Planning my 1st short barrel AR pistol project and could use some advice. The goal is to build a reliable setup on a budget of 800 dollars maximum for the base gun.

My plan is to eventually run this gun suppressed and eventually install a FRT . Ammo cost is not a problem for me. I do not mind doing mods or swapping out internal parts like buffers and springs to get the timing right. The base gun just needs to fit the budget and be available to buy right now.

Here are the main features for the build:

• Short barrel: Looking for something small, around a 5 inch barrel.
• Caliber: Open to 9mm or 45 ACP options.
• Setup: The system needs to handle increased gas blowback from a suppressor. The bcg must be reliable and able to handle full auto if for a .45..
• Last round bolt hold open: This feature is a high priority for the build but not a total dealbreaker if the gun runs well.

I already looked at GForce and Bear Creek but backed away due to quality control issues, weird barrel threads, or missing features. Foxtrot Mike is great but always out of stock so please do not suggest them.

What complete setups or upper and lower combinations are available today under 800 dollars that offer a reliable foundation? What are the standard recommendations for extra heavy buffers or springs to manage gas blowback and cycle timing safely?

I am more than happy to replace parts or perform modifications to get the build running perfectly.

Thanks for any tips from anyone who has worked on a similar build!

Is anybody running a 4.5 inch 9mm barrel from RTB Arms? Have you experienced any problems with the feed cone. I am waiting on an Angstadt Arms bcg so I haven't shot is yet but the cone seems to me not to be beveled too deeply. I will put a trigger kicker on it and I am wondering if I need to purchase a Stern barrel or if this one will handle it. I know I am putting the cart before the horse but curious if anybody has experience with this barrel.

Milled 80% receiver with Stern Defense adapter, BCA bufferless 7.5" upper, Huxwrx Flow 9k Ti

She shoots real nice and runs like a dream. Will polish the feed ramp in the coming days but she ate through Blazer brass with no issues. Only put about 50 rounds through it that day.

I could have sworn it was Tubbs, but I remembered after that my dumbass sold an extra Tubbs I had on GAFS a while back and kept the “other one” and unbeknownst to me it’s not a fit for our needs with Kynshot.

Needless to say after I searched the sub and found out it’s on the no good list.

Leaving as a PSA. My Colt Build was almost complete last night 😭

I’ve got a bunch of spare AR parts and want to put together a 9mm PDW. The plan is to have a 4” barrel and shoot suppressed 90% of the time. Do you guys recommend just sticking with a heavy buffer? Radial delay is cool but for the cost of the bolt and barrel I might as well just put the money into an MP5 clone. Other options like the Maxim roller delay buffer seem promising but I’m not sure if it’s worth the extra cost and complexity. Any feedback would be great.