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I have to admit I was really excited about the MRO. I've really enjoyed all my other Trijicon products and the larger objective seemed to make it a "better" Aimpoint micro. So I ordered one for under $500 to put on my 300 BLKOUT gun.
Surprisingly, there were some things i didn't like right out of the box:
- Slight magnification
- Adjustment knobs lack "clicks"
- Green tint
- Noticeable parallax
The slight magnification was something that took me a little while to notice. Initially, I thought larger objective was making my eye think the image was a little bit larger. After looking at a 50 yd target through an Aimpoint H1, Eotech XPS, and MRO, I realized this optic is more like 1.1x magnification.
While Trijicon claims the MRO has "positive-click reticle adjustment." I found that be a stretch at best. I was expecting the positive and audible clicks used on my ACOG. It's not even close. The "clicks" on the adjustment knobs feel more like the winding timer that comes with a board game. When trying to make a 1-2 click adjustment, it seems to be more like 3-5 as you can't be certain how many actual clicks have passed when turning. You can't feel them, and the only way you can hear them would be a quiet indoor room. Hardly effective for field adjustments.
The green tint is something that plagues nearly all red-dots except the Eotech. While I've become used to it after shooting the aimpoint on my MP5, the MRO seems to be a little too green for my liking.
Parallax is also something plagues nearly every magnified and non-magnified optic. Despite getting older, I still have perfect vision. It's hard for me to notice a parallax on the Aimpoint. If I try to look for it, I can find it. On the MRO is noticeable at all distances and situations. It's not a deal breaker, but it's something I easily noticed after using many different optics for many years and then picking up the MRO.
Now, I'm not saying the MRO is bad. I'm not even saying it's not good. It's still a quality optic and I'll continue to use it. The construction and light weight are among the top optics in the business.
It's a rare occasion that I shop locally and/or buy factory ammo. However, I needed some 7.62x39 for an upcoming assault rifle video... I went to my local Walmart and purchased some Wolf because it was all they had in said caliber. Brass-cased ZQI was all they had in .308 but I was surprised to finally see some 300 Blackout!
I didn't see any subsonic offerings, but there were several boxes of Remington 120 gr. supersonic up for grabs. I've read/heard that Walmart has been offering 300 blackout for a while. This is the first time I've ever seen it at my local Walmart.
I've spent a fair amount of time troubleshooting the process of converting .223/5.56 cases to 300 blackout. Here is the setup I'm using:
- Dillon Precision XL 650 223 Progressive Reloading Machine
- Dillon Precision RT-1500 Electric Case Trimmer 300 Blackout
- Dillon Precision Carbide 300 AAC Blackout Rifle Three Die Set
- Ballistic Tools case mouth gauge
- L.E. Wilson Cartridge Case Gage 300 AAC Blackout
My original plan was to save my many times used .223 reloads with split necks. I average about 5 reloads on a .223 case before the necks start to split. Initially, I was converting them with no issues. I had them trimmed to around 1.350" and they gauged just fine. I realized some of my newly reloaded 300 blackout rounds would not chamber correctly. The bolt appeared to be out of battery. The forward assist did not work and round was noticeably hard eject manually.
My range day was cut short when I realized about 1 of every 15 or so had this problem. I loaded over 300 rounds so I figured I would pack up and try to figure out what the issue was. I started by looking at the head stamps. While shooting, I noticed that most of them were RWS cases. I put all my loaded rounds through the EGW gauge and noticed that while they all gauged fine without bullets, some where no longer gauging and some were barely still gauging. In some cases, an additional crimp fixed the problem but that wasn't a real solution.
So I ended up finally getting to the bottom of it. The reason the RWS cases didn't work is due to the actual case thickness. I verified this by reading various forum posts and comparing them against two different types of factory 300 blackout cases using a caliper. The magic number is .334 which is the outside case diameter needed to properly seat in the chamber. We arrive at .334 by:
- .308 (projectile)
- .013 optimal case thickness. Double to .026 for each side of the projectile
- .013 + .308 + .013 = .334
Back the RWS case issue. I cut some more of them and noticed the case thickness was around .015 which puts the loaded rounds over the magic number of .334! Several other brands of cases proved to have the same problem. At the end of the day, the easiest way avoid having this problem is to use Lake City brass for 300 BO conversions. I used a few hundred LC cases from various years and they all worked just fine.
The only downside to using the Dillon 300 blackout forming die/trimmer is that because the blade comes down on top of the case, there is not expander ball present like a full-length re-sizing die. While it cuts and forms the shoulder, the case mouths are severely undersized. This requires another step using either a sizing die or neck-sizing die. Since I don't own a neck-sizing die I run them through the full-length re-sizing. I then verify them with a case mouth gauge. This is critical to ensuring you can properly seat bullets. If you have too much neck tension, the will be very difficult if not impossible to seat the bullets without cutting into the jackets or bending the case. With too little, the bullet can be pushed back into the case causing an unsafe condition.
IMPORTANT: Your unloaded AND loaded rounds should fall out of your case gauge. If you have to push them out front to get them out of the gauge something is wrong. A good example of this is factory new ammo. It's slides in and out with no issues. Your reloads should behave the same way.
For a list of approximate thickness, see this thread: