1911 feed ramp questions

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A little help here...

Posted by Ironlung.
"Just a couple questions for my first post.

Was the weapon being worked on in the photos having feeding problems before the work was performed?

What is the tolerance on the feed ramp depth and angle?

Did you indicate the slope after getting it close with the angle gauge?

Is the .360" vertical ramp height a minimum? How was the angle height measured? I would imagine a coordinate measurement machine is needed to get the intersection of the magwell and ramp relative to the "top" to get three decimal place precision.

Is the angle and the depth more important than the location of the ramp relative to the hole (.790" dimension)?

Am I being to picky? .360" min +1/16 and 31.5 degrees +- 1 degree close enough?

Is there a spec for flat land between the radius cut of the endmill? Is that a standard size endmill?

By the way some beautiful work done over at rogers precision.

I guess that was more than a couple.


One more question if any have the time to reply.

How much would a job such as this cost if done by a competent gunsmith?

Thanks"

Lets see if anyone can help answer these questions and welcome!
Joe
 
31-31.5 degrees. Height is taken flat off the rails. Angle is from vertical.

.360 can be considered a minimum, but you can get away with less if the magazines don't let the rounds nose-dive into the ramp. The precise intersetion isn't that critical, and there's a good bit of wiggle room...again...depending on properly functioning magazines.

The angle is the most critical, and a well-defined top corner at the junction of ramp and barrel bed is paramount. That's where people get into trouble with polishing. Roll that corner, or create even a slight "humpbacked" shape on the ramp...you've got problems. Felt wheels and bobs and even fingertips aren't rigid enough to prevent it unless one is extremely careful...and even then, there's a risk.

I don't polish ramps with a Dremel, and only with a fingertip if there's a rough spot...and only then just enough to smooth it out. Any reshaping or alteration is done with a scrape...by hand. Wish I had the necessary machinery to do things like that...but I don't. I'm very careful to stay off the top corner in any event.

If the ramp geometry is correct...and the barrel ramp is good...mirror polishing isn't necessary, and can create problems if the geometry isn't right. Polishing is an enhancement...added insurance...that is correctly done AFTER everything is else is right, and done with the proper equipment and understanding of HOW to do it. (Using a Dremel while sitting in a recliner watching Gunsmoke reruns is not considered to be the right way to do it.) Polishing is not a quick-fix used for the first response to a feeding problem, although it does work often enough to be encouraging it when the problem isn't with the ramp's surface finish in the first place...which leads one to believe that his "Double Throwdown Ramp 'n' Throat Job" was so good that he then starts doing it for all his friends. The laws of probability will catch up with him sooner or later, and he will either buy the pistol that he screwed up...or pay a pro to have it repaired...or he'll lose friends.

The barrel ramp is a clearance...not a feedway or a guide. Contact with the bullet nose beyond a very light brush as it glances off the feed ramp is setting the gun up for a malfunction. The smoothest feeding pistols don't show any contact at all. My feeling is that the barrel ramp angle is a minimum of 20 degrees...and even that's pushing it. 25 is better. The limit, of course is the fact that as it gets less steep, it also gets longer. If the barrel ramp goes too deep into the chamber...you've got head support problems. How much limit is on that depends to a great degree on the other barrel specs, and how well it's fitted. Headspace is a limiting factor. Barrel endshake is another one. It all ties in.
 
The barrel ramp is a clearance...not a feedway or a guide
1911Tuner

Most important concept stated above, but very hard for people to get their head around it. That's why they feel they must have those "mirror" barrel ramps, in order for the pistol to work properly ??!!

Once they are able to understand completely what 1911Tuner has stated above......... the need for that sandpaper doesn't take such a high priority.

It's all in the small details .................

JF.
 
Tuner, by what means are you measuring yours?
Click to expand...

With a diemaker's square. The closer I get to 20 degrees, the more trouble I have with many pistols...which is why I called it a minimum...but it's not chisled in granite by any means. As long as the case head support is good, I just like for it to be a little less 'cute. :)
 
?

Starrett Diemaker's Square:
1378.jpg
 
Iron,
I'll try my best! :)

"Was the weapon being worked on in the photos having feeding problems before the work was performed?"
Unknown. I was routinely adressing a shallow feed ramp.

