This is VERY common with M14 shorties, especially ones that have been comped and shoot even lower due to less muzzle climb. This is why I usually raise the front sight base about 1/8" on most of my my M14 shorty builds.
The quick and dirty solution is to get a taller front sighty,
OR,
grind some metal off the back of your rear sight track, so it can go down further. I prefer to leave enough metal on the track so the sight won't come all the way out of the gears when cranked up to full.
Unfortunately, if you have a fat cheek, this fix might not be enough.
Next step would be to take a bit of the stock comb, to allow you to comfortably use your lowered rear sight.
PS: just to remind you do it yourselfers, the DIY M14 shortifying instructions ARE posted as a sticky ... including the sight modifications advice.
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LAZ 1