First time loading subs, 200gr rex

[savage204]

Hello everyone, it's been awhile since I've posted anything.

I I've been thinking about loading some subs for the first time and picked up a couple boxes of 200g Maker REX bullets. I've read through the Maker thread and learned a lot, thanks to everyone who contributed to it.

I just wanted a few opinions before I start putting everything together. In the Maker thread it was mentioned to seat the bullet to the groove closest to the tip, I also saw where a lot of people had a COAL of 2.1. I loaded a dummy and at the top grove I get a COAL of 2.111, which seems like a good place to start.

I have 5lbs of 1680 that I wanted to start testing with, I also have a few pounds of 296 if the 1680 doesn't work out. In the Maker thread I saw a few loads with 1680 around 11gr. I obviously want to work up to where I need to be but how low of a charge should I start at?

This is a 10in 1/7 AR, pistol gas, and a adjustable block.

Thanks for the help!

[BJK]

In decades past I found out the hard way that starting low and working up was the wrong thing to do for subs in 5.56. But that was with a 16" barrel. Too little pressure and one gets the hiss of "death" as the bullet passed the gas port and didn't have enough steam for the bullet to make it out of the barrel. But that was with a longer barrel. When I was developing a load for my 10" I still started high and worked down just to be sure. Use good data and plenty of it and compare loads to make sure one "accidental" load hasn't been put online*. A chrono' is your friend. You might hear the supersonic crack or the lack, but don't count on it. I think I used data for heavier bullets than what I was using, knowing that my lighter bullets (same construction) would result in lower pressures and I adjusted from there.

* I was the guilty party in this once on this site. I meant well but I wrote the wrong powder. I also quickly corrected the error. Stuff happens.