Author Topic: Pitted bore (Read 1208 times)

robin-hood-90 · « **on:** December 02, 2004, 05:55:32 AM »

Well here's how the story goes. I've always wanted a model 70 featherwt.. About a year ago I found one in 30-06 at a real bargain. The gun was in excellent shape, the bore looked OK, other than being very dirty( copper fouling, mostly ) I bought it , cleaned it, shot it a few times. It would group about 2-3 inches at 100yds. I just figured it did'nt like the loads I tried. ( I've never tried factory ammo ) I've got other rifles that I hunt with so the fwt just sat there being pretty in the safe.
Well I finally decided to get serious and work up a load for it. I took it out and cleaned it, and cleaned it and cleaned it some more. After about 2 hours with Sweets and Flitz I finally got the copper fouling out. Then I discovered some pitting about 2 inches ahead of the throat. Evidently it was hidden under all that copper.
My question is , can I expect acceptable hunting accuracy out a slightly pitted bore?

Patriot_1776 · « **Reply #1 on:** December 02, 2004, 07:30:54 AM »

Quote

My question is , can I expect acceptable hunting accuracy out a slightly pitted bore?

Acceptable, yes. Preferrable, not really. I mean 2-3" groups at 100yds is ok, but I would prefer around 1-1 1/2" just in case a longer than desired shot is the only order of the day. But, I'd say try and get the bore polished up a bit; with pitting like that, you'll waste more time (and $$$) cleaning the copper out of it thoroughly than you would like I'm sure. But I am led to believe that pitting can cause further degradation of accuracy after awhile. Reason being is the stress imparted in that area in general. It will not be so even as when the bullet contacts the smoother part of the bore. Think of it as having the bullet going nice and smooth, then run some coarse sandpaper over the bullet's body/shank. See what I'm talking about? The main problem to worry about is an erratic flight pattern. The pitting is basically a whole different factor to cause inaccuracy. I hope my advice sounds proper in the eyes of the "more experienced" shooters around these parts. :wink: (no offense guys.) If you shoot it again since you cleaned it out thoroughly, please post on how it groups, how much it took to clean it thoroughly again, etc; I am kind of curious.

Patriot

Moral of this story:

"Always buy a new gun whenever you can. Don't impart your trust on someone else's word about how they took care of it, how in good condition it's in, etc. Unless it's a gun from a really close friend, you don't know what it's been through, what was done to it, or how it was treated. Time will/could almost always tell otherwise."

Broken-arrow · « **Reply #2 on:** December 03, 2004, 09:18:16 AM »

Well after all the cleaning and polishing, the winchester shoots even
worse. Tried 3 different loads and all 3 grouped 4-5 inches. Thats
DEFINITELY not acceptable hunting accuracy. Before I even noticed
the pitted bore I thought it might be a bedding problem. It's got the
factory Win. hot-glue job, but it looks OK. I mean it's not cracking and
the action does'nt move when you loosen 1 screw. The prettiest rifle
I own and it's the worst shooter. Can't bring myself to sell it, believe
I'll rebarrel it and chalk one up for experience.

jgalar · « **Reply #3 on:** December 03, 2004, 05:31:20 PM »

You may want to try the electronic bore cleaner thing first....at least before rebarreling. http://members.rogers.com/snidey/borecleaner.html

Mikey · « **Reply #4 on:** December 04, 2004, 03:12:23 AM »

robin_hood_90: What do your groups look like - are they more of a pattern than a group? Is it a 'strung out' group, er what. Some factory bedding jobs don't work worth schmidt.

How did you go about polishing your bore - did you use a 'grit' medium and if so, what size grit?

Yes, a pitted bore will affect, or rather can affect your accuracy but I have seen pitted bores shoot incredible groups. I would try re-bedding the action first before I give up hope and I would rebed to no further down the barrel channel than the end of the chamber. Also, I would relieve the remainder of the barrel channel to assure that there is no part of the fore-end impacting the barrel.

One thing about the Featherweights is that they are nice to carry in the field - however, since they are a bit lighter in weight your barrel may heat up quickly and open up your group. How do your first two shots group and then do the rest open the group up or how do they print.

Lastly, before rebarrelling, if you feel that is what is required, I would try lapping the barrel ala Veral Smith or Beartooth Bullets. Often firelapping a barrel can minimize the negative efects of bore pitting and return to you a serviceable hunting rifle.

HTH and please let us know about the grouping. Thanks. Mikey.

Broken-arrow · « **Reply #5 on:** December 04, 2004, 11:41:19 AM »

Hey Mikey, Forgot I was logged on as Robin-hood 90 last post
( Thats my son ) There is no set pattern as to how this gun groups.
The first shot from a cold barrel varies from 2-3 inches, usually up and down, the second shot might go any direction, then I let it cool. The pitting is not that bad, and yes it's rust pitting, not fouling. I've
polished the bore, or I guess you'd say lapped it with 600grit, then
finished it with flitz. The pitting is still there, you have to look real hard to see it now, it's a spot about 2 inches long just ahead of the throat. I just
can't see something that minor ruin a rifle's accuracy. Think I'll take your advice and rebed before I rebarrel. Ordered a kit from Midway already.
I know from experience that a bad bedding job can and will totally
destroy the accuracy of a fine rifle.
.

fastvfr · « **Reply #6 on:** December 04, 2004, 01:41:09 PM »

Yeah, AcraGlas can sometimes make a big difference.

But, to be honest, it likely won't fix that eroded throat.

The best plan I can think of is to get started in reloading...it's only slightly more than $100 for a Lee single-stage press with the scale, ect. and dies for one caliber.

The powder, primers and slugs will set you back another $30 or so.

Then you can experiment with bullet seating depth, and you may find that a longer load, .01" or .015 from the lands, will give you excellent groups.

You can't be sure if this rifle ever shot well, though. Did you check the fired cases for runout? That'll tell you if the chamber is centered on the bore properly.

Then again, if you have no plans for ever reloading, you will be best served by having a good smith rebarrel it for you.

If you glass-bed your rifle now, the new barrel will likely not be of the proper profile to fit properly anymore, making for a lot of work augering out the barrel channel before glassing in the new barrel.

Good luck!

savageT · « **Reply #7 on:** December 04, 2004, 02:00:53 PM »

Broken arrow,
A quick and inexpensive fix could be as simple as having the crown re-cut on the muzzle. I wouldn't take for granted it's the pitted bore causing your accuracy problem A cheap recutting of the crown might just fix it!

Jim

savageT · « **Reply #8 on:** December 04, 2004, 02:05:40 PM »

...one last thought I came up with. Have the gunsmith slug the barrel to find out what the bore is. You should have a .308 bore, and if per chance this barrel is past its prime, you can justify looking for a new barrel aftter all.

Jim

Broken-arrow · « **Reply #9 on:** December 04, 2004, 02:28:20 PM »

Hey Fast, I do reload for 6 different calibers. And the throat is not eroded, the gun does'nt look like it has been shot a whole lot, it just looks like the bore was neglected. The rifling looks excellent all the way to the crown. I bought a .22 years ago that had a dirt daubers nest in the
barrel. After a thorough cleaning it had rust pitting in a spot about 2 inches long. The rest of the bore looked good. Thats exactly how this
one looks. BTW The .22 would'nt shoot for #^&* and I sold it.
I'm going to give it a good bedding job and see if that helps, I'm sure
it won't hurt.