End of chamber area...

[gunsandgunsmithing]

I've done 30 degrees and saw no changes. I think what would help with erosion/clearance would be larger FB diameters or even two diameter FB's if preventing bullet damage is your goal.

You may be right. My thinking is more about the flame and smoothing out any abrupt features from the case mouth forward. That step is abrupt and is a common area for fire cracking to start. Just my thoughts. Certainly nothing absolute about it. Thinner necks will make this area less abrupt as well..fwiw Rather tight neck chambers but I'm sure you understood

 

[DaveTooley]

You may be right. My thinking is more about the flame and smoothing out any abrupt features from the case mouth forward. That step is abrupt and is a common area for fire cracking to start. Just my thoughts. Certainly nothing absolute about it. Thinner necks will make this area less abrupt as well..fwiw Rather tight neck chambers but I'm sure you understood

Once that area gets gas cut and heat checking appears it's part of my cleaning routine to use abrasives in that area. The frequency is dependent on severity and caliber.

 

[gunsandgunsmithing]

Once that area gets gas cut and heat checking appears it's part of my cleaning routine to use abrasives in that area. The frequency is dependent on severity and caliber.

Yes, and once it starts, I don't think any of this is gonna matter much. The idea being to prolong the "premium" life of the bbl, fwiw. Once it gets roughed up, it's a much more efficient heat sink. And yes, I do the same with jb, as maintenance on this area...but same idea, to keep it smooth for as long as possible and of course keep carbon at bay.

 

[Ray Gross]

I had this conversation some time ago with Ray and the feedback I received was that the area was so small that it didn’t really matter if it was called out as a sharp corner or radius. You weren’t going to get much if any radius let alone a consistent one.

Jamie, getting a consistent or specific radius in the small transition area is the main issue. Virtually all of the inside/concave corners on a chambering reamer are going to have some small amount of radius in the corner. It is function of the radius that exists on the working edge of the wheel.

The wheels we use in the CNC machines purposely have a small radius dressed onto the edge. You could dress it to a sharp corner, but it would nearly instantly decay to a small radius anyway and you would have to make constant offset adjustments to the machine as the edge breaks down. With a small starting radius, the wheel wears much more slowly and evenly. So the reamers that come out of the CNC grinders are going to have a radius of about .007-.020 in the transition corner. If you are willing to pay the price of tying up one of those machines, that radius can be programmed to almost anything you want (bigger than the wheel radius, not smaller).

Most of the one-off, custom reamers are ground manually with a different type of wheel. A radius will develop on the working corner of that wheel more quickly. There are some other wrinkles as well. But the bottom line is that they will also have some radius in that corner and it will be slightly more radius than you will see on the reamers that come off the CNC grinders. It would be more difficult to specify a specific radius on the manual machines. The wheel is dressed square and the features (angles, radii, etc) on the reamer are the result of the templates used. To be honest, I am not sure we would be able to dress that wheel with a specific radius. Maybe, but again, it would be costly to have us dick around trying to achieve some oddball setup.

 

[Ray Gross]

It seems just about everything has been tried. Not much conclusive here so far. Perhaps there is nothing gained but to my mind, it's hard to see it not helping.

Interesting story, A few years before I came to work for Dave (Manson), I called and asked him about laying that 45 degree transition down. He was a lukewarm to the idea and nothing came of it at the time. Once I had worked my way up tot he point that Dave turned me loose designing reamers, I designed a few for Fullbore (Palma) with 15 and 30 degree transitions*. Around the same time, ELR was starting to take off and as I began designing more of those reamers I 'discovered' that the .50 Browning and 416 Barrett were already commonly designed with a 15 degree transition. Pretty much everything in shooting has been tried before.

*SAAMI doesn't have a word for that particular feature, so we just call it a 'Transition'

 

[Ray Gross]

As with anything engineering related there is a balance or trade off. What that is in this case I am not entirely sure. I don’t know if there has been a side by side A vs B study done to quantify the change. I have to believe in a long FB chamber like the T15 the bullet May never even notice. If it was a short FB like a CLE or Wylde meant to fire mag length ammo then results might be different.

