1911 "Who knows the breechface isn't supposed to be straight?"

[prs]

Apologies to 35remmington who's words I purloined for the title of this thread. He scribed that in a recent thread concerning 1911 reliability and that remark was actually a two sentence phrase; "Who knows the breechface isn't supposed to be straight? Are they making them that way?"

Well, got to looking and just by eyeball the breech faces of my two samples from Ruger seem to have been milled straight, with one little caveat. EDIT, IT IS THE LEFT SIDE, THR EJECTOR SIDE! LEFT hand side (shooter's perspective, the ejector side) has a slightly raised sort of "quarter moon" shaped area right against the side wall. A few thousands of an inch above the face proper, I guesstimate. The cartridge case's head does rest upon that little ridge and spent cases do show its imprint, especially loadings beyond plinking power. Some of my older cases have been so embossed all the way around to where it has obliterated the brass brand name or at least the bottom half of it. I have seen another report (complaint) about that on a Ruger forum. I never gave it much consideration since the function and reliability are excellent and the brass continues to cycle regardless the imprinted crescent dents.

Is what I notice the way it was and should be? Is it a machining error or an easy way around doing it "correctly" (or the old way)?

prs

[DougGuy]

All the 1911s I ever owned the breech face was flat. Never had one that imprinted brass. That sounds like a manufacturing tolerance that should have been or should be addressed. It likely won't hurt anything safety wise or how the gun functions but brass is expensive and if it deforms the bottom of the case, it won't be long that it won't fit in a shell holder properly and then you got a different set of issues.

[jrayborn]

My ruger "Commander" had a raised area maybe a couple thousandths high on the side opposite the extractor that left marks on the brass. I stoned it off.

[prs]

My ruger "Commander" had a raised area maybe a couple thousandths high on the side opposite the extractor that left marks on the brass. I stoned it off.

Well, I was going by memory, by golly, it may well be the ejector side. I will have to look again this evening. Both my Commander and full size have the same little crescent area.

prs

[gray wolf]

I thought they were on the ejector side, it's known as a J cut. I don't know the origin of it, some pistols have it and some do not. My springer does not. It can be milled off it it prsents a problem.

[Sax.45]

I have a S&W 1911 that had that problem, I carefully filed it down.

[35remington]

It's all off topic in terms of the above comments. The breechface is supposed to be less than straight as an aid to controlled feeding. Picture a wall. The bottom of the wall is two feet, exactly, from the tips of your toes. The top of the wall is 23 inches from the tips of your toes. This is just an example to illustrate the direction of the "out of square."

The top of the breech is supposed to be "overhanging" the bottom. The spec is just about one degree, actually 52 minutes, from square. It is part of the controlled feed criteria in that it maintains frictional contact of the rim while feeding. A little known feature of the 1911. Having a correct breechface helps the pistol feed as it's designed to.

[prs]

Excellent explanation; floor to ceiling, intentionally out of plumb with positive rake.

So, I am considering the removal of that ridge in each pistol; maybe request it be done by Ruger, unless they declare it to be normal.

prs

[seagiant]

Hi,
Anybody got Kuhnhausen's Vol II 1911 book! I do but I"m to lazy to look! Any of you guys think you can out R&D J M Browning..... I'd think again!:smile:

[wv109323]

I have seen the same thing you are describing on my 1911 (Colt). It leaves an indentation on the brass. I took it to be that the breechface was broached the width of the barrel hood. The rest of the breechface was machined in a separate operation. I just assumed the two surfaces were not exactly "flat".