9mm AR pistol barrel length

[rd62]

I picked up a Quarter Circle 10 lower designed to take Glock mags probably two years ago along with a BCM LPK, pistol buffer tube, and a brace. Since then the project has just been sitting.

I'd like to get it completed this year and have been looking at uppers to finish the project. QC10 has a number of barrel options and I'm considering either the 7.5 or 10.5" options.

This is my first foray into 9mm ARs though and I don't know what I don't know. I'm familiar with SBRs in 5.56 and have had a 10.5 LMT for years. Is there a big difference in reliability or terminal performance between the two lengths in a blow back 9mm offering?

QC10 seems to have moved to side charging uppers only which I think I'd prefer a traditional charging handle for similar operation to my other ARs so I'm open to suggestions on other uppers/barrel lengths that would work with my lower too.

Any suggestions from those here more familiar with these pistols than me?

[Bigghoss]

All I can tell you is that it's possible to push a bullet too fast to the point it becomes less effective. So if you wanted it for anything serious a shorter barrel might be better.

[SeriousStudent]

I went with a 5.5" barrel, to more closely duplicate pistol barrel ballistics. But my PCC is also suppressed, and I stick with 147-grain loads.

[rd62]

From that it looks like 7.5" may be the way to go. Thanks for the video link.

[awp_101]

I found real estate to be the issue when I converted my Scorpion EVO3 from the 7.75" pistol to the Micro-K 4.25" barrel and handguard. I don't have big hands and there just wasn't enough room for me to get comfortable so that's something to keep in mind as well.

[rd62]

I found real estate to be the issue when I converted my Scorpion EVO3 from the 7.75" pistol to the Micro-K 4.25" barrel and handguard. I don't have big hands and there just wasn't enough room for me to get comfortable so that's something to keep in mind as well.

Thanks, and good point. Wasn't looking to go shorter than the 7.5".