The First Thousand Shots

[phlegethon]

I've not been impressed with search functions in most online forums. Tim, perhaps you could link some of these threads, if you find them easy to locate?

 

[sniperstudent]

Well that's some ahhh..... good information Tim. Nice pedigree. I usually let my grandkids stick their hand in the fire so they can learn for themselves. Keep up the good work justin ,helping out the common man.

 

[oldfatguy]

Why would I get annoyed ?
nothing on a forum annoys me, it’s kind of like yelling at the puppy for wizzing on the rug, ultimately, they grow up.
For Justin, it is very simple, fairly bad methodology.
when you take pictures before and after, BUT, you improperly clean your barrel, precisely what you learning ? Any valid testing should incorporate some discipline about your testing procedures as much as your tests, why I deleted my posts, these likely to follow soon.
Trying for answers....very worthy exercise. Not asking the right questions to begin with.....not so much.
As I said before.....not really my opinions. Don’t kill the messenger.

Ok Tim. What is the right question?

OFG

 

[justin amateur]

Tim, if you have more data, add it.
I don't make any claims to being anything other than just another interested amateur.
There are a butt load of forum posts, but all anecdotal.

Web search Rimfire barrel break-in

When you read through them, there are so many contradicting opinions
you really do end up having to prove it for y'erself.

 

[justin amateur]

You'd like to know the topics I researched before starting this?

Hammer forging
Steel alloys used in barrels
Button cut
Single cut
Chamber reamers
Barrel machining
Abrasives
Hydraulic lapping
Material hardness
Hand lapping
Solvents
Chemical composition of primer and powders
Chemical composition of the burn residue of primers and powders
Leade erosion
Pitting
Crown erosion
Barrel break-in
Barrel wear
Barrel damage
Sleeving
Lead deposition
Copper deposition
Bullet lubricants
Bullet heel expansion
Bullet defects and trajectories
Borescopes
Pressure variations relative to bullet location in the barrel
Forensics involving firearms

One topic links to another.
Before you realize it you've accumulated an amazing amount of technical information.

None of which answered my question.
What happens to the bore of a 22lr rifle during the first 1000 rounds?
I'm finding out.

 

[drglock]

Justin the ignore button is an awesome feature.

 

[oldfatguy]

Justin, that there kind of illustrates a point.
Did you really do ONE search on RF barrel break in ?? Could prove useful if that was actually a thing.
How about RF barrel wear, RF barrel life, RF barrel erosion, and on and on ?
How about searches on the appropriate forums?
It took me about 10 minutes to find a pantload of stuff.

Still waiting for your “right question”.

OFG

 

[Tim7139]

Justin the ignore button is an awesome feature.

Less time on snarky posts, more time learning how to measure groups(0 for 6).

 

[justin amateur]

Ignore Tim? Not happening.
He was the one who pointed out I lacked documented facts
necessary to support my thoughts regarding barrel wear.
This thread wouldn't exist if he hadn't made that observation.
As long as he keeps posting, I'll keep reading what he has to offer.
At this point, all I'm doing is collecting information.
When it's complete, I expect a lengthy critique.

 

[Gleedus]

@AGrizz...that's my problem, couldn't find any documentation of rimfire barrel wear during the first 1000 shots.
Plenty of opinions as to what is occurring and claims of improved accuracy after 2 bricks of 22lr sent.
However, no actual documentation of change over time. That's what Tim pointed out in a previous thread.
I was basing my comments on unsubstantiated information. A search of the internet showed he was correct.
Opinions and anecdotal evidence aplenty, hard data/images none with rimfire. When ya' can't trust y'er information
ya' have to try it for y'erself. I've been doing that with rimfire for about 9 years .
Determining if those internet rimfire truisms are based on fact or wishful thinking.
Things like free floated barrels, find the brand y'er rifle likes, sub-moa all day long,
precision shooting with 17hmr and 22wmr, consistent accuracy at 200 yards, supersonic transition.
Try 'em, document 'em, figure out what works and what are incorrect conclusions based on minimal data.
Everyone needs a hobby, rimfire keeps me occupied.

