It’s no secret, we’re fans of Criterion barrels here at AccuracyTech. There’s a reason: they offer outstanding value. The accuracy is routinely half moa or better and the barrels are a bargain at their price point. Some people claim only cut rifled barrels are capable of exceptional accuracy and in our experience, that just isn’t the case. Premium button rifled barrels from Criterion consistently offer match level accuracy and at a bargain of a price to boot. So when it came time to put a new tube on my AR10 6.5 Creedmoor rifle… a Criterion barrel was the logical choice!
Breaking In The Criterion Barrel
We’ve talked about barrel break in procedures in a prior post that you can read here, if you haven’t already. We’ve also got a number of articles in the works that are going to be publishing as I get this new Criterion barrel cooking on my AR10. Specifically, I’m going to do an article on muzzle velocity and how much it can increase for this caliber from new to approximately 120ish rounds. I’m currently shooting factory Hornady 120AMAX through it to get the barrel to settle in velocity wise. Then I’m going to do some load workups using 123gr Lapua Scenars and 130gr Berger AR Hybrids. The goal is to get the Bergers up to 2800-2850fps or so and that should make for an excellent performing round.
The reason I’m running some factory ammo through the gun first, as mentioned in the break in post, is that velocity tends to pick up in the first 100-150 rounds through the barrel. Minor imperfections on the barrels interior surface and small changes to the throat as it adjusts to the pressure and heat of rounds being fired through it typically result in an increase in muzzle velocity. When I originally wrote the review on some Copper Creek Ammo I was surprised the initial velocity was around 200fps slower than advertised. Then I had rounds landing way high during a match I was shooting at the T3 Ranch. The reason was a velocity change!
Velocity Changes Ballistics
You don’t have to change your muzzle velocity a whole lot for it to make a big difference downrange. This is why it’s so important to hand load consistent ammunition. So that you know, for a fact, how fast the projectile is leaving your barrel. New barrels, as they break in, will pick up some speed. In my case the muzzle velocity jumped more than 150fps during the match and made adjusting on the fly a bit difficult. Partly because the whole idea was new to me. Lesson learned, if you’re seeing impacts land high you may have to true your ballistics curve on the fly. That’s why devices like an Applied Ballistics Kestrel are so useful. You can bring pre-printed dope cards with you, but if you have to change something on the fly, it’s a lot harder to do without the calculator on hand!
We’ve been working on a series of articles having to do with load development and the use of a Chronograph. The first part of the series has already been published. Part of the holdup on the second and third installment is I want to collect some data to use in addition to what I already have regarding the process and how it works with the new Criterion barrel. I want to show you some hard numbers and real world photos of example targets shot during the development process. This way it’s not just anecdotal evidence of me saying it works, but I can show you how it works as we go. So stay tuned for those, they’re on the way!
Initial Accuracy Report
My initial accuracy impression with the new Criterion barrel is good, though mixed. I put forty rounds through the gun at the Cherry Creek range to get started and was pleasantly surprised. I managed two pretty nice three round groups, one under half moa and one just over a quarter moa at 100 yards. I say mixed results, because my five round groups were a touch over half moa. However, I’m not holding that against the barrel because Cherry Creek is absolutely horrid for any kind of group shooting or accuracy testing. The benches all shake when anybody fires a round, regardless of the lane, the noise level is high from neighboring lanes and it’s just less than ideal for accuracy shooting.
I’ve got 120 rounds or so of the factory Hornady ammo to put through this rifle to get the speed to settle in. After that I’m probably going to do a quick pressure test working up to a prior recipe for 123gr Lapua Scenars since I still have some of those loaded. Then after that I should be up around 150 rounds through the barrel and I’ll start load development with the new Berger 130gr AR Hybrids. If I can get those up between 2800-2850 they’ll have less drift than the faster Scenars. Should make for an accurate platform! Stay tuned for the details and the companion articles that are all going to piggyback on some of the information that’s gathered along the way! If you have any questions or comments, drop them below!