Trapdoor Sight Measurements

[Gunor]

I have a H&R Officer Model Trapdoor and a 1879 rear sight (stamped "R") and found a local gunsmith that answered my questions on his machine setup - some confidence...

I need some measurements/dimensions for placing the rear sight. From my understanding, trapdoors had the same dimensions:


Between rear sight holes
Location of the rear sight



Does anyone have the dimensions for the above.

Like to measure from front of the receiver for the rear sight hole.

Thanks to Larry G. for all his threads on this....

Geoff in Oregon

[calaloo]

On an original 1884 infantry model as close as I can measure it is 2.410 from the front of the action to the center of the rear sight screw. Hope this helps.
Calaloo

[Gunor]

Thanks for the info. Hopefully some one can confirm that on another - just in case. Not doubting...

Geoff in Oregon

[Tom Trevor]

OK, The m-1879 sight is 2.425 from face of reciever to center of rear screw hole on sight.

[Larry Gibson]

Tom gives the correct measurement taken from his very nice M1873 OM.

Larry Gibson

[Gunor]

Thanks for the numbers and confirmation.

That picture of three trapdoors, nice....

Geoff in Oregon

[StrawHat]

OK, The m-1879 sight is 2.425 from face of reciever to center of rear screw hole on sight.

Tom Trevor, the top rifle appears to have an octagonal barrel. The other two are round. Was the top rifle reworked by someone other than Springfield?

[Tom Trevor]

The Springfield with the octagon barrel was made outside the arsenal. In 1879 it was decided that all arms serial number 50000 and under would be turned in for new arms. The rifles and carbines were broken down and sold as scrap metal. It is believed that Schyler hartley and Graham had Whitney take the parts they purchased and built these sporting rifles. They show up in dealer catalogues thru out the west from 1881 on.
After the initial notice that the parts were being re-used the arsenal then damaged parts beyond use before selling them as scrap.

[wgr]

The Springfield with the octagon barrel was made outside the arsenal. In 1879 it was decided that all arms serial number 50000 and under would be turned in for new arms. The rifles and carbines were broken down and sold as scrap metal. It is believed that Schyler hartley and Graham had Whitney take the parts they purchased and built these sporting rifles. They show up in dealer catalogues thru out the west from 1881 on.
After the initial notice that the parts were being re-used the arsenal then damaged parts beyond use before selling them as scrap.
gov. has not changed destory the parts befor you let them be used

[Gunor]

106705

Thanks for the measurements.

My 1879 sight has been installed. Looks level

106859

So now for the search for the carbine load - or something close. I want the 1879 sight to be dead on @ 100 with the carbine 405 load - to be developed. Front sight, again, the globe/blade - Beach?


106708
Or
106709
Or
106710

The last is 405 grain....might be the one for the short term testing.

So I'll see what bits of powder I have in stock....for launching.

I do plan to buy a Lee 405 HB.

And I have a micro groove to feed - that why I was hoping the .459 sized might be large enough...

Thanks again to Larry and the guys

BTW - it feels like a real rifle with a real rear sight now. Tip up tang sight just was not cutting it.

Geoff in Oregon

[Larry Gibson]

Geoff

With the sight radii on my OM with the '79 "R" rear sight I use the "80% rule" for sight adjustment. Once you get the rifle zeroed with a "service" 1873 level load (a 400 - 415 gr cast at 1350 fps) then use "80%" of the estimated or measured range for the M1879 rear sight range setting. With my OM and the rear sight set at the bottom (100 yard range setting) the group hits just above POA at 100 yards with service level loads. For 200 yards the sight is set on 160 yards, for 300 yards the sight is on 240 yards, etc. So far it works very well to 1000 yards (that would be with an 800 yard sight setting) with my OM.

Contrary to some opinion I do not find the recoil of service level loads in the OM "troublesome". It can be annoying from the bench if one has a poor shooting position crouching too low on the bench. However, if one uses a correct height of rest and elbow pads then even off the bench shooting service level rifle loads in the OM is not troublesome and quite fun actually.

I have read numerous reports of the 45-55 Carbine load being favored in the OM because of recoil however I do not quite accept that. That is mostly written by those who are writing about others shooting the OMs. It is my belief based on actual shooting of the 45-55 Carbine load that such load was favored because it first of all hit closer to the actual POA at 100 yards than did service level M1873 45-70 ammunition. The original OMs, just like the infantry rifles and Carbines, were sighted to hit close to 12- 14" high at 100 yards. This was simply because the soldiers were trained to aim at the bottom of any target (our 6 o'clock hold). The 45-55 ammunition, because of its lower velocity, hit much closer to point of aim at 100 yards and second of all for its use the 45-55 ammunition even then hits very close out to 250 - 300 yards and even sometimes close to 400 yards depending on the initial zero. That made it accurate for hunting (foraging of game animals to supplement rations was quite common) and it often gave the impression the officers were "excellent" shots. It is amazing how having a properly zeroed rifle can give that impression. However, beyond those ranges the 45-55 carbine ammunition does not stay regulated to the sight settings of an "R" of "C" M1879 rear sights nearly as well as does the 45-70 service load with the "R" M1879 rear sight. Having extensively tried both sights with both 45-70 and 45-55 cartridges I went back to the "R" rear sight and simply use the "80% rule" because the OMs sight radii is 80% of the rifles. It works out quite well.

I find when I want to just shoot for fun I most often use the OM.....it has become my most often shot rifle.

Larry Gibson

[Gunor]

Larry,

Any thoughts on a MVA Beach front sight? (combination). The existing front bead sight - need to see where that shoots at first. I am still rather use/see a blade from my m14/m16 days...

I like your comments about the carbine vs. rifle loads in the OM - and I understand them. But I think in my current shooting - lack of a KD range - I'll start with the carbine loads. Lower recoil, and shooting on my two hind legs - carbine loads. Now I am re-searching for your threads on 45-70 loading.

I know you started a 45-70 reloading thread - I wish you/someone would make sticky with all of your trapdoor stuff - (C.E. Harris - how many times have I read that...)

I am very temped to try the BP route - I have 2-3# of the 2F type....

And I notice my pictures did not work in my prior post - I'll work that tonight

Geoff in Oregon

[Larry Gibson]

Geoff

The MVA Beach front sight is the one to get. The Buffalo Arms is too small and too short. The Pedersoli is too tall. The MVA's blade is high enough to allow filing down for proper zero once you decide on a load. My blade front sight is .425 from the bottom of the sight (dovetail) to the top of the blade. My pin sight is slightly higher and is used for the tang sight. I also use the pin sight with the M1879 sight set at 100 yards (bottom setting) for a 50 yard zero with my Rapine 275 gr at 1050 and the Rapine 210HB at 800 fps.

If you don't have Spence Wolf's book on loading for the TD (the45-70book.com) then it should be on top of your priority list, especially if going to BP loads. The Ray-Vin '03 Sight micrometer (RAY-VIN.com) is an excellent sight adjustment tool for precise ½ moa elevation adjustments and return to known zeroes.

Larry Gibson

106817106818106819

[Gunor]

Larry,

Thanks again.

The MVA sight looked the best with all the choices in heights. And your where reading my mine on providing your front sight height...I'll measure my existing bead sight.

You can shoot lighter bullets? - Just kidding - my backyard is being mowed now. I trying to beat back the Scotchbroom (lovely invasive plant) - So to regain my 75 yard range.

Ray-Vin '03 Sight micrometer - now there is my second reason for buying one - after my 1903 sights.