Surefire x300 Ultra and MR07 1911 Rail

Amazon recently had a sale on Surefire x300 Ultras (aka U-boats) that I couldn’t pass up. It’s a duel CR123 500 lumen weapon light. I’ve been carrying a 500 lumen Fury for a few months now so I was excited to try the U-boat. However, the only railed handgun I have is a Glock 19 that I carry daily and I don’t want to give up my crossbreed supertuck which is not light compatible. I have a Springfield 1911 that doesn’t get carried too often so I decided to try out sure fires MR07 rail adaptor.

The MR07 comes as simple kit, a rail, a new slide stop and a shim in case you need to tighten it up.


Install is easy.

– Remove the slide stop.
– Put the rail in place.
– Insert the new slide stop, be careful not to scratch anything, it was a little tighter than my factory slide stop.
– Tighten the set screw. It’s important to do this before putting your light on the rail so you have access to the screw.

That’s it.


I had a little trouble getting the u-boat to slide on to the MR07 the first few times however it became easier with use, I would not recommend adding or removing the light from any rail while the weapon is loaded. The MR07 is truly a drop in part which is a rarity for 1911 parts. The mount is solid and does not negatively affect functionality of the weapon.

X300 Ultra

As far as the Surefire X300 Ultra its a great light. It’s 500 lumens, pushing the switch forward works as a pressure swich, up or down switches it on in the middle it’s off. I really like the 500 lumens the extra brightness is nice.

It’s a big boy, 1.477 inches wide, compared to a Glock 19 which is 1.001 or a 1911 or .905 at the slide. On the Glock 19 the lamp protrudes about an inch and a half from the front of the slide. It’s more or less even with the barrel on the 1911.

The U-boat swich rides a little lower on the MR07 from the slide 1.352″ compared to 1.130″ on a Glock 19. However I don’t find that to be an issue.



Here is the light at night, the fence is at about 50 yards the tree 30 and the wall 3.


While I have found a custom holster option, and there are some universal duty style holster that will work, may of the big names holster makers do not make holsters that accommodate the MR07. I wish they would. For now this 1911 will go on bedside duty once I get a proper holster.

Bottom line the X300 Ultra is a great light and the MR07 is a good solution for adding a rail to a 1911. The only drawback is the lack of holster support for the MR07.

In action.


Update: I was never able to find a suitable holster for this set up. Raven no longer makes a Combatable holster and both of the small shops i reached out to did not fulfill my order. Which is a shame because it is a nice set up.

So the MR07 has gone into the parts bin and the U-Boat rides on my G19 in a Raven Concealment Phantom when I can OWB carry.