Tag Archives: Dark Bore

How to Bullet Drop Test a Barrel

One of the challenges with older AKs is to figure out what kind of shape the barrel is in.  Yugos especially are famous for shot out bores.  The slang term is “dark bore” meaning the barrel is so corroded that it is no longer shiny and usually they are pretty shot out but not always – it pays to do some testing.

One quick way to check is known as the “bullet drop test”.  Basically, you put the bullet end of a cartridge into the muzzle and if the cartridge stops on the bullet then there is still some life left.   If it drops in such that the case is hitting, the barrel is pretty well worn out. It’s not a perfect test but it is quick and easy.

Pass on a Yugo M72 barrel

DSC_0057

Fail on a Yugo 72 barrel – notice how the bullet can’t be seen at all.  The rim of the case is sitting in the bore.  This isn’t too bad – I have seen some that drop in all the way into the shoulder of the case!

DSC_0048 DSC_0049

With that said, I have known tons of builders who went ahead and built battlefield pickup style rifles or just “fun guns” where they could more or less hit a man sized target at 100 yards.  Personally, if I am going to all the effort to do a build, I’d rather have an accurate rifle vs. one with a worn out bore.

Now, there are new “endoscopes” that are 5.5mm and can let you look into the bore of rifles.  I reviewed a $17 GiraffeCam that connected to my Android phone and was pretty amazed and what I could see especially given its low cost.  Click here for the full review.


If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@ro*********.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.