Muller makes incredible barrels, best luck to you, Justice.
The subject of land height brings up several other relevant topics, such as obturation pressures to engrave the bullet and how those pressures are manipulated through various means.
Pac Nor land height is less(.002), and their steel is much tougher. Lothar Walthar uses a very tough steel also, but I can not remember their land height. A gunsmith that pre bores the chamber with a boring bar will never have any issues with these tough steel barrels where the finish reamer is only cutting .015 per side or less. It is when a gunsmith tries to jam the finish reamer into the barrel that he experiences the true toughness of the different steel.
I have had some very, very fast Pac Nor barrels, extremely accurate also, 223, 6 PPC, 6 BR, 7 STW, and 257 Weatherby. The 7 STW with an 11 twist, 3 Groove, zero freebore, 27" shoots the 140g Nosler C/T bullet at 3700 fps into bug holes, and has taken many deer, near and far. The 257 Weatherby, three groove, with zero freebore, 26", 10 T, shoots the 100s at 3850 into tiny bug hole groups with the 80g TTSX doing 4200. Pac Nor has some world class gunsmiths working for them, make no mistake about it, and they have over 2000 reamers, only Douglas has more.
Less engraving pressure during obturation can pay some big dividends. Many have played with bullet lubes and coatings to reduce bullet friction during obturation, and Norma did extensive research on this subject that they claimed led to much longer barrel life.
There was one gunsmith in Tenn who used to stamp on the outside of the barrel the bore dia that he found in trying to fit the reamer bushing to the bore, he is now deceased. He would also cast a lap and push it through each bore he chambered, each barrel had it's own story. I wish that every custom gun had the bore dia stamped on the outside for several reasons.
There is not much we can do about the bore dia we have available today, but we can design reamers that will exhibit less engraving pressures on the bullet as it obturates, and use a bullet lube that will dramatically reduce the engraving pressure which also drops SD to very low numbers.
A few years ago, I cut off some barrel stubs, ran the reamer into the depth of the shoulder. Using an arbor press, I started various bullets into the lands of the barrel stubb. A couple of things I found out. A 1* leade angle changes force needed to start the bullet into the lands vs a 1.5* and 3* leade angle on barrels of the same bore dia measured to the 0.0000 using simple reamer pilots.
Second, a bullet lube changed the obturation pressure to such an extent that was just hard to imagine. I used three different types of lube, all giving the same results or dramatic reduction in obturation pressure. I suspect that jacket damage would be much less with the lube also. Norma has done extensive testing with their Diamond line of ammo on barrel life longevity, but none of the bullet lubes are popular with the masses and I doubt it it ever will.
While it should not be a shock, to the degree that it was, a lube used on a bullet simply was a discovering GOLD. SD of less than 3fps is not unusual, less copper fouling, a longer burning chamber so the flame temp is spread over a longer distance, but it takes just a tad more powder to bring the velocity to the node of the naked bullet, perhaps .5g. If "stuff" is not read about in a magazine or endorsed by a top notch shooter, then shooters will not accept it.
Land Height has another issue when it comes to manufacturing a barrel, and that is the difficulty in machining, whether it is a cut rifle or button rifle. When a guy is having a custom barrel installed, he should insist that a careful examination of the bore be done by the gunsmith to avoid getting a really rough barrel, I can not stress this enough. If you ever get a rough cut rifle barrel, you have a sack of pure Heck on your hands. I have not seen rough button rifle barrels from any of the top tier manufacturers that I have owned, but care should be taken by the gunsmith in QC prior to chambering, NOT just depending on the name of the maker to ensure quality. If a guys send a barrel to a gunsmith, it is reasonable for the gunsmith to never examine the barrel. This should not be the case, but it is. So, if you are sending the barrel to the gunsmith, do your own due diligence prior to shipping.
With the Teslong bore scopes being so inexpensive, it would not require much of a gunsmith to make a video of the bore prior to chambering, and send that video to the customer, may as well video the chamber quality when it is finished at the same time, prior to pulling the barrel out of the lathe. None of this is going to happen, integrity take time, and "an honest man walks in the light so all his deeds are known".
History of land height and land width is a real mess, addressing uniform bore dia, heat treat, lubes used on button rifle buttons, and cutter design on cut rifle barrels. We are living at a time where the best of barrels are being made. You just need to make darn sure that your barrel blank is bore scoped prior to chambering, what ever the brand.
