1911 School: Feeding

J

John Travis

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In order to effect a better understanding of the dimensions and conditions critical to reliable feeding in the 1911 pistol, I thought this might be a good idea. I'll break it into parts to avoid a long, boring post. For the sake of continuity, I ask that comments be held until I reach the end.

The first critical spec is feed and barrel ramp angles. The feed ramp is ideally 31-31.5 degrees and no less than .300 inch deep in the frame measured from the rails, though many old GI pistols did fine with .280 inch. Many custom builders go much deeper, but I've never found it necessary with magazines that don't promote nose-diving. The top corner of the ramp should be sharp and clean and well defined. This is where many people get in trouble with polishing. If the top corner is "rolled" or rounded even slightly, it causes problems about as often as not by sending the bullet nose straight into the barrel ramp.

The barrel ramp isn't a guide. It's a clearance, In a correctly functioning pistol, the bullet nose shouldn't touch the barrel ramp below the top corner as the cartridge glides across it and breaks over, or...at most...lightly brush it as it climbs toward the chamber. This is critical in positively holding the barrel down on the frame bed.

The barrel ramp should be 31-32 degrees with a light rounding at the top corner permitted. The bottom of the barrel ramp must not sit flush with the top corner of the frame ramp. It should properly sit .032-.035 inch forward. A little more is okay, but no less than .032 inch. If this condition is present, no polishing beyond seeing that the ramp is smooth and free of burrs is necessary.

All this is aimed at holding the barrel in place until the cartridge is nearly horizontal and well into the chamber with the rim under the extractor. The barrel should not move until it makes contact with the slide breechface. If the barrel moves forward and up too early for the lugs to engage with the slide's lugs smoothly and without interference, an intermittent feedway stoppage is virtually guaranteed.

Next: Slide Specs
 
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The 1911 was designed around the controlled feed principle. That is, the cartridge must remain captive from the magazine to the chamber. One problem with many modern parallel-lipped magazines with the familiar timed release point is that they release the round too early and too abruptly. If the gun loses full control of the cartridge at any point...even for a very short instant...the opportunity for a stoppage is present.

Since the slide moves at fairly high speed, its dimensions are absolutely critical in maintaining full control. One dimension that so many fail to consider or even know about is the angle of the breechface itself. Assumed to be dead on at 90 degrees, it isn't. Print specs call for 89 degrees, 8 minutes with no toerance given. ANyone who understands machining knows that the smaller the tolerance, the more critical the dimension, and this is the only dimension I've ever seen on a blueprint that provides no tolerance. This tells the machinist that it must be adhered to within tenths of thousandths of an inch and hundredths of a degree.

This very slight departure from what appears to be 90 degrees is to maintain contact between case rim and breechface when the cartridge reaches the final release point....when it fairly "jumps" the last bit to get fully under the extractor's control. It was actually one of Browning's redundancies to keep the round from getting loose should the magazine release it a little too early due to feed lip damage or dimensional variation.

The two small, rectangular guide blocks on the underside of the breechface...the extractor passes through one of them...are correctly between .482 and .486 inch apart with .484 being ideal, and the distance that I always worked for when the distance was narrower. I can work with .486, but any wider than that made fitting and adjusting the extractors more problematical. Not impossible, but less forgiving. More on the extractor later.
 
The extractor's role in feeding is often misunderstood and underestimated. Most important is the deflection. That is, the amount of the wall behind the claw that protrudes beyond the guide block into the breech area...and this is where I've found problems in pistols produced in the last 20 years or so. Specifically, there's been too much. Sometimes, far too much.

There should be between .008 and .012 inch of that wall showing beyond the block, with .015 inch as an absolute maximum and even that much makes it necessary to reduce tension more than I like to see in a working pistol. See to those dimensions, and the gun will feed so smoothly that you can barely tell that it fed at all.

The nose of the extractor must not contact the forward angle of the case extractor groove, and the tip of the claw must not make contact with the bottom oo the groove. This calls for a claw depth of between .032 and .036 inch with .032 being the bare minimum and .038 inch as an absolute maximum. The bottom corner of the claw should be lightly radiused and the bottom corner of the wall should be lightly broken at a 45 degree angle. If deflection is correct, there's no need to use a heavy bevel on the bottom corner of the wall, and that can be a serious detriment to clean ejection if taken just a little too far. Much better to see to proper deflection and do minimum work on the wall.
 
