I am loading lake city 223 brass with a cci 400 primer, 24.9 of H335 powder, 55 grain Hornady spire soft point bullet and a coal of 2.255, the accuracy is excellent 1/2 " groups at 100 yards.
The Hornady book says coal for that bullet is 2.200, I tried that and the accuracy dropped way off, why ?

If I loaded a coal of 2.200 would I be able to match the accuracy by using less powder ? By seating the bullet deeper in the case to get the coal of 2.200 that would leave less space inside the case so would less powder give me the same pressure and velocity and accuracy ?

As long as the feed well and are not showing any pressure signs, load them to the COAL that you want. After finding a good powder/charge weight, the next thing to play with is how far to seat the bullet. Gennerally speaking, seating the bullet closer to the lands yeilds better accuracy.

As far as you theory of case capacity/pressure/accuracy etc... Nice thoughts, but it doesn't exactly work that way.

If your oal/bullet/ powder charge is working, why change anything?

If I'm getting half inch groups at 100 yards, I'm not changing anything.

AMEN!

Seriously. The COAL for .223 is established by what will fit into AR/M16?M4 magazines and SAAMI. This is ususally the COAL used for load data developement. Some really specialized target bullet loadings excepted.

Now, seating the bullet closer to the rifling (longer COAL) can improve accuracy by reducing the bullet jump to the rifling and reducing the tendency of the bullet to skid while engaging the rifling.

The problem here, is that doing that can increase pressures, because load data was developed with the original COAL. The exteme case of seating the bullet touching the rifling can act as a cork and cause dangerous pressures.

You don't mention which rifle you're using. If the rifle has a 5.56mm chamber, it has a longer freebore and a slightly different leade than .223 chambers do. How much so depends upon who designed/made the reamer, how close the actual reamer is to the specifications and various variables due to the machining process.

Since 5.56mm ammo is not a SAAMI cartridge there is no load data that duplicates the higher pressures of that cartridge.

FWIW, I seated a bullet long in .30-06 for various reasons and got the 1/2 MOA spoken of earlier.

You're using 24.9 H335? I think you might want to check the Hornady manual again. The last two editions show the max load of H335 to be 23.2. Also you might check the capacity of the Lake City brass. Military brass sometimes has less capacity than commercial brass.

Your surmise about seating the bullet deeper raising pressures is correct. The less "boiler room" in a case the higher pressure generated with a given amount of powder. Seating the bullet out will lower the pressure and have the secondary benefit of placing the bullet closer to the rifling thus lessening the bullet jump from case to rifling (leade).

If you're getting 1/2" groups out of your loads at 2.255" Go back to that. As long as the bullet is, say, .015" from the rifling you should be safe. DO CHECK YOUR LOAD THOUGH IT WOULD SEEM THAT YOU ARE A GRAIN AND A HALF OVER CHARGED.

Good luck and let us know how things work out, Pecos

I've worked up to 26.5 grains in my .223 with no pressure signs. Got pressure signs (gas leakage around the primers) at 27.0 and stopped. It all depends on which manual you look at. My Lyman 49th lists a min charge of 24.3 and a max charge of 27.0 (albeit with the Sierra 55 grain).

Hodgdon lists a start of 23.0 and a max of 25.3 with a 55 grain SP.

I found my rifle to group with the Hornady 55 grn SP's very very well at 25.0 or 25.2 (depending on which scale you believe) of H335.

Like said above, the charge of 24.9gr H335 under a 55gr bullet is just fine according to Hodgdon who lists a max charge of 25.3gr.

Also like said above, with 1/2" groups I wouldn't touch a darn thing on the load! That load should get listed as one of your "Pet Loads".

I have a Varget load for my bolt action .223 rifle that produces .4" groups @100 yards. That load won't be seeing any changes either!

__________________
Freedom is never free!!
SWCA #3437

I am using the Lyman book, that is why I load to 24.9 without any pressure signs. It is not a max load according to the Lyman reloading book.
What are you loading your oal to ?

Gentlemen, just because you don't see "pressure signs" doesn't necessarily mean you don't have high pressure!

Quantitative judgements about pressure made by "signs" are not reliable.

The gentlemen are using published load data AND not seeing indicators of high pressure. Sounds like pretty safe practice to me. YMMV.

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James

2.21"

I wanted to end that there but the forum is making me enter in at least 10 characters for my reply. This should handle it.

You quoted a COL from Hornady's info so I assumed you were using the Hornady book. Since you're using the Lyman book it shows a COL of 2.260" but that is for a Sierra 55 gr bullet. You had me a little confused I guess. I thought you were using load data from Hornady. Sorry about taking you to task your load is safe according to Lyman. As I said if it works go for it, Vern.

In one of the older editions of the Handloaders' Digest, there was a fairly exhaustive article concerning all of the factors influencing grouping. One of the conclusions of the article is that there is more to be gained by finding the optimal jump of the bullet from the casing to the rifling than any other single factor, including uniformity of case, bullet, and powder charge weights. And it's not necessarily "less jump is better" as in some cases a fairly long jump may be better. My personal load development work has confirmed this. I believe that there are three key elements that must be addressed if one wants an accurate load: determining the optimum bullet jump for your specific rifle, trimming cases to uniform length, and turning a uniform case neck wall thickness. I have found that no other uniformity factors are as critical as these three, including uniforming primer pockets, flash holes, and weighing each bullet and propellant charge.