The two most common reasons a rifle like you described won't group well are a) the driver is not capable of shooting better groups and b) the ammunition is not optimized for the rifle. If you're shooting 1.0-1.5" groups at 200 yd (basically 0.5 - 0.75 MOA), I'd say you're doing pretty well behind the gun, which suggests tweaking the load may offer you some improvement. With a well made .308 bolt gun and a quality barrel, almost any of the bullets described above could probably be made to consistently shoot under 1/2 MOA with reasonable care and attention to detail in the reloading process. The gun will really tell you what it likes to shoot.
Your original post suggests you reload, as you mentioned buying bullets rather than loaded ammo. If so, you should be able to get a pretty wide range of bullets to shoot well out of your setup if you're willing to put in the time and $$$ on load development. If not, simply changing bullets is not likely to get you where you want to be. Regardless of the vast number of rifles described on shooting forums that will "shoot under 1/2 a minute all day, every day", the reality is that it can take a lot of time and effort to develop a load that consistently shoots that well. And although the specific load (powder, charge weight, seating depth, etc.) may vary considerably between different bullets, it is usually possible to find loads that work for different bullets in the same rifle.
The barrel on your rifle should allow you to choose from bullets anywhere from around 150 gr up to 200 gr, with the twist rate being most optimal for the 175 gr to 200 gr range. Doesn't mean you can't get 155s to shoot well out of it, I've done it a couple different rifles having 10-twist barrels; however, you really don't need to spin the shorter (lighter) pills that fast. My thought would be to stick with the 175s and tweak the load to get where you want to be. Alternatively, the Berger 175 gr Tactical and 185 gr Juggernaut bullets are really well made, fairly easy to develop loads for, and should shoot well out of your rifle with proper load development. They are going to cost a little more, but you inferred that in about 6 months you might have access to a range that will allow you to shoot farther than 200 yd. So my thought would be that getting a longer (heavier) bullet with a higher BC shooting well now would set you up perfectly for when you're able to stretch it out farther. No matter what you might read, a 155 is not going to outperform a properly loaded bullet with a much higher BC at long range. You simply can't push 155s fast enough safely to make up for the lower BC. It's possible to get them close, but not better. Any load with a longer high BC bullet you can get working well at 200 yd should also work well for you whenever you get the opportunity to shoot longer distances.