"What is the tolerance on the feed ramp depth and angle?"
From my experience, 31.5 is ideal with an 'in-spec' frame. Some frames require closer to 30.5 but this is less than ideal.

"Did you indicate the slope after getting it close with the angle gauge?"
I believe my use of the protractor gets me within 10 minutes or so. 1/6th of a degree.

"Is the .360" vertical ramp height a minimum?"
In my experience, yes.

"How was the angle height measured?"
Eyeballing a depth micrometer.

"Is the angle and the depth more important than the location of the ramp relative to the hole (.790" dimension)?"
Some frames require a steeper angle and a shallower depth. The limiting factor is the length of the bridge, on the barrel bed, between the vertical impact surface and the top corner of the feed ramp. Too short of a bridge will require excessive barrel throat set-back with subsequent loss of cartridge case support. I consider .248" length a minimum.

"Am I being to picky?"
No

".360" min +1/16 and 31.5 degrees +- 1 degree close enough?"
.360" - .420" depth x 31.5 - 30.5 degrees.

"Is there a spec for flat land between the radius cut of the endmill?"
?

"Is that a standard size endmill?"
No. It is ground to .480" diameter.

"By the way some beautiful work done over at rogers precision."
Thanks! :)

"One more question if any have the time to reply.
How much would a job such as this cost if done by a competent gunsmith?"
How hungry is the smiff? ;)
 
I still wanna see the pictures from the Little Shop of Horrors that were created by Dremel Dan and his stupid cousin, Buffin' Bubba.

Wish I'd taken a few along the way. Some of'em were truly awful. The ones that had the frame and barrel ramps blended to eliminate the barrel to frame gap are among my favorites.

Some were salvageable. Others had to go somewhere for ramp inserts. It all depends on how early in the exercise our dremel jockey discovers that he's made a miscalculation.

Whenever I get a phone call or a PM asking for help...and the first thing I hear or read is: "Welp...I grabbed that ol' Dremel and done me a real good ramp and throat job on'er, and she still won't feed."...I go ahead and take a handful of Excedrin before I even see the gun.
 
The ones that had the frame and barrel ramps blended to eliminate the barrel to frame gap are among my favorites.
Click to expand...

And well they should be. When I was young and impressionable, before GCA '68, all the gunzines had articles about how to improve your surplus guns. Most recommended blending the ramps on 1911.
 
Thanks for the replys guy's.

Let me clear this up in my mind.:confused:

The ramp in the frame is the feed way. There is some pretty generous wiggle room on depth and position as long as the bridge is not shortened to much and the top corner is left sharp and the angle is correct.

Is this correct?

Chuck I think I get what your talking about with the bridge and vertical impact surface. If you could check my picture to see that I know what your saying. I'm still learning the terminology.

The ramp in the barrel is clearance and if the rounds ride this area there is a problem.The angle and position are less critical. As long as the round clears and is still fully supported by the chamber it's O.K. correct?



My clear as mud question about the radius left behind by the endmill. I'm asking how you made the cut.

Was the endmill placed above the part as you had it fixtured centered exactly between the rails, lowered into the magwell to an adequate depth and the table of the mill moved in the X axis(left to right) only(no movement in the Y axis)?

In a section view normal to the angle of the frame ramp, is the shape a perfect "U" with a .240" radius of the endmill? Does the "U" have a flat at the bottom from some y axis movement?

Chuck Rogers and 1911tuner thank you for your generous sharing of the details. I think I need to get a book. Do you recommend any?

Should this thread be merged with the sticky I referenced with the thread starter?
 

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Ironlung...The frame ramp deflects the bullet nose and orients the cartridge...gets it headed in the right direction, for lack of a better term...so that it can glide over the top of the barrel ramp. Picture sliding a heavy box up a flight of steps. Across corners is what you want. If the edge of the box hits the face of a step...you stop.

When the bullet nose hits the barrel on the face of the ramp, it pushes the barrel forward. When the barrel moves forward, it moves up. If the barrel lugs try to enter the slide's lug recesses too early, before the slide is in position...the front corners of the barrel lugs crash with the rear corners of the slide's lugs...and it causes problems. Some pistols will push on and go to battery...but the lug corners suffer. For the ones that don't...the gun is unreliable. The barrel isn't supposed to move forward until the breechface contacts the barrel hood...when the slide is in position to accept it.

