I have an M&P15 Sport, took it to the range for the first time this Sunday, shot flawlessly through 160 rounds and I had a blast, didn't take much adjusting to sight it in with the stock irons/mbuis.

Anyway, I also have an extra Vortex Crossfire II 1-4x24 that I think I would enjoy on the M&P15 Sport. It's a 30mm tube.

It's my first AR, and I'm not informed with all the options. What kind of mount do I need? I see one piece ones that place the scope farther forward, is that necessary? Does the quick disconnect stuff come in handy or do most people never really remove the optics anyway? What would I look for if I just wanted to run scope rings? Medium height, tall, extra tell, any specifics to know?

I went with the same scope and a Burris PEPER mount. It is quick detach, something I may never use but what I wanted. It comes with rings. Very nice combo. M&P Sport plus Vortex Crossfire II make a great pair

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M&P9/9C/Shieldx2/Sportx2/15-22

Most people never switch from optics to irons.

You need a mount designed specifically for AR's like the PEPER mount mentioned by Grjfer. Simply using extra high rings won't allow the scope to be mounted far enough forward.

The scope should be mounted with the objective even with, or forward of, the rear of the receiver. You will be able to access the charging handle much easier with it mounted even with the receiver and modern technique with an AR requires being square with the target instead of blading sideways. You may even have to shorten the stock one or two notches for this technique, but you will find the rifle is much easier to fire fast and accurately.

Excellent, really appreciated the reticle picture to confirm the front sight not being an issue. Although you showed it zoomed in.

Does it peek into view at lower magnifications?

Yes at lower magnification you will see the front sight post. Once above 1.5-2 it ghosts, above 2 it is unnoticed.

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M&P9/9C/Shieldx2/Sportx2/15-22

I've got standard 2 piece (high) rings on my 3X9. The rear of the scope is even with the rear of the charging handle.
Scope has 3.75 in. eye relief at all powers so it works great.

1.5 in. groups at 100 yds. with Wolf Gold ammo.

AR's are one of the few (only) Semi-auto rifles that you can bore sight by looking down the barrel. Put me right on paper at 100 yds.

This one from Primary Arms works nice.
https://www.primaryarms.com/Primary_...padlxsmext.htm

I like the LaRue QD with my Aimpoint. Pop it off when cleaning the rifle.

One of the advantages of a good one piece mount vs rings is that lapping is usually not necessary. Pay attention to weight. Some of the one piece mounts weigh as much as the optic. I've been happy with my primary arms deluxe 30mm (on a 15sport)and nikon m223 1"(on a 15-22) one piece mounts. Both cost around $60, about the cost of a good set of rings. I've owned/own several qd mounts but can only recommend LaRue & Bobro. I'm currently using qd bobros on two of my rifles. They're expensive but if you want a mount that actually holds your zero when you remove and replace it, spend the money. Do you "need" a qd mount, no but they're nice to have. Congrats on your new rifle.

+1 on the PEPR mount. I just mounted a Bushnell 1-4x 30mm scope on my Sport and love it.

I've used the fixed Burris PEPR on a number of my 556/223 and 308 semi's. Good strong mount for and inexpensive price. I use blue locktite on the mount and ring screws and torque the base screws to 40"pounds and the ring screws to 18"pounds I've never had a scope slip or leave ring marks on the scope tube.