I think Tim might be a bit annoyed that I don't agree with his opinions/experiences.

It's possible I might have pissed him off-fa-fa.

I do affect some folks that way.
Likely because I question everything.

The Free floated barrel and find the brand your rifle likes... I'm listening!! Well ok I dont care on the free floated barrel thing because i have seen rifles that shoot better with some pressure at the forend and some that dont.

But seriously do you have any thoughts on what makes a rifle like a certain ammo. Be it a brand or a lot. Is it just vudoo and you have to test them all? Or will a rifle have a tendency to prefer something regardless of lots etc.
Now I'm thinking mostly regarding the 200 yds. (50s boring) yes I know ammo..... but but some shoot better then others why? Just because the ammo is more consistent? Or??? Is there a link that any ammo with that characteristics likes? Certain velocity, bullet weight, certain bullet, etc?

Subsonic vs HV? well on average the HV shoots as good or better then the SV at 200. So I think its something else.

Off topic but you brought it up first.

I'm easily entertained too. Wife says boring... what ever that is...

Hey I enjoy you posts and ability to take peoples jabs non-personal and have fun!

Tim I like your making sure Justin keeps it on the straight and narrow lol!

 

[~JM~]

Tim I like your making sure JM keeps it on the straight and narrow lol!

If that is a reference to me, I'd like to know the cause. Can't recall making any controversial comments.

 

[Gleedus]

If that is a reference to me, I'd like to know the cause. Can't recall making any controversial comments.

Sorry my bad! I was thinking JA in my head but....

 

[justin amateur]

Find the brand y'er rifle likes is a lie.
The label on the box is not a guarantee that you'll obtain predictable trajectories.
Find cartridges with tight muzzle velocities and minimal defects, you get great results.
I've actually tried every rimfire brand available for purchase to determine if there was any truth in it.
Brand made no difference. Only cartridge quality. Eley, Lapua, RWS, SK all did well.
And then the next box purchased didn't. Why? MV spread, varying bullet seating, bullet shape differed.
When I obtained a brick of properly assembled cartridges, results were good in all my 22lr rifles.
When I received cartridges with visible problems and mv spread,
they produced poor results in all my rifles.
That's why lot testing is critical for top level competition.
Finding those better cartridges isn't easy. Even though they all may have the same label
what comes off the assembly line varies over time. It's not all the same.

 

[Gleedus]

So your in the camp of there are good lot# not the there is good lot# for me and then different for you? Relating to 200 again.

 

[justin amateur]

Have you ever noticed that some lot numbers disappear overnight,
and others linger for weeks being sold off in dribs and drabs?
Those batches that produce great results get noticed and word gets out fast.
When you find cartridges with minimal ES and correctly assembled well made components
they shoot well in all rifles. Get y'er hands on some of that ammo
the results on target will astound you.

 

[oldfatguy]

Have you ever noticed that some lot numbers disappear overnight,
and others linger for weeks being sold off in dribs and drabs?
Those batches that produce great results get noticed and word gets out fast.
When you find cartridges with minimal ES and correctly assembled well made components
they shoot well in all rifles. Get y'er hands on some of that ammo
the results on target will astound you.

If I understand what you are saying finding a ”good” lot is about the quality of the lot and very, very little about your particular rifle’s preference.

OFG

 

[justin amateur]

I've tried to find a brand my rifle's "liked".
It's one of those internet fables based on a limited sample size.
Someone buys a box of CCI SV, cartridge quality is above average, they get good results.
Hey! My rifle "likes" CCI SV! Brags on a forum about how great his results are.
So Bubba buys a few boxes to try. Oops...the boxes purchased were made on Monday
and the assembly line techs were a bit hungover from the weekend. Cartridge quality was a bit off.
Bubba tries 'em and complains about how bad CCI SV is.
No, no, it wasn't the CCI SV, I got great results with 'em...y'er rifle just didn't "like" them.

