David Tubb’s 37XC,
The Quest for the Ko2m rifle cartridge
David Tubb’s 37XC cartridge and its siblings are making the run on the web and on the ranges. We seek to find why by providing aggregated information about the 37XC and help you get to the 2mile target with equipment you probably already have if you’re reading this.
Left to right: 338 lapua (empty)- 33XC Warner 256gr Flatline – 33XC head – 37XC Warner 361gr Flatline – 375 Cheytac (empty) Note – the XC case length VS. the 375 Cheytac. Pic. courtesy of Vestals custom rifles.
The quest for the ideal 2-mile rifle cartridge has taken us far and wide on numerous forums, phone calls and social groups as well as a trip to Italy and Denmark in search of what others are doing to be able to connect with that elusive 2-mile target 48”x60” (120cmx150cm) rectangle (3200meters) – now synonymous with the King of 2 miles competition. The competition has spread like an Australian wildfire from the US to Europe, Latin America, South Africa, Russia and the list keep growing. The addiction is real and the quest is on for the ballistic king of the hill. After our recent trip to the 2 mile facility at Coldbore Range, Denmark, we were even more hooked partly because we saw the potential of a team working well together while acknowledging that we were limited with our 300Norma Mags to about 1700-2000m especially in wet ground which gobbled up our bullets. David Tubb’s 37XC cartridge seems an appealing option.
Above: Wind drift comparisons for 300Norma vs 37XC vs 41XC vs 416Barrett for 10mph full value wind. Notice, very little is being lost to the larger 416Barrett with a 40inch barrel. The 37XC and 41XC are using a 33-inch barrel here to achieve this performance. The 300Norma is there to accentuate the difference in level of performance. What the 300Norma is capable of at 1mile, the 37XC will do at 2500m with ease (windage-wise)
We’ve spoken to a few tens of industry leaders to understand what is it that would make an ideal chambering for this purpose. What bullet, cartridge, barrel length, action, scope, mount combination would bring us closer to achieve this? Are we anywhere closer to achieve this goal? Maybe, the combinations are increasing.
US Optics Sn9 3.8-22×58 – old school scope with exterior adjustments offering 235MOA plus of elevation adjustment seen mounted on a DTA. We need approximately 180 MOA of elevation and 15-25MOA of windage at 2 miles depending on wind speed.
Roberto Buccolo of Windcut bullets from Italy customised this DTA HTI with a 50inch barrel chambered for 460Steyr :0
Earlier last year we visited Mattia Molina of BCM Arms in Italy to see what lies in stock in Europe’s finest armouries and custom rifle makers. Here we spotted an ultra-long 338 barrel approx 40inches long.
Above: The 40 inch border barrels at BCM plus an assorted collection of ELR cartridges that would make any shooter drool!
That would make a nice 33XC barrel!
Which one are you eyeing in your sights? 375CT, 460 Steyr, 408 cheytac, 338 LM
It was readily apparent that this quest was largely dictated by how big you want to go, both in terms of expenditure but also in terms of weight and size of your platform. We’ve seen everything from benchrest style rigs to Fclass platforms on steroids to tactical looking rifles which seize to be tactical and now became sentry guns only for the fittest of squaddies or two men teams.
These are proper 2-mile rigs purpose built to accomplish one thing – Extreme Range performance with a similar price tag 😊
F-Class Rig extravaganza – Italian work of Art by BCM proudly owned by G. Zanoni, Ferrari’s ballistic equivalent is right there topped with March genesis 6-60×56
The quest for the ultimate cartridge is not complete without mentioning the bullets that are available for David Tubb 37XC cartridge. Back when .375 caliber bullets where largely reserved to the 375H&H and similar hunting cartridges, only a few where considering .375 chambered barrels and cartridges. Looking at a few threads online from 10 years ago, it is apparent we have now come a long way thanks to those innovating in this space – Cutting Edge Bullets, Warner Tool Company, Hornady, Berger, Cutting Edge bullets, Badlands precision, TPM Balle, Solid solution design (SSD) among others and creating new slick bullets with impressive ballistic coefficients. Some real, some hype or hope, we have come miles closer to our goal.
Look at what professionals use, it saves you having to walk down the road and back.
However, recalling from lessons learnt in other shooting disciplines, the key to help a sport grow is accessibility, modularity and affordability. In other words, do I have to build a new rifle from scratch for every discipline? Ideally yes, however this would make an already expensive sport almost prohibitive – the equivalent of Dragster racing for the shooting sports. The number of facilities in Europe is still limited making dedicated 2 mile platforms somewhat overkill?
