Isn't .223 Remington (5.56 x 45mm NATO) Subsonic ammunition basically just turning my AR/High Powered Rifle into a .22 LR?

No. Our subsonic .223 ammunition utilizes a 55 grain projectile or larger. The added weight in the projectile creates much more energy than a .22 LR.

Schneider barrels are very expensive aren't they?

About the same as anybody else's...around $300, installed. I prefer Schneiders for two reasons:

He has been making the USMC M40 barrels for about 30 years. If there was somebody who made a better barrel, the Jarheads would be using them.

Unlike others, there seems to be no deviation between a cold bore shot and the rest. Pro'lly why the Jarheads use 'em.

Can you justify paying for a custom barrel for shots that will be less than 200 yards?

Absolutely. Placement is critical when you have so little ME to work with. You are already going to pay a good riflesmith around $150 to pull your factory barrel and thread it correctly...why not go a little bit more and be happy with the results?

What is the maximum effective range of the .308 with subsonic ammo for deer size game?

I tell people to keep their shots within 125 yards..it is a matter of trajectory. Play around on our Ballistics Computer on this website. A subsonic round, whether .22 or .50 cal, will have an extremely curved trajectory. As a rough example, when zeroed at 100 yards, the subsonic will be about 15" low at 150 and 42" low at 200 yds. Since trajectory is a parabolic curve it can be seen that at extended ranges, the projectile is basically falling in like a mortar round. I've kept on an Iron Maiden at Ft. Benning at 350 yards, but if I'd misjudged the range by 10 yards, I'd have missed. The rounds are very consistent, but since wind has a LONG time to act on them, and for the above reason, most folks should keep their shots within 125 yds.

What grain projectiles are you shooting?

At Engel Ballistic Research, we use a variety of projectile weights for different applications. You will find that heavier projectiles are used in our subsonic ammunition than are used in our high velocity (supersonic) ammunition, including our frangible line. For example in the .308 Winchester caliber we utilize a 180 and a 175 grain projectile for the two different rounds we offer, while we use only a 125 grain projectile for our frangible in the same caliber.

Why is a 1:10" twist necessary in my .308 Win rifle? I looked at a twist rate chart and it would appear that 1:12 would suffice.

Looking at a chart (or reading stuff on the Internet, etc.) does not always get you where you want to go. The Subsonic World is a whole different realm. The distinction was best explained to me long ago by the famous barrelmaker and ballistician, Boots Obermeyer (who has done projects for Uncle up to 30mm). At Subsonic velocity, you have not only 1/3 of your forward velocity, but also 1/3 of your *rotational* velocity. Think RPMs. It is therefore more difficult to stabilize a subsonic projectile than a high velocity projectile of exactly the same BC, profile, etc. Ergo, you "spin it up" to assist in this stabilization process. The reason EBR recommends 1:10" for use with both supersonic and subsonic velocities is that this twist rate is sufficient to stabilize a reasonable subsonic round, yet gets great performance with the commonly-used 168-175 gr. high velocity projos.