This is not correct and I might suggest switching to a different barrel manufacturer, or at the very least, get information from someone else within the facility that knows what they are talking about. You made a wise choice going with the 30" barrel, hopefully it is working out well for you.
To the OP: a 30" barrel for a .223 Rem F-TR rifle is more than sufficient. The most important thing a longer barrel might buy you is to achieve the same velocity at a little less pressure. However, the trade off for decreased pressure is increased friction where the bullet is engraved by the rifling and greater risk of bullet jacket failure. With an even shorter barrel (i.e. 28" or less), you have to run even higher pressure to hit specific accuracy nodes with the 80 to 90 gr heavy 0.224" bullets. Poor brass life is often a problem with a 30" barrel, that would only get worse with the shorter barrel, forcing you to adjust the load accordingly. Ultimately, there are no specifications set in stone for this purpose, only a range of things to try and see how they work for you. Fortunately, there is quite a bit of expertise here at the forum with regard to people that have successfully used .223 Rem with heavy bullets in F-TR and other types of competition.
I have two 30"-barreled .223 Rem F-TR rifles. I recently had a couple barrels chambered for the original of the two using the 223 Rem ISSF reamer from PTG, which cuts 0.169" freebore. IMO - this freebore is way too short if you intend to exclusively shoot the 90s. It shoots extremely well, below is a 3-shot group I shot yesterday at 114 yd while doing some seating depth testing. However, a rifle will certainly be running higher pressure at a given velocity loading 90s with the shorter 0.169" freebore. As far as using a tuner, I went that route on my 2nd rifle, but not the first. As you can see, you don't need a tuner to shoot very tiny groups with a properly-tuned .223 Rem. My .223s always shoot like this with properly-tuned loads using the 90 VLDs, tuner or not. Although it can be argued that a tuner will increased the width of the optimal window, I have not personally found one to be much of an advantage in a .223 with 90 VLDs for use in F-TR. A tuner is extra weight and also a lot of extra work. I also have a tuner on a .308, and that combination seems to be of more benefit. The .223 Rem shoots so well in my hands, I just don't see a huge benefit to putting a tuner on it.
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My 2nd rifle has 0.220" freebore, and I could have even gone a tick longer and still loaded the 90s easily. If you intend to shoot a lot of the 88 ELDMs or 90 A-Tips, I would suggest that you go with
at least 0.220" freebore; those bullets have very long bearing surfaces. When going with a freebore that long, you might run into issues seating the 85.5s optimally in the same chamber, not 100% sure as I don't shoot those. As an example, in a chamber cut with the 223 Rem ISSF reamer that has 0.169" freebore, you can still load the Berger 80.5 Fullbore bullet without having to jump it a country mile. If you're going to have a chamber cut specifically for the Hornady heavy (long) .224" bullets, you will want to also consider the bullet with the
shortest bearing surface you might want to use, then see if you can't come up with a freebore length that will work with everything. You have at least half the length of a .223 rem case neck to play with (~0.100" or so), so deciding on an optimal freebore that will accommodate a variety of different heavy bullets should be achievable.
Take your time, figure out exactly what you want to do, and you'll end up with a rifle setup that can accommodate several of the heavy .224" bullets, which should easily make weight and work very well for you in F-TR.