This is a discussion on Sig P220-10 Bar-Sto Match target barrel fit PART 3 within the Gun Projects forums, part of the Gun Forum category; The ending sentence from Part 2 with photos promised "You will notice in some of these last photos how the two barrel seating "eyebrows" are ...
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|07-09-2016, 10:51 AM||#1|
Join Date: Aug 2014
Location: North Georgia
Sig P220-10 Bar-Sto Match target barrel fit PART 3
The ending sentence from Part 2 with photos promised
"You will notice in some of these last photos how the two barrel seating "eyebrows" are showing on the barrel. one at 6 o'clock front of barrel and one at 12 o'clock 1/2" in from the muzzle. I have slightly "softened" just these two areas with a fine stone/oil - nothing at 3 & 9. This is where I want the extra .0025 to stay.
These next two photos may make this more clear."
as you are fitting the breech distance, take note of this area in red. this side barrel "face" make contact with the slide hood front and need a couple of file strokes on the barrel side face to relieve it. you can be paying attention to all else and this can sneak up on you.
As I have relieved the two mentioned areas and the hood breech end has been stoned to a tap in fit this completes the hood/breech, muzzle fit.
When I received this barrel it would not flat drop on the frame lock block. what I mean by that is the distance between the cam tip and the back "angle" (which comes to you rounded and uncut) would not just drop down on the block. Here's a barrel as received pic again. Note the rounded area. This is left for you to fit.
This next series of photos shows the sequence of fitting areas. This afore mentioned angle is the first addressed. It is shown first in natural & then in red.
This angle cut allows the barrel to flat drop from battery (after the cam hits the block) down to flat sit on the frame block.
This next blue area had to be hand filed down to allow the top of the barrel hood to clear the upper inside of the slide as it came back into counter battery.
The next and final area is the flat that is most important. This Green area sitting on the frame block is what high locks the barrel into the slide. It's a bit tough for me to tell this in black & white words on a screen as to "how much" to remove. i figured a safe way was take a #3 Grobet file and work on the front 1/8th inch of the flat, just a stroke or two at the time, reassembling the barrel in the slide and trying it on the already slide-to-frame fit unit - pretty much over and over. When it just stared to pre-lock. I worked the rest of the flat to that depth - and a stroke or two at a time from there on into dead-lock. If you can't file straight, practice.. There's none of this comes to you. Some are better than others but all had to work at it - if they were truly interested.
First photo is my slide just hand lowered to stop. Second is my thumb just touching the side back. Third is a slight thumb push and barrel goes into high-lock with slide going into battery.
It has the pretty wood grips put up & stored and is in Raptor garb but it's bank vault tight.
Note the slight relievement on the tops of the polished ramp sides. Made just a touch of an angled chamfer there. i also polished the very bottom of the breechface up to about where the case starts to slip under the extractor. And also the inside to of the barrel chamber about 1/2" in from about 2 to 10 o'clock - all with Dremel, hard felt 3/8" bob, and stainless steel compound. didn't over do it, just a light polish. These are the two areas where the case head and bullet nose hit pretty much at the same time. You are not removing any metal to speak of and it gives that bit of easement, especially needed with this factory 22lb spring, which requires a round to do some angular things pretty fast.
Again, if you want these photos, copy/paste them. I guess the text will always be here. I'm working on another way to post photos.
Well fellas, that's it.
In my years posting these I have always hoped in some way there might be a builder out there that I can trade some ways of doing things with and learn something from. Still looking.
BTW, this is just a real serious "interest" of mine. I do not have an FFL nor do I do outside work.
Last edited by was1911; 07-09-2016 at 11:03 AM.
|07-09-2016, 02:09 PM||#3|
Join Date: Aug 2012
Location: SC Lowcountry
Everything really looks very professional. You may be the first person on here besides me who said they measured the barrel diameter when fitting a barrel. Nice pictures too.
The one question that I have is this: What point on that Bar-Sto barrel is called the zero point? Not an easy question is it? Does the barrel come with the front of the hood in the correct or zero place? Or does the head space come from Bar-Sto already correct? (must not be the head space because you shortened that some) Did you remove any metal from the front of the hood? Where is the ZERO place front to back?
Another question which is separate is did you find it necessary to remove any metal from that large flat on top of the barrel right in front of the hood? That would allow the rear of the barrel to move up higher in the slide and tighten up the barrel in the barrel bushing area. This would only be necessary if the barrel arrived with a smaller diameter. The last Bar-Sto barrel I received had a diameter that was .0020" smaller than the stock barrrel that came with the pistol. They would not exchange their barrel for me.
Here is your missing picture:
|07-09-2016, 05:47 PM||#4|
Join Date: Aug 2014
Location: North Georgia
Shows up as 2nd photo on Part 1 on my screen.
I've never heard of a "zero point" - although you may have a lot more experience than me.
If you are referring to a "datum" point, that would only be pertinent during the barrel manufacture from a blank at Bar-Sto.
A datum point has no bearing on the fitting of the barrel.
Bar-Sto would have sent me one .002 smaller in diameter than the factory barrel if I had not inquired from jump street what the diameter of their barrel was as my first question. It's the reason mine was cut (requested) with a .5925 diameter. Over the years I have learned to ask.
Last edited by was1911; 07-20-2016 at 04:18 AM.
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