Re: DTA SRS 308 win. 22" bbl or 26" bbl?
I have a Covert with both the 16" 8-twist and 22" 11-twist barrels, as well as a brand new 18" 10-twist barrel from Mark Gordon at Short Action Customs. I just had the new barrel out for the first time this past weekend. All these barrels shoot very well, generally in the 0.75 MOA range in my hands. If anything, the new 18 incher is even a little better than that.
My overall feeling regarding precision is that it is a more challenging for me personally to drive the Covert chassis to its full potential. I'm sure in the right hands, the Covert with any of the three barrels would be more like a 0.5 MOA rifle, or even slightly better. Although I find the bullpup design very comfortable and easy to use, the shortness of the foregrip and thus the location of the bipod close in to body of the rifle makes it more challenging for me to hold it as steady as a longer rifle system when shooting groups at 100 yd. YMMV.
My understanding is that foregrip conversions between the SRS and Covert lengths are currently (or soon will be) available. Obviously, the 16" barrel is much too short to use in the standard chassis, unless the foregrip is shortened. So if you go with the standard chassis, you'll need the foregrip conversion kit if you want a barrel shorter than 22". Regardless of the chassis, I'm not sure what a 26" barrel in .308 will buy you with this system. I've used both the 22" and 16" barrels out to 600 yd with ease. As mentioned above, others have taken both out to 1000 yd with no problems. So a 26" barrel might buy you somewhere in the neighborhood of 40-60 fps more muzzle velocity, but it will also come at the expense of mobility and ease of handling.
As far as the comparison to GAP rifles, I can say for certain that both of my GAPs are more precise in my hands than the Covert (regardless of the barrel used) by a fair margin. As I mentioned above, this could well be due to my shortcomings as a Covert driver. But really, having shot thousands of rounds through both types of rifle systems, my take is that their strengths and optimal usages are quite different. The strength of the SRS systems is their small size, lighter weight, ease of handling, and caliber exchange capability. Of course, very good precision comes along with that. In contrast, both of my GAPs were intended for F-class competition shooting and weigh in the neighborhood of 16-17 lb decked out. They are unbelievably precise and absolutely shoot bugholes, but I wouldn't want to lug one around through the woods all day. However, that is not why I purchased them. So deciding how you will use the rifle most often should help you determine which system's strengths best fit your intended purpose.
Frankly, you won't go wrong with either type of system, depending on your intended use. Below is a link to a little review of the Covert I did a while back if you're interested. Good luck with the decision!
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1597047&page=16