Chamber dimensions to allow not cleaning

[HighUintas]

Let's try to actually keep this one on track.

The topic is what chamber dimensions/clearances are needed to allow no cleaning.

Form have you had any barrels with a total neck clearance of 0.003 or throat clearance of 0.0005 that have gone thousands of rounds with no cleaning and no ill effect?

 

[Formidilosus]

Form have you had any barrels with a total neck clearance of 0.003 or throat clearance of 0.0005 that have gone thousands of rounds with no cleaning and no ill effect?

No clue. Factory barrels are what they are, aftermarkets are spec’d by the gunsmith with a discussion of my expectations. Most have been standard SAAMI chambers, a few have been throated for the bullet I wanted to shoot.

 

[Wrench]

The truth is there are probably not 10 guys on this forum that can legitimately measure to the tenths. I'm sure there's a hundred who claim they can with their midway Chinese calipers though.

 

[Article 4]

He means absolute minimal condition change affecting rifle zero/poi shifts. There's never a state of significant change due to cleaning, just an evolution(or lack there of) of the dirty fouled bore.

Didnt reply for some time as I wanted to think through a reply. Thanks for trying to clarify and I would have appreciated the person saying it, explaining their own term.

Before I began learning and growing in the rifle community, I had an extensive career in math and science. I hope this is seen as paying things forward.

Static Zero Tension in a rifle barrel is not possible / in a clean or dirty barrel it does not exist.
Universal Rule: The only way to have zero tension is to have two bodies move in circular motion around each other without touching. (Imagine two planets orbiting each other) Result: There is no friction because the objects are not touching.

In a rifle barrel we are talking about a Coefficient of friction, ratio of the frictional force resisting the motion of two surfaces in contact to the normal force pressing the two surfaces together. It is usually symbolized mathematically by the symbol mu or μ = F/N, where F is the frictional force and N is the normal force. There are two actions taking place in a rifle barrel (well 4 but i will address the two we are discussing) where two separate objects with unlike unlike and unmatching compounds are creating tension. Objects rotating around each other experience friction. e.g. bullet in a rifle barrel. There will always be a coefficient of friction.

In a rifle barrel, when two bodies are touching there will always be tension. Add or subtract any additional gaining surface e.g. fouling and adding additional compounds to the surface area, you change the rate of friction.

Will their be outliers, always; due to the fact that we are dealing with 300 million variables (the number of guns in the US per FBI and an endless combination of variables in bbl metalurgy, bullets, powder burn rates etc....)

Does it affect accuracy, I believe over time it does. Perhaps you don't. Great. Ill clean my bbl and you wont. Cool

 

[atmat]

I believe over time it does.

You are welcome to believe whatever you like. But as you’ve acknowledged, you’re never tested your theory — it’s entirely theoretical with no experimental results.

Believing in things doesn’t make them true. Lots of people believe lots of silly things.

 

[wind gypsy]

Didnt reply for some time as I wanted to think through a reply. Thanks for trying to clarify and I would have appreciated the person saying it, explaining their own term.

Before I began learning and growing in the rifle community, I had an extensive career in math and science. I hope this is seen as paying things forward.

Static Zero Tension in a rifle barrel is not possible / in a clean or dirty barrel it does not exist.
Universal Rule: The only way to have zero tension is to have two bodies move in circular motion around each other without touching. (Imagine two planets orbiting each other) Result: There is no friction because the objects are not touching.

In a rifle barrel we are talking about a Coefficient of friction, ratio of the frictional force resisting the motion of two surfaces in contact to the normal force pressing the two surfaces together. It is usually symbolized mathematically by the symbol mu or μ = F/N, where F is the frictional force and N is the normal force. There are two actions taking place in a rifle barrel (well 4 but i will address the two we are discussing) where two separate objects with unlike unlike and unmatching compounds are creating tension. Objects rotating around each other experience friction. e.g. bullet in a rifle barrel. There will always be a coefficient of friction.

In a rifle barrel, when two bodies are touching there will always be tension. Add or subtract any additional gaining surface e.g. fouling and adding additional compounds to the surface area, you change the rate of friction.

Will their be outliers, always; due to the fact that we are dealing with 300 million variables (the number of guns in the US per FBI and an endless combination of variables in bbl metalurgy, bullets, powder burn rates etc....)

Does it affect accuracy, I believe over time it does. Perhaps you don't. Great. Ill clean my bbl and you wont. Cool

Dude, that's a lot of deep thinking to address if a bore condition and it's impacts on shooting change more on a recently cleaned bore vs a never cleaned one.

