I've been intrigued by the ROMEO2 type optics that Sig and others offer... (http://www.sigoptics.com/product/romeo1/)
...and I was wondering if the 10mm is too much for them?  Do these sights require machining the slide to mount, or will they work off the existing dovetail?

Well, originally the 10mm was going to be the first sig pistol to have one. In fact the pistol in the image shown on the site you linked is the originally planned hunt ready. Now it looks like they are having issues with them on the 10mm. The optic is supposedly ready, but sig is very shy about saying anything about the Romeo hunt ready model. Originally they were not going to release a camo 10mm with target sights, it was going to have the romeo.

For the past few months sig was willing to say less and less about the real hunt ready model. Now since shot show all they do is refer you to the 320RX line rather than actually answering any question about the 10mm with romeo.

I did get a note back from Bruce gray about the 4.4" model. Gray guns has finally submitted the suggested recoil system for the 4.4" but it hasn't really been tested or validated. He said the 4.4" needs lots more time on the test bench that sig doesnt have and that we shouldn't expect it any time soon.

Seems to me like sig made one hoorah into 10mm just to appease the 10mm group a bit and now is working to abandon it again. This also seems to be evident in the ever dwindling supply of sig 10mm's on gunbroker.

Hmm?  That's an interesting observation Bruno.  I know Sig has been very tight-lipped about any forthcoming models in 10mm, so maybe you're right?  Hopefully they're not leaving it. 

Returning to the subject of reflex optics on a 10, I noticed the Glock G40-MOS includes their longslide in 10mm.  Anyone know how much testing they did with those optics on that G40?

I'd think the slide battering is directly related to perceived recoil. More recoil means more battering by the slide. That being the case I thought I'd share my subjective impression of firing a SigP220/10 and a SigP227/45. In shooting the 10 I was using PriviPartisan 180 grain hollow points and for the 45 Remington FMJ 230s. I also fired a magazine of Underwood 165s in the 10. The bottom line is the 227 had far more perceived recoil than the 10. I suspect the bullet weight was a main factor but the 220 is also more than 7 ounces heavier at 39 plus (the 4.4 inch barrel steel 220 is listed at 39 but I can find no weight specified for the 5 inch 220/10) while the 227 is 32. Both grips fit my hands excellently and without any doubt the 220 was more comfortable to shoot. A friend who shot it immediately decided he just had to have one. When I run some Underwood 180s and 200s through it I'll pose my impressions should I remember to do so.

I think Sig has bit off more than It can chew in so many areas that It can't deliver on all of its promises.

MCX calibers and accessories
MPX calibers and accessories
New 210
Legion
Are just Some that come to mind.

Just google for results on RMR sights on 10mm guns.  Several guys here have different brands of RMR style sights and run them fine as far as I know.

No reason a quality mini reflex from Sig wouldn't do just as well.

As far as their supply line issues, or perhaps loose cannons in the marketing department promising unrealistic timelines, that is probably a different item.

I spoke to Sig at the NRA show yesterday.  He said that the Romeo version of the 10mm will be out late summer.  He mentioned that the 10mm slide had considerably more recoil to deal with but did not say that it was the problem with the delay.  I looked at the Romeo mounted on I believe was a 320.  It looked good and was mounted low.  He also told me that there is only one version of the 220 available to the general public.  They make 4 versions but the other 3 are exclusive to one distributor.  They had the camo version on display so I assume that is the one available to all distributors.  I said that I have one of the DA/SA models on order and he said that my dealer would have to buy it from the special distributor.  I assume that to be Lipskey?
Tom

While the Romeo looks good, so does the Trijicon RMR and Leupold Deltapoint Pro. 
I have this crazy idea about finding a top notch gunsmith to create something similar to a Glock MOS on my Witness Hunter.  So if I decide to remove the optic, I can still replace the milled section with plate that matches the slides configuration. 

Anyone know if this would work?  And who is capable of doing this job? 

Quote from: Reverendpdp on February 12 2016 08:08:01 AM MST
While the Romeo looks good, so does the Trijicon RMR and Leupold Deltapoint Pro. 
I have this crazy idea about finding a top notch gunsmith to create something similar to a Glock MOS on my Witness Hunter.  So if I decide to remove the optic, I can still replace the milled section with plate that matches the slides configuration. 

Anyone know if this would work?  And who is capable of doing this job?

I don't see any reason that you couldn't I think the hard part would be matching the finish rather than the contour if you don't have the whole slide done.

I am snagging one of the Vortex Venoms and taking in one of my p220 10mm to be milled to fit it. I just ordered the venom from midway $99 off. Reviews on it seem to be solid.

Great.  I've been looking at that Vortex as well.  Who's doing the install for you?

I've been thinking of having Lone Wolf mill my G20 slide for a Fastfire, though I have yet to look into work-quality feedback.

Quote from: Benchrst on February 13 2016 01:29:03 AM MST
I've been thinking of having Lone Wolf mill my G20 slide for a Fastfire, though I have yet to look into work-quality feedback.

There's no questioning LWD's machine work quality. It's top-notch. However, milling an OEM Glock slide has drawbacks, and will require a surface treatment afterward. The Glock slide is treated, either Tenifer on earlier Gen's, or surface-hardened and coated on later. Either one will rust very quickly when the surface treatment is removed. LWD offers an excellent and inexpensive surface treatment, which is SBN (Salt-Bath Nitride). Unless you insist on co-witness sights, a much better option is a flat-top drill/tap. This is what I do, and it works well (I do my own machine work). The only real advantages to the "slide melt" is cosmetic, and a 1/8-3/16" reduction in bore-axis departure, which is insignificant, in my experience.