Beside the Sig legion call I mentioned prior, I called a few manufacturers and for the most part, never had any real issues.
Sig P320 VUP: Called, got RMR, sent back 4 P320s (9mm, 357 Sig, 40, &45), and 40 xChange subcompact slide. Turn around total was 1 week.
Ruger MKIV pistols: Called, got RMR, sent in 2 MKIV frames. Turn around total was 1 week and they sent back 2 additional mags with the corrected frames.
S&W MP15-22 Safety recall: Called, spoke with rep about bolt face problem, requested plastic tool to do the check myself (other option was to send rifle back to them), tool came in a couple of days, check revealed my rifle didn't have the issue.
Glock G19 Gen 4: Call and spoke to Glock tech thinking I might be having the recalled recoil spring issue. Verified my spring was the newer corrected spring and he gave me advice to shoot 124 gr to break the pistol in more.
Beretta M1a1 free optics plate, and M4a1 free optics plate and 2 free mags with FDE base plate. The gave me a code right away for the M1a1 to order the plate no charge. For the M4a1, they had a piece of paper that came with the gun that said when registered, they'd send me the code for the items. This was during the supply chain issues, I waited a month or two and never got the email code. I emailed them and they sent me the code for the plate and said the mags were first come first served so no timeline given. Plate (like the M1a1), came a few days after order. When asked for a ballpark date on the mags, I got the code and got them a few days after I ordered them, all were no charge.
Yankee Hill Machine: I called them after I bought a special build 300 blk at a gun show that had a YHM hand-guard that was listed as discontinued. I wanted some pic rail attachments for their propitiatory hand-guard attachment points. Man this guy was helpful, telling me not only the rails to order from them, but how they ran a batch of hand-guards on their CNC machines before switching to make other models. They would mark the ones just done as discontinued, but they'd be available again if another run was produced. He was very helpful.
FN: I need to send in my FNS 9c due to recall and will probably do this through my LGS. I haven't called yet for RMR, so hopefully no issues will arise.
PTR: I recently bought the 51p (PTR 91 308 pistol), and it was extremely hard to rack, the racking lever would also stick making it difficult to pull down to get my hand around the level to even allow racking. LGS said it was normal and needed to be broken in (several tried racking it). They offered to send it back in with my concerns which I took them up on. PTR had it for 8 weeks, but when I got it back with the list on what they did, it was impressive and easy to rack. I am very happy with the work they did on the firearm.