For the record, the never clean thing has not worked for me. I generally trust what Form has to say but not cleaning seems to cause issues with some of my rifles so i understand what @HighUintas is trying to understand with this thread.

 

[Article 4]

Dude, that's a lot of deep thinking to address if a bore condition and it's impacts on shooting change more on a recently cleaned bore vs a never cleaned one.

For the record, the never clean thing has not worked for me. I generally trust what Form has to say but not cleaning seems to cause issues with some of my rifles so i understand what @HighUintas is trying to understand with this thread.

Yeah I agree we need to stay on task. I hope we are helping @HighUintas

Cleaning or not cleaning is a personal choice. He now has a ton of info to help him decide.

My input was an attempt was to share my experience as a builder, ballistician, wildcat caliber freak, and bbl maker. My name here has a label of FNG but that is not always the case. If folks here took that as a personal afront, let me apologize for that now.

 

[Formidilosus]

not cleaning seems to cause issues with some of my rifles so i understand what @HighUintas is trying to understand with this thread.

What rifles did you have issues not cleaning, what were the loads, how were they loaded, and what were those issues?

I want to know, because I/we meet people that say that, and actually tell me the exact combo that causes it, and yet when I buy the same barrel and cartridge, I/we don’t have those issues. Every single time I have worked with someone that has to clean or they have precision degradation or “pressure” issues, it has come down to them getting cute with chambers and loads- really minimum spec chambers, loaded touching or close the lands, and running with “barley” pressure or “near” pressure signs (which means already over 65k); and/or they are making determinations with small sample sizes. I don’t think you or Lawnboi are unintelligent or doing something wrong- I am also wanting to know why I, and everyone I am around don’t clean, and don’t have issues.

 

[Formidilosus]

For some clarity maybe, these are the cartridges and barrels I have used extensively, or have watched used extensively for most of their barrel life in the last 5 years. Quite a few forum members have shot these barrels and seen these barrels shot for several thousand rounds, and watched them stack groups afterwards.

5.56mm chrome lined- more than 50. No barrel has had to be replaced before 10,000 rounds, and all maintained the same 30 round group size for that time- zero cleaning, zero issues.

223 Factory Tikka/Sako and multiple aftermarket barrels (proof, X caliber, Rock Creek, etc)- more than 20. None have had to be replaced before 4,000 rounds and that was on heavy use on gas guns and very damaging bullets/ammo. The rest have all made 10k plus. Some of the after-market barrels opened up a bit around 6k rounds from 1.1-1.3 MOA for 30 rounds, to 1.3-1.6 MOA for 30 round groups. By far the best/longest lasting barrels have been Tikka factory barrels. Zero cleaning, zero issues.

243win/6ARC/6XC/6cm- 8 to 10 barrels in those various chamberings. Never cleaned and barrel life was as expected- 1,500-2,000 rounds for the 6cm’s, still haven’t shot out a 6ARC. The 6XC’s are between 700-900 rounds know, with no issues and no cleaning.

6.5cm- about 20. Various factory barrels, and multiple different aftermarket barrels. Had one aftermarket 6.5cm go wonky at around 450 rounds with a bad fit. The replacement is around 900 right now and is shooting better than when new. Other than that, all 6.5’s have lasted as expected with normal shooting going for 3k’ish rounds, heavy/hot firing going for 2k to 2.5k rounds. The best/longest lasting have been Tikka factory barrels. Zero cleaning, zero issues.

A handful of 6.5 PRC’s- only one has been replaced at between 1,200-1,500, the rest are between 500 and 1,000 rounds. Zero cleaning, zero issues.

308’s- 20 plus. None have been replaced due to being shot out. One on a comp rifle was pulled thinking it has went at about 14,000 rounds because 10 round groups had went from just under 1 MOA in demand, to randomly producing 1.3-1.4 MOA groups. The gunsmith found out the barrel was loose and was unscrewed by hand without tools. Have multiple that are between 8,000 and 12,000 rounds and still average around 1 MOA for ten round groups. One is between 18,000 and 20,000 and it’s last ten round group was .7” at 100 yards. Never cleaned. The best/longest lasting have been Tikka factory barrels.

300wm, Norma, etc- 10’ish. All lasted as expected- 1,000- 2,500 rounds depending on use. Zero cleaning, zero issues.

338L, 338NM- 5-7. All lasted as expected. Zero cleaning, zero issues.