I think that is a good summary. As long as you have sufficient freebore remaining, I don't think laying the transition angle down hurts anything. But that does raise the question of what is a sufficient length.

I don't know if changing the angle helps yet or not. Anecdotally- I have chambers with 45 degree transitions that have small chunks of metal missing due to the depth of the firecracking. So far, in the chambers with 15 and 30 degree transitions, the firecracking is more pronounced (or at least more easily seen) on the leade and a few inches down the bore than it is on the transition corner.

 

[gunsandgunsmithing]

Jamie, getting a consistent or specific radius in the small transition area is the main issue. Virtually all of the inside/concave corners on a chambering reamer are going to have some small amount of radius in the corner. It is function of the radius that exists on the working edge of the wheel.

The wheels we use in the CNC machines purposely have a small radius dressed onto the edge. You could dress it to a sharp corner, but it would nearly instantly decay to a small radius anyway and you would have to make constant offset adjustments to the machine as the edge breaks down. With a small starting radius, the wheel wears much more slowly and evenly. So the reamers that come out of the CNC grinders are going to have a radius of about .007-.020 in the transition corner. If you are willing to pay the price of tying up one of those machines, that radius can be programmed to almost anything you want (bigger than the wheel radius, not smaller).

Most of the one-off, custom reamers are ground manually with a different type of wheel. A radius will develop on the working corner of that wheel more quickly. There are some other wrinkles as well. But the bottom line is that they will also have some radius in that corner and it will be slightly more radius than you will see on the reamers that come off the CNC grinders. It would be more difficult to specify a specific radius on the manual machines. The wheel is dressed square and the features (angles, radii, etc) on the reamer are the result of the templates used. To be honest, I am not sure we would be able to dress that wheel with a specific radius. Maybe, but again, it would be costly to have us dick around trying to achieve some oddball setup.

I had thought about just that. It's pretty impressive how well those dimensions are held and maintained, and then you throw in the grinding wheel...more tight tolerances to be held. But yes, I had wondered how much a radius would actually help in that area vs a 12.5-15° angle. Clearly, you very much understand my logic with wanting to give it a try on a match reamer. Are you aware of any downsides to accuracy that aren't obvious or that I may be just over looking? Thanks for your reply.

Interesting story, A few years before I came to work for Dave (Manson), I called and asked him about laying that 45 degree transition down. He was a lukewarm to the idea and nothing came of it at the time. Once I had worked my way up tot he point that Dave turned me loose designing reamers, I designed a few for Fullbore (Palma) with 15 and 30 degree transitions*. Around the same time ELR was starting to take off and as began designing more of those reamers I 'discovered' that the .50 Browning and 416 Barrett were already commonly designed with a 15 degree transition. Pretty much everything in shooting has been tried before.

*SAAMI doesn't have a word for that particular feature, so we just call it a 'Transition'

Again, interesting and thanks for your help.--Mike

 

[Ray Gross]

Are you aware of any downsides to accuracy that aren't obvious or that I may be just over looking? Thanks for your reply.


Mike

Mike,

I have not seen anything in my own rifles or heard of anything from others who are using one of those reamer designs.

I think it would be sub-optimal to sacrifice too much freebore length, just to lay the angle down. But I have no idea where that crossover point is. I think everything I have designed a 15 or 30 degree transition with has a remaining freebore length of at least .065 and most are .150 plus. My completely un-scientific rule of thumb is to try and keep at least a 1/4 caliber of freebore length. Subject to further review

 

[gunsandgunsmithing]

Mike,

I have not seen anything in my own rifles or heard of anything from others who are using one of those reamer designs.

I think it would be sub-optimal to sacrifice too much freebore length, just to lay the angle down. But I have no idea where that crossover point is. I think everything I have designed a 15 or 30 degree transition with has a remaining freebore length of at least .065 and most are .150 plus. My completely un-scientific rule of thumb is to try and keep at least a 1/4 caliber of freebore length. Subject to further review

Is it for optimal bullet alignment or something else? I may give one a try anyway. Should I ask for you when I call?

