Cut or button barrels.

[SuperV]

Hey just opening a big can of worms here. What better cut or buttoned rifled barrels.

[Seddo]

That's like a Holden vs ford question and we all know the answer to that................. Holden.

[Frank Green]

Any barrel manufacturing process can make good and junk barrels. It goes back to the place making them that they are paying attention to what they are doing is the biggest thing.

A button barrel can make a very good barrel. That's been proven. Same with cut rifling (when I talk cut rifling I'm talking about single point cut rifling). There is only one real downside to a cut rifled barrel. The amount of time to do the cut rifling but then we don't have to restress relieve the steel after rifling like a button maker can. The downsides to button rifling........

On average they don't last as long as a cut. This is due to the button rifling process work hardening the bore of the barrel. This isn't me just saying blah blah blah either. Bullet maker/ammo manufacturers keep very good data on test barrels that they buy for doing ammunition testing. One of the top bullet makers shared they're data on barrel life with me a few years back. In the same caliber and types of bullets being fired a cut rifled barrel lasted on average 15%-20% longer. Also years ago when old man Hart and Obermeyer were both buying they're steel from Crucible and came out of the same lot Hart and Obermeyer had conversations about this subject. Boot's told me they always found the cut barrels lasted longer than a button. Even when the barrels were rifled to the same bore and groove spec. Obermeyer normally tends to have a tighter bore.

Cut rifling produces a more uniform/consistent twist. During button rifling if the button hits a hard spot or soft spot in the steel it can slow the twist of the button down and it can speed back up then as well but either way you end up with a non uniform twist barrel. This is because the twist/lands is built into the button. Some button makers are trying to help guide the rotation of the button to help with this problem but not all.

Button rifling induces a lot of stress into the steel. Even though most of them restress relieve the steel in the blank after rifling no barrel maker can measure if there is any residual stress in the blank. When they finish turn the barrel, flute or when the gunsmith cuts and crowns the muzzle etc....during the secondary machining operation if you hit a stress point the machining operation will relieve the stress and typically this makes the bore go sour/open up on you. Where it happens and how much stress is in that area of the steel etc...can make it vary how much it opens up. The last place you want this to happen is right at the muzzles crown. Also I've seen button rifle barrels where the shooter got it hot enough that the barrel relieved itself during shooting and the bore went sour and it never came back.

Also we finish turn all of our barrels before reaming and rifling etc....if the barrel bows during turning the blank is scrap at that point. A button maker cannot do this. The blank has to be at the same size during the button rifling process. If the barrel would have a shape to it etc...there is no way they could come close to holding size. Button rifling is a cold swaging process for a lack of better terms. It's like a snake swallowing a mouse. The steel is going to expand and relax as the button goes down the barrel. As an example to do a .308 barrel they might be using a .3115" size button. That button could work like a million bucks but then they get a different lot of steel and that button might not work. They might have to use a different button bigger or smaller etc...to try and stay at that .308 size.

Tracy and I were both offered jobs at a button barrel maker after we were gone from Krieger. While we were starting up Bartlein. I turned the offer down for both of us. I was asked why by the maker. Because I told them I know of the short comings of making button barrels and couldn't work for a maker and sell a product that I don't believe in. That's not me.

Later, Frank
Bartlein Barrels

[aaronraad]

Any barrel manufacturing process can make good and junk barrels. It goes back to the place making them that they are paying attention to what they are doing is the biggest thing.

The John West tagline used in their ads is very true for manufacturing in general. You need to be harder on yourself than your customers. The problem is that accountants can't look at a large pile of scrap and utter terms like profitable and efficient.

A button barrel can make a very good barrel. That's been proven. Same with cut rifling (when I talk cut rifling I'm talking about single point cut rifling). There is only one real downside to a cut rifled barrel. The amount of time to do the cut rifling but then we don't have to restress relieve the steel after rifling like a button maker can. The downsides to button rifling........

Later, Frank
Bartlein Barrels

Do these caveats of rifling hold true for the chrome-moly through to the so called stainless steel barrel metallurgies?

How tough has it been recently to source quality target barrel steel given the demand for firearms in the States over the last 4-5yrs? I see barrel makers literally committing months worth of production to keep up with barrels to suit M16 uppers.