Beyond those, there are various cartridges mixed in, but none with enough different barrels being shot out to say much. 3x 6UM’s that I know of- Ryan’s two with 650’ish in his first still shooting great before being turned into a FF barrel, and I believe around 400 on his current; and mine with about 150 rounds- zero cleaning, zero issues. 300 RUM’s with 500+ rounds zero cleaning, zero issues. I don’t believe Ryan has cleaned his 33XC barrel either, though I’m not sure how many rounds are on it. A couple/few 22CM’s, but none have been replaced that I remember due to being shot out.

Again, I’m not saying that there aren’t combinations that have issues, but something other than “barrels need to be cleaned” is going on when I can walk into Scheels today, buy a rifle with a good barrel, buy a barrels worth of ammo for that rifle, shoot all that ammo and never clean and never have issues.

 

[TaperPin]

SAAMI specs for the throat diameter in many of the newest cartridges is .0005” over bullet diameter, with the tolerance of - 0000” +.0020”. So throats may be .0005” over or up to .0025” over and still be within spec.

Chamber reamers aren’t cheap so we could all agree there is a big incentive to buy reamers on the large extreme of the spec so they can be sharpened multiple times before being too small and needing to be replaced. There’s also a competing incentive to prevent the customer service phone from ringing, so the larger the throat the fewer phone calls for carbon rings, and it would make sense that many companies would retire the reamer before minimum specs are reached.

Christensen is often picked on for carbon rings and I would bet lunch those problem rifles simply have been cut with reamers on their last sharpening before being too small to still meet spec. Maybe they try to cut all minimum chambers with retired reamers used previously on barrels for other companies. Do they chamber for other companies? Whatever the reason for the barrels that need cleaning, I’m glad they do - so far I have nearly new takeoff barrels in 6.5 PRC, 7mm08, 300 PRC and maybe 6.5 Creed and 28 Nosler if I win those auctions. *chuckle*

Carbon rings were almost unheard of in production rifles prior to the Creed/PRS/ARC mainly because the SAAMI minimum was so big. The 243 has a MIN throat of .2463”, or .0033” over bullet diameter - and goes clear up to .0053” with allowable tolerance. Hotdog down a hallway.

 

[Chris_in_Idaho]

Static Zero Tension in a rifle barrel is not possible / in a clean or dirty barrel it does not exist.
Universal Rule: The only way to have zero tension is to have two bodies move in circular motion around each other without touching. (Imagine two planets orbiting each other) Result: There is no friction because the objects are not touching.

I think we might be confusing "zero tension" with "zero retention"?

I'm pretty sure Form meant the rifle's zero (poi/poa) doesn't change. Not whether tension exists...
 

 

[wind gypsy]

What rifles did you have issues not cleaning, what were the loads, how were they loaded, and what were those issues?

I want to know, because I/we meet people that say that, and actually tell me the exact combo that causes it, and yet when I buy the same barrel and cartridge, I/we don’t have those issues. Every single time I have worked with someone that has to clean or they have precision degradation or “pressure” issues, it has come down to them getting cute with chambers and loads- really minimum spec chambers, loaded touching or close the lands, and running with “barley” pressure or “near” pressure signs (which means already over 65k); and/or they are making determinations with small sample sizes. I don’t think you or Lawnboi are unintelligent or doing something wrong- I am also wanting to know why I, and everyone I am around don’t clean, and don’t have issues.

Current example is a tikka with a benchmark chambered in 6 creedmoor. Seems that approaching 100 rounds fired i start getting sticky bolt lift and degrading accuracy. Its only in the lower 300's IIRC total rounds on the barrel but twice now after cleaning the sticky bolt lift and ejector stamps go away. That's with virgin alpha and 40-41 grains of h4350 behind 108 EH or 106 TAP and numerous factory ammo options (hornady black 105, match 108, sig match 107smk, barnes 95LRX, norma 107GT).

That said, i do think the chamber machining on this barrel is less than ideal and I may send it elsewhere to get set back and rechambered. Freebore should be close to SAAMI now. I had to send it back right away because it started with a short throat meant for bergers even though it was supposed to be a SAMMI reamer.

I've had other rifles that i let go for a while that just seemed to shoot better after cleaning but cant remember anything where the dirty barrel was shooting like garbage and pulled a complete 180.

 

[Formidilosus]

That said, i do think the chamber machining on this barrel is less than ideal and I may send it elsewhere to get set back and rechambered. Freebore should be close to SAAMI now. I had to send it back right away because it started with a short throat meant for bergers even though it was supposed to be a SAMMI reamer.