What a steaming pile of equine fecal material.

Cartridge quality is not a constant. Tolerances change on the assembly line.
Technicians fail to pay attention and things get sloppy. Components vary in quality.
Some batches are great, some reek and some are just okay.

It's not the brand we're chasing, it's the quality of the cartridges that we're looking for.
If I find a brick of well made cartridges, I get good results from all my rifles.
If I get a brick of factory seconds, those targets produced look like birdshot patterns, with all my rifles.

No rifle can make poor quality cartridges produce consistent trajectories.
Either they have tight mv's and minimal cartridge defects or y'er gonna end up with strays and fliers.
Unless y'er doing y'er shooting at distances where ammo quality has no effect.

Any rifle can hit a dime every time, if'n you get close enough.

 

[68hoyt]

I bought a brick of eley team none of my rifles liked it , I bought a brick of eley wolf match extra none of my rifles liked I bought a 40xb and it dosent shoot very well with any of the ordered brands ,,,,, but ,,,,, it loves this brick of team and wolf and will shoot with or even out shoot the other rifles with ammo they like
I don’t know how this throws in your mix but it was something I noticed in one case

 

[Gleedus]

I bought a brick of eley team none of my rifles liked it , I bought a brick of eley wolf match extra none of my rifles liked I bought a 40xb and it dosent shoot very well with any of the ordered brands ,,,,, but ,,,,, it loves this brick of team and wolf and will shoot with or even out shoot the other rifles with ammo they like
I don’t know how this throws in your mix but it was something I noticed in one case

If your bored... and you have a way to measure base to ogive length? Is the wolf and team the same? What does the stuff measure that doesnt shoot?

I dont care about consistency I'm just wondering average length.

 

[justin amateur]

Hoyt...If that happened to me, I'd already have my chronograph out front
and I'd be looking closely at every cartridge before chambering.
It'd drive me nuts (okay, nuttier than I already am) if I couldn't figure out why it was happening.
There has to be a reason why the results changed.
Wind, mv shift, bullet asymmetry, damage occuring during chambering if from a magazine
or possibly some movement between the stock/receiver/barrel/me messing things up.
It's why I have my barrel block rigs. Is it the ammo, the rifle or me?

 

[justin amateur]

Question came up...How do you know it's not just the lead causing the smoothing?

Had to think about it to maybe provide an answer.
Air rifles use lead pellets at a decent fps.
Do pellet rifles show smoothing of the rifling?
No burn residue involved.

I've never seen the inside of my Crosman 1322 air pistol barrel before...it ain't pretty.

This ones had about 3 tins of 14 grain 22 pellets through it. 1500 shots
I don't see any signs of smoothing...yikes.
Good thing it's only used at less than 10 yards.

Not exactly what I would call polished...would you?

Captured multiple locations.
That be some rough rifling.

And yes, that's after passing a bronze brush through the bore.

Link to the rest of the images https://photos.app.goo.gl/ZBBV82v6WindM7Ef6

 

[Sgeorge]

Not sure a Crosman barrel is a fair comparison to a competition SS barrel used in an air rifle for Benchrest.

 

[justin amateur]

Maybe not, but if you want to see if lead rubbing on steel will smooth out the imperfections,
I'd offer that after 1500 pellets down the bore, it don't look like they do much smoothing.

I'm going to check my AirKing springer later this week.
See if that bore looks as bad. It's had almost 5 tins through it.

 

[Tim7139]

If your bored... and you have a way to measure base to ogive length? Is the wolf and team the same? What does the stuff measure that doesnt shoot?

I dont care about consistency I'm just wondering average length.

