pressure rating of the firearm I'll add a 1/10 or two of charge weight and make five or six rounds.

I'll take those cartridges and fire them paying close attention to the weapon itself. You can feel when a firearm is 'being a slouch' and when it is 'struggling to contain'. Then I'll police up the cartridge cases, put on my spectacles (or even better get a magnifying glass) and very very carefully examine the case for signs of overpressure and underpressure.

If there are NO SIGNS of overpressure, I'll go add 2/10 grain of charge weight to five or six more cartridges, and repeat the examination. I'll continue with this load/fire/examine/ process, backing off to 1/0 grain increments as the primer begins to show breach face imprint. As soon as I see the breech face imprint, and the shoulder of the primer flatten noticeably, I'll stop and call it good.

Yes, that very much DOES mean changing primer brands, case manufacturers or powder lots, can screw up the load data. That is exactly why once I find my happy load I'll make as much of it as I possibly can "all in one sitting".

This process is not flawless. Fortunately the worst repercussion I have had so far has been a significantly bulged barrel on a S&W 14-4 .357 magnum revolver. The barrel looked like a snake that had swallowed a football.

On the other side of that coin, compare these numbers to your load manual, I have learned that I can push a 250gr lead bullet 950+FPS out of a 1911, My 180gr 10MM load zips along about 1450FPS, I've got a 140gr .308 load that runs along over 4000 FPS, a .270win load topping 4500FPS, last . . and least ( ) a 5.56 55gr load that runs 4400-4500FPS out of a 16" barrel.


The energy delivered to the target on all those loads far far exceeds what "should be". And ain't even in the ballpark with published load data.

[e.money83]

Good...fucking...god...

[Capt. mike]

That 4500 fps 55gr load what pressure is that at

[Rumbler]

That 4500 fps 55gr load what pressure is that at

I do not have a proofing setup. But with a published maximum pressure for the 5.56 NATO cartridge at 62,366 psi, I'd say it is a safe bet I am probably there plus a little because I use a heavy barrel (as opposed to a standard "military" barrel.

I know that you know the 5.56 NATO cartridge will often flatten the crap out of the primers. My load only occasionally flattens a primer and I believe that is because I use exclusively once fired NATO brass and some primers seat more firmly than others.

[Capt. mike]

So an AR in 5.56 is rated for around 62,000 psi assuming a normal mil spec barrel what is the typical point of failure assuming its an over pressure cartridge? I would think the bolt lugs or is it the actual chamber, barrel, primer, casing, ect given there is no bore obstruction

[Rumbler]

Based on what I have read the most common thing that usually happens is bolt failure. It shears the little locking nubbins off.

[Rumbler]

That is because you are ARMY. They give you guys the watered down version so you don't hurt yourselves.

[Capt. mike]

I tested mine out and like I said they should not be considered safe as they are over max loads but with 25.5gr of CFE 223 the 75gr hornadys averaged 2692 FPS out of my 1/7 twist 16" upper. Luckily I ran into mapper and he was generous enough to let me put his chrono in harms way. The primers were getting flat and I plan on bringing the next batch down a bit and using a thicker primer as well. Another note on the load when fired from a sar3 5.56 AK with no muzzle device there was no visible muzzle flash as opposed to the 55gr tula that had a very loud and visible fireball when fired in the same gun so I think this would be a good load for shorter barrels