Rifling through a bore scope

C

cw308

New member
I bought a Lyman Bore Scope but you have to know what your looking for . Is rifling at the start of the barrel as high as it is at the crown or is it at a taper ?

What does a washed out barrel look like . Fire cracking copper and carbon fouling isn't hard to see but I wish I could have seen my barrel when it was first installed . Now with 3000 through the tube to me it looks pretty good. I'm shooting a 308 30 rounds each week with a mild load , taking time between shots loading one at a time . I kind of baby the rifle , clean after every range trip . Would just like to know what a barrel should look like as asked above . Thanks.

Chris
 
All I have seen are the same from start (breech) to finish (muzzle).

The only thing different that I have seen is a progressive twist rifling.

There are enough eyeballs floating around that maybe someone here has seen such as what you ask about. Maybe one of our resident gunsmiths?
 
My rifling at the start isn't a straight cut height but angled , sides are sharp. It's hard to describe , when the round picture the bullet going into the free bore slamming into a wall of rifling or a sloped angle maybe to cut down pressure or is that what washed out rifling looks like. I don't know . When checking base to bullet ogive , it hasn't changed much . Would be easier if I had a few barrels to look at. Was looking on line trying to see what the rifling looks like at the start of the rifling.
 
Not sure what you are describing. After the freebore the chamber reamer has a shallow conical angle that cuts the leade of the rifling to have a taper. That tends to widen and lengthen with wear. Whether or not the height of the lands is narrower at the muzzle than at the breech is a barre-to-barrel thing. You can put a slight taper on by firelapping, which is considered best for cast bullet shooting, but jacketed bullets don't seem to care, as near as I can tell.

If the barrel is chrome-moly steel, 3,000 rounds is about where most High Power shooters find they are at end of life and start to throw the occasional un-called flier. 3500 is more typical for stainless. Just keep in mind the High Power course of fire included rapid fire which increase heat stress a bit. If you shoot like a sniper, very slowly and cleaning every ten rounds, you can sometimes get a good deal more life.

The heat stress cracks are the proximal cause, as the surface between them can chip off and make the throat uneven which randomly tilts some bullets just enough to make them impact outside the group. David Tubbs says his throat conditioning abrasive bullet Throat Maintenance System will double barrel life by cleaning that throat up if you want to try it. At around $40 with shipping, it's a gamble, but cheaper than a new barrel.

Can you post a photo of what you are seeing? I have a Hawkeye bore scope but no camera attachment. I would think the Lyman, being video, would have an image capture feature, but admit I've not looked at it closely.
 
In vast majority of the cases, once you are past the throat at the rear, the rifling is consistent all the way to the crown.

As noted there is a transition area, how they do that is per era and mft. So if they ease into it there will be more of a ramp.

Some are just downright square.

While a boro scope is good for condition, you can't actually measure anything with it.

Hammer forged barrels are smooth, button and cut rifled barrels are not (depends on how much lapping is done)

Until recently hammer forged were not noted for accuracy.

Button and cut were despite the rough looking.

Savage is downright awful (they don't lap) but they generally shoot good.

If you want acualy measurements there are other tools to do that correctly from checking how deep the chamber is worn to the rifling.

Like most things it take experience even with examples.
 
My lands have a gradual taper as the start , I don't know if it was like that from the start of they are wearing down . It's a M24 Rock Creek stainless steel barrel with 5R rifling 308 caliber . I guess I should call the company
( Accurate Ordnance ) to find out. If I didn't buy a bore scope I would have watched my round count and group size . Somethings ignorance is bliss. The Lyman bore scope can store pictured but trying to download to show them on line would make my head explode , sorry guys my shortcomings. Your advice an opinions are appreciated .

Chris
 
Last edited:
Dufus
Thank you , two great articles . Answered my question. I felt they were cut that way but wasn't sure. Thanks Again .

Chris
 
Normal rifleing tapers from none at the chamber too full all the way down the barrel
With wear lines on the lands and grooves

The bad barrels I have seen were -- one side of each land was worn down to a taper ( one side to the other )
Chunks of the lands were missing ( looked broken )
Pitting in lands and or grooves
Lands worn at the muzzle ( cleaning rod rubbing on barrel )
Or all of the above
 
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