Baer Barrel Fit

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[size=48]Here is a picture of a typical Baer (top photo) barrel bottom lug fit. The barrel has approximately 0.010" of bearing surface for lockup. This means the barrel will drop out of battery after slide has traveled 0.010". Translates to higher slide velocity and more felt recoil. The headspace was good on this barrel and sides of hood were sloppy loose. Also the upper barrel lugs were unfit! So QC was on low end of totem pole as usual. The barrel I am fitting has 0.075" of bearing surface for lockup which means slower slide velocity because barrel stays in battery about 7x longer; yes it makes a difference. Proper upper lug fit and hood fit. Baer barrel easily rotates when placed into slide. My barrel will NOT rotate. Hood and upper lug fit prevent it. I've only seen one Baer 45 that the bsrrel was fit correctly in over 20 years. Just because it feels tight in battery doesn't make it right. Just thought I'd share.[/size]
[size=48]Jon[/size]

Nope, probably chamber smoothness, pressure etc. maintaining case/chamber adhesion.

Jon Eulette wrote:It's delayed blowback.......that's why it's not a fixed barrel :p)
Jon

Well, the U S Army Ordnance department manuals and references, almost all of the engineers in gun manufacturers, experts like Jerry Kuhnhausen etc. say it's a short recoil system.  

But I'll defer to you guys, after all you're the gun techs...

Me?  I was a mechanical systems design engineer in the aerospace industry for over 30 years and I did a lot of kinematic design...so what do I know?

Titles and nomenclature are just words. Descriptions are based on personal experience. I didn't know what a VIS was until maybe 6 months on a 1911 but have been building 1.5" 50 yard 45's since 89. So it really doesn't matter. Does the gun shoot excellent or not is what's important. I'll take real world experience over academia any day. Winning is winning right?
Jon

I don't know why that happened, I've seen cases trapped while the next round was entering the chamber. I've also removed the extractor to demonstrate  that it will eject cases without an extractor. I would think that there should have been enough pressure in the barrel to at least push the case out enough to get trapped by the slide as it attempts to chamber the next round. Only thing I can think of is that the next round in the magazine stopped the case from coming completely out then pushed it back in.
 I have a friend that quotes Kuhnhausen like a preacher quote the bible, I have read Kuhnhausen and found that he will say something in one section then say another a few chapters later. I know a few good smiths that don't think very highly of Kuhnhausen. I am one of those though I'm not a gun smith. I just build a few for myself and friends. However they are all Masters or High Masters. I do agree with Jon, how or what happens means very little to a shooter, it's the accuracy and reliability that matters. Anything more is like telling a Bumblebee it can't fly. It don't care as it fly's away doing what it wants.  Plus how many guns did Kuhnhausen build? Does anyone have a Kuhnhausen 45? Simply put he is just an author, gathered information and wrote quite a few books. 
 Given your back ground Wobbly maybe you can calculate the pressure in the barrel at the time of unlock, it would be interesting to see the pressure curve plotted against time. I quite honestly would be very interested in seeing that.

Froneck wrote:......., it would be interesting to see the pressure curve plotted against time. I quite honestly would be very interested in seeing that.

Some where in all my saved stuff are some tests done with a Pressure Trace II.  The pistol ammo was tested with a Thompson Contender so the the curves were higher and longer than they would be for the same load in a 1911.  It was interesting to see the different curve shapes with the different powders.  I do remember the same 230 gr load that ran 850 FPS in the 1911 was almost 200 FPS faster out of the Thompson. 

While I was typing this I went out to their website and they didn't have any pistol ammo examples, but they had some secondary burn examples which was brought up in another thread.
https://www.shootingsoftware.com/pressure.htm
- Dave

I honestly believe Kuhnhausen may not be the great pistolsmith, but , we the masses are much more knowledgeable about our firearms thanks to his detailed publishings.

Thanks drowning, I will go to that site listed but if you do come across that other info please post it.
 Granted Kuhnhausen did make a lot of good information about firearms. However that does not mean he knew anything, he simply gathered what information was available and published it. If you wanted to have a very accurate, reliable pistol built who would you consider, a man that wrote books on how to do it but never did or someone that never wrote a book but made many pistols considered by the top contenders in bullseye to be the very best? To stretch  that thought what about if you elected to have brain surgery, the guy that wrote the book or the surgeon that did it successfully many times?
 My back ground and education was in engineering I decided to operate a machine shop though all my work history was always in engineering and never worked in a machine shop. Lucky for me my father was considered one of the best machinist in the area. Often I read books on the subject and found them not helping me and turned to my father. He in no time was able to solve my reason for looking for help. Now after running a shop after 20 years I see articles and videos that are completely wrong or misleading! The problem with those that talk to experts decipher what was said then write it in there own words without being able to actually do what they are writing is knowing what they are writing is correct or not.  A former coach of the AMU had just about the entire team wanting out of Bullseye. According to most of them the safest place to be on range when the coach was attempting to shoot was standing in front of the target! Yet he's working on his Doctoral Dissertation on target shooting! One day at Perry I was talking to the guy that was the coach of Team Springfield and was told about a time when he heard Adam tell the coach "We know how to shoot" and the coach replied oh yeah how many books on the subject did you read? Too often these writing become a standard, granted it might have been what was understood to be, For example most think that electricity flows from + (positive or plus) to - (negative or minus) but it don't, flows - to +

Here ya go

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Don't forget those are for the ball round. Since we shoot charges at about 9000 psi just cut the pressures in half.  

The cover is my source.  The ngineering design guide published by the Army in 1970.

Wobbley wrote:Don't forget those are for the ball round. Since we shoot charges at about 9000 psi just cut the pressures in half.  

