Long Action 300 WSM: Superb Performance Pairing

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Thanks to a recent video by Vortex Optics, the 300 Super WSM has been in the spotlight. The one issue with their view was their 300 WSM was throated to SAAMI spec. This means it wasn’t a true long-action 300 WSM because, aside from bore rider bullets, their 300 WSM was limited on bullet selections. Over the past 6 years, I have built and loaded for four different 300 WSMs. I have a love for that cartridge, but it wasn’t until over two years ago that I decided to build a true Long Action 300 WSM.

The 300 WSM (Winchester Short Magnum) as a chambering has been around since it was introduced in 2001 by Winchester. While the original 300 WSM did a lot of things well, it was limited by a SAAMI cartridge overall length (COAL) of 2.860”. The cartridge has a rebated rim (the rim diameter is smaller {.535”} than the body of the cartridge case {.555”}) and a 35-degree shoulder. This gives the short stubby case a surprisingly high powder volume. The problem with the SAAMI chamber design was the short COAL and .188” freebore. This meant that heavy for caliber bullets had to be seated deep into the case, eating up the volume for powder.

The Long Action 300 WSM has been around for a bit in the F-Class and Long-Range Bench Rest shooting sports. The cartridge made a name for itself as being very easy to tune, accurate and an efficient cartridge. When I first started considering the Long Action 300 WSM, I knew if I picked the right bullet, I would have easy success with load development.

With a 1 revolution per 10 inches of barrel (1-10 twist) SAAMI spec, the 300 WSM as it was could still handle a lot of heavy for caliber bullets. Bullets such as the 215 Berger Hybrid Target, 212 ELD-X, 210 Nosler Accubond Long Range (ABLR) and the 225 ELD-M are plenty stable in a 1-10 twist. When I started my Long Action 300 WSM, I knew I also wanted to try some heavy for caliber copper bullets like the 210 Patriot Valley Arms (PVA) Cayuga and the 212 Barnes LRX. Both of those bullets are bore riders so I knew the SAAMI chamber wouldn’t be an issue, but it would be for the cup and core bullets I listed above and the 205 Badlands Bulldozer 2.

Dummy Rounds

I started by making some dummy cartridges with the 225 ELD-M, 230 A-Tip, and the 205 Bandlands Bulldozer 2. Knowing I wanted to push some of the heavy copper bullets, I went with a 1-8 twist BSF barrel. I also wanted to have this rifle suppressed, so I elected for a 22” barrel. I had a Remington 700 Stainless Long Action that I was going to use for the action. I used PTG Truing Kit and trued up the action in my garage. The tools were easy to use but it took some time. I was pleasantly surprised with the results when my gunsmith went to chamber the barrel and checked the action for true.

I had Marc Soulie from Spartan Precision Rifles chamber my barrel. Marc is world renowned for his rifle work and he is local to me so that was an easy decision. With my dummy rounds made, Marc added .130” of extra freebore onto the chamber. Besides the chamber job, I wanted to do all the work I could on my own. Once the barrel was chamber and installed on the action, I dropped it in a Grayboe Pheonix (the eventually to the Grayboe Pheonix 2). I bedded the action to the stock with Marine-Tex and started load development.

I had a KGM R30 suppressor coming for the rifle, but I had to start the load development without it. With little to no load data out there for a long action 300 WSM, I began doing pressure ladders with multiple bullet options and powders. I used ADG brass and Federal 215 (Large Rifle Magnum) Match Primers. With the heavier bullets and increased case capacity, I wanted to use some slower burning powders. It was a chore finding a good combination to start with because most load data is for faster burning powders and low weight class bullets. I admittedly started with too many options and that took me longer than expected to find a good load. I found that Alliant Reloader 23 gave me very consistent velocities, good case fill and great accuracy. I didn’t end up with my targeted velocity with that powder, but the accuracy was something I could not ignore.

I let the BC of the bullet do the work for me and kept the charge and velocity lower. I settled on a 215 Berger HT, RL-23, and Federal 215M primers loaded to a COAL of 3.150”. This load produced a pedestrian 2660 fps, but I can, on demand, shoot sub one-inch 10-shot groups with that rifle. When I say 10-shot groups, that is having 10 cartridges at the ready and shooting them as fast as I can load them and fire them in a stable position. I do NOT let the barrel cool between shots. When I only shoot 5-round groups, I can on demand shoot sub 1/2-inch groups. This is with a hunting weight rifle at just over 12 pounds.

Rifle Set-Up

Depending on what optic I have on the rifle, this rifle loaded with three in the magazine and two in an Inflection DE OS Ammo Caddy, KGM R30 suppressor, Armageddon Gear Suppressor Cover, Magpul MS1 Lite Sling weighs 11 lbs 5.7 oz. Depending on what bipod I’m using, the full setup ready to hunt will be 12 lbs 2 oz to 12 lbs 13oz. I know some people are going to say that is too heavy of a rifle for “hunting,” but that rifle is so well balanced it feels lighter than it is. I also do not build rifles for carrying; I build them for shooting.

This type of accuracy held for about any bullet I put over the same charge weight. I hunted for 2 years with that load and killed a black bear, two bucks and a doe with it. This year I have committed to trying to use a copper bullet. Luckily the 210 PVA Cayuga shoots phenomenally with that same load. The velocity is the same as the 215 Berger HT and the BC is very close to the same. I am jumping those 210 PVA Cayuga (and 212 LRX) a whopping .310” at a COAL of 3.300”. For most people that would be scary, but I have had good luck with jumping bullets a country mile.

The 300 WSM in the Long Action configuration gives you a lot of options that a lot of other cartridges don’t. Using a long action, you are not hindered by the magazine length. I used the Hawkins Precision Hunter DBM and Long Action (300 PRC) Magazines. Hawkins also offers a spacer for the back of the magazine, which allows me to load the cartridge to a max of 3.35” and feed very reliably.

With the newish release of the Ramshot Grand Powder, I just had to try that with this cartridge. The problem I was running into with some of the other slower burning powders in the H1000 burn rate was I just could not get enough of the powder into the case to reach max pressure. I had previously tried Ramshot Magnum, and while the velocity was decent, the accuracy and temperature stability of that powder left me wanting more. I have done some testing with that Ramshot Grand in recent days and it’s impressive for this Long Action 300 WSM. While I am still not close to pressure, I was able to get over 2800 fps out of that powder with the 212 LRX in virgin Lapua 300 WSM brass. I was getting good accuracy with that combo as well but with spring bear season fast approaching, I will have to test that combo out later in the year.

Just Right

While it’s no hot rod, this Long Action 300 WSM is the most accurate hunting gun I own. I can attribute that to a good barrel (BSF) and a great chamber job from Marc at Spartan Precision Rifles. If you invest in a good barrel and chamber job, you will have similar results as I have. I am currently sitting at over 800 rounds down this barrel over the past couple of years and expect another 500-600 rounds before I pull the barrel. That is another nice thing about this cartridge; it is not overbore, so you can expect some extended barrel life. It also helps that I am not stepping on my handloads.

This cartridge isn’t for everyone though. While I have tried some factory 300 WSM ammunition in this rifle, you just don’t get the same type of results. When I can get an extreme spread (ES) under 10 fps with my handloads, I am lucky to see an ES of under 80 fps with some factory loads.

If you are a handloader and want to try this cartridge out, I am confident in saying you can have some amazing results. For the factory guy, the Long Action 300 WSM does not make any sense for you.

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