33 SM…Build and load work up

Just want to share my experience as a hobbyist gunsmith in building around this awesome caliber. For those who haven't heard about it, the 33 SM is essentially a 33-300PRC imp and is similar a 33 Nos.

This project started life as 338 Win Mag that I was trying to make work as a longer range gun to augment my primary gun, a 243 Win. With the 105 AMax, I've consistently harvested whitetail and axis deer at ranges up to and just over 600yds. I wanted to have less wind drift and the option to reach out to 1000yds on game effectively. I know I could just save longer for a custom gun, but at this time I had a tiny budget and no patience! I saw Rich's post about his new 33 Sherman Magnum and the wheels started turning. After talking with Rich, I realized I could use my 338 Win Mag and rechamber my existing rifle without setting the threads back. That meant I could do this myself. The factory TC Venture had already shot many half MOA groups, but was honestly a .75 MOA gun. I thought a new chamber could improve that. But the TC Venture has nearly zero aftermarket support. I began measuring my action and comparing it to existing actions. What I found was that the REM 700 and the TC shared the same dimensions from the recoil lug back to load port. The rear action screw was .100" further back than a REM 700 long action.

With that knowledge I wanted to get my hands on a decent, but low cost (in case I destroyed it) REM 700 LA stock. I found a Stockys Fiberglass VG2 here on the classifieds for a great price. My thought was to seat the TC action in the REM stock but open the rear action hole from 3/16 to 5/16 and then just bed the stock, filling in the old screw hole with Marine Tex. It's wasn't that simple of course. The TC has a side bolt release and the bolt knob sits .100" (a common difference I found) further back than a REM. So after some tedious work with a file to relieve those areas, the stock fit just fine and after bedding the entire action, I think it looked great too. But now what bottom metal?

I found I could use REM pattern bottom metal as well, but relieving the .100" in the rear action screw left about .125" of aluminum. So far, this hasn't been an issue with setting action screw torque to 55lbs. I ended with a BDL bottom metal and a Wyatt's PRC length mag. I'm still tuning the feeding, but for now, I have no issues single feeding.

I picked up a new trigger spring kit (1.5lb crisp trigger now) and bolt knob from anarchy outdoors and a 20 MOA rail from EGW. I bought a clamp on muzzle break from Witt's Machine. Man it is ugly, but it works great! I finished the stock off with a hunters rail from UM.




Now off to loading for this beast. It sits at 11lbs 6oz with the Vortex Viper HS. I could drop that to 9lbs 7oz with a carbon VG stock, but I'm fine with this weight.

Now I had to find a load.

This is a wildcat round so I knew there was little data. The case capacity is slightly over 33 Nosler capacity, so I started there and Rich shared some of his testing data posted on his webpage.

I am using Peterson and Hornady brass and 225 CE MTH(my wing mags favorite), 230 ELDx, 270 ELDx, and 300 SMK to run ladders. I want to shoot the 270 ELDx. R26 and R17 powders. I have both on hand and Rich touted the R26 but KH_Outdoors found the 4350 burn rate best.

Fireforming the brass proved to be a challenge until I removed my ejector. Before removing the ejector I was getting 50% FTF with a jammed bullet or a false shoulder. After removing the ejector, every case fireformed easily. I can only assume the ejector was pushing the case/bullet further from the firing pin. I used 67gr of leftover Win 780 and a 300gr SMK. No issues with fireformed brass.

I was surprised that I couldn't find pressure max with the CEs and R26, but I was just testing that for data. 230 eldx shot a great group for a ladder, but these were also just for data. I did exceed 2900 with the 270 ELDx, but it took two trips as I only worked up to 82gr in the first trip and then referencing Rich's 285eldm data, I decided to try higher. But I had a hunt in between and settled at 81gr R26 at 2748fps for the hunt. Here is my data plus a pick of the ladder groups and my hunting load. I'll likely tune for a 270 ELDx load in the 2850fps range later.










Overall, I like the 33SM. I do plan to build a high quality custom on a REM 700 footprint later, but for now this was a fun project. The TC actions can shoot, but the lack of aftermarket support will always kill these budget actions. I stayed well under $1500 total cost including rifle and scope. Not bad given the current market, IMO.

Thanks for reading, hope this adds to the 33SM data pool that is out there.

Thanks for sharing and glad to see more guys using the 33 Sherman Magnum!

I'm surprised that it hasn't gathered more attention. It's within a couple hundred fps of an edge and uses 25gr less powder plus fits in a 3.8" load port/mag.