Cut rifling produces a more uniform/consistent twist. During button rifling if the button hits a hard spot or soft spot in the steel it can slow the twist of the button down and it can speed back up then as well but either way you end up with a non uniform twist barrel. This is because the twist/lands is built into the button. Some button makers are trying to help guide the rotation of the button to help with this problem but not all.

I have no reason to doubt this statement, but just playing the devil's advocate for a minute ...

Does this mean that a cut rifled barrel, by method of manufacturing, simply does not provide the opportunity to identify hard or soft spots along the bore during or after the cutting process?

How do hard/soft spots affect the potential accuracy and wear rates etc. for a barrel?

If these hard/soft spots are critical, I can see quality button barrel makers investing in equipment to QA on twist rate and rejecting barrels before lapping or further processing. Again if hard/soft spots are critical, how does a cut rifled barrel maker identify these and perform QA?

If so, what sort of limits can you apply to the volume/area and hardness deviation when a spot is identified. What limits are achievable with modern barrel steels that you have experience with, given these spots are predominantly tied to the quality of the steel supplied; and what guarantee/test certificate can/does the supplier provide you?

...switching from "devil's advocate" mode to "sponge" mode now; God forbid I learn something and make a better vehicle to travel down the roads you build .... never thought I would have got to use that Twisted Evil smiley as a pun on a forum - ticked that box anyway

[williada]

Frank, I endorse your remarks.

Aaron in my experience in the manufacture of buttoned barrels, the biggest problem was the certified steel did not often meet specification and extra costly heat treatments were needed at several stages. The fact that the button displaces metal, there are new internal stresses encapsulated in the steel almost like layers in a rock formation; and there were problems associated with the lubrication varying as the button is pulled through and the temperature at which the operation was performed. Some barrels are made by the button being pushed through like a bull dozer. Both methods impart a grain in the product like the nap on a pool table. This can lead to some barrels fouling more than others. If the hardness varied it could of course alter the spring back and internal dimensions and as Frank has said, the twist rate. I saw a few variable twist rates that were certainly not gain twist! I have previously mentioned on oher posts the method of determining whether a barrel has a variable twist. Barrels needed to be straight profiled before they were buttoned but as soon as a tool was put into them, due to the concealed stresses in the steel, they had a tendency to open up unless they were thoroughly stress relieved at appropriate stages. In terms of fouling and variable velocity, the wear patterns are completely different in barrels with hard and soft sections. This also plays havoc with acoustic vibrations which we know alter the bore size. Of course a properly manufactured buttoned barrel will perform as well as any cut barrel and the air gauge revealed amazing uniformity of bore size.

There are a few ways the button is pulled through, with the best being the old fashioned index guide which rotates the extension rod with the attached button silver soldered on. Others have used sine bar methods like on cut rifling, while you can also use a hydraulic ram drawing the button with an attached hydraulic motor having a variable speed adjustment to determine the required twist rate. So you really need to know how your buttoned barrel is made to be confident in one.
The best buttoned barrels are heat treated, drilled, reamed with two different sized reamers, bore honed or lapped, profiled, and heat treated again before the button is drawn through, heat treated again, and finished lapped.

A cut barrel process is very simple, in that it has less variables to deal with in terms of lubrication, and heat treatment. It can be re-profiled without the fear of opening up hidden stresses. It’s always in the back of my mind that a buttoned barrel might be a walker as it heats up.

The steel supplier usually stamps the billet and colour codes it and supplies a certificate as to its state of general hardness in relation to the steel’s intended purpose i.e. barrel steel. An astute barrel maker then has a sample of the billet tested by a metallurgist for steel state and composition. This information is then given to the heattreater before it is drilled.
David.

[aaronraad]

So you really need to know how your buttoned barrel is made to be confident in one.
The best buttoned barrels are heat treated, drilled, reamed with two different sized reamers, bore honed or lapped, profiled, and heat treated again before the button is drawn through, heat treated again, and finished lapped.

Are these first two heat treatment processes of the normalising type, with the final type being of the hardening & tempering type? Certainly a handy little except for anyone using buttoned barrels by choice, or by availability!

The steel supplier usually stamps the billet and colour codes it and supplies a certificate as to its state of general hardness in relation to the steel’s intended purpose i.e. barrel steel. An astute barrel maker then has a sample of the billet tested by a metallurgist for steel state and composition. This information is then given to the heattreater before it is drilled.
David.