 

[Ray Gross]

Is it for optimal bullet alignment or something else? I may give one a try anyway. Should I ask for you when I call?

I think free bore helps to guide and align the bullet, so I would avoid short changing it if possible.

Call anytime, ask for me. Tomorrow is our last day, this year. Back to normal Jan 2nd

 

[Aero]

Pretty much everything in shooting has been tried before.

This is way off in left field to what you guys are talking about, but the original Sharps rifles and possibly the Remington's used in the first American Long Range match at the Creedmoor range in 1874 used a 7* transition angle with no freebore. Just a long shallow funnel into the bore.

In the late 90's, Browning produced one of their 1885 Highwall replicas set up as a Black Powder target rifle. Chambered in three calibers, the 45-70 version's chamber was cut to SAAMI specs, but the 40-65 and the 45-90 Creedmoor had no SAAMI spec to worry about, so the guy who had put the project together at Browning designed the chambers with shallow transition angles and long freebores to seat bullets way out. I own one of each and I've never heard of one those guns that did not shoot very well with properly made cast bullet black Powder loads. My 45-90 Creedmoor has held just over X-ring (1.25-1.5 moa) vertical at 1K more than a few times under match conditions in a game where most are lucky to hold 9 ring vertical (3 moa).

I designed and had ground a 45-70 Match reamer using the 12.5* transition angle and longer freebore that the Browning 45-90 chamber uses and it works exceptionally well.

This whole ramble is apples to oranges for a number of reasons in this discussion that I won't bore you with, but I will say that I have both the Fullbore reamers that Ray designed, 223 and 308, and they seem to work very well. Just put a fresh barrel on my Palma rifle chambered with the 2019 Fullbore reamer and accuracy with the Palma Team spec load is very good with only a handful of rounds through it so far. Barrel I pulled off had just over 4200 rounds through it (same reamer, diff WI barrel make) and still shot two 5-shot groups back to back just over .3" each just a few weeks before being unscrewed. I can't blame the rifle if I don't pound the X-ring.

 

[VA_XTC_Shooter]

The other benefit to the shallower degree, I would think, is less of a "ridge" to create turbulence and allow the carbon ring to develop as quickly or at all.

 

[762plinker]

you could shorten the distance from case end to the 45...as in 5thou total or so.
just rim the brass every time
imho now too small of a gap for large heat transfer

 

[rogina]

This is way off in left field to what you guys are talking about, but the original Sharps rifles and possibly the Remington's used in the first American Long Range match at the Creedmoor range in 1874 used a 7* transition angle with no freebore. Just a long shallow funnel into the bore.

In the late 90's, Browning produced one of their 1885 Highwall replicas set up as a Black Powder target rifle. Chambered in three calibers, the 45-70 version's chamber was cut to SAAMI specs, but the 40-65 and the 45-90 Creedmoor had no SAAMI spec to worry about, so the guy who had put the project together at Browning designed the chambers with shallow transition angles and long freebores to seat bullets way out. I own one of each and I've never heard of one those guns that did not shoot very well with properly made cast bullet black Powder loads. My 45-90 Creedmoor has held just over X-ring (1.25-1.5 moa) vertical at 1K more than a few times under match conditions in a game where most are lucky to hold 9 ring vertical (3 moa).

I designed and had ground a 45-70 Match reamer using the 12.5* transition angle and longer freebore that the Browning 45-90 chamber uses and it works exceptionally well.

This whole ramble is apples to oranges for a number of reasons in this discussion that I won't bore you with, but I will say that I have both the Fullbore reamers that Ray designed, 223 and 308, and they seem to work very well. Just put a fresh barrel on my Palma rifle chambered with the 2019 Fullbore reamer and accuracy with the Palma Team spec load is very good with only a handful of rounds through it so far. Barrel I pulled off had just over 4200 rounds through it (same reamer, diff WI barrel make) and still shot two 5-shot groups back to back just over .3" each just a few weeks before being unscrewed. I can't blame the rifle if I don't pound the X-ring.

