I have always liked having backups of stuff. interchangablility etc.. so I have been trying to stay away from dedicated lowers, and wanting to use mag blocks instead.

Is there some advantage I don't see to using a dedicated lower for pistol cartridges?
I get you don't have to adjust a mag block, but that isn't an every day occurence.
I would have a lower specifically for this, so I don't need to swap around much. I just like the idea that I could change if my lower had some issue and still shoot.

Better looking, no adjustment required, can go with glock mags if you want. That's about all the advantages of a dedicated lower I can think of off the top of my head.

Nothing wrong with a mag block, but for me I really don't see the need to ever switch it out. I have other guns that shoot the normal calibers, why would I want to take 20 min to remove a mag block and swap out uppers? This is especially true for me when you can pick up a standard lower for ~$70 if you really want a backup.

If bang for your buck or space concerns are paramount for you though, a mag block is going to win every time in versatility.

For the price of a good mag block you can buy a dedicated lower. If you plan on making it an sbr, it is a little harder to pay the $200 tax stamp again for another lower. I decided to go with a dedicated lower just for the looks and ability to use the lighter Glock mags.

I'd get the dedicated lower.

A PSA lower runs $50, and a Hahn Block of all things can go for $180. If you are worried about swapping back to an AR15. Lowers are at the cheapest they have ever been.

it isn't just swapping lowers for 223.
if the dedicated lower dies, I have nothing left to shoot that ammo using those mags.
so having multiple 223 lowers is great, but means my pistol caliber stuff is useless then.

Simply put they look better IMO.

With mag block:



Dedicated lower:

I don't go with dedicated lowers so I have options if I want them.

it's all gonna come down to what you like visually, the dedicated lower is gonna be more expensive but is more appealing to some

Dedicated lowers all the way and don't look back. Take it from a guy that have done both. Mag block conversion is not worth the time,  effort, or money. Sure they may work fine, but I guarantee you'll be fiddling/adjusting the mag block to get it to run 100%. Yeah its no big deal to adjust the block, but you'll need tools, which you may not have or forgot to bring while you're at the range. I went through 2 different mag blocks before finding one that worked perfectly (Hanh). Back then dedicated lowers did not exist and mag blocks were the only options. I had even considered pining the block to the lower (like Colt's 9mm) as it was the only way to ensure it would not move. When DDLES came out with their dedicated lowers I went through the same debate you are. Once I bought the DDLES lower I never regretted it. My 9mm now runs 100% all the time. This is how the 9mm AR should look and run from the very beginning. No more lingering doubts about mag block issue again. If I could make a personal suggestion, buy the Quarter Circle 10 or Black Creek Precision lowers. Stay away from the CMMG and Rock River Arms. Nothing wrong with them and I sure they run fine, its that they look just like your standard AR lowers.

Dedicated.   Mag blocks may or may not be a problem.   I have a Promag block that works perfectly with any mag.   Other people report problems with even very expensive blocks.

This...



I went with a glock compatible lower to make use of our glock collection.    I'm not too concerned about the lower getting broken to the point where it's rendered useless.  If I ever have to run it that hard then life's seriously broken down.

Still waiting on the F1 to sbr it.  2-3 months and counting.  Finally got my F1 approved to build the dedicated can for it yesterday, 7" in titanium so it'll be a little shorter than the Octane 45 I have on it now.