I am wanting to put together a competitive F restricted rifle and I have a technical question needing answered. The rule in the DCRA book, rule F2.3. says -"An ‘F’ Class Restricted rifle is limited to .223 Remington or .308 Winchester calibre chambers or their commercial metrification equivalents. Chamber dimensions must conform to SAAMI or CIP dimensions."Now I am wondering does that rule prevent me from having a barrel chambered with .340" or smaller neck ?
F class restricted chambers ???
- Thread starter stormdog
- Start date
I am wanting to put together a competitive F restricted rifle and I have a technical question needing answered. The rule in the DCRA book, rule F2.3. says -"An ‘F’ Class Restricted rifle is limited to .223 Remington or .308 Winchester calibre chambers or their commercial metrification equivalents. Chamber dimensions must conform to SAAMI or CIP dimensions."Now I am wondering does that rule prevent me from having a barrel chambered with .340" or smaller neck ?
If either SAAMI or CIP dimensions mention that neck size or smaller, you're ok. Otherwise no. - dan
Good question - the DCRA rules are based upon the issue of factory ammunition at matches and tight necks have a potential (overpressure) safety concern in wet/dirty chambers with thick neck brass. Most (but not all) F-TR shooters are shooting handloads and don't share the same concerns as the TR brethren.
At the end of the day, my position is what Dan has indicated - what does SAAMI (N.America) or CIP (Europe) indicate, as we are still dealing with the .308 Winchester round, not some 'improved' variant (otherwise, you should be shooting F-O). Those dimensions need to be the guidelines.
Dimensions are presented in recognized industry publications ... so here is the rub ... does everyone have access to these publications, so that anyone knows the limitations in advance?? I have not been able to locate ('free' on the internet) a SAAMI diagram or table that gives the parameters for the .308W cartridge.
EDIT - it's been a year since I looked ... going back to check, I now see that the SAAMI site has a copy of the ANSI 'voluntary performance standard' for download.
At the end of the day, my position is what Dan has indicated - what does SAAMI (N.America) or CIP (Europe) indicate, as we are still dealing with the .308 Winchester round, not some 'improved' variant (otherwise, you should be shooting F-O). Those dimensions need to be the guidelines.
Dimensions are presented in recognized industry publications ... so here is the rub ... does everyone have access to these publications, so that anyone knows the limitations in advance?? I have not been able to locate ('free' on the internet) a SAAMI diagram or table that gives the parameters for the .308W cartridge.
EDIT - it's been a year since I looked ... going back to check, I now see that the SAAMI site has a copy of the ANSI 'voluntary performance standard' for download.
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Looking at the saami download it seems to say .3442" plus .002" to a max of .3462". Is this the interpretation of the rule?? I read an article in 6mm Br about the 2009 F TR world champion shooting with regularity .10 to .20 groups at 100 yards. I just can't believe the neck isn't a little tighter than .3442" to .3462" for a rifle to shoot that well. I interpret the rules to be that if a factory saami .308 win round can be chambered then the rifles chamber meets saami specs. If your using Lapua brass a .340" neck or bit smaller should advantageous and would accept a factory round. Is my interpretation correct??
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Mystic Precision
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- Summerland, BC
The diameter of the neck area of the chamber HAS NO AFFECT ON THE ACCURACY OF YOUR RIFLE.
Everything has to do with the throat and of course, the alignment of the chamber with the bore through said throat. Throat length is critical to maintaining accuracy. Even the throat angle is not that big a deal.
The only reason for going to smaller neck diameter is to prolong the life of the case neck ie neck splits.
When BR shooters started turning necks to get rid of poor manf, they also found that normal sized chambers allowed their brass to grow too much and neck splits occured. Going to a 'tight' neck reduces this clearances and stretch.
All that is required is for the neck to have enough clearance so that the the case will never jam into the chamber walls during the firing process. As long as the ammo has no runout, the case shoulder aligns the cartridge with the throat/bore. The neck just holds the bullet in place.
Remember that the bullet is well on its way down the barrel before the neck expands enough to hits the chamber wall.
And yes, I have played with many chamber dimensions while wildcatting to see what would happen...
Jerry
Everything has to do with the throat and of course, the alignment of the chamber with the bore through said throat. Throat length is critical to maintaining accuracy. Even the throat angle is not that big a deal.
The only reason for going to smaller neck diameter is to prolong the life of the case neck ie neck splits.
