What kind of ammo do you use in your testing? And, what kind of ammo delivers decent accuracy?
We use Federal American Eagle .223 55 gr. FMJ with good results for testing. This is not match grade ammo, but is priced well and we’ve shot some decent groups with it. For really good groups try Hornady V-Max 55 gr., or any of the variety of match grade ammo available. It may require some testing with various ammunition to determine which brand will help your rifle perform best.
Is it safe to shoot 5.56 NATO ammo in my VEX?
Your Varmint Exterminator is safe with decent factory loaded 5.56 NATO ammo. We put .223 on the barrel as that is what is recommended for best results, match grade .223 ammunition. The VEX has what is called a “5.56 Compass Lake” chamber. This means the leade (amount of freebore before rifling) is shorter than on a 5.56 but not as short as .223. Also the angle into the rifling is a little different. The overall chamber dimensions are slightly tighter as well and the bolt is matched to the chamber for better accuracy. Frank White of Compass Lake Engineering developed the chamber many years ago and is also the same chamber that was used in the Bushmaster DCM competition rifles and the Predator rifles. I have fired Federal M855 5.56 NATO ammo in VEX rifles with no ill effects. If you should fire any foreign 5.56 ammo through it just keep check of the primers and make sure they aren’t backing out or popping. Some of the foreign stuff can run a little hot.
Can I break my VEX in with moly coated bullets?
I have not tried any moly coated bullets. From what I gather from searching around on-line it’s best to break the barrel in with normal copper jacketed bullets first. Also moly coating can cake in the rifling after a while if the gun is not properly cleaned. So it is important to make sure the bore is cleaned after each range session.
What’s the difference between 5.56 NATO and .223 Remington ammo?
The basic difference is that 5.56 NATO ammo tends to be hotter than .223 Remington. The leade dimension (freebore before the start of rifling) is longer on a 5.56 chamber, on a .223 chamber it is tighter. Therefore the .223 chamber can develop excessive pressure when a 5.56 NATO round is fired in it. Our chambers are all safe to fire 5.56 NATO or .223 Remington ammunition in. All our guns have chrome lined chambers with the exception of the VEX rifles which have a stainless steel fluted barrel. These are also marked .223 rather than 5.56. We do this primarily because the chamber is a little tighter and better suited to match grade .223 ammo. While the chamber is tighter than 5.56 in the VEX, the leade is still longer than .223 Remington. We have tested these rifles with 5.56 ammo as well and they are perfectly safe with that ammo too.
Can I shoot steel cased ammo in my Windham Weaponry Rifle?
We don’t generally recommend steel cased ammo, but if you are going to shoot the steel cased variety, you should break the gun in with up to 100 rounds of brass cased ammo first. You will have better luck with steel cased if you take this first step. Steel cased bi-metal jacket ammo will also reduce your barrel life by about 4000 rounds if shot exclusively. Here are a couple of good articles on the issues with steel cased ammo:
http://www.theboxotruth.com/docs/edu18.htm
http://www.luckygunner.com/labs/brass-vs-steel-cased-ammo/