Working Up My First Load

[MN_Condor]

I just started reloading, and this was my first attempt at working up a load. The gun is a 300 Blackout AR pistol with an 8.5" barrel, with a 1:7 twist. I'm using once-fired Armscor brass, Winchester 296 powder, CCI no. 41 primers, and Speer TNT 125 grain bullets. All the work was done on a Lee classic turret press and Lee dies. I have read the Lyman and Lee reloading handbooks, as well as an old version of the ABC's of Reloading and some data from Hornady. After looking at all the load data from different companies, I decided to start at 15.7 gr of W296, and work up in .5 gr increments to 18.7 gr.

Pics: https://imgur.com/a/WUbvsTT

First, I tumbled the brass. I deprimed and full length sized the cases with the Lee die. Then I trimmed with the Lee case cutter and lock stud tool, and chamfered and deburred the mouth. I primed the cases on the press. I checked the weight of each primed case before and after charging. I loaded 5 rounds at each .5 gr increment with the Lee auto drum. The bullets were seated to an OAL of about 2.100". There was some variance in length, but I believe it's the bullets, as I measured a few and there are some differences in bullet length. I don't think it's enough to matter. I put a light crimp on the rounds.

The day I went to the range, it was about 41° F with a crosswind blowing from the left at 9 mph. I have a Vortex Viper PST scope on my gun, which was already zeroed at 50 yards with factory 147 gr ammo. I did notice that most of my shots seemed to be a little high and to the right, but I'm not sure if that was the wind, bullet weight, the handloaded rounds, or something else. I first shot 20 rounds of factory ammo, then let the barrel cool for about 10 minutes. My process was to let the barrel cool for 10 minutes, run a bore snake through once, fire the 5 round string, pick up my brass and check for high pressure signs, repeat for the next load.

I just want to say here that I am by no means a proficient marksman, I am self taught, besides attending one Project Appleseed event, where I did get my Rifleman patch. I still need lots of practice to call myself an accurate shooter. I decided on 50 yards, as that is where I zeroed my scope, and it's a distance I feel comfortable with. The gun was set in a tack driver sandbag, with the smaller bunny ears bag for the rear.

My first string of 15.7 gr was ok, felt pretty good compared to my average groups. After that, from 16.2-17.7 gr, the groups opened up considerably. I had one protruding primer at 17.7, but it may have been one that I didn't seat deep enough, or a loose primer pocket. At 18.2 gr, it was immediately noticable that the group tightened up. It was a pretty big change from the previous strings. 18.7 gr also produced a tight group, but I noticed one flattened primer as well, indicating high pressure.

My next step will be to fine tune the load. I plan on loading up 5 rounds each at 18.0, 18.2 and 18.4 to see if there is any difference. I would feel comfortable sticking with 18.2 gr, but I just enjoyed the process, so want to do a little more tinkering with it. I also plan on developing a subsonic load, with Accurate 1680 and Berry's 220 gr plated bullets.

This experience has taught me a few things. There is a definite benefit to reloading, as far as gaining accuracy from your ammo, but also becoming more intimate with your guns. I also have a better understanding of how ammo responds to different factors, like the weather, or different guns of the same caliber, and even different guns of the same make and model. And it doubles as shooting practice! Once you get into a groove while reloading, there is a feeling of Zen that comes from it.

I've also learned that the cheapest reloading tools are definitely not the best, and I plan on upgrading a few things. The Lee auto drum powder measure was very inconsistent, and leaked pretty bad with the fine grained 296 powder, so I will be upgrading to the RCBS Uniflow III. I bought a cheap MTM digital scale, which was also pretty inconsistent, so there's another item to replace. Luckily, I can still use that scale for archery. I have had some bad luck with a few other Lee products as well, missing threads on a shell holder, broken mount for a primer feeder, a new die scratching my cases, dropped primers, etc. Lee may be a budget friendly beginner option, but I do wish I would have saved up for a higher quality kit to start with, or just picked things up piece by piece. These hiccups have impeded my progress and made reloading frustrating at moments. There are things that a person can get by without, like automated case prep tools, digital measures, progressive presses, and other high cost items, but if you are going to stick with the basic tools, they need to work every time, consistently.

Like I said, I am brand new to reloading, and relatively new to shooting in general. If you have any tips, comments or questions, please share them with me, as this is all a learning process.

[BJK]

I'm extremely cautious when working with small case capacity cartridges and fast powder. I make .2 grain changes. IMO .5 grain changes are for rifle (slow) powders and large cases and maybe not even there. It all depends. I'm extremely cautious.

Using .2 grain changes I'd fine tune things. Not up, down.

I'm not going to comment on your load data, I assume you know how to read a manual.

I've forgotten who makes hard and soft primers. There is a potentially more "accurate" way to check for pressure by using a mic' that reads to the .0001. Calipers won't do it. Info for doing that is probably online. I never looked for it there though and it's been a long time since I pushed things and needed to use it so I can't help with it. It might be something you want to look into. Me? I just don't push things today. If I need more power I use a different cartridge.

I did a net search for "case head expansion as pressure guide" and got a bunch of hits. It wouldn't surprise me if it refutes what I told you since what's in my grey matter regarding it is quite dated. Obviously case head hardness will affect expansion. Anyway, it's something for you to research.

Remember, pressure is our friend, but it can get out of hand and become an enemy very fast. Be cautious, small steps.