The cover is my source.  The ngineering design guide published by the Army in 1970.

It's also for a machine gun which could be 100% blow back, I'm pretty certain the pressure curve would be different for a 1911.  Barrel length may also come into play on velocity #'s

Also what impact does the powder burn rate have on the curve, I'd assume for the same pressure the width of the bell would change.
- Dave

These curves are usually developed in pressure test barrels.  Note that the travel ends just above 4 inches which is the bullet travel to exit in a 1911.  

So, how would a blowback system change this?  Please explain it to me.  Don't forget that the USArmy had the 1911 and the M3 and both systems had to use the same ammo.  And no that doesnt make the 1911 a delayed blowback system either.

In the identified reference, the case travel during firing was calculated to be a whopping 0.053 inches. That was with a 3 pound bolt behind it.       So that can't be much change?..

If you had a 1 lb bolt verses a 3 lb bolt there would be a difference, how much would only be proven through testing.  Any different movement would give different results, it's just a matter of how much.  Agreed both the M3 & 1911 had to function with the same spec round, which probably explains why military 230 gr ball ammo is so harsh.

I remember we got very different velocities from the same round fired through the Thompson Contender with a locked breach, the TC had a 6" barrel.
- Dave

Take a regular standard pistol like a government model and push the slide until it releases the barrel.  On my standard ( out-of-the-box) Series 70 Gold Cup  this is the travel required to release the barrel.  The travel to start the barrel swinging down is about half that. 

Wobbley wrote:  And no that doesnt make the 1911 a delayed blowback system either.

Delayed blowback, does describe part of what happens. It's a short recoil operated pistol, that starts with a locked breach and ends with slide blowback.  Duration and timing of the lock have big impact on accuracy.

The barrel is locked to the slide via the locking lugs, the round is fired and BOTH the slide and barrel moves very slightly backwards until the link "pulls/swings down" the barrel from the slide locking lugs.  Then the slide continues rearward on it's own, a delayed separation (unlocking) of the slide/breach from the barrel and you could say that slide/breach blowback happens at this point.

If there was no blowback the slide would not move any further after unlocking from the barrel
- Dave

Wobbley wrote:Take a regular standard pistol like a government model and push the slide until it releases the barrel.  On my standard ( out-of-the-box) Series 70 Gold Cup  this is the travel required to release the barrel.  The travel to start the barrel swinging down is about half that. 

If that is a stock Gold Cup I guarantee that there is vertical barrel play when 100% in battery. Only gets worse as slide moves to the rear when cycling. I've never saw a stock Gold Cup shoot better than 3" from a machine rest.
Jon

This is more than 0.053.   In the 0.053 was for a blowback operated machine gun it had NOTHING to do with how the 1911 operates.  It was a reply to dronning.

The Browning short recoil system Is complex to mathematically analyze in that the hammer acts as a retarder.  In order to fully cock the hammer the slide travels about 6 times the distance shown above to unlock the barrel.  This is why a smaller radius on the firing pin stop works so well in reducing the slide velocity shooting hardball.  The energy absorption of the recoil spring is minimal; about 6 inch pounds.  All it really does is close the slide and keep it closed.

It was only used as an example of normal geometry.     

How much slide travel to unlock on your pistol when it is assembled?  Pics please...

I'll measure several pistols. I will measure when barrel drops 0.001" from slide. Then I will measure slide travel. 
Not sure how quickly I will do it but in near future.
Jon

I don't know anything about a 1911 but very interest in know how they operate.  I assume the barrel drops down to help pick up a round. If this is true is it the only reason? Also to me it would seem that the longer it stays locked up the more accurate it would be.  Like a bolt action.  Am I understanding this right?

285wannab wrote:I don't know anything about a 1911 but very interest in know how they operate.  I assume the barrel drops down to help pick up a round. If this is true is it the only reason? Also to me it would seem that the longer it stays locked up the more accurate it would be.  Like a bolt action.  Am I understanding this right?

Mainly it drops down to come out of lockup with the slide, which allows the slide to go back, cocking the hammer and picking up the next round. Maybe that was what you meant, but just trying to be clear.

What would be really interesting is accurate felt recoil tests of 2 pistols shooting the same loads and both weighing the same. That coupled with ransom rest testing. All the back and forth would be settled quickly.

w4ti wrote:

zanemoseley wrote:What would be really interesting is accurate felt recoil tests of 2 pistols shooting the same loads and both weighing the same. That coupled with ransom rest testing. All the back and forth would be settled quickly.

Actually, I'm not sure that is so, and here is why:

http://maaw.info/DemingsRedbeads.htm

#3 is especially relevant:

"Knowledge of one source of system variation, such as the proportion of defects (red beads) in the incoming supply, cannot be used to determine the total effect of system variation, such as the proportion of defects in the output. This is because unobservable factors will always affect performance and there is no basis for assuming that the effects of these factors will be equally distributed across workers."

I can promise you that if you took an old Clark, Shockey and Giles and shot same exact load through them and then shot one of my pistols you'd either sell the others or make them safe queens! They would beat you to death. There is a huge difference between a modern built 1911 and an old school 1911. Put the same springs in all of them and it would be really interesting
I run 10# recoil spring in my builds. You put a 10# in those old guns and it would rattle your teeth. I prove this to shooters all the time. I'm not trying to be arrogant, I've proven it and have had many many shooters share the same results with me. I'm not a typical pistolsmith; how many can say they broke 2650? Not many. Building guns and shooting guns are normally two different things. I can do both.
Jon

Jon,

I for one am very thankful every time you and the other outstanding gunsmiths share your insights. Thank you.

paul