When BR shooters started turning necks to get rid of poor manf, they also found that normal sized chambers allowed their brass to grow too much and neck splits occured. Going to a 'tight' neck reduces this clearances and stretch.
All that is required is for the neck to have enough clearance so that the the case will never jam into the chamber walls during the firing process. As long as the ammo has no runout, the case shoulder aligns the cartridge with the throat/bore. The neck just holds the bullet in place.
Remember that the bullet is well on its way down the barrel before the neck expands enough to hits the chamber wall.
And yes, I have played with many chamber dimensions while wildcatting to see what would happen...
Jerry
lejarretnoir
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If the rules doesn't state you cannot have a .340 neck or less, then you can IMO. They probably never had to worry about that since nobody sees an advantage over other competitors.
Tight necks are not a problem.
This is Technical Rule F1.9:
The spirit of the F-Class Rules is to encourage innovation, and Match Referees and
Committees will bear this philosophy in mind in ruling on issues not covered by these rules.
Tight neck cartridges have never been an issue in the past. The question as to whether a neck is truly part of the chamber has been debated in the past, and it has never been an issue raised at any match that I know of.
BCRA F-Class Director
This is Technical Rule F1.9:
The spirit of the F-Class Rules is to encourage innovation, and Match Referees and
Committees will bear this philosophy in mind in ruling on issues not covered by these rules.
Tight neck cartridges have never been an issue in the past. The question as to whether a neck is truly part of the chamber has been debated in the past, and it has never been an issue raised at any match that I know of.
BCRA F-Class Director
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Someone like Obtunded will be better to answer this observation but the only time I have ever heard/read about checking a chamber, they simply took a rd from the competitor and dropped it into a chamber guage.
Looks like a barrel stub with a chamber cut to SAAMI or whatever max dimensions the rules allow.
If the cartridge goes in, good to go. If it doesn't, chamber is out of spec and illegal.
With F TR, being able to 'game' the dimensions would allow for more powder to be used which is an advantage.
I really don't think I would see anyone checking any chamber until we shoot at the prov or nats.
But it is a good idea to take out your calipers and check your brass. SAAAMI max dimensions is only a few thou larger then what you see in cartridge dimensions in reloading manuals.
With the wide range of custom reamers, it is possible to get an oversized chamber cut.
Keeps from embarassing moments at a match....
Jerry
Looks like a barrel stub with a chamber cut to SAAMI or whatever max dimensions the rules allow.
If the cartridge goes in, good to go. If it doesn't, chamber is out of spec and illegal.
With F TR, being able to 'game' the dimensions would allow for more powder to be used which is an advantage.
I really don't think I would see anyone checking any chamber until we shoot at the prov or nats.
But it is a good idea to take out your calipers and check your brass. SAAAMI max dimensions is only a few thou larger then what you see in cartridge dimensions in reloading manuals.
With the wide range of custom reamers, it is possible to get an oversized chamber cut.
Keeps from embarassing moments at a match....
Jerry
rnbra-shooter
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- New Brunswick
Hi stormdog welcome to the game, I hope you build a great F/TR rifle and have a lot of fun and success shooting it.
As far as I know the question of tight necks in F/TR has never formally been "tested", so it is open to speculation how a future Match Committee might rule on such a challenge. My own guess is that there's a good chance that they might take a plain reading of rule F2.3 and disallow tight necks. Also, were the ICFRA F Class Committee asked their opinion on this, my guess is that they might come to the same conclusion; I don't know if it would be a good idea to formally ask them, or if it would be better to not ask.
To be honest, it probably is true that if you simply used a tight neck and never said anything about it you would probably never be "caught". And if you were "caught", some people (including probably me) would view it as a technical but essentially irrelevant infraction of the rules that did not result in any unfair advantage being gained. Though there probably would be some people who would be offended at a deliberate attempt to do something against the rules, regardless of advantage gained or not.
Perhaps more important though, the assumption underlying your question should be addressed. Put simply, TIGHT NECKS DO NOT HELP ACCURACY. While some extremely accurate rifles (mostly BR rifles) do sport tight neck chambers for a variety of good reasons, their accuracy is not aided by their tight necked chamber. And there is nothing I know about loading for improved accuracy that requires or is helped by having a tightly fitted neck. BR shooters use very close-fitted necks for ammo loading convenience and for super extended brass life. I am willing to bet that a world-class BR rifle (i.e. the most accurate rifles in the world) could have its neck diameter opened up .010" in diameter and the rifle would still shoot to the same accuracy.
