Bullpup Ballistics: 7mm RSAUM in Desert Tech SRS Rifle
Here is the view from 9500 feet ASL. The SRS in 7mm Rem SAUM almost outran the Swarovski laser…
7mm RSAUM in a bolt-action bullpup? Yes it works. A talented shooter, who calls himself “ColdboreMiracle” in social media, has a Desert Tech SRS bullpup rifle chambered for the 7mm SAUM, and it hammers. The 7mm Remington SAUM (Short Action Ultra Magnum) is popular with F-Open competition shooters. It can also work well for long-range hunting and tactical tasks. Learn more about the 7mm Remington SAUM in our 7mm Cartridge Guide.
ColdboreMiracle explains how he selected the 7mm Rem SAUM chambering for his Desert Tech SRS Bullpup: “I just did a comparison between barrel life, velocity, brass, etc. and came to the SAUM. I can tell you this, if you go with one for your SRS, make sure you use long bullets like the 183 or 195, and seat them long. That will aid in smooth cycling.”
Mr. ColdboreMiracle tested the new generation 183gr Sierra MatchKings (item # 1983). These impressive projectiles are “tipped” at the factory. Claimed G1 BC is a lofty 0.707 (at 2300 fps and above). We have heard other reports that these bullets “hold waterline” exceptionally well at 1000 yards. That indicates the bullet-to-bullet BC is very consistent. No doubt the factory uniforming/pointing of the bullet tips helps in that regard.
As you can see, these 183-grainers shoot well in ColdboreMiracle’s SRS rifle. Here are five shots at 100 yards. That’s very impressive for a tactical-style rifle shot from a field-type bipod.
ColdboreMiracle says: “This is the only reason I need to shoot Sierra bullets. On the right (above) you can see the results of the 183gr SMK from my 7mm SAUM. Five shots at 100. A huge thanks to Mark at Short Action Customs, LLC for [chambering this barrel] for my Desert Tech SRS.”
ColdboreMiracle says the bullpup design has many advantages: “The Stealth Recon Scout (SRS) rifle from Desert Tech is a bullpup-configured precision rifle with a shorter length than many carbines. The SRS has a multitude of barrel options that can be swapped in under a minute — all of them come with a 1/2-MOA accuracy guarantee and return to zero. The SRS’s bullpup design puts the rifle’s COG closer to the shoulder, making the rifle balance better off-hand. The straight-line geometry of the SRS makes recoil seem lighter, and barrel hop is reduced, allowing the shooter to stay on target better. It takes a little getting used to, when converting from a traditionally-configured bolt gun. But once you do, you won’t go back.” To learn more about this rifle (and other Desert Tech arms), visit ColdboreMiracle’s Facebook Page and YouTube Channel.
7mm Remington SAUM — Key Considerations
In some respects, the 7mm SAUM cartridge may be better than the 7mm WSM. The 7mm SAUM holds less powder — but that’s a good thing, since the capacity is more than adequate to do the job. You can drive the 180s at 3000 fps with a SAUM using less powder than with a WSM. Additionally, the SAUM case has a slightly longer neck. This gives you greater flexibility in bullet seating. With a long neck you can set the throat so the long 180+ graing bullets are above the neck shoulder junction, yet you can still seat shorter hunting bullets close to the lands. Additionally, long case necks, some believe, cause less throat erosion than shorter necks. That’s not “hard science” but it is certainly a view shared by many experienced shooters. The long neck is one reason many varminters favor the 6mm Remington over the .243 Winchester.
7mm RSAUM Is More Efficient than 7mm WSM
7mm RSAUM shooter Steven Ikeeda tells us: “I decided that some type of 7mm was the ticket for doing well at 1000-yard matches, especially if one could drive the high-BC bullets at 2900+ fps. Looking over various 7mm cartridges that could produce those velocities (and didn’t require case-forming), I was impressed by the 7mm SAUM and the 7mm WSM. According to the load manuals, the 7mm WSM offered a bit more velocity than the 7mm SAUM. However, to achieve its small velocity advantage, the larger 7mm WSM had to burn 7-10% more powder than the 7mm SAUM. (The 7mm WSM has 81.0 grains of capacity vs. 73.6 grains for the 7mm SAUM.) The SAUM is a very efficient case. It looks like a 6.5×47 Lapua on steroids.”
