Should the lands in my barrel have a smooth transition
- Thread starter westofpg
- Start date
- Location
- Western Manitoba
I have not cut even one chamber, yet, but I think that is what you get when the throat/leade part of the finishing reamer is smaller diameter than the barrel grooves are. In no way can I predict how a barrel will or will not shoot, just by looking with a bore scope. About only thing that I use one for any more is to see progress (or not) as I use various products to try to clean the bore - I do not care what the kid behind the counter said about how good a particular juice is - I can see with bore scope for myself - about only useful use I have made of it after having one for perhaps 8 or 9 years.
Probably your best bet would be to show that picture to whomever cut that chamber, and see what they say about it. It might be a non-issue regarding performance, or it might be a glaring warning about what is to come - I do not know. For sure, after some number of rounds, that entire leade area ahead of your chamber is going to be burned away - not sure if that is after 10, 100 or 1000 rounds.
As I understand what will occur - a bit of your leade is going to erode ever time you fire that rifle - hence old-school bench rest guys used to mention "chasing the lands" - apparently, at least one commentator on You Tube has got different thoughts about whether that "chasing" is useful or not. However, if you believe that a specific distance (like 0.023" bullet jump) is critical to your accuracy or average group size - your "bullet jump" distance is going to change, probably most times that you reload. You have to measure where the leades are, to know.
Probably your best bet would be to show that picture to whomever cut that chamber, and see what they say about it. It might be a non-issue regarding performance, or it might be a glaring warning about what is to come - I do not know. For sure, after some number of rounds, that entire leade area ahead of your chamber is going to be burned away - not sure if that is after 10, 100 or 1000 rounds.
As I understand what will occur - a bit of your leade is going to erode ever time you fire that rifle - hence old-school bench rest guys used to mention "chasing the lands" - apparently, at least one commentator on You Tube has got different thoughts about whether that "chasing" is useful or not. However, if you believe that a specific distance (like 0.023" bullet jump) is critical to your accuracy or average group size - your "bullet jump" distance is going to change, probably most times that you reload. You have to measure where the leades are, to know.
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That's a terrible angle do see what's going on in there.
To me, it looks like he is inserting the endoscope into the bore from the muzzle, and the leade is on the right.
It's difficult to get a pic of so anything at all will have to do.
From what I see, what you're worried about is the transition point called the "leade"
How much taper will depend on the way the reamer is ground.
That looks OK to me.
What looks like a ridge is actually the incline the bullet feeds into before fully engaging the rifling. If it weren't there, you would get all sorts of issues you don't need.
T
To me, it looks like he is inserting the endoscope into the bore from the muzzle, and the leade is on the right.
It's difficult to get a pic of so anything at all will have to do.
From what I see, what you're worried about is the transition point called the "leade"
How much taper will depend on the way the reamer is ground.
That looks OK to me.
What looks like a ridge is actually the incline the bullet feeds into before fully engaging the rifling. If it weren't there, you would get all sorts of issues you don't need.
T
Jonnyofalltrades
Regular
- Location
- North-central Saskatchewan
Hard to form much of a judgment from 2 stills.
Not the smoothest, for sure. Could use a little break-in.
Not the smoothest, for sure. Could use a little break-in.
OK, I see it now.
It's OK, what your photo shows is the trailing edge of the leade where it becomes full dimension rifling.
The marks to the left are from the part that inserts into the bore to keep the reamer running true, called a pilot.
Some reamers don't have rotating pilot sleeves.
It's a bit steeper than normal and likely the reamer wasn't as sharp as it could have been, leaving some "lines" which are normally called tool marks.
If the reamer was properly ground and run at the appropriate speed, the area would be more polished in appearance.
IMHO, it's fine. I've seen much worse than that on off-the-shelf commercial rifles and even a few "custom" jobs.
