One of those days

Brad

Benevolent Overlord and site owner
Staff member
Decided to go to the “new” indoor range. This was a range that closed last winter but was reopened by a gun shop that was in a poorly visible location. What the hell, give it a shot.

Took the 1911 and some am,o I wanted to try. Based on Ian’s finding with PC I wanted to see if .451 bullets shot better or worse than .452. Load was a .451 PC 200 swc over 4.8 gr of Promo.

Good news is that they shot very well for me. Better than I expected.
1529968B-B80B-46C9-BCC2-0C97A9A8B419.jpeg
 

Brad

Benevolent Overlord and site owner
Staff member
Settled in for a 100 round test. Had 4 mags loaded with 7 rounds each. The first 2 mags went well. Part way thru the third I looked down and saw something was wrong.

Rear sight appeared to have adjusted itself for 400 yard shooting.

0B1CDDB7-5355-4EA2-8CB9-426EE2E9C016.jpeg
 

Brad

Benevolent Overlord and site owner
Staff member
Unloaded gun, cleared mags, and packed up for home. Did find the 2 tiny springs that push the elevator up.
Screw came out easily, that was a good thing. Head sheared right off. Doesn’t look like a very strong design to me. The screw slot is deep enough to reduce the strength of the head/shank area.

Gun has 10K or more thru it with no troubles so fatigue is a likely culprit.


1CBAAB29-8014-4E60-87B8-CC398332452A.jpegAD159027-DA15-409E-9838-15D33D86A263.jpeg93073CBE-EBC2-4985-8F54-B34825E1E8CB.jpeg
 

Brad

Benevolent Overlord and site owner
Staff member
Now to find a replacement screw?

Any ideas Bill?
 

Rick

Moderator
Staff member
There's a name for that Brad . . .

It's called an ooopsie.

What brand sight is it? Do you know the thread and the length? I have a few rear sight screws here so maybe, possibly, could be I could help ya out.
 

Brad

Benevolent Overlord and site owner
Staff member
I found one that should work. Thread length and diameter match as does head thickness and diameter.
Making one wouldn’t be hard except for the decent notches around the head.

Shipped it was 12 bucks.

Not sure who made the sight Rick, it is just stamped Colt.
 

Ian

Notorious member
Glad you finally got some shooting in after all your travels. If the range will let you use your handloads it might be a decent place to go for handgunning in foul weather.

I'd just round off the flats on the lathe and cut a new slot with a Dremel and cut-off wheel, touch it up with some cold blue and call it done.
 

Brad

Benevolent Overlord and site owner
Staff member
We will shoot a fair bit at this range. They are open evenings so it works for me to shoot with my wife. It is also a 10 min drive so location is important.

Being able to shoot with her makes the cost not significant.
 

CZ93X62

Official forum enigma
That sight looks a bit more substantial than the Elliason contraption that graces my Series 80 Gold Cup. I have an aftermarket replacement sitting on the bench I need to install, and I keep forgetting about doing it.
 

Pistolero

Well-Known Member
Make a new one yourself, Brad, out of 4140 and heat treat it. Just heat red hot in pliers or in a thin
wire hook and drop into a tuna can of oil. It will be strong as heck, nicely blacked and you'll not have that problem
again. I have never seen one of the real Bo-Mars break anything, and there were dozens of them in my
club and I own a couple on 1911s that have shot in the 70-80K rds each, are fine. The various clones seem
to all have some issues. Cutting the notches on the outside will be a bit if a hassle, though.
An indexing head will move it, if you have one. then either just a couple passes with a file or find
a V type pointed mill cutter. The key design point is a good transition radius from the head to the
shank. If that is a sharp corner....the head will pop off. :) What is the thread?

There is a Kimber clone, and a friend has had that break twice, sigh blade broke off of the
round part which slides laterally in the windage thread. There are a number of clones, hard to
know if they are all the same supplier. If you could find a real, old-stock Bo-Mar, grab it. They are
almost literally bullet proof. Certainly 1911 slide proof.

Al - I ran two Gold Cups in competition for a long time, many tens of thousands of rounds. Broke one
cross pin, replaced it with 1/16th piano wire with a slight bend to keep it from moving, no more problems.
And eventually broke the cross slide threaded adjuster. Got a new sight. As much grief as the
Elliason's get thrown at them, they really aren't that bad. Not 100% but not junk either. Pretty
durable for as small as they are.

Bill
 
Last edited:

Spindrift

Well-Known Member
Maybe you should try that load at 400 yards before you fix the sights, it might just be up to it. That is some nice shooting!
 
  • Like
Reactions: Ian

Brad

Benevolent Overlord and site owner
Staff member
Bill gave me some pointers last year when we shot with him. Made a huge difference.
One of the things that really stuck with me was the idea of using a marker to make a 1-2” Dot on paper and fire a magazine at it. Goal is a one hole group. I tend towards 7-10 yards for this. It does make you focus on sights and trigger control.
 

Brad

Benevolent Overlord and site owner
Staff member
It is a 6-48 screw. I may attempt making one but need to decide if I want to first.
 

Rick

Moderator
Staff member
No doubt those Bo-Mars were the real deal. A very sad day all across the shooting sports when they closed down. The guy making them passed away, I have no idea why the family had no interest in keeping it going or if they tried to sell it. Selling the sights sure wasn't an issue, couldn't make them fast enough. From all that heard at the time they just shut it down. Very sad indeed.
 

Brad

Benevolent Overlord and site owner
Staff member
This isn’t a “real” Bomar Rick. Just a Colt knockoff.
The sight works fine, the screw was just poorly designed/made.

I looked at a 6-48 does for making a screw and I can get a couple more for the cost of one die. Single point threading something that fine doesn’t strike me as ideal. If nothing else the die won’t have issues with deflection when cutting threads.
 

Rick

Moderator
Staff member
Brad, should you decide to make one (yep you should) keep in mind that the spacing and depth on those notches are critical to repeatability. One of principal issues with many aftermarket and T/C sights. Not with the Bo-Mars though.
 

Brad

Benevolent Overlord and site owner
Staff member
That is a big issue for me Rick. If I had a rotary table or dividing head it would be easy but I don’t have one.
Good thing is that once I get the sight set it will likely never move as it will only see a single load.

Think back to Keith’s thread on cost of machine work. This is a case where the tools required drive up the cost of a single item. I can’t justify spending hundreds of dollars to make an 8 dollar screw. Maybe in time once I have a dividing head?
 

Pistolero

Well-Known Member
I have a dividing head that I haven't yet used. Single pointing that size is doable. I did
a telescope eyepiece adaptor.....2"OD by 0.50" wall aluminum tube, with IIRC 60 tpi. Worked
fine. I surprised myself. Gripping it without distorting it massively was a major issue.
Turned a close fitting plug and gripped it that way. I did it on my old Sheldon, a fine
machine. If there is room, I would give serious thought to upgrading to a #8-48, (nonstd) if
you care about precise click values. If you don't, then cheaper, easier 8-40 thread, either is WAY
stronger, and if made of 4140, heat treated with a .020 radius from head to shank....will be far,
far stronger. This is the kind of stuff they used to pay me to do....although I just drew it and
the shop would make it, heat treat it.

Bill
 
Last edited:

fiver

Well-Known Member
good you got it off.
I had a screw break on the rear sight on one of my Dan Wesson's.
jezuz.
it broke right even with the top of the frame, I didn't even try, it went straight to the gunsmith.