223/20 ga Ammo Questions

I only recently became a 24 F .223/12ga owner. I have not fired any 5.56 military ammo through mine. I don't know enough about the pressures involved with military ammo to want to risk using it. I use it in my Bushmasters, but not in guns chambered for .223 Remington.

That said, I tested some 55 grain .223 from Wolf and PMC, very cheap stuff that was given to me. Both were very unstable right out of the barrel. I loaded up some .223 based on 27 grains of Varget and 40 grain Nosler ballistic tips. It made a great group at about 35 yards with the flip sight. Next, a scope.

This evening I loaded some 55 gr Sierra BTHP with 27 gr of Varget (from the Speer loading book #14). We'll see how that works with the slow twist on he Model 24 rifle barrel. I hope it is better than the Wolf or PMC.

I have shot just about every type of 20 ga ammo there is thru my 24V's with no problems except punkin balls.

You are correct. I've done extensive research on the difference between the 5.65 and the 223.

The cartridges themselves are essentially identical, the difference being that the 5.56 Nato uses slightly thicker brass, so when using the same load, it produces about 5,000 psi more pressure than the 223. The lead on the NATO spec is .002" longer than for the SAMMI spec 223. So you are correct that when a 5.56 is placed in a 223 SAMMI spec barrel, it may cause even higher pressure.

The thing here is that most commercial barrels are not exact SAMMI or NATO spec like the test barrels that are used for the pressure testing. Most manufacturers of either the 5.56 or the 223 make their barrels slightly looser than spec because they know someone may fire these other rounds due to their lower costs. The exception is normally in their rifles designed specifically for high accuracy, such as their target or varmint rifles.

This was the reason for my initial posting asking if anyone had actual experience in their model 24. While I know that there is no certainty that all 24s are the same, I'm willing to make an educated guess on mine if I get a decent amount of response from people with actual experience.

I don't have the equipment to cast my own, or the reamer to cut it properly, and from what I have been able to determine; to purchase the good ones that I would want if I was going to do it myself would cost me about 75% of what the gun cost me, and a great deal more than Gun Parts listed replacement barrels for.

Some very good articles, and some are ones that I read in doing my research on the differences between the cartridges.

From what I have been able to determine from all of the articles like this that I've read, the actual difference in pressure between the 2 cartridges is normally only about 2 - 5,000 psi when measured the same way and fired in the same gun with the longer leade. The problem may may occur and an extra 10 -15,000 psi may occur when the NATO is fired in a 223 barrel that is actually cut to the tight SAMMI specs. But most barrels aren't cut that tight.

Add to this the fact that most barrels are proof tested at or slightly above even this higher pressure, so obviously most barrels will handle an occasional 5.56 round through them. Certainly not meant to be a routine practice.

But from most everything I've read from all of these sources is that generally the difference in pressures found in actual shooting of these rounds is about an extra 4,000 psi when using the 5.56 NATO. Most of this testing was done and the results were given that when fired in the AR type rifles used for testing, generally the only real concern was that occasionally the higher pressures would cause a primer to pop out or a case swelling may cause some extraction trouble.

Obviously, these are not concerns for use in most bolt action or break open type rifles. I've fired several hundred rounds of 5.56 M193 ball ammo through my Savage 112 and through my T/C Contender with absolutely no ill effects, but these are bull (or heavy) barreled where I'm sure the extra thickness of these barrels will allow them to withstand much higher pressures than the thinner barrels used on the Model 24.

That was the reason I posted my original question asking if anyone had first hand knowledge of using any of these rounds in their guns. I've painted the bullet and front of the neck on several 5.56 cartridges and fully inserted them into my 24. When I pull them out, I can see marks in the paint lower on the neck, but none at all on the bullet, leading me to believe that this must have at least a slightly longer leade than the actual SAMMI specs. And you can usually feel quite a bit of difference in recoil if you have the tighter spec gun with the shorter leade. But even if it is labled as 223, when there isn't much difference at all in recoil, it's probably cut to a slightly longer leade more similar to the 5.56.

Since I have about 100 rounds of soft point 223, and about 900 rounds of M193 ball, it would just be nice to know before I attempt something that may be stupid.

And a note to "gastonguns", you may be right. While Savage told me and says in their booklets for their center fire guns that all 223 barrels have a 1:9 or a 1:7 twist, mine certainly doesn't look that fast either. I'll have to try to measure it and see. But I still get fairly tight groupings with the 55 grain soft point PMC ammo. I haven't tried anything else yet as the temperature here has been way too cold for me to get out and shoot just for the fun of it.

And to "bigkelly", thanks, that's what I needed to know. I've had several people including the rep at Savage tell me not to use steel shot or slugs. Others have said that didn't make sense to them, But I felt sure someone on here could tell me if they had used either safely or with no problems. The slug part made no sense to me, but I have heard that the steel shot does not compress like lead and may scratch the barrels in some older guns not designed for it, causing accuracy or patterning issues in later use. Nice to hear from someone with actual experience in theirs. That's what I was hoping for on the 223 question also. I'm sure there are people out there who have tried it and I'd like to hear from them.

I'd be really surprised if Mdl 24 barrels have a 1-9" twist. Most 223 hunting/varmint rifles produced even today have a 1-12" twist, which is more effective with 35-45 gr. bullets.

Posts in the old forum have reports of 223 Rem in 1-14" twist, which were obviously barrels originally destined to be 222 Rem chambered, but then switched to 223.

In any case (and I'm ready to be surprised), let's have some reports on Mdl 223 twists. My 222 Rem is 1/14".

That's the 5.56 I believe the original twist for the .223 was 1-12.
Of course the "weight" of the bullet has nothing to do with it, it's length.
First thing to do is make sure you're shooting a flat base bullet. Then try and avoid anything with a long nose/ogive. A VLD boat tail bullet is going to be a poor choice for 1-12.