I would therefore recommend that you find out what kind of chambers winning F/TR shooters are using, and either use one of those chambers, or you'd like a customized chambering, derive your chamber specs from looking at what is used to win. You will find that tight neck chambers are *NOT* used to win in F/TR shooting.
The 2009 F Class World Championship F/TR winner was Russell Simmonds, who won with a pretty plain jane setup, and by quite an impressive margin too. I asked him what chamber he used , and he told me that it was a SAAMI spec standard neck, using a reamer made by Dave Kiff.
Chamber specs to worry and fuss about would be throat length (it would be nice to choose a throat length so that you are perfectly matched to the bullet you are using. A Lapua 155 for example needs quite a different throat length than a Sierra #2156). And perhaps also throat diameter or leade angle.
Though to be honest, the simplest though most unadventurous way to build a competitive F/TR rifle would be just to call up Dave Kiff and order the same reamer that was used to build Russell's rifle, look up Russell's ammo details on the internet (Berger 155.5 and H4895, if I recall - i.e. first rate stuff, but nothing magic), then do some load development work and fine tuning. There really is nothing preventing you from building an F/TR rifle fully capable of winning a World Championship. Which BTW will as a cute parlour trick will also safely chamber and fire commercial hunting ammo, military hardball or tracer ammo etc.
As far as I know the question of tight necks in F/TR has never formally been "tested", so it is open to speculation how a future Match Committee might rule on such a challenge. My own guess is that there's a good chance that they might take a plain reading of rule F2.3 and disallow tight necks. Also, were the ICFRA F Class Committee asked their opinion on this, my guess is that they might come to the same conclusion; I don't know if it would be a good idea to formally ask them, or if it would be better to not ask.
To be honest, it probably is true that if you simply used a tight neck and never said anything about it you would probably never be "caught". And if you were "caught", some people (including probably me) would view it as a technical but essentially irrelevant infraction of the rules that did not result in any unfair advantage being gained. Though there probably would be some people who would be offended at a deliberate attempt to do something against the rules, regardless of advantage gained or not.
Perhaps more important though, the assumption underlying your question should be addressed. Put simply, TIGHT NECKS DO NOT HELP ACCURACY. While some extremely accurate rifles (mostly BR rifles) do sport tight neck chambers for a variety of good reasons, their accuracy is not aided by their tight necked chamber. And there is nothing I know about loading for improved accuracy that requires or is helped by having a tightly fitted neck. BR shooters use very close-fitted necks for ammo loading convenience and for super extended brass life. I am willing to bet that a world-class BR rifle (i.e. the most accurate rifles in the world) could have its neck diameter opened up .010" in diameter and the rifle would still shoot to the same accuracy.
I would therefore recommend that you find out what kind of chambers winning F/TR shooters are using, and either use one of those chambers, or you'd like a customized chambering, derive your chamber specs from looking at what is used to win. You will find that tight neck chambers are *NOT* used to win in F/TR shooting.
The 2009 F Class World Championship F/TR winner was Russell Simmonds, who won with a pretty plain jane setup, and by quite an impressive margin too. I asked him what chamber he used , and he told me that it was a SAAMI spec standard neck, using a reamer made by Dave Kiff.
Chamber specs to worry and fuss about would be throat length (it would be nice to choose a throat length so that you are perfectly matched to the bullet you are using. A Lapua 155 for example needs quite a different throat length than a Sierra #2156). And perhaps also throat diameter or leade angle.
Though to be honest, the simplest though most unadventurous way to build a competitive F/TR rifle would be just to call up Dave Kiff and order the same reamer that was used to build Russell's rifle, look up Russell's ammo details on the internet (Berger 155.5 and H4895, if I recall - i.e. first rate stuff, but nothing magic), then do some load development work and fine tuning. There really is nothing preventing you from building an F/TR rifle fully capable of winning a World Championship. Which BTW will as a cute parlour trick will also safely chamber and fire commercial hunting ammo, military hardball or tracer ammo etc.
If the rules state SAAMI or CIP, then tight necks are not allowed, which answers the question, as opposed to discusion on benefit.
I can provide CIP specs.
Regards,
peterdobson@ns.sympatico.ca
I can provide CIP specs.
