February 26th, 2017

A Few Seconds at Best — The Short Operating Life of Barrels

Stopwatch barrel life

Here’s a little known fact that may startle most readers, even experienced gunsmiths: your barrel wears out in a matter of seconds. The useful life of a typical match barrel, in terms of actual bullet-in-barrel time, is only a few seconds. How can that be, you ask? Well you need to look at the actual time that bullets spend traveling through the bore during the barrel’s useful life. (Hint: it’s not very long).

Bullet-Time-in-Barrel Calculations
If a bullet flies at 3000 fps, it will pass through a 24″ (two-foot) barrel in 1/1500th of a second. If you have a useful barrel life of 3000 rounds, that would translate to just two seconds of actual bullet-in-barrel operating time.

Ah, but it’s not that simple. Your bullet starts at zero velocity and then accelerates as it passes through the bore, so the projectile’s average velocity is not the same as the 3000 fps muzzle velocity. So how long does a centerfire bullet (with 3000 fps MV) typically stay in the bore? The answer is about .002 seconds. This number was calculated by Varmint Al, who is a really smart engineer dude who worked at the Lawrence Livermore Laboratory, a government think tank that develops neutron bombs, fusion reactors and other simple stuff.

On his Barrel Tuner page, Varmint Al figured out that the amount of time a bullet spends in a barrel during firing is under .002 seconds. Al writes: “The approximate time that it takes a 3300 fps muzzle velocity bullet to exit the barrel, assuming a constant acceleration, is 0.0011 seconds. Actual exit times would be longer since the bullet is not under constant acceleration.”

We’ll use the .002 number for our calculations here, knowing that the exact number depends on barrel length and muzzle velocity. But .002 is a good average that errs, if anything, on the side of more barrel operating life rather than less.

So, if a bullet spends .002 seconds in the barrel during each shot, and you get 3000 rounds of accurate barrel life, how much actual firing time does the barrel deliver before it loses accuracy? That’s simple math: 3000 x .002 seconds = 6 seconds.

Stopwatch barrel lifeGone in Six Seconds. Want to Cry Now?
Six seconds. That’s how long your barrel actually functions (in terms of bullet-in-barrel shot time) before it “goes south”. Yes, we know some barrels last longer than 3000 rounds. On the other hand, plenty of .243 Win and 6.5-284 barrels lose accuracy in 1500 rounds or less. If your barrel loses accuracy at the 1500-round mark, then it only worked for three seconds! Of course, if you are shooting a “long-lived” .308 Win that goes 5000 rounds before losing accuracy, then you get a whopping TEN seconds of barrel life. Anyway you look at it, a rifle barrel has very little longevity, when you consider actual firing time.

People already lament the high cost of replacing barrels. Now that you know how short-lived barrels really are, you can complain even louder. Of course our analysis does give you even more of an excuse to buy a nice new Bartlein, Krieger, Shilen etc. barrel for that fine rifle of yours.

Permalink Gunsmithing, Tech Tip 2 Comments »
November 29th, 2012

Great Gear Items under $35.00 — Editor’s Picks

To help you in the quest for good deals this holiday shopping season, the folks here at AccurateShooter.com have searched through scores of items on Amazon.com. We’ve located some of the best shooting accessories and outdoor gear you can get for under $35.00. And, mind you, that’s just the upper limit. Many of these items are under twenty bucks — that’s a bargain.

Your Editor personally purchased and now uses many of the items shown here, including the MTM Rimfire Box, Tipton Jag Kit, Kintrex Temp Gauge, Frankford Arsenal Bullet Puller, Leupold Lens Pen, Uvex Safety Glasses, Hoppes Gun Cleaning Pad, Transcend Flash Memory, SKIL Li-Ion Screwdriver, and Olympia Deerskin Gloves. These are all fine products for the price.

The box below displays 12 items. Refresh the page to see more selections or visit our Amazon.com affiliate store. There you’ll find recommended gear, books, optics, electronics, and more.

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October 31st, 2011

New iPhone Shooters’ App Has Multiple Functions

ShotMuse3 programShotMuse3 is a handy new App for iPhone users. Functioning like a log-book, this multi-purpose App can record shot locations, scores, and wind values during practice. In addition, ShotMuse3 has built-in databases that can list your ammo supplies and your firearms inventory. (However, for security reasons, you may decide NOT to place a list of your firearms in your iPhone.) ShotMuse3, priced at just $3.99, can be purchased via the Apple App Store. For more information, visit the Apple App Store or contact developer Mike Lersbak: auxxpad [at] gmail.com or (509) 435-1640

Save Chron Data to Your iPhone
One feature we really like is the Chronograph Mode. We often use a PVM-21. This is a great chronograph, but the PVM’s data recording software is complicated and buggy. So, we usually dispense with a laptop and record our chron data manually. With ShotMuse’s Chrono Mode, you can record your chrono results at the range, and then email the data to your main computer. Note — you must still manually input shot values into the App –ShotMuse3 does NOT automatically connect with the chrono.

ShotMuse 3 Functions and Features:

  • Target Practice Mode – This handy feature lets you record shot placements and shot values during practice. As with a manual log-book, you can record wind value and direction for each string, along with temperature and other conditions. A variety of target types can be selected the ShotMuse Target Archive.
  • Chronograph Mode – Input shot velocities from your chronograph when doing load development. Weather, distance and range can also be recorded with each string.
  • Weapons Database – Keep track of your weapons including weapon data, shot count, strings shot, and any other notes or information you want to record.
  • Ammo Database – Track the ammo you use — both store-bought and your own reloads. You can also store notes and photos.
  • Timer Mode – The built-in shot timer can record your shot strings. Both individual shot times/intervals and total string time can be recorded. This is useful for action pistol shooters and 3-Gun competitors.

ShotMuse3 program

Permalink New Product, Shooting Skills No Comments »
April 28th, 2010

Waveceptor Watch with Countdown Timer — $13.99 Today Only

If you compete in matches with time limits for record fire, a timer with both count-down and stopwatch functions comes in very handy. Creedmoor Sports sells a nice, basic battery-powered match timer for $26.95, item C1033. If you don’t want to pack an extra piece of kit, and want something more versatile, consider a watch with a count-down timer and stopwatch.

Casio WaveCeptorRight now BlingDaily.com is selling a Casio Waveceptor Watch with an easy-to-use countdown timer AND a chronograph stopwatch. For the next 9 hours only, the price on this watch is just $13.99! Typical selling price is about forty bucks. One cool feature of this Waveceptor watch is that it automatically sets the correct time, to the second, by “tuning in” to the official “Atomic Time” radio signal (in both the USA and the UK). The watch also displays world time in 48 different cities around the globe. That is handy for travelers. SORRY — WATCH is SOLD OUT!

Act now if you want the watch for $13.99. The offer expires this afternoon. This Editor owns another Waveceptor watch. The auto time-check feature really works. For months, my Wavecepter has been accurate, to the second, when checked against the National Institute of Standards and Technology (NIST) atomic clock.

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