PSA mid-length 16" upper - scope or no scope?

[seamaster]

I recently got a new PSA mid-length 16" upper with 1-7 twist. I put a DD A1.5 fixed rear sight on it. I'm wondering if I should get a scope for more precise longer shoots.

With the iron sights I'm shooting about 8" pattern at 100 yds and I can hit a 12" dia plate at 150 yds most of the time. I wear glasses and with the thickness of the front sight I think this is as accurate as I can get with the irons.

My use for this rifle will be mostly 100-300 yard or farther plinking/target shooting. I would like to see how far it could shoot accurately.

What level of accuracy can I expect from this upper and what magnification would be appropriate?

[M1A Shooter]

i really like my 1-4x variable. i run a millett dms and make reliable hits out to 400 with it. it has a 1moa dot in the middle so its not as precise as you can go but its a fast reticle up close as well. if you are doing ok seeing the target at 100, then you can follow a general rule of 1x/100 yards.

ammo will make or break the accuracy. if you are shooting the cheapest 55gr fmj you can find, then accuracy wont be great. if you truly want to see what its capable of, i would get a 3-9x scope on it with a fine reticle and bench it with some 75gr match ammo or similar.