First Muzzle Crown is done.

[frwillia]

I had a burr on the crown of my .22-250 which is what got me started tooling up to do barrel work. It looked like this:

I spent the fall and winter getting tooled up, reading, watching videos, and "interacting" here to learn what to do and how to do it.

I cut the crown yesterday after spending some time (like 3 hours of playing around and experimenting) aligning it in the headstock. I used a Grizzly rod and the Gritters method to align the bore near the muzzle. The breech had about .012" of run out on the other end when the bore at the muzzle was aligned. One of the things that took so long was I aligned the chamber end the same way just for fun. With the inch of bore after the throat aligned with the lathe spindle the muzzle was making a 0.056" orbit on the other end.

I cut the crown with a freshly ground and honed HSS-Co bit and pipe threading oil.

It looked like this just before I took it out of the headstock.

With the tooling I made this winter(cat head and spider chuck), this 12x36 Gearhead seems to be a nice lathe for barrel work. As you can see here, the 26" fits nicely and it will work just fine for considerably shorter barrels. The cuts are light for this kind of work so the lathe is plenty rigid, very easy to use, and doesn't take a lot of space.

I bolted my home made barrel vise to the mill table for re-assembling the receiver to the barrel. I only used about 40 ft-lbs of torque on the wrench so this was probably overkill, but the mill didn't move.

Fitch

 

[operator1]

Looks great. That spider chuck is pretty slick.

 

[cwood3]

Fitch,

You're giving me the blues.................I need to find me a rich sugar mama, take up to my 300 acres north of Crockett, TX and get to to outfit my shop building. I don't mind doing the cooking, I just need the funds as early retirement (49 yr old) will not keep my retirement portfolio happy at this juncture in my life.

Oh yea, she needs to have lots of insurance and maybe be kinda sick.........


(I like your set-up)

curtis

 

[f21sh]

Nice crown

Hello frwillia
Nice crown I have a Birmingham 13 X 40 I am currently setting up to begin the same process. I was interested in what type of micrometer stop (appears in your picture) do you have mounted on your lathe. I have been looking just have not found one yet. Oh and nice spider where did you purchase the backing plate .

Thanks

 

[frwillia]

Hello frwillia
Nice crown

Thanks

I have a Birmingham 13 X 40 I am currently setting up to begin the same process. I was interested in what type of micrometer stop (appears in your picture) do you have mounted on your lathe.

It's the micrometer carriage stop for my 9" South Bend. I got to looking at it one day it occurred to me that I could make a new clamp foot for it, get a slightly longer bolt, and have it fit my import lathe with no other changes. I still have the South Bend clamp foot so it's no trouble swap it back and forth between the two lathes.

Oh and nice spider where did you purchase the backing plate .

Thanks

I don't use the 4J very often and didn't want to buy a backing plate, so I took my 4J off it's backing plate and made the Spider chuck to fit in it's place. I can swap the 4J onto the backing plate in about 5 minutes if I need it (remove the 4 bolts holding the spider on, bolt the 4J on using the 4 bolts that fit it). I never need both the 4J and the spider chuck at the same time so it's working out just fine.

I had the piece of rusty rod end that I made the spider chuck body out of in my junk box so all I had to buy was bolts. I think that project cost all of ten or fifteen bux.

Fitch

 

[msalm]

frwillia,
That is a FINE lathe for gunsmithing work. I have one that looks almost identical to that only it has South Bend on it. It was their G26T toolroom lathe. Not a heavy lathe by any means, but it works extremely well none-the-less.

 

[frwillia]

More borescope time.

I took the rifle back over to to visit the local gunsmith yesterday evening to inspect the recut crown using the borescope. It looks good to the eye, but the real test other than how it shoots is to see it up close and personal with the borescope, and I did. There is good news and badnews.

The good news is that the crown as cut looks essentially perfect even through the borescope. Nice crisp edge with zero visible burr or rimming of the edge anyplace even at that magnification. I had cleaned the rifle and there wasn't any patch fuzz on it either. I might be able to do a better job but it wouldn't be visible to my eyes even using the borescope. This is the good news.

The bad news is that I focused too much on the crown burr last time when I was trying to see what the defect looked like, and didn't pay enough attention to the bore condition just inside the barrel.

Last night, because one of the guys on the Practical Machinist Gunsmithing forum said, that "it was amazing how much better some of his rifles shot after cutting a half inch off the barrel and recrowning them". Reading that, which happened after I cut the crown, I wondered why that might be. So last night I looked in my rifles bore to see if I might see something that might be significant and which could be eliminated by cutting a half to five eights of an inch off and recrowning. Sure enough, there are boogers in the bore back about half an inch, maybe a tiny bit less. The nearly pristine smooth and shiny condition of the bore farther in looks very good.

So the question is, was the bore always a bit boogered near the muzzle, or is that cleaning rash? I don't know for sure, but it sure doesn't look like anything that was done by a systematic process. It's not periodic down the bore like reamer chatter, or rifling broach chatter. It's a bit random axially and around the ID which looks to more like cleaning rod rash to me than factory defect. I'm not talking a lot of damage, but there is "some" damage and it is right before the bullet leaves the muzzle.

This leaves the open the possibility that I might be able to improve it even more, maybe even "enough", if I were to cut off a 1/2" or 5/8" of muzzle and recrown it. I may do that but I want to get good group data on it in it's present condition before doing anything more. The data acquisition could start today, but I won't get it all done today.

However it raises the choice, given the good group data is in hand, between bobbing the muzzle and recrowning and setting the chamber back. Which one to do first? I think the answer is bob the muzzle and recrown, but I'm not hard over on that.

Thinking out loud here, I only get so many chamber setbacks before I run out of room, like exactly one. If I take a half to five eighths of an inch off the barrel, it's no big deal, and I could do it again were more boogers to appear later on. I think if I set it back and it shoots good enough to compete with at the local club ground hog matchs (it doesn't quite ... yet), I should hold off on the chamber set back, regardless of how much fun that might be, to maximize useful barrel life.

Looking through that borescope last night I again had the thought "I GOTTA get me one of THESE!" If one is interested in things in the barrel, it's an indispensible tool.

Fitch

 

[Butch Lambert]

Barrel makers love bore scopes. Said they are really a sales tool for them.
Butch

 

[Bnhpr]

Get an olympus iplex, they are the best i've used.

 

[RoyB]

I believe it was Ed Shilien that said more barrels were ruined by cleaning and having the jag drop out of the muzzle than any other way.........

I've looked at dozens of barrels that exhibit exactly what you were seeing.......And cutting an inch off and recrowning almost always improved accuracy.........

BTW, that lathe looks just about perfect for gunsmith work. I have a 1985 Jet 12X36 that I refuse to give up because the headstock is so short. But yours even looks shorter.........

 

[cwop]

barrell

roy

are you saying that just like gunsmithing cleaning a barrell is something that needs some training to do. us ordinary weekend shooters can do a lot of damage to a rifle and not know it.

bob

 

[frwillia]

BTW, that lathe looks just about perfect for gunsmith work. I have a 1985 Jet 12X36 that I refuse to give up because the headstock is so short. But yours even looks shorter.........

It works really well for barrels through the headstock and about any other thing I've ever tried to do with it. Now that I've cross drilled the back end of the spindle it can handle barrels as short as 18.5".

I think it is essentially the same as the small Grizzly gunsmith lathe except the slowest speed on mine is about half the slowest speed on the Grizzly.

Fitch