Regards,
peterdobson@ns.sympatico.ca
Daniel,
Great post. Just a note that in BR the consensus is that much beyond about .003-.004" clearance and accuracy does suffer, even if only a tiny amount. Theory being that the bullet has a greater chance of getting cocked when the neck expands and releases. True or not, I don't know. I just don't know anyone running more than a few thou of clearance in BR. The debate these days is about a light turn neck vs a heavy turn neck, but both are still tight necked.
Great post. Just a note that in BR the consensus is that much beyond about .003-.004" clearance and accuracy does suffer, even if only a tiny amount. Theory being that the bullet has a greater chance of getting cocked when the neck expands and releases. True or not, I don't know. I just don't know anyone running more than a few thou of clearance in BR. The debate these days is about a light turn neck vs a heavy turn neck, but both are still tight necked.
rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
Thanks Rick, I will certainly defer to a real BR shooter. With a typical chambering and bullet, I wonder if you took bullet:throat clearance, multiplied by shank:throat engagement length at the time of firing, whether it would be plainly demonstrable that more than .002" of bullet cocking would be possible? (I really don't know what current BR chambering practice was; last reamer I had was a pretty vanilla .262 neck JGS 6PPC, about 15 years ago)
A pet theory of mine is that out of a hundred things that we do to help accuracy, 98 of them probably don't matter and we could easily skip them or at least scrimp on them, Trouble is, it's likely more practical to just keep doing all 100 things, rather than truly determining what matters and what doesn't. Which ends up making us all look a little bit superstitous. Did I tell you that I won a big match last year while wearing some stinky felt-lined green rubber boots, in the heat of August? ;-)
A pet theory of mine is that out of a hundred things that we do to help accuracy, 98 of them probably don't matter and we could easily skip them or at least scrimp on them, Trouble is, it's likely more practical to just keep doing all 100 things, rather than truly determining what matters and what doesn't. Which ends up making us all look a little bit superstitous. Did I tell you that I won a big match last year while wearing some stinky felt-lined green rubber boots, in the heat of August? ;-)
SAAMI specifies cartridge maximum and chamber minimum dimensions and manufacturers within signatory countries must be compliant. CIP chamber neck min. is .346", of course converted from metric.
Interesting postings by Dan and the also the informative Mr. Pollock.
An advantage to a tighter neck is also less wear on the neck, which is usually expensive Lapua stuff, for which I thank you!
Regards,
Peter
Interesting postings by Dan and the also the informative Mr. Pollock.
An advantage to a tighter neck is also less wear on the neck, which is usually expensive Lapua stuff, for which I thank you!
Regards,
Peter
Daniel,
No need to defer on anything! We are in this together.
Hard to say what amount of cocking could take place, (if any). Another thing that pops into mind is that necks don't normally release in a perfectly uniform manner (judging by distribution of powder residue around the neck) Usually one side seals before the other.
If I was still in F-class I would never tight neck it. I would want to be able to chamber a variety of rounds and hundreds of preloaded rounds, or if I am stuck for ammo, maybe even borrow a few rounds away from home. I don't want dust or residue over the course of the day to interfere with the chambering of a live round. The accuracy gains would not offset the risk of having to clean the rifle half way through the string.
The vanilla 6PPC 262 reamer is still in use. Latest info from Dave Kiff in terms of popularity is that it is running about 50/50 for the 263 Boyer reamer vs the 269 light turn reamer.
I am happy to report superstition is alive everywhere. Lucky hats, tokens, chicken innards are in use. Voodoo chants are common, but usually said in the head, for fear of revealing all the tricks in one day. Also please advise where can one purchase said boots?
I also agree a lot of what we do may be a feel good exercise. I for one never clean necks, inside or out, but others do . I still clean primer pockets, but others feel it is a waste of time. Who is to say which is better, since it seems to work either way for those competing.
Rick
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rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
Peter raises the main attraction for tight(er) necks - less wear and tear on the brass.
The pluses and minuses of tight necked chambers needs to be considered in the context of fullbore shooting. Just because a certain practice (in this case, tight necks and fitted chambers) is demonstrably the way to win in BR, does not automatically mean that it can be beneficially applied to fullbore (TR and F-Class). A lot of time and effort has been wasted in blindly copying the winning ways from other disciplines (then again, this is one way that progress is eventually stumbled upon, so it's certainly not all bad).
