David Tubb is excited to introduce the 33XC AND 37XC
After shooting a 338 Lapua Improved and then necking it up to 375 followed by 3 different 375 Cheytacs. I came to several conclusions about what I think would be the better cartridge approach to shooting ELR.
375/338 Lapua Improved – Fire forming and ill-conceived design surrounding the Lapua Improved (current reamer headspacing as well as resize die maker parameters create a short case life).
From shooting and borescoping barrel life would be very good… shot over 1500 rounds and the throat looked excellent at that point.
375 Cheytac – overbore (too much case capacity) along with other issues
1. Buy a New larger reloading press
2. Custom dies which are overpriced
3. Larger action diameter - so a new gun is in order
So several thousand dollars later you have a 375 Cheytac.
From shooting and borescoping barrel life was very short - 2 of the barrels I shot gave up at less than 500 rounds each.
Selfish me would prefer the best of both worlds along with the ability to use my TUBBGUN platform which allows at the range caliber changes…..so the 33XC (neck up to 37 XC if desired) came to life.
Uses Superior Shooting A7 tool steel (with integral neck shoulder bushings) dies along with 7/8” x 14 tpi reloading press.. No fireforming – all the case improving (> 20 grains more powder capacity, 35 degree shoulder, longer neck) done in a production case.
Significantly more velocity than a Lapua improved and the Remington Ultra mag improved.
The 33XC (eXtra Capacity) has up to 130 grains of useable powder capacity while leaving the .393” neck unfilled - depending on the powder density and drop tube length.
Based off of a .580” bolt head it will extract with ease when using a properly polished chamber when using a maximum powder charge.
Peterson Cartridge Company is making the brass for Superior Shooting Systems.
The 33XC has a 35 degree shoulder /.350” more body length with less body taper as well as an additional .065” longer neck when compared to a 338 Lapua case. Total case OAL is 3.087” (.415” longer than a Lapua and slightly longer than a Cheytac).
The 33XC favors 50 BMG / Reloader 33 / Vit 20N29 burn rate powders with either 250 or 300 grains bullets. 300 gr jacketed/lead core bullets leave at over 3150 fps and 250 gr jacketed/lead core yield over 3450 fps. Monolithic 250 grain achieve the same velocities with approximately 3 grains less powder. Test barrel -- 28” Schneider 5 P/ 9 twist barrel in a medium weight profile.
In 37XC - H1000 and Retumbo burn rate powders work well. Warner Flatline 361gr easily fly at 3075fps with just over 120 grains of either powder. Test barrel --33 inch Schneider 5P barrel 7 twist.
If you plan to shoot jacketed /lead core bullets then stay with a 9 twist barrel otherwise your bullet may fail from the excessive spin rate of quicker twist barrels.
If you already have a 338 Lapua and desire to rechamber Superior Shooting Systems has dies, 33XC brass and rental 33X and 37 XC reamers. Dave Manson is making the reamers so you can order your own if desired (810 953 0732).
The 33 XC --A7 tool steel resize die (7/8 x 14) comes with 2 different (365/.367) 33 and a 37 integral neck shoulder bushings. This is designed to work in your standard (7/8x14) press. Additionally the modified competition bullet seater is designed to seat 338 bullets and can be ordered for 375 diameter bullets....... so all you have left to do is purchase a 338 or 375 Sinclair type expander mandrel depending on you caliber choice and inside neck diameter you desire.
Results of testing from 4 different Schneider barrels – use caution when reloading by starting with a reduced charge.
33XC - 34 inch barrel. Warner 256 gr Flatline. 7.5 twist
113 gr Retumbo 3375 FPS
118 gr Reloader 33 3400 FPS
123 gr 50BMG 3475 fps (can shoot over 100 fps faster if desired)
37XC 33 inch barrel. Warner 361 gr Flatline 7 twist
121 gr H1000. 3075 FPS
122 gr RETUMBO 3090 FPS
33XC with 28 inch Schneider 5 P rifling barrel - 9 twist – medium contour
124 gr H50 BMG 3160 fps with Berger 300 gr
128 gr H50 BMG 3380 fps with a 250 Solid Badlands bullet
128 gr H50 BMG 3320 fps with a 250 Sierra
121 gr Reloader 33 3120 fps with a Berger 300 gr
125 gr Reloader 33 3425 fps with a 250 gr Badlands solid
128 gr Reloader 33 3460 fps with a 250 gr Sierra
All of the data loads were gauged by the bolt opening WITHOUT any stickiness associated with pressure / a dozen cases were used and reused for entire the 28” barrel testing.
Keep in mind I did load up to velocities with which I did experience pressure signs. My standard for the above listed loads was to back off the charge by 2 grains and then do a retest for confirmation.
I loaded a single 37XC case over 20 times when breaking in one of the Schneider 375 barrels. The Primer pocket became loose but would still shoot with no gas leakage around the primer.
Dave Manson makes the reamers for the 33xc and the 37xc
His phone number is 810-953-0732.
Note the throat length on the reamers for either the 33xc or 37xc are for a turned solid bullet. The throat length would have to be extended if you want to use a 300 grain lead core bullet, or you would have to purchase a separate throater
Throat length for a 300 grain lead core bullet is .250" straight section (freebore).