Metallurgists and Heattreaters...another two variables to try and smooth-over when the SHTF.

I don't think it's been mentioned before, but from what I understand your cut rifled barrel markers don't have to go out and order a new button every time you want a different, new or gain twist rate. They might charge you for a non-standard twist, but at least you're not waiting another 6 months for a new button to be ground.

[David B]

For many years I would only use cut barrels but now results have given me a change of heart
This link does answer all or most of the criticisms of buttoned barrels, http://www.riflebarrels.com/about/default.htm

[Triplejim]

[quote="SuperV"]What better cut or buttoned rifled barrels.[/quote]
IMO, neither.
Button barrels are volume barrels due to barrel dimensions being reliant on button size, steel type, heat treatment etc
Cut barrels are basically custom barrels available in almost any configuration

[williada]

Aaron the first heat treatments are normalising to enable the drill and tooling to cut efficiently. Being an engineer you could look up your tables for 416 stainless or 4140 chrome moly to see the ranges. Because the button process work hardens the steel the last process is usually tempering to leave the finished product in the range 28 - 32 Rockwell C scale. This is up to the heat treaters. The vacuum processes reduce scale. As I mentioned before, the best barrels are double reamed and lapped so the button is not ironing out tool marks. If done properly the buttoned barrel will hold very tight tolerances. Having lapped a few buttoned barrels in the past, I noticed the buttoned barrels can leave a feather on the edges of the lands which is knocked off by hand lapping. But equally, a cut barrel will lap up to fine dimensions too. It all depends on the quality you are prepared to pay for. If a buttoned barrel is air gauged and demonstrates an internal taper it can be turned to an advantage by chambering the other end. Edit: the early stainless barrels we higher in sulphur content and I believe some were buttoned between 20 and 24 R. Being softer it might explain why they did not wear as well. The sulphurs stringers in early barrel steel also led to catastrophic failure and more so in freezing conditions. We now use a low sulphur stainless designated 416R. it can be used from 24 to 32 RC or even harder. Its major benefit is that it laps beautifully to final dimension and if treated right work hardens a tad. My son who is an engineer tells me that chrome moly is still a safer steel to use and a true pressure vessel steel and with a bit more work it too dresses up fine although a little harder to clean. For a bit of trivia, I think Boots Obermeyer had some impact on the Border Barrels and they too produce a buttoned Archer barrel which is well regarded. I'm sure they would back their product as well. David.

[macguru]

Sounds like you can get a good one either way, best to just try one or the other and hope for the best

[Josh Cox]

Frank,

Do you have an agent in Australia ?.

Cheers,

Josh

[Frank Green]

Frank,

Do you have an agent in Australia ?.

Cheers,

Josh

Josh, Not a agent per say......

but Craig McGowan has a valid import/export permit and has barrels on order.

Also David Kerr has a valid import/export permit and some barrels on order as well.

Those are the only two I can think of off hand.

Later, Frank
Bartlein Barrels

[Frank Green]

David (Williada), Very well said in both of your posts!

Your comment is very good about paying for what you get as well. You do get what you pay for.

Been working with a metal treatment house inspecting barrels over here for them. They do metal treatments for manufactures and barrel makers (cannot go into exact depth at this time). They have been having consistent problems with one button barrel maker that they are doing treatments for. They are being blamed for a lack of a better terms that they're treatment process is effecting they're bore sizes.

So the treatment facility has been sending the barrels to us before and after treatment and we have been measuring and inspecting the bore sizes. The bore and groove sizes have been all over the place. No consistency anywhere. The muzzles have been as much as +.001" larger than other areas of the barrels and also where the barrels have been fluted the bore and groove sizes have been larger and not uniform/consistent. These are those secondary machining operations and I believe are relieving the stress in the barrel blank and causing the bores to go sour. The question both I can the treatment facility cannot answer and what we suspect is the steel is not being properly heat treated and stress relieve. Either by they're manufacturing process or the way they are getting the steel to begin with.

Later, Frank
Bartlein Barrels

[Frank Green]

Any barrel manufacturing process can make good and junk barrels. It goes back to the place making them that they are paying attention to what they are doing is the biggest thing.