Here's my experience with brass life in conventional .308 target chambers (non tight neck).
Fired brass from my .308 Obermayer chamber measures .343" neck diameter. When I size it, I use a .335" bushing (Lapua brass), so the neck brass is being shrunk .008" each time it is loaded, and expanded .008" each time it is fired. I don't know how long it will be before this causes neck cracking, but it is more than 20 firings - which means, it is long enough that it is economically irrelevant. Whether a piece of brass lasts 20 firings or 40 firings, is the difference between 4 cents a shot for brass life versus 2 cents a shot for brass life.
When I started shooting, I neck-turned a few hundred pieces of '92 Palma brass, in an effort (that I now realize was misguided) to get every last bit of accuracy. I made the necks thinner than I should have, 12.2 thou if memory serves. So a loaded round had a neck diameter of 332.4 thou, which expanded to 343 thou on firing - so the neck was being worked by 11.6 thou each way upon firing (actually it was being worked more than this because I was using a conventional button-type sizer die). This brass started to show neck cracks on the 17th reloading, so it was honourably retired. Even with a newbie mistake like this (making the necks a bit too thin), brass life was more than adequate.
In BR, there are much bigger costs per piece of brass than the buck or so that each case costs - the hour or so of prep time per case springs to mind. So in BR, it is more important that a case last for 100+ firings rather than "merely" 40 firings.
Most people would be amazed at how well good unsorted factory .308 brass (Norma, Winchester, Lapua) will shoot. It's a pretty spectacular level of performance where brass prep becomes worthwhile.
Rick - a funny story on F-Class ammo interchangeability. I was shooting my F/Open rifle in a warmup match at 900m in Ottawa, some number years ago, paired with an American shooter, who started to develop misfires. Turns out that his ammo had gotten wet in a rainshower the night before. I asked him what caliber he was shooting - it was the same as me, 6.5-06. Intrigued, I asked him what reamer he used to cut the chamber - answer, Clymer, the same as mine. I asked him what load he used - a Sierra 142 at (some reasonable speed). I offered him some of my ammo, which was loaded with 139 Lapuas at a pretty similar speed. I am pretty sure that ours were the only 6.5-06s out of the three hundred rifles there that year. Not only did my ammo chamber in his rifle, the first shot of my ammo was only about 14" above the centre of the target (an inner, just out at 12 o clock). I was pretty impressed, it being 900m and all... ;-)
You can get the felt-lined green rubber boots at any reputable redneck supply store. The secret of course, is in how the bootliners are, ummm, "seasoned"... it can take months! ;-)
The pluses and minuses of tight necked chambers needs to be considered in the context of fullbore shooting. Just because a certain practice (in this case, tight necks and fitted chambers) is demonstrably the way to win in BR, does not automatically mean that it can be beneficially applied to fullbore (TR and F-Class). A lot of time and effort has been wasted in blindly copying the winning ways from other disciplines (then again, this is one way that progress is eventually stumbled upon, so it's certainly not all bad).
Here's my experience with brass life in conventional .308 target chambers (non tight neck).
Fired brass from my .308 Obermayer chamber measures .343" neck diameter. When I size it, I use a .335" bushing (Lapua brass), so the neck brass is being shrunk .008" each time it is loaded, and expanded .008" each time it is fired. I don't know how long it will be before this causes neck cracking, but it is more than 20 firings - which means, it is long enough that it is economically irrelevant. Whether a piece of brass lasts 20 firings or 40 firings, is the difference between 4 cents a shot for brass life versus 2 cents a shot for brass life.
When I started shooting, I neck-turned a few hundred pieces of '92 Palma brass, in an effort (that I now realize was misguided) to get every last bit of accuracy. I made the necks thinner than I should have, 12.2 thou if memory serves. So a loaded round had a neck diameter of 332.4 thou, which expanded to 343 thou on firing - so the neck was being worked by 11.6 thou each way upon firing (actually it was being worked more than this because I was using a conventional button-type sizer die). This brass started to show neck cracks on the 17th reloading, so it was honourably retired. Even with a newbie mistake like this (making the necks a bit too thin), brass life was more than adequate.
In BR, there are much bigger costs per piece of brass than the buck or so that each case costs - the hour or so of prep time per case springs to mind. So in BR, it is more important that a case last for 100+ firings rather than "merely" 40 firings.
