A Look Inside Sierra’s 300m Underground Test Tunnel
Ever wonder how (and where) Sierra tests its bullets? The answer is underground, in a 300-meter test tunnel located under Sierra’s factory in Sedalia, Missouri. The photo above shows the construction of the tunnel back in May, 1990. Like most bullet manufacturers, Sierra does live-fire bullet testing to ensure that Sierra projectiles perform as promised, with repeatable accuracy. Sierra’s 300-meter test range is the longest, privately-owned underground bullet test facility in the world. Sierra offers free tours of the test tunnel as part of Sierra’s Factory Tour Program.
Sierra Bullets tests every new bullet design and each lot of bullets. Sierra tells us: “When [we] change to a new bullet they are continually shooting them until they get the bullet properly set up and running and the range releases them to run (meaning the bullets shoot to spec). [Testers] are required to shoot at any lot change and periodically throughout the lot … even if it is just a press operator change. Lot sizes can vary from 5,000 to over 100,000 thousand. If anything changes — it is a new lot. When a new operator comes on — it is a new lot.”
Bevy of Barreled Actions for Bullet Testing
Sierra Bullets uses dozens of barreled actions for testing bullets. These barreled actions are clamped in stout, return-to-battery test fixtures. These heavy test fixtures provide near-perfect repeatability (with no human-induced holding or aiming errors). Each barrel has its own logbook to track the barrel’s usage. Interestingly, Sierra does not have a specific round count for barrel life. When a barrel starts “opening up”, i.e. showing a decline in accuracy, then the barrel is replaced, whether it has 800 rounds through it or 5,000.
Click Photo to Zoom
Sierra Bullets 10-Shot Groups at 200 yards
What kind of 200-yard accuracy can you get in an enclosed, underground test range? Would you believe 0.162 MOA at 200 yards with a .338? Check out these 10-shot test groups shot at the Sierra Test Range at 200 yards. Note that the numbers listed on each sample are actual measurements in inches. To convert to MOA, cut those numbers in half (to be more precise, divide by 2.094, which is 1 MOA at 200 yards). For example, the 0.340″ middle group works out to 0.162 MOA at 200 yards.
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Tags: .338 Lapua Magnum, Factory, Sierra Bullets, Test Tunnel, Underground
Not sure how old this AccurateShooter article is, but there is a 1000 meter tunnel range in Germany (private as best I know) – http://www.stl-rifles.com/europe-meeting-2015-am-18-bis-20-september-in-marienberg-sachsen/
I was unable to find a website for this range. If others do, please post to this thread.
Excellent translator at https://translate.google.com/
So when will Sierra add a doppler radar to provide accurate G7 data?
Don’t understand why it needed to be underground..
Aono HAHA nice, sweet sweet subtle burn!
ELR Researcher
It may be 1,000 m, but you are unlikely to get most bullets that far without hitting the roof. Even if fired from floor level, the tunnel looks about 3 metres high, so unless you are firing seriously fast and/or very low drag projectiles, most calibres up to 308 won’t make the distance. Calibres above and including 338 Lapua might just make it.
Mike C.
The reason for it being underground, other than the very important lack of wind, is most likely temperature stability. Differential heating of the tunnel due to the sun, i.e. the sun heating one side more than the others, would cause motion of the heated air within that varies during the day. This is not something you want. Bury it within the ground and this effect is greatly minimised.
I thought the rws factory in Germany had its own 500 m test range.
The advantage of an underground range, would be a more stable Temperature environment along the day, and from day to day. That is also why the French are keeping their expensive wines in underground cellars or “cave”.
Sierra has used doppler radar on more than one occasion at the Yuma Proving ground. They aren’t new at this game!
These are secret tunnels just like Area 51. They don’t want you to know they exist and will deny it to the end. All that ballistic data is highly classified.
Have visited and toured the underground reloading/shooting/testing facility and it was well worth the trip. Employees at Sierra are first class, top notch, very knowledgeable folks. Would like to go back someday.
Joe: that is good to hear, but makes their lack of accurate G7 data all the more frustrating. The triple G1 mess has got to go. It’s frankly bizarre that in 2016 the gold standard for Sierra projectile ballistic data is the empirical shooting of their competitor’s chief ballistician.
Sorry about that, I meant Richard above.
how much did it cost? I want one!!!!