I had one of those Highwalls with a Badger barrel and it would shoot 5 shot groups just under 6 inches at 1000 yards.

 

[Dave M.]

Well, it's cold out so I'm bouncing a couple of things that I've been considering for a while off of the vast knowledge base on here.
Right now I'm thinking about the area of the chamber between where the case ends and the throat begins. It's that 45° area at the end of the case mouth of the chamber.
Just thinking here and again, wondering if others have tried it or just what your thoughts on this are.

Any point like this that is fairly abrupt or has sharp angle changes becomes a heat sink area. We almost all have a borescope of some type these days and it's pretty clear that firecracking begins right there...and it makes sense that it would. Lets focus on this area for a minute. Exact neck diameter can affect the exact numbers but you'll get my thinking pretty fast, I think. In a pretty typical, say .272 6mm neck chamber, this 45° bevel is about .015 long..so it's short and abrupt, right?
I understand that very short freebores won't always work here but lets say we make that area 15° instead of the standard 45°. So, instead of it being about .015 long, it's now about .045 long, so you have to have at least that much freebore before you can even really consider this.

Bottom line, we've smoothed that heat sink down a lot. Will that help bbl life and will it affect accuracy in the short term? Logically, I see no reason accuracy should change either way but I see a very big potential for increasing useful barrel life.

Years ago, when Smith came out with their then new 500S&W revolver, they had pretty significant issues with flame cutting of the top strap portion of the frame. One of their engineers told me how they fixed it and it WORKED....they polished the inside of the top strap!! No rough edges to serve as a heat sink. The flame traveled smoothly over the smooth surface and didn't cut into rough areas, proliferating the whole issue as it grew and grew. I look at barrel break in pretty much the same way but that's a different subject.

So what are your thoughts. I think it has huge potential in regard to bbl life without any negative aspects as long as you have enough freebore in the given chamber design/bullet length etc. Maybe this should go in the gunsmithing forum but I'm mostly interested in competition gunsmith and shooters' opinions. Fire away. I think it's worth discussing unless someone that's done it can shoot it down. Thanks!--Mike

Very interesting Mike. I’m standing by to hear the true experts and world class gunsmiths chime in. In theory, it seems like it should help but perhaps I’m not considering something some of the older more experienced smiths and shooters will note.

 

[Dusty Stevens]

Thanks for chiming in with your knowledge Ray. We appreciate you being here

 

[Dave M.]

I think that is a good summary. As long as you have sufficient freebore remaining, I don't think laying the transition angle down hurts anything. But that does raise the question of what is a sufficient length.

I don't know if changing the angle helps yet or not. Anecdotally- I have chambers with 45 degree transitions that have small chunks of metal missing due to the depth of the firecracking. So far, in the chambers with 15 and 30 degree transitions, the firecracking is more pronounced (or at least more easily seen) on the leade and a few inches down the bore than it is on the transition corner.

Love reading your posts Ray and really appreciate your willingness to share your knowledge and experience. Hope to see you and shoot with you soon brother. Keep up the great work. Hope you had a great Xmas and stay safe over the new years.
Dave

 

[Ray Gross]

Love reading your posts Ray and really appreciate your willingness to share your knowledge and experience. Hope to see you and shoot with you soon brother. Keep up the great work. Hope you had a great Xmas and stay safe over the new years.
Dave

We have a match in Midland in the morning, Dave…

Happy new year

 

[gunsandgunsmithing]

We have a match in Midland in the morning, Dave…

Happy new year

I plan to call ya next week on a reamer Ray. Thanks for the help.--Mike

 

[Keefe300]

This is an interesting read and proves that we are always looking for ways to make improvements and or progress.

I like to visualize things so I took a picture of the area this thread is talking about. In the photo you can see the end of the brass, followed by a gap, and then the dark looking section is the 45 degree angle. This picture also shows a view looking head on and you can see the case is proud in relation to this area. So this section would be a turbulent area when the cartridge was fired.