History
David Tubb of Superior Shooting Systems built the 33 XC in 2020, and within a few seasons it dominated the top tier of King of 2 Miles and ELR competition. The round is designed around his 299 grain .338 DTAC bullet, HBN coated with the NOSERING treatment to tighten the drag function, running roughly 3,075 fps from a 27 inch test barrel.
Tubb sells it as factory ammunition, and it is also handloaded. No SAAMI or C.I.P. standard exists for a proprietary cartridge, so this page covers caliber, twist, and the loads while a house cutaway awaits a dimensioned case print. The draw is a very-high-BC .338 launched fast enough to stay supersonic far past a mile.
Lineage
The 33 XC fires .338 inch (8.59mm) bullets and belongs to Tubb's XC family, the .338 ELR sibling of his 6XC and the larger 37 XC and 41 XC. It feeds from a magnum-length action and takes a large rifle magnum primer. Its peers are the other big .338 ELR rounds: the .338 Lapua Magnum, .338 Norma Magnum, .338 EnABELR, and .338 Edge.
Specifications
| Spec | Value |
|---|---|
| Case type | Rimless, bottlenecked (~35° shoulder) |
| Bullet diameter | 8.59 mm (.338 in) |
| Neck diameter | 9.40 mm (.370 in) |
| Shoulder diameter | 14.25 mm (.561 in) |
| Base diameter | 14.87 mm (.585 in) |
| Rim diameter | 14.93 mm (.588 in) |
| Case length | 78.36 mm (3.085 in) |
| Family | XC line (David Tubb / Superior Shooting Systems, 2020) |
| Primer size | Large rifle magnum |
| Belted | No |
| Rifling twist | 1 in 9 in (recommended, for 300 gr .338 match) |
| Max pressure | No published SAAMI/C.I.P. figure |
| Recommended barrel | 36 in, 1:9 twist |
Dimensions are from the maker (David Tubb / Peterson Cartridge) maximum-cartridge print. The case has a published shoulder datum (.4375 in); cartridge overall length is load-dependent, so the bullet on the cutaway is representative.
Barrel Design
The twist I'd recommend is 1:9, enough margin to keep the long 299 grain DTAC and its 300 grain class peers stable deep into the transonic range past a mile. These are long, high-BC projectiles, and they need it.
I set the baseline at 36 inches. That is an ELR length, collecting velocity and holding the heavy .338 supersonic well past 2,000 yards. The build is dedicated and expensive to feed, which suits a cartridge made to win two-mile matches. The tables below are computed at that 36 inch barrel; muzzle velocity is scaled from the maker's 27 inch test figure and moves with barrel length, so confirm your own on a chronograph before trusting any dial.
Handload Performance
Handload · 299 gr Superior Shooting DTAC
| Range (yd) | Velocity (fps) | Elevation (mil) | Energy (ft-lb) | Windage (mil) |
|---|---|---|---|---|
| 0 | 3150 | -0.2 | 6587 | 0.3 |
| 100 | 3040 | 0.0 | 6134 | 0.1 |
| 200 | 2931 | -0.2 | 5704 | 0.3 |
| 300 | 2825 | -0.7 | 5297 | 0.4 |
| 400 | 2720 | -1.3 | 4912 | 0.5 |
| 500 | 2618 | -1.8 | 4549 | 0.6 |
| 600 | 2517 | -2.5 | 4207 | 0.8 |
| 700 | 2419 | -3.2 | 3885 | 0.9 |
| 800 | 2323 | -3.9 | 3583 | 1.1 |
| 900 | 2229 | -4.6 | 3300 | 1.3 |
| 1000 | 2138 | -5.4 | 3035 | 1.4 |
| 1100 | 2049 | -6.3 | 2787 | 1.6 |
| 1200 | 1962 | -7.2 | 2555 | 1.8 |
| 1300 | 1876 | -8.2 | 2337 | 2.0 |
| 1400 | 1793 | -9.2 | 2134 | 2.2 |
| 1500 | 1711 | -10.3 | 1943 | 2.4 |
| 1600 | 1630 | -11.4 | 1765 | 2.6 |
| 1700 | 1552 | -12.7 | 1598 | 2.9 |
| 1800 | 1475 | -14.0 | 1444 | 3.1 |
| 1900 | 1399 | -15.5 | 1300 | 3.4 |
| 2000 | 1326 | -17.0 | 1168 | 3.7 |
| 2100 | 1256 | -18.7 | 1046 | 4.0 |
| 2200 | 1188 | -20.5 | 936 | 4.3 |
| 2300 | 1126 | -22.4 | 841 | 4.7 |
| 2400 | 1084 | -24.5 | 781 | 5.1 |
| 2500 | 1057 | -26.8 | 742 | 5.4 |
| 2600 | 1035 | -29.2 | 711 | 5.8 |
| 2700 | 1015 | -31.8 | 684 | 6.2 |
| 2800 | 996 | -34.6 | 659 | 6.6 |
Muzzle velocity 3150 fps is the factory figure from a 36 in test barrel. Expect your own barrel to read a little differently. Velocity is color coded green supersonic, yellow transonic, red subsonic; treat transonic and subsonic rows as approximate.
Trajectory
FAQ
What barrel length and twist should I run?
A 1:9 twist for the heavy 300 grain class .338 match bullets, and a long 36 inch barrel to collect velocity and hold them supersonic past a mile. It is a dedicated ELR build.
Is the 33 XC a SAAMI cartridge?
No. The 33 XC is a proprietary David Tubb / Superior Shooting Systems cartridge, available as Tubb factory ammunition or handloaded. It has no published SAAMI or C.I.P. standard, which is why this page omits the case-dimension table and cutaway pending a maker print.
How does it compare to the .338 Lapua Magnum?
The 33 XC is a purpose-built ELR cartridge optimized around a specific high-BC bullet and load, and it has been winning at the top of two-mile competition. The .338 Lapua is the standardized, factory-supported choice with ammunition on every shelf. The 33 XC trades that availability for an edge at the extreme end.
What is it good for?
Extreme long range: King of 2 Miles and similar two-mile competition, where keeping a heavy, high-BC .338 supersonic past a mile is what wins. For anything inside that, a standardized .338 or a smaller cartridge does the job with far less expense.