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The next critical dimension is the cartridge OAL itself. Too short or too long and you'll have problems. The issues that so many people ascribed to the 1911's failure to feed hollowpoints came from the old Speer 200 grain JHP "Flying ashtray" in the 80s...but it wasn't the size of the cavity that caused the problems after the barrel ramps were opened up. It was the length of the round that did it. It was too short.

Cartridge OAL should be 1.220-1.240 for hollow points and 1.250-1.260 for bardball, though many hardball rounds exceeded that by as much as .015 inch. Nominal spec for .38 Super ball is 1.280, so it'll work if it's a little longer than the 1.260 inch ideal. I've also seen the 2nd design Hornady XTP 200-grain hollowpoints work well when loaded to 1.210 inch in pistols with proper feed and barrel ramp dimensions, but I've noticed that Hornady loads them to about 1.230 in their commercial ammunition. So, you handloaders who have a little trouble with your hollowpoints, try adding another .010 inch to the OAL. You may see the problem disappear.

Next: The mysterious magazine.
 
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Now we've come to the magazine. So few truly understand John Browning's magazine and how it correctly offers the round to the chamber...and how many of the present magazines don't.

It's said that the magazine is responsible for fully 90% of all feed related malfunctions. but that's an overstatement. I'd estimate it at about half, though the magazine is usually the first suspect without a close examination of the gun.

A proper magazine works within the controlled feed boundaries, and doesn't effect the final release of the cartridge until it's actually under the extractor...or at least as close as it can get so as to minimize the time and distance that the cartridge isn't under the control of both at the instant of release. In other words, the magazine and the extractor's influence should overlap, with the magazine not relinquishing the round until the extractor has it. Anything else leaves the round with the opportunity to escape.

Modern magazines with parallel feed lips and an early, abrupt release point...called "timed" release...offer too much opportunity for escape, and many do just that. Instead of being controlled all the way into the chamber, they get knocked ahead of the slide, causing the extractor claw to snap over the rim...and if the angle on the extractor isn't exactly to sopec...it can bring it all to a screeching halt.

For those that do successfully effect the push feed/snapover, the reward is an extractor that loses tension frequently and can and usually does cause the claw to break. If the magazine does its job properly...and the extractor deflection is as it should be...the extractor should be able to go 50,000 rounds and beyond before needing attention beyond periodic cleaning.

A proper magazine provides a slow, late release that places the rim of the case under or very nearly under the extractor claw at the moment of final release. It does this by allowing the rear of the cartridge to rise as it moves forward...and it does that by way of tapered feed lips that gradually spread from rear to front. This can be seen in the old GI "Hardball" magazines, and with the "Hybrid" magazines that Colt designed in the early 80s that combine the gradual taper with the timed, abrupt release point with comes a little later than most of the new offerings.

Along with the proper magazine design comes the little pip on top of the follower that is eliminated with so many newer designs. Here is a perfect example of the belief that they've outsmarted Mose. That little bump has an important job, and it's an example of a Browning redundancy. It keeps the last round in the magazine during the recoil cycle when the magazine spring tension is at a minimum and the slide smacks the frame, trying to jerk the pistol out from under the cartridge. If anyone has ever had the slide lock with a live round lying loose in the port...Here's yer sign. Likewise, if you've ever found live rounds among the empty brass on the ground. Look to your magazine for the answer to that mystery. Or, if you've noticed small, "D" shaped dings on the rear of your rims, with a small burr on the edge...the gun is push feeding, and usually on the last round. A weak spring can make it happen more often, maybe on the last two rounds.

Other things that can allow the round to escape are the bump being too small or in the wrong place, and the tension of the spring itself.

As it relates to hollowpoint malfunction...most hollowpoint ammunition is of the +P variety. +P means the recoil is more lively. The harder the frame hits the slide, the more likely it is to cause the last round to escape the magazine. Sometimes it only takes a little. And there you have another shooter blaming hollowpoint ammunition for a feed failure that is actually the fault of a poor magazine design.

And an oversprung slide makes it even more likely. Original spec was about 14 pounds at full compression, and 13.5 at full slide travel...not the 16 that so many experts insist on.

Finally, a proper .45 magazine is 7 round capacity with the original stamped follower...with the speed bump and 13 spring coils. With that follower, when it's at the last round, there are three spring coils against the rear leg of the follower. One in the top corner...one in the middle...and one near the bottom. The follower can't nose dive and it provides support to the cartridge as it enters the chamber.