It will have zero to do with OAL, UNLESS you have and extremely short or long chamber.
The only accurate way to measure it is to have a small piece of barrel with a partial chamber cut to make a die and can then yield accurate OAL measurements.
It is only important with certain MI match barrels cut for a particular OAL lot, lots can vary at least .010” .

 

[AGrizz]

This is taken from 4-D Chamber Reamer Rentals. So you see chambers and cartridges can be all over the place. It is important to have ammunition that is compatible with the ammunition type, size and length, firearm action and type. Barrel groove and rifling dimensions must also be taken into consideration. These are in no way all the chambers that are out here. There are even more European chamber sizes.

Yes it does make a difference in the bullet overall length and the profile upon entering the forcing cone of the chamber. The lands and angle of the forcing cone are as well important. Lube is one more critical application on the projectile.

Do all .22lr shoot the same? Hell no. It is a search that is never ending due to chamber, twist rates, groove dimensions, temperatures, vibrations, etc. We are just fortunate we have people that are willing to experiment and try to find a few answers to our questions on what is happening in a firearm that makes them break in and shoot for us. It is putting this infinite number of combinations together that we win with an accurate firearm.

Is Justin amateur learning and showing us one aspect for barrel polishing and accuracy associated with it? You dammed betcha.

For the Crossman barrel you may call that an indicator or a clue, possibly creating more questions.

 

[Gleedus]

It will have zero to do with OAL, UNLESS you have and extremely short or long chamber.
The only accurate way to measure it is to have a small piece of barrel with a partial chamber cut to make a die and can then yield accurate OAL measurements.
It is only important with certain MI match barrels cut for a particular OAL lot, lots can vary at least .010” .

My chamber shouldn't be any extreme. I didnt measure is so could be its long. In theory its 0.6 I ordered a Calfee 4. (I dont have a 22lr reamer)
Now with the Rim X I have a 0.050 head space this gives enough clearance with the fixed extractor to avoid issues with dirt at a match. So longer then I typically would do. Maybe that plays a part?

My results agree with what you. My best shooting ammo at 200 has the biggest variation in length.

What I'm wondering is. Do rifles prefer a length in broad strokes. I have found that long lots of a ammo shoot better then short lots of the same. Also ammo that is all long I can shoot multiple lots with simular results even if the velocity are the different lot to lot. At 200 that is at 50 some of the short ammo is best. Center X, Eley match.

At 200
0.76s dont shoot. Low 0.77s is hit or miss. 0.776- 0.781 shoots great. I have some 0.75 to try. I have nothing over 0.78 to try.

 

[1badDart]

Pellets aren't a good comparison, the lead in pellets is dead soft and velocity is low, probably around 400 fps. As mentioned already I doubt the quality of a Crosman barrel is very high.

 

[barronian]

It will have zero to do with OAL, UNLESS you have and extremely short or long chamber.
The only accurate way to measure it is to have a small piece of barrel with a partial chamber cut to make a die and can then yield accurate OAL measurements.
It is only important with certain MI match barrels cut for a particular OAL lot, lots can vary at least .010” .

doesn't the affinity of a given rifle for different ammo types have more to do with headspace and the different rim thicknesses ?
At least that appears to be my experience. It may be self delusion but i think i can bias a gun towards a particular ammo type by tuning the headspace to ammo type... Note this doesn't mean that i can get bulk ammo to shoot well - just that given two 'match grade' ammos one or the other will shoot better depending on how the headspace is adjusted.

 

[AGrizz]

Pellets aren't a good comparison, the lead in pellets is dead soft and velocity is low, probably around 400 fps. As mentioned already I doubt the quality of a Crosman barrel is very high.

As for air rifles. You Sir, evidently have absolutely zero experience with them. Please gain some information prior to your answers. Pyramid air would be a great place to start.

 

[AGrizz]

justin amature is working with barrel polishing from possible powder residue. Or what ever in the barrel changes to afford the change in the barrel for accuracy or break in. Plus the documentation to witness this process as best possible. I have never seen anyone else willing to work on this in the slightest. Not for the 22 rimfire barrel.

