1911 Reliability Tricks: Shooter45 : Feed Ramp

Discussion in 'The 1911 Forum' started by LDBennett, Feb 10, 2009.

  1. LDBennett

    LDBennett Well-Known Member

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    Shooter45:

    I just read parts of the sticky on reliability tricks for the 1911. Not too long ago there was a discussion here on the jump from the frame ramp to the barrel ramp. The poster (I don't remeber who) claimed that the transistion should be smooth with no jump. When I pointed out that the Jerry Kuhnhausen book on the 1911 , and the AGI Instructor (well know once head instructor for the college gunsmithing program at the well known Northern California gunsmithing school ... sorry but I forgot the name of the school) said the jump MUST be there, the poster insisted that he learned to eliminate it from a famous (to him??) gunsmith. I think you got it right: the jump MUST be there. Maybe that poster will read this and mend his ways (???).

    "Now place the barrel into its slot in the frame and push it back and down until the link support legs contact the back of the slot in the frame. The barrel should rest on the curved support surfaces of the frame. Note the gap between the bottom edge of the feed ramp in the barrel and the forward edge of the feed ramp in the frame. This gap should be at least 1/32nd of an inch, and could be as much as 1/16th of an inch. If there is a smaller gap than this, (or no gap at all), the chambering cartridge can and probably will hang up on the lower lip of the barrel’s ramp. That gap is absolutely crucial to smooth chambering. If the gap is not at least 1/32nd of an inch, the solution is to file the bottom of the barrel feed ramp back until that gap is achieved. Then the ramp is re-shaped carefully with files or a Dremel grinder so that the barrel feed ramp is once again close to the bottom of the barrel. Be careful – do not extend the ramp much, if at all, deeper into the chamber, and keep the same upward angle as before. In the 1911 design, the ramped barrel leaves a portion of the case unsupported, and if the ramp is too deep, it increases the possibility of a case blowout. This could have serious consequences for the pistol and for you!"

    LDBennett
  2. delta13soultaker

    delta13soultaker New Member

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  3. LDBennett

    LDBennett Well-Known Member

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    delta13soultaker:

    No, I don't think so. It was more than a year ago. We had a battle of the wits about which was the correct way (jump or no jump) and the responder only cited his "expert" gun tuner when I cited two authorities, one with a famous book on Colt 45ACP pistol maintennace and the other an instructor of gun design and gunsmithing. It was obvious that no amount of evidence would persuade him his "expert" was wrong.

    According to good gun design practices it is a ratio between the gap between the barrel and the frame to the horizontal jump that has to result in a minimal jump (more jump is OK). Gaps as small as 0.001 inches still results in the need for a jump according to the practice.

    MTNBOOMER response seems to indicate he removed the jump but his response I think to be ambiguous (??). That would be a lot of polishing with a ceramic rod !!! He may not have meant that he removed the jump. If he indeed did he may see feeding problems later or with some ammo.

    LDBennett
    Last edited: Feb 10, 2009
  4. delta13soultaker

    delta13soultaker New Member

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    Okay, I understand.

    When I read your post, I immediately remembered the ceramic rod/polish thing MTNBOOMER posted, and remembered you writing previously on the thread also.

    I highly agree with you about the ceramic rod, based on my experience using them for sharpening fillet/skinning knives ($1 hardware store rods)....it would take a hell of a long sitting at the bench to polish the jump out of a 1911 with one, at least the rods I'm familiar with. I admit it did raise my curiosity, but since I've no intention of doing such a thing, I decided not to inquire.
  5. scroc

    scroc New Member

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    LD, I agree with you, the "jump" is mandatory for reliable feed especially with lead action loads. Possible the fella you were referring to is Bob Dunlap, instructor & now retired from the Susanville Community College?
  6. Pat-inCO

    Pat-inCO New Member

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  7. LDBennett

    LDBennett Well-Known Member

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    scroc:

    While Bob Dunlap is retired from Susanville Community College (many years ago now) he has a shop in the Northwest (outside Calilfornia) and has made up Video courses for AGI (American Gunsmithing Institute). While Bob is not their only instructor, he is the one for the Master Gunsmithing course done on tape more than ten years ago and converted to DVD in the last five years. His employee, Ken Brooks appears in some of the more recent AGI videos and is heir apparent to Bob's gunsmithing business and apparently plans to continue with the teaching tasks on AGI videos. Ken is an excellent instructor having been one of Bob students in Susanville and has worked along side Bob in his gunsmithing business for sometime.

    AGI offers a monthly DVD magazine in which Bob and Ken appear regularly. AGI is owned and run by another former Bob Dunlap student. These AGI people are good people! I only wish I could afford the Master Course (well into the multiple thousand dollar range price wise now). I have a thurst for the detailed knowledge but no outlet if I got it since I am happily retired and 67 years old (too old for another career, if I even wanted to work again!).

    LDBennett
  8. johnlives4christ

    johnlives4christ Former Guest

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    i once acquired a compact springfield armory 1911 from a friend and discovered that it had previously had someone try to polish the frame feed ramp to much and thus had a barrel overhang instead of a gap. the surprising thing was that the gun never malfuntioned for my friend that had it before me nor me. after i discovered this i promptly re-shaped the frame feedramp as it was not an arc but cone shaped. and then cut the barrel feed ramp back very slightly, polishing with a dremel tool and some ultra fine polishing compound. i am not the authority on 1911's but i do know some of the basics and studied informaly in hopes of one day becoming a gunsmith and because i had somewhat of a sound idea of what i was doing i attemped and was successful in fixing the pistol. i thought about swapping it back to my friend of off to someone else but couldnt in good conscience do so thinking that it might be used for self defense. i figured if i screwed up i wouldnt be out anything because what i had to start with wasn't going to leave my posession until deemed safe and reliable. i did swap the gun back to my friend after that and unless he has receintly traded, he still has it and it never gives him any trouble.

    ~john
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