Of course, one should only use iron sights, but in some competitions use of red-dot sights is universal.
Problem is a Colt 9mm 1911 with milled back end of slide (and taped) to receive a Venom red-dot sight. In other words, a flat, horizontal surface replaces the rear sight. Will need to add slope to the flat surface because the pistol shoots quite low with the sight's adjustment all the way down. It is desirable to change the flat's slope enough that the sight's elevation ends up about in the center of the sight's vertical adjustment.
Question: what is the expected total vertical adjustment of Venom? I will add half of that to the error now seen (about 12 MOA) and know the new slope.

Looked, but did not find information about the vertical range. Thought someone here would have at least an estimate. Thanks. Mac

quote:

Venom red-dot sight

I was curious so took a quick look on the vortex web site...
Max Elevation Adjustment 130 MOA

Your title is too vague. Please use the title to actually describe the question.

Thanks Arc and hrcjon. Sorry not to have crafted a better title. Have no idea how now to change.

1. The current situation is: poi is 12 inches below poa. Not 12 MOA. So with sight bottomed, off by about 48 MOA.
2. I had not found the range of adjustment information on Vortex site. Thanks again hrcjon.
3. By actually clicking, I found the total vertical adjustment range to be close to 120 MOA. Thus to have poa and poi occur near the middle of the vertical dynamic range requires a tilt of 1.8 degrees.
4. Colt has a loose frame to slide fit (it is a Colt, not a Dan Wesson), but everything on the slide is tight so I expect it to shoot most of the barrel's capability.

Thanks all, Mac

I'd talk to pro shops that do this kind of work. This is an infrequent but real problem. A shop that will remain nameless (although they do have a good rep and I have used them with good results) did a couple of CZ slides for two of my buddies. Maybe they are/weren't used to working on CZs but both run out of elevation adjustment when zeroing their DPPs. One junked that slide, another had it re-milled for an adapter plate system.

It's not a scope that you have to dial elevation so why do you care where the adjustment is its range?

I had one of my 2011 slides milled for a delta point. The shop didn't factor in the length of the barrel into the equation (commander length vs govt) and after a couple trips back and forth, they finally milled an angled shim out of aluminum to correct the issue.

One degree seems to be the norm from those I've talked to in regards to milling. You might be able to use a derlin shim or multiple shims from a place like UM tactical to resolve your issue, but I suspect that you will need a custom made plate if you are that far off.

Thanks. 1.8 degrees equates (for the length of Venom) to lowering the front close to 1.5 mm. Amazon has 1 degree shims to raise the back. For pointing maintenance, lowering front is preferred to raising the rear. I will see what the mill operator thinks.

The 12 inch offset of poi and poa was at 25 yards.

quote:

Originally posted by P320Mac:
Will need to add slope to the flat surface because the pistol shoots quite low with the sight's adjustment all the way down.

Doesn't depressing the rear sight cause the gun to shoot low? Have you tried dialing in elevation?

I'm confused. You milled the slide, mounted the Venom, and exhausted its vertical adjustment (60ish MOA) and you are still shooting 48moa low? I'd vote that you have a serious issue in either the sight itself or the milling. Round numbers thats 100MOA low overall. There is simply no way mechanically for that.

hrcjon -- The first milling of a flat in place of the rear (iron) sight turns out to have a slope that points the red-dot sight upward too much. The slope of the rear flat needs to change by 1.8 degrees (just a bit more than 100 MOA).

Consider someone wishing to shoot a rifle at a target that is 300 yards away. It is expected that the striking point will be below a line straight out of the barrel (bore axis). For any sight to point to the striking point (in this case) the sight must point downward with respect to bore axis. Hardware exists to provide a needed downward pitch for sights.

Yes. Issue with the first milling of the slide - it turns out that the flat needs a 1.8 degree rotation from the present slope.

quote:

Originally posted by hrcjon:
It's not a scope that you have to dial elevation so why do you care where the adjustment is its range?

Primarily because if your "up" adjustment screw cannot turn anymore and your gun is still hitting low, you're screwed, pun intended.

YVK it never occurred to me when I posted that one could mill a slide so poorly that you would run out of elevation adjustment. I assumed P320mac was complaining that he was using a pretty good part of the 60+moa available which is meaningless on a red dot. Now of course I understand that is not the case.
I'd be 1. getting a new vendor to mill my slides 2. making the old vendor get me a new slide.
There is simply no excuse for a milling job on a pistol to not be parallel to the major slide axis. I've now milled (or had milled) a very large number of slides and this has never been an issue. and it shouldn't be...

I agree. It does sound inconceivable that pocket can be milled way off, but humans can screw up anything. I presume that gun being a relatively uncommon choice for the dot at that time may have been a contributor.

Pw20Mac
Once you mount the red dot sight you can simple,
while zeroing it in simply adjust your red dot, if even needed after zeroing it in, just raise the dot up. They adjust up or down or sideways.
Once zeroed the bullet hits where the red dot is.
The above should work for you if I understood
your question correctly.
Stay safe
Poli Viejo

Horn you missed the boat on this one. Issue is after full adjustment on the dot he's still not there. It's a milling issue and a pretty bad one.

quote:

Originally posted by P320Mac:
Thanks Arc and hrcjon. Sorry not to have crafted a better title. Have no idea how now to change.

To change a thread title, the originator of the thread needs to edit their first post, the one that originally created the thread.

After you click the edit button that first post, both its title box and text box get opened up for change.