The subject of land height brings up several other relevant topics, such as obturation pressures to engrave the bullet and how those pressures are manipulated through various means.
Pac Nor land height is less(.002), and their steel is much tougher. Lothar Walthar uses a very tough steel also, but I can not remember their land height. A gunsmith that pre bores the chamber with a boring bar will never have any issues with these tough steel barrels where the finish reamer is only cutting .015 per side or less. It is when a gunsmith tries to jam the finish reamer into the barrel that he experiences the true toughness of the different steel.
I have had some very, very fast Pac Nor barrels, extremely accurate also, 223, 6 PPC, 6 BR, 7 STW, and 257 Weatherby. The 7 STW with an 11 twist, 3 Groove, zero freebore, 27" shoots the 140g Nosler C/T bullet at 3700 fps into bug holes, and has taken many deer, near and far. The 257 Weatherby, three groove, with zero freebore, 26", 10 T, shoots the 100s at 3850 into tiny bug hole groups with the 80g TTSX doing 4200. Pac Nor has some world class gunsmiths working for them, make no mistake about it, and they have over 2000 reamers, only Douglas has more.
Less engraving pressure during obturation can pay some big dividends. Many have played with bullet lubes and coatings to reduce bullet friction during obturation, and Norma did extensive research on this subject that they claimed led to much longer barrel life.
There was one gunsmith in Tenn who used to stamp on the outside of the barrel the bore dia that he found in trying to fit the reamer bushing to the bore, he is now deceased. He would also cast a lap and push it through each bore he chambered, each barrel had it's own story. I wish that every custom gun had the bore dia stamped on the outside for several reasons.
There is not much we can do about the bore dia we have available today, but we can design reamers that will exhibit less engraving pressures on the bullet as it obturates, and use a bullet lube that will dramatically reduce the engraving pressure which also drops SD to very low numbers.
A few years ago, I cut off some barrel stubs, ran the reamer into the depth of the shoulder. Using an arbor press, I started various bullets into the lands of the barrel stubb. A couple of things I found out. A 1* leade angle changes force needed to start the bullet into the lands vs a 1.5* and 3* leade angle on barrels of the same bore dia measured to the 0.0000 using simple reamer pilots.
Second, a bullet lube changed the obturation pressure to such an extent that was just hard to imagine. I used three different types of lube, all giving the same results or dramatic reduction in obturation pressure. I suspect that jacket damage would be much less with the lube also. Norma has done extensive testing with their Diamond line of ammo on barrel life longevity, but none of the bullet lubes are popular with the masses and I doubt it it ever will.
While it should not be a shock, to the degree that it was, a lube used on a bullet simply was a discovering GOLD. SD of less than 3fps is not unusual, less copper fouling, a longer burning chamber so the flame temp is spread over a longer distance, but it takes just a tad more powder to bring the velocity to the node of the naked bullet, perhaps .5g. If "stuff" is not read about in a magazine or endorsed by a top notch shooter, then shooters will not accept it.
Land Height has another issue when it comes to manufacturing a barrel, and that is the difficulty in machining, whether it is a cut rifle or button rifle. When a guy is having a custom barrel installed, he should insist that a careful examination of the bore be done by the gunsmith to avoid getting a really rough barrel, I can not stress this enough. If you ever get a rough cut rifle barrel, you have a sack of pure Heck on your hands. I have not seen rough button rifle barrels from any of the top tier manufacturers that I have owned, but care should be taken by the gunsmith in QC prior to chambering, NOT just depending on the name of the maker to ensure quality. If a guys send a barrel to a gunsmith, it is reasonable for the gunsmith to never examine the barrel. This should not be the case, but it is. So, if you are sending the barrel to the gunsmith, do your own due diligence prior to shipping.
With the Teslong bore scopes being so inexpensive, it would not require much of a gunsmith to make a video of the bore prior to chambering, and send that video to the customer, may as well video the chamber quality when it is finished at the same time, prior to pulling the barrel out of the lathe. None of this is going to happen, integrity take time, and "an honest man walks in the light so all his deeds are known".
History of land height and land width is a real mess, addressing uniform bore dia, heat treat, lubes used on button rifle buttons, and cutter design on cut rifle barrels. We are living at a time where the best of barrels are being made. You just need to make darn sure that your barrel blank is bore scoped prior to chambering, what ever the brand.
