I don’t buy them prebuilt, not even the uppers. I only build them. A lot of sellers try to make standard features some sort of selling point for folks who haven’t done research. LRBHO- while pretty much the industry standard in 2020, makes for a weapon that you’ll just have to get used to without it. I make sure I always have a hold open feature. If you TRAIN, you can get used to whatever you end up buying and make sure it works for you. Palmetto makes an inexpensive lower and it DOES have lrbho. I own and fire multiple Palmetto lowers as the base for my setups. They have the right size magwell and take all Mil-Spec components or aftermarket Mil-Spec. It’s never hiccuped on standard white box Remington and it’s been running for around 5 years now without so much as a stovepipe. Running certain types of hollow rounds could induce a failure but only if using the magpul Glock mags. I’ve had 2 of these failure to feed when the gun was kinda new on the magpul magazines so I stopped using them in my PCCs. Otherwise, ALL other Glock mags work great. I’ve used 6 different Glock style magazines all are just as good as the oem. BUT, the oem Glock mags are still the best for reliability sake if you are new to this.
If you have a pistol with popular magazines, the ar9 makes sense. Run a setup that utilizes the same ammo and mags for both your sidearm and your pcc, it’s very easy to save money this way. Plus 9mm is way cheaper than rifle calibers. (Buy more ammo to train with!!) In addition, you only need one ammo type and one magazine type which makes a load out or kit design a pretty good contingency plan. It’s a backup to a backup. This kit should not be a main kit for hunters or police, but to a family defending their property or killing pests around the farm… 9mm is super good at rodent murder. Although, 9mm is not the most excellent primary weapon round out there, but is very useful in many close engagements and a perfect way for you to perfect your skills.
Facts: If you plan on a 16” ar9, you missed the purpose of the pistol caliber carbine. The combination of a 9mm round and 16” barrel yields a maximum effective range against human sized targets about 100 yds. While bench shooting, training, target shooting MAYBE about 200 yds. (With a 24” bullet drop) The drop on a 9mm round at 100yds is about 12”. So good luck shooting out further than around 50-75yds without having to significantly change your poa for an accurate poi. It’s a 50yd gun for most intents and purposes.
Just a tidbit for giggles and kicks:
A piece of data you may want to investigate - the nomenclature of “carbine” being used for the PCCs of today doesn’t make sense to me even though it’s a carbine “platform” without the actual carbine firing cycles - momentum from blowback instead of the carbine gassing. The AR9 and PCCs don’t utilize any gas blocks or gas tubes. Radial delay blowback operated (in 99% of the PCCs today, tell me why is it still considered a carbine. no timing to adjust like in our standard black guns with adjustable gas systems or piston systems.
Hope this information is useful.