Happy Monday, and boy has it been a Monday. Have you ever stopped and wondered what makes a Monday, a Monday? Is it just the nature of getting back into the routine of things again at work that takes a bit of getting up and doing? Or is there something inherently misfortunate about the first day of the workweek that really just seems to have a bit of a bite to it? It is something of a mystery to me, and judging by everyone else’s struggles, it is a mystery to them too.
There is a bit of good news. I have a few projects I am working on. These are continuations of previous projects. It’s hard for me to believe that about 5 years ago I built a 338 Spectre AR-15 rifle. While I have loaded and put a few rounds through it, I never really got to where I had a few good loads developed for it, nor did I get to really put the rifle through its paces. Not that the rifle is anything special. It is, what you might call, a “Franken gun”. It just so happened that the opportunity presented itself this weekend that I was able to kill a couple of birds with a single stone. I did a bit of product testing and I cracked open the 338 Spectre can of worms.
For those not familiar with the cartridge I did a write-up on it, which can be found here. It is very similar in concept to 300 Blackout, except it’s scaled up to 338 calibers. Designed to fire a 300 Sierra Match King at subsonic velocities. Unlike the 300 Blackout, pressures for this cartridge top out at 37,000psi. Some will say that you can push the pressures higher if you use 6.8 SPC brass, but I am not much of one to push the pressure envelope with my firearms. Energywise, it is similar to a 44 Magnum, but the ballistics are much better as you are able to use a wide range of bullet weights all designed with sleek ogives.
At this time the only source of barrels that I am aware of is from Southern Ballistic Research. The cartridge is proprietary to them and they do support it. I would love to have them chamber a 700 Rem barrel for this cartridge. They used to do it but I do not see it listed on their website currently. Muzzle pressures are similar to that of most pistols thus it is safe to use 9mm Suppressors. A coworker of mine suggested a 10.5in SBR with a can would make a very sweet and handy truck gun.
The loads I work up with all with a 300gr Serria Matchking. It just so happens I have tons of those bullets kicking around. They were pull-downs, so the jackets are a bit blemished. I am sure they would shoot fine from my 338 Lapua Magnum, but when you pay nearly $2.00 a shot, you just want to have the perfect bullet. Eventually, I will likely switch to a cast bullet with a Hi-Tek coating for the 300gr Subsonic Loads. A few mold makers offer an option and I would love to experiment with a 300gr cast projectile with a cavity in the nose.
My plan is to work up a few supersonic loads, I have not decided on what bullets I will use, but I will likely load with a 225gr solid copper. I have a bunch of factory second bullets designed for 338 Federal with very large open tips. I am curious to see if I can get some terminal performance from them in the 338 Spectre. I know Barnes Bullets makes some copper solids around 160-180gr, which might be an interesting load to try. I thought Liegh Defense was offering some super-light bullets around 130 or 110gr that I thought would be interesting but I do not see them listed.
I used 13.1gr of CFE BLK for this load. Burn speed for this powder is very close to A1680 which is an old standby powder for these subsonic loads. Mainly because the powder generates a lot of gas at comparatively low pressures. This gas volume is needed to cycle an AR-15 reliably. There really are only a few powders that work well for subsonic loads in AR platforms. CFE BLK, A1680, and Shooters World Blackout are the ones that come immediately to mind. Quickload estimated a bit north of 1100fps, and I generally find QuickLoad to be optimistic with velocities so I figure this would land me close to the 1050fps which is typically considered the upper threshold for subsonic loads.
When doing the first batch of 338 Spectre back nearly half a decade ago, I had issues with the cases cracking in the body after the first firing. These cracks went the full length of the body, rather than around the head which was odd. Prior to testing pulled the barrel off and then retorqued it. Hoping that maybe it was not seated right and the headspace was a bit long. I’ll be keeping a close eye on it as I test these loads, the brass is all the same, from the same lot of Starline brass I bought 5 years ago so if the issues crop up again, I am not sure what I will do. All part of the adventure. Maybe I’ll anneal the case necks, we will see.
The mag I had for the rifle was pulled apart and the follower was missing. Turns out a follower designed for a 223/556 cartridge does not work well in a magazine designed around 6.8 SPC. It was worth a shot. Function testing this load showed that the bullets were seated a bit long for reliable feeding in the mag and that the mag needed a proper follower. I’ll seat the bullets back a bit and swap out for the right components and try again. Since it was a function test I was not set up for velocities, I get those when I can get out to a proper range and actually get some shots downrange.
The reason I started the website was to share my passion for handloading and reloading. I have a few other projects that stray from this theme but honestly, it’s nice to return to the roots and share what I was able to do over the weekend. I am hoping to spend a good deal more time in the reloading room over the next few months so I hope to be able to bring a bit more content like this. I also hope that will spawn a few more write-ups and help others who might deal with the same problems.
Anyway, that’s what I have for this week. As always if you are looking to get in touch, the best way is to send me an email at jay@theballisticassistant.com. You may check us out on Parler, Facebook, Instagram, and Reddit. If you’d like to submit a load to our load database, the instructions are here.
As always, shoot straight and stay safe!
The Ballistic Assistant