Something to ponder on. No, really. Ponder it.

The 1911 pistol was designed by a genius, and it was ultimately going to end up on the killing fields in faraway places, where one extra round could easily be the difference between life and death for some poor widow's son. Does anyone really believe that the fact that the magazine would physically accommodate 8 rounds with a little modification to the spring and follower somehow escaped his notice? Or has anyone considered that if he could have made it work with bet your life reliability with 8 rounds...he would have?

The farther we stray from Browning's specifications, the more likely we are to have trouble.

Discuss.
 
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John, thanks for posting the above.
 
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Thanks for taking the time, John Travis! Well done, as always!

BTW, that Colt Sistema you helped me with... yeah, the one we beat on with a hammer, that one... my daughter wants it! I've let her borrow a Springfield GI Champion, but she says she doesn't shoot it well. She's shot the Sistema many times, so she wants to give me back the Champion, and shoot the Sistema.
 
Thanks for another great lesson! Too long between them lately.
 
John, thanks as always!
I am glad you decided to share your wisdom again.
I've been present too many times when 1911 "experts" chose to argue with you.
You've always been a gentleman and proved them wrong.
I can't thank you enough for all the info you have shared over the years.
If you ever decide to stop sharing, there will be a lot of shooters who will miss your wisdom.
The few that feel they know better than you can just move on to a site where they can play know-it-all.
You are treasured here.
 
@John Travis a couple questions if you’ll indulge me.

In the original design, and for many years thereafter, the frame ramp was on the frame and the barrel ramp was on the barrel. Today it seems common to have the frame ramp eliminated and space cut for a barrel that incorporates what used to be the frame ramp. I expect that the parts are more expensive to manufacture, but easier to fit and maintain. What are your thoughts on ramped barrels generally?

Second question is about a repair. Bought a commander sized 1911 of the pre-80 persuasion, it had formerly been owned by a guy whose name must have been Dan. Well Dan worked the frame ramp until it was super shiny but wouldn’t feed, then he worked the barrel ramp until he could over spring it to make the problems mostly go away, at least the feeding problems. Replacing the springs and adjusting the extractor tension a hair has alleviated most feeding problems, but unfortunately the sanding/polishing process shortened the chamber a bit more than anyone would like. I believe that my options are to have a frame ramp welded in and a new barrel fit, or to machine out the old frame ramp and fit a new ramped barrel. Do you have thoughts on either approach?

Good to see you posting again.
 
Good grief, JimB! That's one thing I learned from Johnny... how to tell if the feed ramps had been polished or <cringe!> dremeled, and then to Run Away!
 
JimB said:
a couple questions if you’ll indulge me.
Click to expand...

Ramped barrels are unnecessary in the .45 caliber pistols and I don't care for them for a couple reasons. They became all the rage when the gamers started blowing up pistols with grossly overloaded .38 Super ammunition and they soon spilled over into other calibers because people became convinced that the standard divorced barrel setup didn't offer enough case head support.

For a repair to your Dan victim, either will work, but I prefer the ramp insert over the ramped barrel because if the ramp angle isn't exactly right, it brings on other problems.
 
MacEntyre said:
Good grief, JimB! That's one thing I learned from Johnny... how to tell if the feed ramps had been polished or <cringe!> dremeled, and then to Run Away!
Click to expand...

I didn’t have an opportunity to meet him until after I acquired this beautiful piece of work. I actually didn’t even know about the perils of ramp polishing at the time. I surely should have noticed the marks from the Drexel-driven grinding stone where it got away from Dan and marred the top of the mag well, but it was dark and I was in a hurry, lesson learned. BTW, purchased from a member of whatever the forum was three generations ago, I forgotten what was before CSC.

The gun is heavy, the matte nickel finish has seen a lot of use, it has the problems described, and the grip safety bites into the chubby part of my hand, but it points very well for me so I gotta fix it.
 
Years ago about 5 of us made the trek to John's for a Saturday 1911 party. After drinking John's coffee I don't think I slept for a couple days but that is another story for another time. I have forgotten so much of what was talked about so I am excited to see this info being posted. I am a very visual learner so seeing John disassemble his Norinco and point to all the area's he was speaking about was really awesome and cost me gas and a box of dog biscuits. For these posting my only suggestion would be, add pictures for people like me who are visual learners.
 
Thanks for posting again. Excellent presentation & explanation w/o illustration: so smooth even a know-nothing like me learned a few things!
 
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