Brass Prep for Precision Rifle
I sit here thinking about what to write about brass prep. I do this while sitting in my garage while my Giraud
annealer runs my latest batch of brass. I’m getting ready for a ~ 3-400 round month of local and major PRS
matches. I define brass prep as whatever I have to do to get new or fired cases ready to load (primer, powder,
Why do we care about brass prep, SD, concentricity, powder measurements to the kernel? Ultimately its where the bullet impacts that counts. We want to do what we can to limit the vertical dispersion of the impacts at range. As we get better at this game, things like our wobble on a barricade starts getting smaller. Our application of the fundamentals gets more automated, our wind calls get better. All of these things help us make our hit probability go up (and are arguably more important than measuring powder to the kernel..). The total sum of the skills of the shooter, an accurate rifle and the best ammo we can purchase or make culminate to make our shot cone smaller at range, which results in more impacts on target. How much does reloading factor in? This article influenced me alot in the past few years: How much does it matter anyway?
To give some context, I’m a ~ 75%er, meaning I usually shoot ~ 75% of the match winner with occasional moments of top 10 finishes in our local matches. While I volunteered to write up an article on brass prep to help newer shooters, I also hope to learn how the top shooters differ from my process. I’ve learned a ton from the great mentors in the Texas clubs. Our online forums/FB pages are also a wealth of great information.
I’ll start brass prep with some advice. Go with the best brass you can afford. Then scrap that and just buy Lapua brass. You won’t be sorry. Buy once and reap the benefits of not having to struggle with brass that doesn’t last or lacks consistency. This is the buy once, cry once theory at play.
Also, I try and shoot all of my brass (~500 pieces) then work brass prep in one big batch. I think batch prepping helps with consistency. This helps make sure you are not overworking one set of brass over another.
Once I get home from shooting, I like to tumble my brass in my super cheap vibratory tumbler. I’m finding that the media only lasts about 7-8 sessions. By then dirt, oil, whatever seems to load up the media. After the media gets loaded up, it don’t clean so well... change it often.
I then deprime the brass using my Dillon 550 and a Lee Deprime die. Folks use other processes that deprime later, but I like to do it before I clean with SS media. Why use a deprime die? I read from Applied Ballistics and The 6.5 Guys that it may help with brass concentricity. I follow that and the no center neck sizing button in my FL die theories.
I anneal next. I obviously believe annealing is important. There really isn’t enough evidence to definitively say if it is worth it. I believe my own results and the results of the shooters I’ve spoken to who see solid performance (less than 10 SD on a Magnetospeed) over a consistent period of time. There is more research on annealing. Bryan Litz of Applied Ballistics included a short study of annealing in Volume 2 of Modern Advancements in Long Range Shooting. His article was focused on neck tension and ultimately found that annealing did not impact the results of his shooting tests. There is something there though. I believe annealing impacts the longevity of the brass, and it makes me feel better by doing it…
Once annealed, it's time for resizing. Lube comes into play here. I’ve had good luck with homemade lube consisting of lanolin and 99% alcohol. When mixed in a 10:1 alcohol to lanonlin ratio, it creates a lube that you can spray on the cases. I like to use a gallon zip lock bag to put the cases in and spray until it looks like they are coated. Using this lube does drive the need to clean it off since it becomes sticky and attracts dirt. Another lube I’ve had good luck with is Hornady One Shot. I use the same gallon zip lock bag process. One Shot does seems to be less messy, but I think the lanolin is better for higher pressure die work (like downsizing the neck on new brass).
One aspect of resizing is getting the body/shoulder of the brass back down to a size smaller than the chamber. In some other shooting disciplines, you can shoot 4-5 firings with only neck sizing. You could probably get away with that in precision rifle too, but eventually it's going to bite you in the form of slowing your bolt speed down. Maybe even to the point where the brass is hard to get into and out of the chamber. Most of the good / top shooters in my region seem to full length resize or use their body die (in the Redding die sets) regularly. I use a FL die every time I resize and bump the shoulder back 2-3 thousandths. This ensures that the case size isn’t going to be the reason the bolt speed is slow. FL sizing also helps keep the pressures stable since the case headspace is consistent.
Another aspect in resizing is concentricity. This means how straight is the case after you’ve put it through your press. If your press introduces an angle through the die, then how straight your brass is going to be will suffer. This is where “floating” your die comes in. It's a simple fix by adding a rubber o-ring in between the die and the press or in the case of progressive presses, using a floating die head. This theory is that by floating the die with a o-ring the die is able to index straighter on the case. The output is a straighter case neck. The straighter the neck that holds the bullet, the more centered the bullet will be in the bore.
At this point, I use a mandrel to set the neck tension/internal neck dimension. Since I’m doing this on a Dillon 550, it's not an extra step. I subscribe to the mandrel (floated as well) in setting a more accurate neck tension, but many get similar SDs from using a bushing die so it is probably a wash in the end.
Once resized, I sometimes tumble again to get the lube off. I don’t always do this at this point (if using OneShot). You can trim, clean out the primer pocket, ect with lube still on the cases. It kinda depends on how OCD you are about it.
Trimming or primer pocket cleaning. Take your pick on which one is first. On trimming, some calibers need it every loading session. Others calibers don’t seem to grow until maybe their 3-4th firings. The key here is consistency. In my mind, if some are a little long then I’ll run them all through the trimmer. This is where a powered trimmer comes in handy if you are working with a large batch. If I’m loading a caliber that I have a Giraud cutting head for, then that is the go-to trimmer. If not, I like the Forester 3-in-1 trimmer head if you have their trimmer body. Getting the inner and outer chamfers while you trim to length is a real time saver.
When we look at primer pockets, we have some work to do. With new brass, it's a good idea to chamfer/deburr the inside of the primer hole. You only have to do this once. This is where the drilled vs punched conversation comes in. It is widely assumed that Lapua drills all of their primer holes (at least I thought that for a long time…). Some folks say Lapua punches both sides of the hole to get to uniformity. Great! However it happens, I’ve not chamfered Lapua brass and still achieved consistent lower SDs (less than 7 usually). But I don’t think it hurts to chamfer Lapua brass. Other brass that is made with less care is sure to benefit from primer hole deburring/chamfering.
With fired brass, cleaning out the primer hole after decapping is something I’ve always done. I think it came from the BR guys doing it and it has served me well. SS media cleaning will achieve this, otherwise you may need to do this mechanically. I’ve used a Sinclair primer hole uniformer with good results. Other options are to use what is in effect a brass or steel brush to clean it out.
At this point I’m ready to load. Notice I didn’t talk about neck turning, sorting by weight, brushing the necks, ect. These may help get another percentage or 2, but I think these are wasted efforts unless your caliber requires these actions.
Tumble dirty brass
Dillon 550 / Lee Deprime die
SS Media clean brass
Forester Full Lenth resizer die
1.4580 shoulder bump
Primer pocket cleaning
Dillon 550 / Forester micrometer seater
Put in carriers