So for the few who don't know - I'm BRAND NEW to any kind of magnified optics beyond a 3X behind an Eotech.

So here's my question - I've been investigating the idea of an LPVO on my shorter AR pistol, and it seems a lot of people are going this way lately.

So I'm looking for an inexpensive (<$1k) used LPVO I can check this setup out with. Something with a DECENT 1X and nice big donut or horseshoe to ease the transition from my EXPS3 and nice fast acquisition. The problem is, nearly all of the reticles I'm finding with any sort of 'CQB' or "1X" sensibility tend to be BDC-type reticles set for 55gr/16". Now I'm an idiot remember, so forgive me if this is a stupid question - but isn't that gonna be pretty useless on my mostly 77gr / 11.5" rifle?

Any help appreciated.

Instead of uniform subtensions between the hashes, BDC reticles will have predefined spacing based on whatever ammo and velocity the manufacturer intended to use.  You can use a BDC reticle with any barrel length, it just won’t match the drops that the manufacturer intended.
Just chrono your ammo through your barrel and plug that into your ballistic calculator like Strelok to find your drops.

BDC stands for Best Damn Compromise, and I detest them.  I would prefer just moa or mil substensions that I can calculate my drops for.  But, they are few and most every scope has some sort of BDC so I just run the numbers from my chrono for whatever barrel length and load and keep notes.  

One way you can minimize the error with BDC is to zero the 300 yard/meter stadia @ 300.

If you get away from the donut of death the delta stryker 1-6 had a mrad reticle and is pretty freaking legit

The most concise answer to your question is "IT DEPENDS"

The Primary Arms peanut butter 1-8x has holds for both 77gr and M855. The manual has a deep-dive on all the capabilities of the reticle, it's quite potent.

Like others have mentioned, a BDC reticle is only useful if you have pushed your ammo/firearm out to range and confirmed your drops. If most of us are honest, we shoot whatever is cheapest and easily available. And we're not typically shooting past 300 yards where a BDC really starts to matter. If your shooting regimen is different, collect dope, print the diagram of your BDC and stick it inside your lens cap.

I wouldn't rush to say that an LPVO on an 11.5 is a better option than a magnified eotech setup. I prefer my EoTech at shorter ranges than my ATACR.

That being said, I zero'd my Elcan for 14.5 with M855 per the spec and shot 77 as well as 55 through it and the BDC wasn't terrible for steel plates at 300 yards but I wouldn't use it for any kind of precision shooting.