The John West tagline used in their ads is very true for manufacturing in general. You need to be harder on yourself than your customers. The problem is that accountants can't look at a large pile of scrap and utter terms like profitable and efficient.

A button barrel can make a very good barrel. That's been proven. Same with cut rifling (when I talk cut rifling I'm talking about single point cut rifling). There is only one real downside to a cut rifled barrel. The amount of time to do the cut rifling but then we don't have to restress relieve the steel after rifling like a button maker can. The downsides to button rifling........

Later, Frank
Bartlein Barrels

Do these caveats of rifling hold true for the chrome-moly through to the so called stainless steel barrel metallurgies?

The s.s. vs c.m. do machine a little differently but we don't have any problems making a barrel from either type of steel.

How tough has it been recently to source quality target barrel steel given the demand for firearms in the States over the last 4-5yrs? I see barrel makers literally committing months worth of production to keep up with barrels to suit M16 uppers.

We have not had any problems with getting quality steel for the most part due to the demand as you say it for M16 style barrels/guns. We work directly with the mill and the lead times involved and try to stay ahead of the game. In the past we have rejected whole lots of steel. As one example we were using primarily Crucible up to about 2008 or so. Our Gov't forgave the debits owed by some of the car makers over here and it killed Crucible at the time. Crucible supplied 80% of the engine cylinder valve material for the automotive industry. Crucible was owed millions. They started taking short cuts in the heat treatment process. We only shipped 14 barrels and those shot just fine etc...but the steel was beating up our tools. We sent the hole lot back and lost approx. $55k in labor that we never got back but to try and use the stuff would've cost us more in terms of time and tooling.

Cut rifling produces a more uniform/consistent twist. During button rifling if the button hits a hard spot or soft spot in the steel it can slow the twist of the button down and it can speed back up then as well but either way you end up with a non uniform twist barrel. This is because the twist/lands is built into the button. Some button makers are trying to help guide the rotation of the button to help with this problem but not all.

I have no reason to doubt this statement, but just playing the devil's advocate for a minute ...

Does this mean that a cut rifled barrel, by method of manufacturing, simply does not provide the opportunity to identify hard or soft spots along the bore during or after the cutting process?

If there are any hard spots or soft spots it doesn't effect us for the most part. If there would be a really hard spot etc..... the tool might tear a chuck out or possibly wreck the tool but then the barrel would be junk but again it doesn't effect us a whole lot.

How do hard/soft spots affect the potential accuracy and wear rates etc. for a barrel?

That's a tough question to answer and test. I will say if the steel is softer it won't last as long but how do you identify where a hard spot is or a soft spot is in the barrel blank? If it's soft in the throat area of the barrel I can see it effecting barrel life etc....but to try and test and inspect every single piece of barrel blank would be almost impossible.

If these hard/soft spots are critical, I can see quality button barrel makers investing in equipment to QA on twist rate and rejecting barrels before lapping or further processing. Again if hard/soft spots are critical, how does a cut rifled barrel maker identify these and perform QA?

If so, what sort of limits can you apply to the volume/area and hardness deviation when a spot is identified. What limits are achievable with modern barrel steels that you have experience with, given these spots are predominantly tied to the quality of the steel supplied; and what guarantee/test certificate can/does the supplier provide you?

You can get all the material certs. you want. The steel can meet spec. etc....but if there is anything wrong with the material it will show up during the manufacturing process. If the steel has a lot of residual stress will see the barrels bowing or have excessive spring back during the turning operation. If the steel has other machineablilty problems it can show up during reaming and rifling but not show it's ugly face during drilling and turning. The steel could turn, drill and ream just fine which going back to the Crucible example it did but when it got to the rifling for us it was leaving a heavy build up on the cutting tools and just beating the tools up. That's when we noticed the problem and stopped using it and returned everything we had.

Later, Frank
Bartlein Barrels

...switching from "devil's advocate" mode to "sponge" mode now; God forbid I learn something and make a better vehicle to travel down the roads you build .... never thought I would have got to use that Twisted Evil smiley as a pun on a forum - ticked that box anyway

[aaronraad]

Great response, thanks Frank!

In the age of CNC machining, I don't know that the average shooter appreciates how much in-process feedback the average customer barrel maker is looking for from the steel (material), the tooling and the machinery. It's not a process someone can set-up and walk away from just because it takes a while and let the machine do the rest.