Help reloading .224 70gr Barnes TSX

[barbasol]

Couple questions that will help a new reloader. I'll be loading a .224 70gr Barnes TSX bullet in once fired LC brass with Tac.

I'm looking to load a cartridge to shoot out to 600-1000yds from a heavy barreled 18" ar15.

Tacs load data shows two subsets of data. The second of which is for greater than 62350psi rated for bolt action and the latest NATO/Mil ammunition. Data found here http://www.ramshot.com/wp-content/up...dgun_rifle.pdf

Questions are:
How do I know my psi?
Ill be starting on the lowest end of the lower pressure load data?
How can I tell if I have 5.56 brass? If I do, I'm starting with 10% of the minimum load to start working up?

More general:
I've loaded some pistol ammo, but how do you guys, "work up a load". I'm assuming 10 rounds at a time and see how they group?

[ExtremeX]

I’m going to take a shot at answering you but I’m no expert…

In order to actually test barrel PSI you probably need some specialized test equipment like test barrels with pressure ports and pressure transducers to graph the data…

There is also software which will run various simulations for load and barrel pressure… I’ve seen software like this but I have never used it. Again this is only a simulation…

Sometimes your components and equipment don’t always match up with what’s in a published recipe. I always consult a few different load manuals and consult the powder manufacture website and find a starting load I am comfortable with…

You can tell if you have 5.56 brass by looking at the headstamp of the casing, but more importantly do not exceed SAMMI pressure levels for the chambering in your firearm. You should be able to use .223 or 5.56 brass. If you plan on using mixed brass, various manufactures can have different case volume / capacity to its good to take note of that. (I use fine sand to test case volume) For my match loads I always separate cases by head stamp…

Working up a load… I’m sure people have their own way of doing this… but in general start with the minimum load and ladder up incrementally increasing the powder charge… Depending on the mix/max powder charge ladder in larger or smaller increments accordingly. As I reach the recommend max for any loading I typically start to use smaller increments for safety reasons. The smaller the increments used for the ladder the more resolution you have when testing… The amount of rounds you make for each ladder is completely up to you…

While testing the ladder look for signs of accuracy nodes and pressure signs.

Hope that helps

[tacloader]

If I can add, I separate cases by weight with the same head stamp and use a chronograph to record velocity. Collect fired brass and segregate by each load to examine for high pressure indicators. In ar I set OAL to fit magazine with 68gr or heavier bullet.

[GeoffLinder]

Best way to determine safe pressure level for your rifle and component combo is through actual testing (over a chronograph if possible).

Definitely weigh cases and use only same batch ones in a weight range of 1.5-2 grains. This will insure consistent internal volume which greatly effects pressure.

First off, load as long as magazine use will allow, this is about 2.255" OAL for .223 in an AR.

Start with charge weight 10% below max listed. Load 5 rounds starting at 10% reduction point and go upward in 3/10 grain increments until you are at max listed charge.

Fire the rounds starting with lowest charge weight (over chrono if possible) at a 100 yard target (200 yards is better) using best group shooting technique for each set of charge weights. Use a separate target area for each group so you can watch group size of each charge weight batch.

Note velocity range for each set. Inspect primers of fired rounds carefully after each test set. Look for primer flattening (starting to lose roundness and smear across primer pocket). Once you see this happening you are nearing max charge weight for your rifle and load component combo.

If you see flattening AND see evidence that primers are flowing around firing pin and into firing pin hole in breech face, STOP immediately as that is at or over max for that combo in your rifle.

You will never be able to easily find the actual pressure, but primers will tell you what is max charge weight you can use for that powder/bullet combo in YOUR rifle.

Charting the velocity and comparing that to group size will help you identify the barrel nodes. You will typically find several points as you work up the charge ladder where group sizes shrink. These are accuracy nodes for your rifle with that bullet. If you note the velocity of that node you will be able to load for the sweet spot in the future by duplicating that velocity. The best accuracy node will usually not be near the max load point.

Once you have identified a barrel node under max point, you can refine testing by working with smaller charge weight increments to determine the exact velocity point of the accuracy node.

More info on what barrel nodes are here: http://www.frfrogspad.com/loaddev.htm

Hope this helps.