Rear Sight Elevation Pinion Assembly

[Orlando]

Just thought I would share some info on how you can rebuild rear sight elevation pinions "if" you can find the parts and have the tools. The drums are next to impossible to find and are the part that wears out. If the detent/tit is not sharp it will not engage the receiver serrations and will only hold elevation if overtightened and will be very hard or impossible to turn the knob .
These are a set of Danish Elevation assembly tools


Setting the pinion in the disassembly holder tool with the disassembly tool on top. A sharp tap with a hammer disassembles the pinion

[Orlando]

This knocks out the cone shaped dog retainer which holds the assembly together

Next set the pinion in the assembly die, and set a new dog retainer on top of the drum. Notice the notch on the tool, the detent/tit on the drum must set in the notch so you do not crack the drum

Set the assembly tool on top of the retainer and drum and give a sharp tap with hammer


The pinion is now assembled and good as new.
If anyone knows where I can find any good elevation drums please PM me

[RDS]

Thank you for sharing. I have never seen spare GI drums.

[m14brian]

Awesome post Orlando!
m14brian

[jason60chev]

AmmoGarand shows drums and retainers, as well as the tool, in stock. These photos and instructions should be sufficient, but a video of the process would be helpful, too. or, if there
is a manual reference.

[Orlando]

ammo garands parts are all reproduction, there is no reference manual to the process

[jason60chev]

ammo garands parts are all reproduction, there is no reference manual to the process

About Rear Sight Elevation Pinion Assembly Hello Orlando......How are you? Did you have any real difficulty in disassembling/re-assembling the pinion and drum? Is there any kind of indexing required? I would think not, because the drum is often repositioned when setting elevation marks. Is there any possibilty of breakage of the pinion? I ask, because I have...supposedly....purchased a complete BMR rear sight assembly and I really want to be certain that I have received what I bought. As far as I can tell, there are no markings on the drum. All of the other parts are marked BMR, but I need to know if the pinion is marked, as your photo shows. Thank you. Jason ........Does it matter if the retainer and springs are repro, as long as they hold everything together? Are the old parts unuseable once the pinion is disassembled?

[Orlando]

There is no possibility of breaking the pinion. The tit/detent on elevation drum must be lined up with the notch in the tool otherwise you will crack the drum. There is always a possibility or cracking the drum even if you do everything right. All parts are reusable except for the dog washer .
Only part you could really tell about being repro would be the elevation drums, the dog washers you can tell are a little different as finish isn't the same. Most people probably wouldn't notice
If you really want to know what you have you can send it to me for disassembly and reassembly, no charge other than shipping but also no guarantees

On the BMR elevation pinion assembly the drum would be unmarked

[jason60chev]

Am being sternly advised NOT to disassemble the pinion because of possible breakage, indexing problems, etc. I don't see the danger, after reading/viewing your tutorial.
As far as indexing, I don;t see where that is a problem, because the drums are usually loosened by the screw and the range marks lined up, then retightened. I guess the on
real "danger" is messing up by not lining up the the drum detents with the notches in the tool.

There is no possibility of breaking the pinion. The tit/detent on elevation drum must be lined up with the notch in the tool otherwise you will crack the drum. There is always a possibility or cracking the drum even if you do everything right. All parts are reusable except for the dog washer .
Only part you could really tell about being repro would be the elevation drums, the dog washers you can tell are a little different as finish isn't the same. Most people probably wouldn't notice
If you really want to know what you have you can send it to me for disassembly and reassembly, no charge other than shipping but also no guarantees

On the BMR elevation pinion assembly the drum would be unmarked

[Orlando]

There is nothing to index when reassembling, the dog & screw can only go into the notches in drum. I have assembled 2-3 dozen pinions and have cracked a couple drums even with right tools. It is possible the drums were partly cracked before I assembled them and didn't show up until afterward. The possibility does exist they will crack even if aligning the tit into cut out on tool

[RCS]

Orlando, there was also an early T105 pinion with the small screw in the center. Early manuals sometimes show it. Some came back with the M1 rifles from Denmark

[Orlando]

Orlando, there was also an early T105 pinion with the small screw in the center. Early manuals sometimes show it. Some came back with the M1 rifles from Denmark

I saw one on eBay awhile back. That was the first time I ever heard of them.

[RCS]

I have an old photo somewhere, the Manual TM9-1275 June 1947 has photos of them

[Orlando]

Were they ever used in actual issued rifles?

[RCS]

Very early M1C sniper photos show the early T105 and standard issue rebuilt M1 rifles that were returned from Denmark and sold though the CMP had them installed too - most do not notice the small screw.