 

[Gleedus]

How fine are we figuring head space? I see Eley averaging 0.035 Lapua 0.038. Or course just the lots i have here.

I shortened the head space on one rifle and got slightly more consistent velocity. But other wise nothing. (I just set the shoulder back so no tuning)
I am considering on another rifle getting a barrel with a nut to look into tuning heads space. But I am doubtful that the results would be noticeable at long range.

 

[1badDart]

As for air rifles. You Sir, evidently have absolutely zero experience with them. Please gain some information prior to your answers. Pyramid air would be a great place to start.

Well Sir, please enlighten me where my error is.

 

[Tim7139]

doesn't the affinity of a given rifle for different ammo types have more to do with headspace and the different rim thicknesses ?
At least that appears to be my experience. It may be self delusion but i think i can bias a gun towards a particular ammo type by tuning the headspace to ammo type... Note this doesn't mean that i can get bulk ammo to shoot well - just that given two 'match grade' ammos one or the other will shoot better depending on how the headspace is adjusted.

For higher grade ammo, not for 20 years. Almost all BR rifles are set @ .043”

 

[Tim7139]

My chamber shouldn't be any extreme. I didnt measure is so could be its long. In theory its 0.6 I ordered a Calfee 4. (I dont have a 22lr reamer)
Now with the Rim X I have a 0.050 head space this gives enough clearance with the fixed extractor to avoid issues with dirt at a match. So longer then I typically would do. Maybe that plays a part?

My results agree with what you. My best shooting ammo at 200 has the biggest variation in length.

What I'm wondering is. Do rifles prefer a length in broad strokes. I have found that long lots of a ammo shoot better then short lots of the same. Also ammo that is all long I can shoot multiple lots with simular results even if the velocity are the different lot to lot. At 200 that is at 50 some of the short ammo is best. Center X, Eley match.

At 200
0.76s dont shoot. Low 0.77s is hit or miss. 0.776- 0.781 shoots great. I have some 0.75 to try. I have nothing over 0.78 to try.

Are you sure it’s .050”, that seems huge. Unless you have an aggressive MI barrel, probably a non-issue.
With those, some chambers are cut looking for a narrow OAL range, which is why I’d assume in the recent past, somebody like Calfee was droning on endlessly about having ELEY post OAL on lot labels. The rifling on those is super shallow almost non existent, and type and depth of chamber super critical as well.
Those barrels can be extremely intolerant about what they like.

 

[Tim7139]

Question came up...How do you know it's not just the lead causing the smoothing?

Had to think about it to maybe provide an answer.
Air rifles use lead pellets at a decent fps.
Do pellet rifles show smoothing of the rifling?
No burn residue involved.

I've never seen the inside of my Crosman 1322 air pistol barrel before...it ain't pretty.

This ones had about 3 tins of 14 grain 22 pellets through it. 1500 shots
I don't see any signs of smoothing...yikes.
Good thing it's only used at less than 10 yards.

Not exactly what I would call polished...would you?

Captured multiple locations.
That be some rough rifling.

And yes, that's after passing a bronze brush through the bore.

Link to the rest of the images https://photos.app.goo.gl/ZBBV82v6WindM7Ef6

Justin....do you realize the bore is probably not rough, you cannot tell, that’s a badly leaded bore.
pellets or 22 slugs, until you learn to comprehensively clean to bare metal, every time you stick that camera in there, it is apples to oranges.

 

[justin amateur]

Tim, I knew you were going to point out my cleaning technique.
That's why I added the note regarding how it was cleaned.

That's not leading of the rifling. It was cleaned with solvent and a bronze brush.
That is the actual steel finish of the barrel...that's some seriously poor rifling.
I do know how to clean a barrel. Not a totally ignorant amateur on this side of the keyboard.

