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Nuts, you did the right thing, hope I didn't convey opposite message.
Looking forward to seeing these!
Not at all. I always appreciate your input.
I took the rifle out today with the new tube, it shoots lights out! Nice to have friends in low places. I shot a match with the old barrel yesterday, we tore it apart after the match, milled out the chamber area, my buddy chambered the new barrel yesterday, went over this morning and cleaned up the mill mess while he threaded and crowned the muzzle end. Assembled the rifle and headed up to the range to check zero, grouping. Loaded up some virgin brass, so it may tighten up some after barrel is broke in and brass is once-fired in the chamber, but it already looks pretty titts!
Back in the saddle!!!
I have a related question..... for those of you who go through barrels at 2-3K rounds and then rebarrel - do you have to go through an entire load development process again? Or is the assumption that as long as you use the same chamber reamer - that your previous loads should (in theory) shoot the same with maybe minor tweaks?
I ask, because with these new hot 6-7mm calibers that are all the rage these days with barrel life often less than 3K and in many cases <2K, a proper load development might burn up quite of a bit of that total life expectancy. Its one of the things that has held me back from moving away from .308. I just didn't want to spend all my time doing load developments everytime I got a new barrel. Sorry for the dumb question, but I've always wondered how that works. Thanks.
Deep Throat lives.......until you sectioned the chamber.
How much did the distance increase ( bullet to lands) grow from new ?
Did you happen to re-measure the throat erosion along the way ?
Ah, if I may ask two more questions. Who or what determines the appropriate free bore length to begin with? Also, I read about some reloaders talk about their rounds liking a little "jump". Are they referring to seating their projectiles a little dealer to ride their free bore space a little longer before land and groove engagement?
I did not track it along the way. I just realized that when shooting at distance, my normal dope was no longer viable. I was having to add elevation to connect on targets that in the past I was able to drill with much less elevation. I would personally have to look at the Reamer specs to see what the free bore is, I know that with our "team load" OAL of 2.82" the Ogive is only about .001"-.004" off the lands (depending on the consistency of my reloading equipment). The free-bore now is not measured in thousandths, rather with a tape measure! There are still lines visible where the rifling was in the throat area, but they are very faint and not well defined like what you would see in a fresh tube. ( I am going to see if we can find one of the fresh take-offs to disect so we can take pics of a new-ish chamber).
Any chronograph velocities logged when new vs the 3000 round mark ?
Wondering how much velocity dropped of along the way.
Nice pics BTW!
That is not a stupid question. If we can be of any help please do not hesitate to contact me. I will do my best to answer your question or find someone who knows the answer to your question.
We do not do load development every time we change barrels. We have two loads we run, the first is our "team 139 Scenar load" and the other is the "team 140 Barnes Match Burners load". Both shoot great, I think because we have a lathe and build our own rifles we are able to keep things very consistent. Consistency is accuracy so when we re-barrel a rifle we dial the bore axis down to 0.0001" and use the same rough reamer, the same finishing reamer and cut the chamber with the same +0.002" head space. That allows us to all use the same load depending on what projectile they are utilizing.
With factory rifles you can have different head spaces, different free bores and things like that. I hope that answers your question.
That question is beyond my pay grade, but I will take a stab at it. ****This is my layman's take on this**** I think that most cartridges that are widely used, have one particular reamer that the free-bore is pre determined by the round. Now if you want to tweak the standard cartridge and "load them longer" for competitions you can get a custom chamber built "deeper" so you can load them longer or run a custom projectile....like some of the Barnes Bore-riders recommend that you have a custom throated chamber to run them. If you can draw it up, PTG can build you a reamer to whatever spec you want, the sky is the limit...depending on how much brass prep you are willing/able to dive into.
As far as "jump" you are correct, if you seat the bullet deeper it gives it more "jump" before the Ogive hits the lands and grooves of your barrel. I ran into a crash course with that with my 6.5 SAUM, I had always been taught that you find where the lands are and load the projectile so that the Ogive is a few thousandths off the lands and that is usually the "happy spot" That has been the case for most calibers I have reloaded for. Then once you are at that point my common practice was to play with OAL maybe .002-.003" at a time to try to find where the rifle shoots that projectile best. I started and pretty much "in the lands" and worked back to .017" off, thinking that was a HUGE jump, rifle still wouldn't shoot better than Minute/minute and a half groups. So then we started down a lonely road of re-torquing everything, field stripping rifle, measuring everything, sent a NF scope (that had nothing wrong with it) back for repair, recrowned muzzle, cut barrel down to make sure enough of the end had been cut off on initial build, bedded barreled action to chassis, (even though we have never had to bed any of our other chassis).....and it still wouldn't shoot. I tried different powders, scopes, you name it and it would not shoot. I finally stumbled on an article by Berger (Berger Bullets Seating Method for VLD Bullets - A "Sweet Spot" with a Long Bullet Jump will give the best accuracy.) I followed their procedure and found that the sweet spot for my SAUM was with the bullet seated for what amounts to a .063" jump. (if I would have tried to do that .002" at a time, I would have shot the barrel out before I found "the load") Now that rifle is an absolute hammer, but I almost broke it over a rock a few times on the journey of finding where it wanted to shoot. Killed a bull elk in Wyoming at 320 yards running away from me with it and a mule deer in Nevada, 560 yard head shot at a pretty steep angle, love the rifle now and am intimately framiliar with my chamber...way more than I ever cared to know about it in fact! Good luck and shoot straight!
I'd like to see your pics Mr Tooley, even with all the ooh's and aah's, to me Hognut's barrel is in remarkably good shape. Though the close ups aren't the clearest, the throat looks totally void of firecracking, a tribute to load or powder choice. The bullets aren't coated, and maintenance can't stop cracks.
I'll wait on a reply from him. I can guarantee you he has heat checking. Also heat checking filled with copper. In one of his photos there is a considerable amount of copper just ahead of the throat area. All the bad stuff is there. I use a stereo microscope and can get considerably more detail. The photo below is just the top of one land in a 338.
Guys before Shot I said I would post some pics and have a discussion about barrel maintenance. If hognuts agrees to me joining in this thread I'll add some pics and start the discussion.. Below is one of a fresh cut 338 Lapua. It's not perfect as it was about 2" piece of barrel thrown in a chuck and hogged out but you get the idea of what a fresh cut throat looks like.