Cast thru M&P Ar-15 best sizing

[500MAG]

Anyone here shooting cast thru their M&P AR-15? It has a 1 in 9 twist and I want to know what sizing to use. .224 or .225? Not interested in slugging the barrel at this point just wanting to know if anyone has info.

[GabbyM]

I use a .225" in all three of my 223's.
Larger to fill the throat may be better but that's all the bigger my bullet drops anyway.
I use a Lyman M die to expand necks.

[500MAG]

I use a .225" in all three of my 223's.
Larger to fill the throat may be better but that's all the bigger my bullet drops anyway.
I use a Lyman M die to expand necks.
Thank you sir!

[Screwbolts]

I use a .225 in 3, 5.56 chambered rifles 2 are 1x9, one is 1x12. I have a bolt 223, 222 and 22 K hornet that also like .225.

I do not expand necks in any 22 cal, I use a heavy chamfer, My Gracy trimmer leaves the necks perfect to seat cast.

[P.K.]

I use a .225" in all three of my 223's.
Larger to fill the throat may be better but that's all the bigger my bullet drops anyway.
I use a Lyman M die to expand necks.

.225. Just a touch with the universal expander in my case though.

[Screwbolts]

The throat of a 5.56 chamber is actually .226 , yes I have 225 sizers both H&A and push threw I will probably be getting a H&A in .226 for the Mihec nato boolitz.

What cast boolit are you expecting to be shooting in that S&W , M&P. I recoment the Mihec Nato. there is a group buy for this going right now, it is the third buy in a year. I flat out shoots great in all 5.56 chambers I have loaded for.

[Larry Gibson]

.225 is pretty much the common sizing for .22 cast bullets. However, my 225438, 225415 and 225462 all drop at .227 with the alloy I'm using. I've a .228 H die for the 450 lubrasizer that just crimps the GC on and lubes them. They all shoot a bit better in my 3 AR's (7, 9 and 12" twists) over the same load of H4895 or RL22 than with .225 sized bullets. They also shoot better sized that way out of my 9, 12 and 14" twist bolt guns.

Larry Gibson

[Screwbolts]

.225 is pretty much the common sizing for .22 cast bullets. However, my 225438, 225415 and 225462 all drop at .227 with the alloy I'm using. I've a .228 H die for the 450 lubrasizer that just crimps the GC on and lubes them. They all shoot a bit better in my 3 AR's (7, 9 and 12" twists) over the same load of H4895 or RL22 than with .225 sized bullets. They also shoot better sized that way out of my 9, 12 and 14" twist bolt guns.

Larry Gibson

Larry, thank you for motivating me to polish my H die from .225 to .2265 . I polished it yesterday during a session of lubing 1000 NOE FN water dropped Boolitz. I have loaded and shot 20 rounds so far with 24 hr old boolitz. I believe it has shrunk my group size by 40- 50% they made one small shiny spot on my 130 yard plate, I was very happy with 2" groups before.

[500MAG]

The throat of a 5.56 chamber is actually .226 , yes I have 225 sizers both H&A and push threw I will probably be getting a H&A in .226 for the Mihec nato boolitz.

What cast boolit are you expecting to be shooting in that S&W , M&P. I recoment the Mihec Nato. there is a group buy for this going right now, it is the third buy in a year. I flat out shoots great in all 5.56 chambers I have loaded for.
I got the NOE 22-055 FN.

[Screwbolts]

That NOE 22-055 FN will work great IMHO, they drop from my mold with my alloy at .226. I had good accuracy at .225, I now have better with a .2265 die. Atlheating has great results with his White Oak Armory 1x12 upper @ .224 . I now like the Mihec Nato better, primarily because the top grease groove is covered with the check still in the neck. I get the same accuracy from both. The NOE will run threw the mag perfect with the top groove exposed and only is a problem IMHO if rounds are exposed to dirty / dusty conditions. I have yet to harvest anything with the Nato, the NOE has been successful on multiple Coyotes , 2 deer, many pigeons and crows at the farm.

[Keith429421]

Thought I'd just say, great info here!
I'm having trouble finding a .224 sizing die, but can get a .225 die.
I'm also using the NOE 225 055 FN mould.
I'm ordering a .225 die now.
Thanks everyone!