What cartridge could make use of existing long range 338 platforms without having to change your receiver, bolt and chassis and possibly your reloading press as well whilst benefiting from the best bullets made to date? > David Tubb 37XC cartridge
Enter the 37XC brainchild of David Tubb, probably the most accomplished competitive shooter.
The 37XC has nailed it. David Tubb has come up with a solution that may just bridge the gap between the two worlds with his line of 33XC, 37XC and 41XC cartridges. Are you familiar with the 338 Lapua cartridge? Well these cartridges make use of the same bolt face that is used for the 338 Lapua, in other words, you can use that same action and bolt for your new build. The 37XC is larger than a 338 Lapua Ackley improved and smaller in capacity than a 416 Barrett. Basically all you need is to rebarrel your action with a 338, 375 or 416 barrel, change the dies and you’re ready to load up some ammo. A barrel with a 1.350 shank will normally fit a 338Lapua action as opposed to those used on bigger actions requiring a 1.700 shank.
I have compiled some of the data I have found on the 33XC and 37XC Info Facebook group. It is not meant to be a pet load for you to start with. Always start low and work up. Thanks to all those sharing their real world data.
The best thing is that most of your standard reloading kit will work just as well for this cartridge as seen in the setup shown by Precision Arms, this person is very knowledgeable in his approach. Find him here
|Cartridge||Avg. Charge||Performance||Powder charge increase|
300 Norma Mag
|2850ft/s 300grain berger
3000ft/s 230grain berger
|This is the base charge. We shall see what it takes with other cartridges.|
|37XC||118 grains of rl23 in a 30 inch barrel
126 gr n570 pressure signs, room for 4gr plus more powder
H1000 / h50BMG, H4831
36inch barrel Re33 126grains
36inch barrel 8133 122.5grn
36inch barrel 131.5gr Re33
36inch barrel 119.5gr H1000
|3150fps with cutting edge 350mth
350 lazer 3091ft/s
400grain Warner flatline 2960ft/s
375Grain Lazer 3053ft/s
377grain MTAC 3075ft/s
352grn MTAC 3265ft/s
CE 352gr MTAC 3165ft/s
|At least 30% increase over a 338 Lapua|
|41XC||126 grain rl26
32 inch barrel 126 grain rl26
32 inch barrel Rl26 124grain
30 inch barrel 126 gr rl26.
|500 grain CEB lazer in 30inch @ 33 degrees 2830ft/s with the .220 freebore
505Gr Warner Flat lines 1.8twist barrel 2860ft/s
500gr CEB lazer 2880ft/s
2900ft/s 500 gr lazer
450 lazer 2930ft/s
|416 Barrett||505 grain bullet 3190ft/s||180-190 grains (52% increase in powder charge over a 37XC
Now take a look at the wind drift chart, is that much difference worth a new build for you? That’s the real question.
Want more load data? At the end of this article there is a link for more load data.
Jeff Prat reports positive results using 120.0 grains of N570 pushing a 400 gr. Cutting Edge Lazer at an average of 3012 fps.
DTA SRS rifles in 338Lapua area easily turned into 2mile steel harassing platforms
Every Reloader’s dream – 0 Standard Deviation. Pictures courtesy of Precision Arms.
In a nutshell, the 37XC is giving us performance approaching that of a 416B with a shorter barrel, less weight, less cost and less financial commitment.
What will it cost?
- A new barrel of this length including muzzle brake should hover around £1300-1400/€1600
- New set of dies $330 plus freight and import costs approx. $450/€415/£365 dollars to Europe
- Brass 37XC Peterson Brass (50 pieces) – $122 they’ll be around €162/50 once they get to Europe
- Bullets – approximately $2.90 each for the 400gr Warner flatline in .375
- Press – Keep the same one you have if you’re already loading 338Lapua.
The increase in popularity and lower financial commitment of the 37XC seems it’s helping it to catch up fast and penetrate the elr cartridge market like a Lazer 😊
If it’s the 416 that you’re obsessed with, you have the possibility to get a 41XC.
Above: 41xc with 450 lazer with 33xc with 265 mth for scale.
The 450 lazer reaches 2930ft/s 30 inch barrel burning 126 gr rl26. Thanks to Ryan Leithwood for sharing the picture.
For more information, I invite you to read David Tubb’s 37XC cartridge guide on his own facebook group
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