Aj from United States, CT Public Profile

Wanted to give this a raving review because there CMMG ZEROED AR15 Extended Ambi Magazine Catch is a 10 out of 10.

But...
Who designed the pads on this? I expected the bolt catch and the mag catch would be a matching set as the name seems to imply. I expected the pads to line up in size and contour, at least the pad surface texture. But no, seems like two entirely different companies designed each.

For now, at least until they get their design team under control, I recommend the Geissele Maritime Bolt Catch

Nothing special, just a good quality bolt carrier group. Price is more but expected as this is a left hand vice right.

A bit more in price because they ALL love to over charge us lefties, but worth it.
As a left-handed shooter, I have 2 uppers using this bolt carrier. Since I'm in Connecticut; I can't buy a true ambi receiver set. The best I can do is modify what I have (not going to risk that) so I'm left with using ambi parts.

I use the Gibbz Arms side charging upper with this bolt carrier. It ejects casings to the left with the side charging handle on the right. With your rifle shouldered, your left hand set on your pistol grip and your right-hand transitions off the hand guard to cycle the side charger. In doing so, the bolt is released and you have a chambered round without repositioning your rifle!
Many variations are attempting ambi bolt releases. Some with levers extending into the trigger guard, WARNING! this type is extremely dangerous as it risks accidentally firing a round! So, if you can't use the lever, what can you do? There are ambi bolt levers that require grinding out a notch in the right side of your lower receiver. If you want to risk that... So the only option is also your best option, a side charging upper.

(Additional note, Gibbz arms quality has been spot on but they are horrible at fulfilling orders on any timeline, and answering their phone or email is laughable. So buy from a distributor vice direct from them.)

The right-side pad is perfect; it has the surface area and shape that fits in the recess of MILL SPEC lowers.
For example, I have DSI and Stag arms lowers where this right-side pad surface area and shape fill the recessed area but has plenty of clearance on all sides so it doesn't rub on anything. More surface area = easier to operate with only a trigger finger.
Some will say that could be bad because that surface area makes for "accidentally" pressing and dropping the mag. This "would" be true IF it protruded (out from the side of the receiver.) But since it is inside that recessed area of the receiver the surface of the pad sits flush with the receiver side. Flush = no accidental mag drops.

And now the "bad" or what they need to fix... The pad on the left side sticks out way too far.

At least 1/8 of an inch too tall. Why... The current height of this mag release pad makes it almost impossible to get in and press the tiny nub on a MILL SPEC bolt catch to keep the bolt held to the rear.

As a left-hand shooter, I run Geissele Maritime bolt catches because you don't need to shift your left-hand grip when operating the bolt release to keep the bolt to the rear. Your trigger finger can reach and operate the Maritime pad with ease. Unfortunately, with the height of the mag release pad being so much taller, it's almost a deal breaker with my grip needing to shift to get around the tall mag release pad. Even with the Maritime pad it's too tall. I could glue a

I had a Springfield Gen 4 aluminum mount on a new M1A with Leupold MK5 HD scope. Grouping was horrible. Sent rifle back to Springfield with scope still mounted. Springfield replaced the barrel and said everything is good but range time says otherwise. Flustrated I replaced mount with Sadlak mount. Instant improvement.
WHY?
There is a threaded hole for a scop mount with three alignment groves built into the side of the rifle. The instructions for the aluminum Springfield mount has you hammer their mount into the groves while tightening their screw. This procedure is intended to press fit/deform the aluminum to sit securely into the groves. Unfortunately, this deforming procedure will not allow the mount to bottom out into the groves (so the mount can't make full face contact with the surface face of the rifle.) As such, the mount teeters on these alignment grooves and your scope mount can tip in (top front end of mount can move to the right causing shots to go low right).

With the Sadlak mount, the vertical grove is only used to obtain the solid, flat, face mount. This allows the horizontal groves to provide alignment without tipping. As an added feature, if any tipping should occur, is prevented by their setscrew on the top forward end of the mount.