Thank you. This is what I’ve seen when it has been an issue- chamber and/or load.

Have shot a couple of benchmark 6cm’s. I believe Ryan’s is a Benchmark and has well over 2,000 rounds. The last ten round groups I saw from his was something around .8 and 1.1 MOA.

 

[Mike D Texas]

What rifles did you have issues not cleaning, what were the loads, how were they loaded, and what were those issues?

I want to know, because I/we meet people that say that, and actually tell me the exact combo that causes it, and yet when I buy the same barrel and cartridge, I/we don’t have those issues. Every single time I have worked with someone that has to clean or they have precision degradation or “pressure” issues, it has come down to them getting cute with chambers and loads- really minimum spec chambers, loaded touching or close the lands, and running with “barley” pressure or “near” pressure signs (which means already over 65k); and/or they are making determinations with small sample sizes. I don’t think you or Lawnboi are unintelligent or doing something wrong- I am also wanting to know why I, and everyone I am around don’t clean, and don’t have issues.

I’m the guy you are talking about here. The only SAAMI chambers I run are 223 & 308 otherwise all of my other cartridges and rifles are an improved version of some sort and ran hot and fast.

I say that to reinforce your point about not cleaning. My 264 Win Mag AI running 156 Bergers with 570 and seated at the lands is the only rifle I’ve seen any issues with and it was from a carbon ring in front of the case mouth.

I scrubbed it out with IOSSO and back to shooting normal. But accuracy never degraded.


Sent from my iPad using Tapatalk Pro

 

[HighUintas]

My chamber reamer's throat is spec'd at 0.3085, neck is 0.342. loaded round is 0.3375. All diameters tolerance -0.00/+ 0.001. Barrel is mullerworks, 10 twist.

Cartridge is 30-284ai, basically a 30-06 with nearly identical case capacity.

Load was 185 juggs, cci200, 55.5gr h4350. Avg speed 2825fps

I had started getting sticky bolt lift and ejector marks last fall, after about 150 or so rounds without cleaning, where I was initially 1.0gr below ejector marks. I was also seeing higher velocity. I scrubbed the throat with JBs to get to bare metal, and that seemed to fix it.

I wasn't able to keep investigating that due to running out of 185 jugg tactical and my only replacement was 185 jugg target,. They measure slightly differently. And I ran out of that lot of h4350.

I'm now close to round count 75 without cleaning again. Since I didn't try dropping charge weight previously... I'll keep going without cleaning.

Figure out 30 round zero, 30 round group size, and 30 round avg speed. I'll keep it going until it seems something changes and then do another 30 round check. If I see pressure signs and speed jumps, I'll drop charge weight. If accuracy goes to pot, I'll just say this barrel needs to be cleaned.

If it needs to be cleaned, I'll consider getting it throated to 0.310ish and try again.

 

[TaperPin]

My chamber reamer's throat is spec'd at 0.3085, neck is 0.342. loaded round is 0.3375. All diameters tolerance -0.00/+ 0.001. Barrel is mullerworks, 10 twist.

Cartridge is 30-284ai, basically a 30-06 with nearly identical case capacity.

Load was 185 juggs, cci200, 55.5gr h4350. Avg speed 2825fps

I had started getting sticky bolt lift and ejector marks last fall, after about 150 or so rounds without cleaning, where I was initially 1.0gr below ejector marks. I was also seeing higher velocity. I scrubbed the throat with JBs to get to bare metal, and that seemed to fix it.

I wasn't able to keep investigating that due to running out of 185 jugg tactical and my only replacement was 185 jugg target,. They measure slightly differently. And I ran out of that lot of h4350.

I'm now close to round count 75 without cleaning again. Since I didn't try dropping charge weight previously... I'll keep going without cleaning.

Figure out 30 round zero, 30 round group size, and 30 round avg speed. I'll keep it going until it seems something changes and then do another 30 round check. If I see pressure signs and speed jumps, I'll drop charge weight. If accuracy goes to pot, I'll just say this barrel needs to be cleaned.

If it needs to be cleaned, I'll consider getting it throated to 0.310ish and try again.

Lots of good info. I keep looking for someone who knows their chamber and history like you do, then opens up the throat a known amount and can describe the difference. Definitely keep us in the loop if you do it.

 

[Sandstrom]

My chamber reamer's throat is spec'd at 0.3085, neck is 0.342. loaded round is 0.3375. All diameters tolerance -0.00/+ 0.001. Barrel is mullerworks, 10 twist.