If the bullet nose clears or just barely brushes the barrel ramp and glides over the top...as the cartridge starts to break over, it exerts a downward force on the barrel...keeping it as low as mechanically possible and reducing the angle of the cartridge as it starts to break to horizontal and center on the breechface. Feeding is smooth as silk.
 
Bubbalicious!

2-9.jpg

3-12.jpg

4-9.jpg

5-7.jpg

6-6.jpg

1-13.jpg

The top corner was moved forward and rolled over reducing the bridge length to approx. .200" !
The barrel throat was then cut far too deep losing necessary case support.
:eek:

Tuner,
It would be great if you could post a couple of pics showing your method of measuring the barrel ramp angle. Bob Rodgers came up with this device. Myself, I use a surface plate and test indicator in conjunction with a protractor.
Bob's device is OK but not perfect. My method takes considerable time. Help us out!

barrelrampgauge1.jpg

barrelrampgauge2.jpg

:)
 
I do it pretty much like you've shown...but with the square and a protractor. I don't get too wrapped up in what the precise angle is...as long as it's not sharper than 20 or duller than 25...I can work around it as long as Dan or Bubba haven't fixed it beforehand.

That peachy-keen ramp & throat job you've shown is typical of what I run into...except that many are much worse...both the frame and the barrel. When I see those, I shrug and recommend somebody like you or George Smith for a ramp insert and a new barrel.

Or, another way:

"I just don't understand! I cut it three times and it's STILL too small!"

:D
 
"The ramp in the frame is the feed way. There is some pretty generous wiggle room on depth and position as long as the bridge is not shortened to much and the top corner is left sharp and the angle is correct.
Is this correct?"
Yes, depending on your interpretation of 'generous'.

"Chuck I think I get what your talking about with the bridge and vertical impact surface. If you could check my picture to see that I know what your saying. I'm still learning the terminology."
Your picture is correct.


"The ramp in the barrel is clearance and if the rounds ride this area there is a problem.The angle and position are less critical. As long as the round clears and is still fully supported by the chamber it's O.K. correct?"
My opinion here differs from Tuner's. I create a mirror finish on the barrel throat. I also use a generous, high polished radius at the transition from barrel throat to barrel chamber.
1911's do not allow 'full support' to the case. I have not seen definitive data on how much 'unsupport' is allowable. For me it is a judgement call based on visual assesment and previous experience.

"My clear as mud question about the radius left behind by the endmill. I'm asking how you made the cut.
Was the endmill placed above the part as you had it fixtured centered exactly between the rails, lowered into the magwell to an adequate depth and the table of the mill moved in the X axis(left to right) only(no movement in the Y axis)?"
The endmill was centered true to the magazine well. The feedramp was plunge cut in .005" increments.

"In a section view normal to the angle of the frame ramp, is the shape a perfect "U" with a .240" radius of the endmill? Does the "U" have a flat at the bottom from some y axis movement?"
The cut does form a .240" radius. The cut does not terminate in a shoulder. It is a 'through and through' cut.

I hope this helps!
 
I have not seen definitive data on how much 'unsupport' is allowable. For me it is a judgement call based on visual assesment and previous experience.
Click to expand...

For lack of any other supportive data ............ I generally use Kuhnhausen's
recommendation on page 68-69 of his first book on 1911s.

.075 inches of exposure from the extractor bevel to where the chamber supports the brass casing........... this plus the headspacing which can be very important when added to the above figure for a total unsupported area.

Kuhnhausen states that generally .090 exceeds safety limits of the .45 acp.
.075 ramp area + headspacing > .090 = unsafe

Jerry has made some errors editing his books, but generally the information he does write down will keep you safe IMHO.

JF.
 
My opinion here differs from Tuner's. I create a mirror finish on the barrel throat. I also use a generous, high polished radius at the transition from barrel throat to barrel chamber.
Click to expand...

There's a specific reason that I like for the feed ramp to maintain a well-defined corner at the top...and it's because of the way that I'm forced to work.