- Location
- Western Manitoba
About the thing to check with your bore scope, is what does the leade look like directly opposite that one?? Was the reamer going in dead centre on that barrel or is that chamber at an angle to the bore centre line? There might be a tolerance difference that is considered "okay" - I suppose that the more that you pay for the job, the smaller the "okay" tolerance should be? Meaning if you got a "great deal" - it may or may not be in there "dead" straight - likely takes considerable machinist time to dial a barrel in perfectly straight at both ends. Might not really make much of a difference to shoot at a deer - might make a LOT of difference, if you are trying for .015" 5 shot groups at 100 yards. Depends what you paid for?
I see some degree of machining marks in the lead in all of my rifles, but yours is more pronounced, and seems to extend further. As bearhunter suggests, perhaps some of it is damage from the reamer pilot. ???? Maybe the pilot wasn't a good match for the bore and that led to more chatter?
If he rotates the bore scope, would he see a different lead on one side than the other if the reamer wasn't going in straight? IE, more removal of the lands on one side of the lead than the other?
I have scoped all my rifles and all are extremely smooth at the lead edge of the lands . Not one has this edge that sticks up at the beginning of the lands and it is rougher then the rest. I have rotated the scope and it seems to be all the way around on all the lands, without question the roughest I have seen .Guess maybe I expected better from a custom shop.
- Location
- Western Manitoba
I do not really know, but I would presume so?
For a pilot to go into a bore, it has to be a smidgeon smaller diameter - that means there is slop. If it has been re-ground, could result in more slop - although likely within acceptable "tolerances" - go crooked and use up all the tolerance on one side, and I presume that would cut deeper into the lands on the other side. Purely conjecture, though - no experience at all doing it, and as previously stated, too much experience at making a judgement based on what I see, and then the rifle shoots groups altogether differently than I predicted - both better than, and worse than. I am pretty sure that action and barrel bedding, the specifics of the load used, the scope brand and type, the rings brand and type, how they were installed - all of those things and probably many more - like how is the trigger released - can lead to "issues" - not sure if the condition of the lands or the bore are the ONLY things at play.
I have a savage barrel that had rifling on one side all the way to the chamber mouth. It would not chamber a round right from the factory. It looks like you have rifling in the freebore like mine had. If you have rifling in the freebore on one side but not the other your chamber might be off centre like mine. Also it looks like whatever cut the leade didn't go far enough in to level off that ridge. If it's off centre I think there should be no ridge on the other side. I don't know how mine got out the savage factory but I sent it back when I couldn't chamber a round a d they burrowed it out so I can chamber a round and now the rifling starts deeper on one side than the other but it shot good enough for savage so I guess it has to be good enough for me too. Hope you don't have a similar problem. Does your chamber look the same all the way around the circumference?
I don't know if Savage/Remington still ream chambers with "non-piloted" reamers any longer or not, but at one time, they both did.
If the machine operator did a sloppy setup, using a reamer held by the tail stock chuck, it could cause a situation such as you describe.
I've seen smiths use the tail stock to hold both piloted and non-piloted reamers and they all knew what they were doing, so the chambers turned out well.
A couple of them said it almost eliminated any chance of chatter. I don't know, as I've never attempted it.
I have a 280 Rem reamer that is causing me all sorts of grief right now. It appears fine and feels sharp but I'm still getting fine rings in the chamber.
I'm using a floating reamer holder which has worked extremely well for me on several other jobs. The one mentioned, not so much. Good thing it's a rifle for me.
It chambers and extracts fine, but that barrel will come off and be replaced with the original 30-06 chambered barrel before it gets sold or passed onto anyone else.
If the machine operator did a sloppy setup, using a reamer held by the tail stock chuck, it could cause a situation such as you describe.
I've seen smiths use the tail stock to hold both piloted and non-piloted reamers and they all knew what they were doing, so the chambers turned out well.
A couple of them said it almost eliminated any chance of chatter. I don't know, as I've never attempted it.
I have a 280 Rem reamer that is causing me all sorts of grief right now. It appears fine and feels sharp but I'm still getting fine rings in the chamber.
I'm using a floating reamer holder which has worked extremely well for me on several other jobs. The one mentioned, not so much. Good thing it's a rifle for me.
It chambers and extracts fine, but that barrel will come off and be replaced with the original 30-06 chambered barrel before it gets sold or passed onto anyone else.