Cartridge is 30-284ai, basically a 30-06 with nearly identical case capacity.

Load was 185 juggs, cci200, 55.5gr h4350. Avg speed 2825fps

I had started getting sticky bolt lift and ejector marks last fall, after about 150 or so rounds without cleaning, where I was initially 1.0gr below ejector marks. I was also seeing higher velocity. I scrubbed the throat with JBs to get to bare metal, and that seemed to fix it.

I wasn't able to keep investigating that due to running out of 185 jugg tactical and my only replacement was 185 jugg target,. They measure slightly differently. And I ran out of that lot of h4350.

I'm now close to round count 75 without cleaning again. Since I didn't try dropping charge weight previously... I'll keep going without cleaning.

Figure out 30 round zero, 30 round group size, and 30 round avg speed. I'll keep it going until it seems something changes and then do another 30 round check. If I see pressure signs and speed jumps, I'll drop charge weight. If accuracy goes to pot, I'll just say this barrel needs to be cleaned.

If it needs to be cleaned, I'll consider getting it throated to 0.310ish and try again.

I was under the impression that the juggernauts were identical, what are you getting for different measurements?

 

[HighUintas]

I was under the impression that the juggernauts were identical, what are you getting for different measurements?

View attachment 668665

If you look at their bullet spec sheet, they have slightly different numbers for the length and I think the other is boattail length.

With mine, the length and base to ogive were different. I unfortunately didn't write any of those numbers down, but they were different enough that I thought there may be an effect on poi. It's possible it was within their tolerances for spec for a single product, but I wouldn't think so. Seemed like two very similar bullets.

The most unfortunate part is that I found out right after using all the older bullets that my rear action screw was loose and was the cause of some poi shifting I'd noticed. So I didn't have a good zero to compare the components to

 

[Formidilosus]

If you look at their bullet spec sheet, they have slightly different numbers for the length and I think the other is boattail length.

With mine, the length and base to ogive were different. I unfortunately didn't write any of those numbers down, but they were different enough that I thought there may be an effect on poi. It's possible it was within their tolerances for spec for a single product, but I wouldn't think so. Seemed like two very similar bullets.

The most unfortunate part is that I found out right after using all the older bullets that my rear action screw was loose and was the cause of some poi shifting I'd noticed. So I didn't have a good zero to compare the components to

They’re the same bullet. They can vary slightly between lots. I’ve have “Target” and “Tactical” Juggernauts in the same mag mixed together. Same/same.

 

[Frank Green]

I 100% agree. It doesn't seem like it should be a thing.

Apparently, it's a thing for Ryan and Form which is why I tagged them in the first post.

Form was saying that cleaning isn't needed for the 22cm. I can't see that working except for having certain tolerances.

I want to know. Because I don't want to clean.

Not poking at you or anyone here but we get this a lot... and we will say this...

Would you drive your car and never change the oil and filter?

I will also say the following in no random order....

Type of powder and cartridge/case capacity is a huge variable. The bigger the case capacity and or the smaller the bore size fouling goes up. You will have to clean it more often.

Some cartridges like 308win vs bore size are vary forgiving. A 300wm or a 300 Norma won't be forgiving. Same for a 6BR vs a 243win or a 6CM. By increasing the case capacity you have turned 243w and 6CM into magnum rounds.

Type of powder and quality of powder. I do think there is a powder quality problem and or availability issues. This in turn is causing a fouling pressure problems which in turn causes accuracy and pressure issues to the point of piercing primers etc... I/we've been seeing issues with box ammo and the powder being used to load the box ammo... and it causing fouling/pressure issues. I just seen it this past November and go figure it was with a 308w gun.

You make the throat freebore diameter bigger and you effect barrel life as well as you will effect accuracy issues. Bigger doesn't mean better... tighter doesn't mean better either. If I had to pick a number I'd say .001" to .0015" on the freebore diameter vs the bullet diameter for clearance. That's as big as I would want to go and still maintain a high accuracy level. You might get away with a +.002" diameter on the throat vs bullet diameter but after that you get what you get. Loaded ammo/bullet runout will also come into play here as well.

Also not talked about is bullet quality or should I say consistency in bullet diameter/sizes.

I hate cleaning as much as the next guy but I will say this... I shoot it... I clean it. Don't clean and you will have issues somewhere down the line. Your just asking for it.

Later, Frank
Bartlein Barrels