Most people would be amazed at how well good unsorted factory .308 brass (Norma, Winchester, Lapua) will shoot. It's a pretty spectacular level of performance where brass prep becomes worthwhile.
Rick - a funny story on F-Class ammo interchangeability. I was shooting my F/Open rifle in a warmup match at 900m in Ottawa, some number years ago, paired with an American shooter, who started to develop misfires. Turns out that his ammo had gotten wet in a rainshower the night before. I asked him what caliber he was shooting - it was the same as me, 6.5-06. Intrigued, I asked him what reamer he used to cut the chamber - answer, Clymer, the same as mine. I asked him what load he used - a Sierra 142 at (some reasonable speed). I offered him some of my ammo, which was loaded with 139 Lapuas at a pretty similar speed. I am pretty sure that ours were the only 6.5-06s out of the three hundred rifles there that year. Not only did my ammo chamber in his rifle, the first shot of my ammo was only about 14" above the centre of the target (an inner, just out at 12 o clock). I was pretty impressed, it being 900m and all... ;-)
You can get the felt-lined green rubber boots at any reputable redneck supply store. The secret of course, is in how the bootliners are, ummm, "seasoned"... it can take months! ;-)
Somebody should sticky these posts of your Daniel! Good stuff.
Peter, you should skip this next comment.
I was one of those guys getting 100+ firing on PPC brass. Back when a PPC case traded for $2 each in the 90's, you never threw one out. Shooters would pick them out of the garbage if you did. These days the cases get tossed probably by the 20th firing or maybe 40th firing if it seems to be working particularly well. The reason is work hardening. Everybody seems to be shooting hot as compared to years ago and the brass just can't take it. As good as Lapua is, at some point the brass gives up, no amount of bumping or fancy sizing dies will save it. It will be hard to extract, causing too much upset in the bags. The work hardening and inability to take high pressure is also why you don't see much (if any) Norma or Sako PPC brass at a BR match. Norma has a new case coming out this year for the 6PPC, it will be interesting to see if it can compete with the Lapua 220 Russian.
Rick
Lots of F/Tr shooters are running chambers w/.341 necks and Lapua brass. If you call Dave Kiff and tell him you want to shoot Lapua brass, this is what he suggests. That gives me 0.004 clearance on my .337 loaded round. Life is way too short to turn necks on enough brass for the CFRC's or FCWC (especially is paired w/ the Imperial meeting) This is especially true when we have access to such fantastic brass. I sorted 600 pcs of new Lapua brass last winter, and culled one case. 599 were within 1.5 grains.
I do know of at least one Canadian F/Tr shooter running a .333 neck w/ turned Lapua brass. I don't care to protest, since I figure it doesn't help him, and probably raises enough blisters that it may hinder him!
I do know of at least one Canadian F/Tr shooter running a .333 neck w/ turned Lapua brass. I don't care to protest, since I figure it doesn't help him, and probably raises enough blisters that it may hinder him!
lejarretnoir
CGN Ultra frequent flyer
- Location
- 162km from Connaught
I'm fairly certain the main reason to turn necks back in the day was to get a concentric diameter around the neck especially when fireforming and/or reducing/expanding necks to different calibers. I can see the logic where a neck .001 thicker or more on one side would not line up in a chamber perfectly.
Tight necked BR chambers make it so you must turn the neck because the chamber dictates. I can see where the BR crowd are now disputing light vs heavy neck turning. Are thin or thicker concentric necks more accurate?
In F-Class Unlimited I usually tailor the reamer for the brass where no neck turning takes place, but also no more than .004-5 fired neck dia. There is no need for tight neck nor too loose either. I don't like oversized fired necks because I usually revert to partial neck sizing to have some neck alignment then in the chamber.
FWIW, slightly tightening the neck is just to save neck reworking and I've never found any accuracy advantage. That's my story and I'm sticking with it.
Tight necked BR chambers make it so you must turn the neck because the chamber dictates. I can see where the BR crowd are now disputing light vs heavy neck turning. Are thin or thicker concentric necks more accurate?
In F-Class Unlimited I usually tailor the reamer for the brass where no neck turning takes place, but also no more than .004-5 fired neck dia. There is no need for tight neck nor too loose either. I don't like oversized fired necks because I usually revert to partial neck sizing to have some neck alignment then in the chamber.
FWIW, slightly tightening the neck is just to save neck reworking and I've never found any accuracy advantage. That's my story and I'm sticking with it.