A smith with a fully-equipped shop like Chuck has can remachine a ramp that's slightly out of spec to get the critical angle, or...failing to have enough front to back distance in the magwell to achieve that...installs an insert. I don't have the machinery to do that, and have to rely on that corner to kick the round as high as it can go to allow it to skid over the top of the barrel ramp in guns with less than optimum feed ramp angles.
If I've got that corner, and the frame ramp is pretty close to correct...I can usually adjust for it.

Reshaping a too-steep ramp isn't hard...but adjusting for one that's 30 degrees...or less...is a challenge. That corner helps a lot.

If all is right...the barrel ramp doesn't need polishing. IF...all is right. I've mentioned my unaltered USGI pistols, and a few commercial Colt Government Models that feed hollowpoints and lead SWCS as well as ball...from the old "Hardball" magazines...and they'll do it with boring reliability.

With all of these pistols, you can coat the barrel ramps with layout fluid...hand-cycle a hundred rounds of ammunition through them...and the only place that the bluing will be removed is at the very top corner of the barrel ramp. These pistols feed so smoothly that it's hard for many people to believe that they have ammunition in them.

The few that I have that do allow light bullet contact with the barrel...I polish in order to reduce the friction to a minimum.

Using magazines with tapered feed lips...such as the old GI mags, and the more recent Colt design that I refer to as "Hybrids" generally eliminates the "ka-chunk" rough feed that some have. Not always, but often enough to make it a viable alternative to throwing another couple hundred bucks at a gun just to set it right.

So...Yes. I do things a little differently than most. I've had good results, and probably won't change. For the ones that are so far out that I can't get reliability without essentially remanufacturing the frame...I refer'em to Chuck or George.
 
Tuner,
This is the last time I will ask, but please show us how you have measured the barrel ramp angle using a 'diemaker's square'.
I've gone over and over this, with no joy to be found.
I will understand if it is a proprietary technique that you do not wish to share. But shy of that, I'm doubting your credibility.
No, I'm not starting a fight, but Bob and myself have been struggling with this measurement for a while. If there is an easy and fairly straightforward means, please give us a clue.
Chuck
Let me add, how does scraping in the transitional radius using a pocket knife, improve upon using specific abrasive products in acheiving flawless function?
:confused:
 
My square is a little different design than yours, Chuck. It's an old, OLD Brown and Sharpe...probably made in the late 40s...that I can use to abut with the bottom of the barrel and adjust to follow the angle of the ramp. You may be able to find a picture if you Google Brown and Sharpe. Try using "Master Diemaker's Square." Not being too concerned with what the angle is precisely, and only need to know that it falls "between the lines" it's not critical that I know precisely what it is anyway. If the ramp is between 20 and 25 degrees...I know that I can work around the other stuff without getting into head support trouble.

The kid has fried the camera, or I'd take a picture of it. Soon as Kelie sits for the state boards and starts work down over at the ER, we can go get another camera. It basically just allows more adjustment with both scales.
 
Anyway....back to Bubbalicious, and thanks for the picture.

Rounding the feed ramp's corner like the one shown essentially changes the angle. Some pistols will tolerate it better than others...depending on how close the ramp's original angle is...and how heavy the fine, new radius is. In some pistols, with the original angle at or below 31 degrees...it only takes a little. For those at 31.5 or a bit steeper...it takes more Bubba to turn a reliable pistol into a clunk that won't even feed hardball consistently.

Ask me how I know...

The puzzling thing is that many of these killer-diller ramp and throat jobs are performed on pistols that aren't even presenting a problem. They're done because our boy Dan reads about it somewhere, and jumps in deep without understanding what the angles are supposed to be...why the correct geometry is so important...and very often without understanding that the barrel ramp to frame ramp 32nd inch gap is supposed to be there.

Why does Dan do this? Because it's all so cool to have a polished ramp and throat, and it's even cooler that he can show his friends how good he is at doin' ramp and throat jobs. "Nuttin' to it!" :rolleyes:

Excedrin, anyone?
 
Tuner,
Feel free to use those pics wherever and however you like.
Just don't allow anyone to think I was responsible for the 'work'. :D
 
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