Let's say you have a SureFire M952 (2 cell w/ ARMS mount).  Add to that a pressure switch to increase mounting options.  (M900 users you can skip this thread.)

Why do most seem to choose the 3 o'clock (for a right hander) mounting position over the 6 o'clock?

As I can see it, the pros and cons are as follows:

3 o'clock:
PRO:
- less likely to damage the light if you go prone and slam the rifle onto a rest;
- light beam is closer to POA/POI;
- easier to use a push button tailcap if that's your preference.
CON:
- increases the width of your rifle;
- hangs weight off of one side, having (an albeit slight) effect on balance;
- adds to the width if you grab the rifle on the horizontal plane (i.e., without the vertical grip)
- very prominent barrel shadow at the 9 o'clock positin in the light beam, even when mounted far forward (could be very distracting when you're looking for strange shadowy objects in the dark).

6 o'clock:
PRO:
- good balance;
- no barrel shadow issue;
- easy to grab the horizontal plane of the light.
CON:
- not as good for push button tailcap users;
- more vulnerable to being whacked on a rifle rest.

I can't think of any more right now.

So, why do you choose 3 o'clock over 6 o'clock??

I'm about ready to get a tailcap pressure switch setup and before I do, I'll want to settle on light position to determine length of the pressure switch tape.

IMHO, the cons of each are barrel shadow for the 3 o'clock and damage potential for the 6 o'clock position.  I'm leaning toward the 6 o'clock setup.

Thanks for your advice.

So no one else using a 3 o'clock light position has noticed the barrel shadow prominently displayed in the light beam?

C4iGrant:

Thanks for the info.  I guess I hadn't thought of that.

Still, the M900 is very popular.  I don't know if the SureFire M95X, etc. series have stolen any of its thunder, though.  I haven't had the opportunity to try them back-to-back.

I have ARs set up both ways.  IMHO the barrel shadow on the side mounted light is very undesireable.  It doesn't make much difference up close, but outdoors it is very obvious.  Watch-Six

You should use the shootiers 1 o'clock position.

[img]http://photos.ar15.com/ImageGallery/Attachments/DownloadAttach.asp?iImageUnq=2384[/img]

I know we've talked about this offline, but I figure my comments might be a useful addition for anyone reading this.  At the very least it will allow others to criticize my logic.

I'll try to add my 2 cents on this without sounding like a blustering idiot, which may be hard for me to accomplish. [:)]





Well, I do have a M952 so I'm good there.





I have the SW02 "clicker" tailcap, but for the sake of argument I'll consider this part of my setup.  You know what I think about pressure tape.  





Why is this a con?  I think it is a non-issue.




I don't notice the balance effect you mention, but I understand that it is there.





That's true, but why would you grab it like that?  If I'm in a standing position and need to brace the rifle with skeletal alignment (elbow on iliac crest) it's more natural and stable for me to turn my hand so that my fingers are pointing toward 9 O'clock.  





True, but there is enough scattered light so that you can still see partially into the shadow.  Shooting isn't a static sport either, so keep in mind that you can always move that shadow around.




The shadow is still there it's just in a different spot.  In a small enough room, that shadow would be just about at head level on a target that you're aiming COM.  Facial recognition is VERY important.  Plus, if that shadow is covering their eyes you've just negated any blinding effect that you may have otherwise gained.





The diameter of the entire system is still the same.  It does rest in the palm a little easier though.



I have a few reasons that I chose the 3 O'clock position over all others.

1.  It just felt natural for it to be there.
2.  It can still be used without the light getting in the way of a mounted bayonet.
3.  There is not enough room on a single rail for my big hands, the vertical grip, and the light.  In order to fit everything on one rail I have to move the grip back so far that it becomes a useless weight.  Grabbing the mag well and magazine instead is much more comfortable.
4.  Shadow isn't at head level.
5.  I have a clicker tailcap.  Using my thumb to push the cap is a lot easier and offers much greater control than using the knuckle push technique.
6.  Future purchases may include a KAC QD bipod mount.  There's only one place for that to go.

M4:

Sorry, I'm using an RASII and don't have a mount point at 1 o'clock.  But I can see how that would put the shadow at a less prominent position.

I'll just have to experiment with both setups.

What momentary pressure switch wire length do I need to mount the light at the forward edge of an RASII in the 3 o'clock position and run it back to a vertical grip mounted just in front of the magwell (most rearward position)?

Would this length wire get in the way if I wanted to switch it to 6 o'clock?

Thanks,

Corey

Who knows.  I may not like it.  I prefer the vertical grip back further than you.  The pressure tape is really the only option for me to either (1) move the light as far forward as possible at a 3 o'clock mount (EDITED TO ADD: to try and reduce the front sight assembly shadow), or (2) mount the light at 6 o'clock and not have to use the workable but still clumsier knuckle engagement of the push button.

Just thought I'd give it a try.



I think it's awkward having to grip both the bottom of the RASII and 3 o'clock mounted light when looking for a horizontal gripping surface.

So, it's an issue for me inasmuch as I'm exploring ways around it.  I may end up right back where I started (push button at 3 o'clock).



No, it really isn't all that noticable.  That I will admit.  However it is there I'll likely end up playing with different options to at least see how they all work.  I'd say it's less of a "problem" and more of a "consideration."



I'm not sure this sounds very comfortable or effective.  Maybe I just don't understand what you're talking about.

I'm referring to grabbing the underside 6 o'clock railcover on the RASII like we did back in the day -- you know, before all this fun stuff that we like to spend all our money on was invented.  [;)]



My concern is more in an environment where you're looking into and at every shadow as a potential threat, why add one more (moving, block shaped) shadow to worry about.  Particularly when this shadow could obscure target ID, or mask the threat itself.



Yeah, I figured as much.  Still, it's something that I'll be playing with.  In fact, I just might have a run at it tonight.

When I had my light at 6 o'clock before, I didn't notice any shadow in typically sized roooms (contact out to 20' or so).  Which isn't to say it isn't there, but perhaps just much less of an issue with 6 o'clock light positioning.



Yes it does.  I prefer dealing with the height of 6 o'clock more than width of 3 o'clock.

The 3 o'clock adds width where it is, IMHO, a gripping problem.  It also adds width where there previously was none -- i.e., it literally makes the package wider.

The 6 o'clock position adds height to the front rail section, but the height is no greater than that presented by the magwell, magazine, pistol grip, stock, etc.



Good point.  I briefly considered that this might be an issue, but didn't have a bayonet to see if it would work or not.



You could probably mount that bipod at 3 or 9 o'clock, you know.  Is there anything on your 12 o'clock rail?  [:\]

Corey

EDIT noted in text.

Who the heck uses a bayonet anymore?  In the real world, a bayonet is not a factor.

Also, at the 3'oclock, when you slice on the left side, yu have to lean out more and expose more of your body if you need to flash the light toward a potential target.

Personally, I mount the vertical grip as far rearward as I can anyway, so I have enough real estate for a separate light.  With an M900, you can mount it farther forward and have a decent amount of horizontal gripping surface.

I mount all my lights at the 9 o'clock pos, 1st the lights which are all M2s are one more object the bad guys bullets have to go thru in order to get to me.

2nd I prefer to have the shadow on my right as I walk thru doors(I shoot right handed), my right eye is stronger then my left eye and therefore is able to see better and needs less light were my left eye needs all the help it can get.

3rd It is one less object that can bang into walls as it is on the same side as most of my body and not hanging out into space. If you get a switch get the smallest one possible, less wire to snag and have to tape or tie down.

Best of luck.