My first question is this. An AR-15 has a front sight and has a red dot sight installed that happens to cowitness the dot with the front sight. If a 3X flip to side magnifier was to be installed would the front sight be much of a problem? I realize that it wouldn't be in focus.

My second question is about a rifle issued to USMC snipers. I was watching a program about USMC snipers, and it was mentioned that they are going to switch to a 20" barrel, with 1/10 rifling from the 24" barrel with 1/12 rifling on their M40-A5 rifles. Is the change in rifling due to the different barrel length or is there another reason, perhaps the development of a new load?

When used with a magnifier, the front sight is either not visible at all, or just barely visible as a slight "ghost image". It doesn't present a problem at all, and doesn't obscure any of your field of view.

A 1:10” twist can handle a larger variety of bullet weights and allows you to run heavier billets over a 1:12” twist. Shorter barrels require a faster twist as well. I run 1:11” and 1:10” twists in all my 30 cal barrels.

I don’t know if that’s the actual reason for the change, but that would be my guess.

Tony

The FSB is a favorite of mine. I shot a 16 inch Springfield Armory Saint last year in that configuration. Zero issues with or without the magnifier.

Your second question, the 20 inch gun serves two purposes. It’s current role is urban use, you don’t lose a lot by chopping the barrel. The second, and probably the major reason is the ability at attach a suppressor without having a 30 inch barrel on a gun that’s considered obsolete by many in the long range crowd.

My son is currently in his first week at the Marine Corps east coast sniper school.

Thank you for the replies. I didn't even consider the attaching of a suppressor, jljones. And that is interesting about a 1/10 rifling twist accommodating a wider variety of bullet weights.

Another RDS question. There is a magnifier that locates in front of the RDS, what would any of you consider the pros and cons of that?

Hmm... I've never seen a magnifier that could be used in front of a red dot.

Are you sure it's intended to go there?

Got a link?

https://monstrumtactical.com/g...w-flip-to-side-mount

Apparently, it's the only one of its kind, as magnifiers go.

That is for a 1x prism optic.
It would work with a red dot but ideally the red dot on a rifle is mounted towards the front of the upper, not the rear, like a prism.

Monstrum Tactical has a reputation for being airsoft grade Chinese junk. If it were my money it'd be a hard pass.

I haven't used any magnifiers so I don't have an alternative suggestion, but I did just want to chime in on that. Good luck in your search.