Some of the early rifles have feeding issues, where the bullet gets snagged on what should have been a feed ramp, and wasn't.
The later rifles really didn't have that issue, and the rifles that were effected were easily fixed by polishing the feed ramp.
The finish on these rifles is the standard Bulgarian military paint, which was never intended to deal with harsher US solvents like Shooter's Choice Bore Solvent, or Hoppe's #9 if left on it for a period of time. Guys who used carb or brake cleaner also washed their finishes off.
The finish is just fine with CLP or Ballistol.
Mine is serial #1620, and I've not had any feed issues whatsoever, BUT, I have seen them first hand in other's rifles. Arsenal took care of them and fixed the issues.
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