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The Ultimate Reloading Manual
Wolfe Publishing Group
  • reloading manual
  • alliant reloading data
  • reloading brass
  • shotshell reloading
  • bullet reloading
The Ultimate Reloading Manual
reloading tech tips

Do You Need A Borescope

Author: Ron Spomer / Wolfe Publishing Co.
Date: Mar 25 2006

A borescope is an optical instrument that lets you light and magnify the interior of rifle bores to examine them in minute detail. Does this make you a better shot? No, but it could help you make your rifle more accurate. Or prevent you from buying a lemon.

You don't need a borescope, but those of us who have used one find it so handy and, well, just plain fun, that we love the durned thing, despite its high price. A scope will cost you as much as a midgrade, factory rifle. I find the device most useful for assessing my barrel cleaning efforts. You'd be amazed at the copper fouling hiding on lands and in the corners of grooves in a "clean" barrel. Study a barrel once you've gotten the powder residue out and you'll see where rough spots or tight spots are by the buildup of copper. Scrub these off, and then see if accuracy improves.

You might find it useful to lap a rough barrel, then check again with the borescope to see if the fouling problem has been solved. Sometimes just a few hundred strokes with a tight brush full of J-B Compound will smooth things out sufficiently to eliminate excessive fouling, leading to better accuracy and more accurate shooting between cleanings.

Borescopes are also handy for studying prospective purchases. You can tell a lot about a used rifle by its exterior, but even more after a peek inside. Run the scope into the chamber to check for rust or pitting, then down the throat to look for cracking or “alligator” steel, an indication of excessive heating and erosion. Study the muzzle for dings and gouges at the crown. Don't assume that every barrel showing rough spots, rust or even pitting is inaccurate. Stories abound of horrid looking barrels that shot well once cleaned or lapped, but they may be the exception rather than the rule.

As we all know, even new factory barrels can be inaccurate, so employ a borescope to check them before purchase. A smooth, consistent barrel may not shoot better than a rough one, but odds should be in its favor.

Other uses for a borescope include peeking into dies to check for rust or pits, into cases looking for head separation. Hawkeye is the only borescope specifically designed for gunsmiths with which I am familiar. Auto mechanics use some kind of scopes for peering inside carburetors, manifolds and similar tight spots, but I'm not sure whether these would work inside barrels. The Hawkeye is narrow enough to fit a .224-inch bore and anything larger.

You certainly don't need a borescope, but if you handload, buy used firearms or work with several guns a year, you'll certainly enjoy using one.