 

[Sgeorge]

Everyone has a different cleaning routine. I NEVER put a brush in my rimfire barrels. Patches only with Rimfire Blend down the bore and the tuner. Carbon remover on a patch soaked in the chamber for 15 minutes.

 

[gkgeiger]

Everyone has a different cleaning routine. I NEVER put a brush in my rimfire barrels. Patches only with Rimfire Blend down the bore and the tuner. Carbon remover on a patch soaked in the chamber for 15 minutes.

Your first sentence says it all.

 

[grauhanen]

This thread has certainly taken a lot of different directions. Airgun barrels, headspace and accuracy, base-to-ogive length and accuracy -- all in the same day.

An airgun barrel, whether its a Crosman or a quality one, shouldn't show visible wear after three tins of pellets, regardless whether they are H&N pellets that are harder lead or whether they are softer JSB pellets. Fifteen hundred pellets is a small drop in the bucket as far as number of pellets goes.

Adjusting a rifle's headspace for a particular brand of ammo is unlikely to show a significant difference. At the risk of bring up his name, Bill Calfee, who knows something about building accurate .22LR rifles, has said on more than one occasion that headspace was less important than excellent ignition. In any case, unless someone was shooting with a known good shooter, lot-to-lot variation plays a bigger role in accuracy than headspace.

With regard to base-to-ogive length and accuracy, it's variation is not so much lot dependent as from round-to-round within boxes from the same lots. To be sure, there's less variation and more rounds are of the same length in top tier ammo than in less expensive fare. But the majority of shooters foreswear sorting rimfire ammo by any means in favor of lot testing good quality ammo for the best accuracy results.

And Justin (known as jaia on another forum) has repeatedly made a very important point that some readers of this thread and others refuse to understand or appreciate. That point is that it's never the brand of ammo that a rifle "likes." It's never "my rifle doesn't like Center X" or another variety of ammo made by one of the major match ammo makers -- Eley, Lapua, or, RWS.

What your rifle "likes" (and that's a lousy term) are particular lots of a variety of ammo. To continue with the example of Center X, not all lots of Center X will shoot the same. It's not because of issues of quality control, of whether a certain lot was made on a Monday to use Justin's example from above. It's very difficult if not impossible for shooters to distinguish betwen lots of match ammo by looking at them or by the measuring methods usually on hand. They all look good, they all appear to be without defects. That's the nature of good match ammo. But lots differ from one another in ways that can be revealed when they are shot. A lot that shoots very well in one rifle may or may not shoot equally in another.

 

[Gleedus]

Are you sure it’s .050”, that seems huge. Unless you have an aggressive MI barrel, probably a non-issue.
With those, some chambers are cut looking for a narrow OAL range, which is why I’d assume in the recent past, somebody like Calfee was droning on endlessly about having ELEY post OAL on lot labels. The rifling on those is super shallow almost non existent, and type and depth of chamber super critical as well.
Those barrels can be extremely intolerant about what they like.

I'm sure on the 0.05 it surprised me as well. It is a prefit I left as is. The gauge sent with the action is 0.051 so I'm at the max. I could set a little tighter but the bolt face would get tight on the barrel because of the rimx fixed extractor.

I'll have to admit i'm lost on the MI barrels....

 

[Tim7139]

Your first sentence says it all.

Actually it’s the 2nd sentence and, let ‘s maybe remember you’ve been doing this about 15 minutes.

 

[gkgeiger]

So it’s your way only. Adding you to my list.

 

[Tim7139]

I'm sure on the 0.05 it surprised me as well. It is a prefit I left as is. The gauge sent with the action is 0.051 so I'm at the max. I could set a little tighter but the bolt face would get tight on the barrel because of the rimx fixed extractor.

I'll have to admit i'm lost on the MI barrels....

That ‘s odd. Somewhere down the line measure how much recess is in the bolt nose.
have you ever set it where the extractor is barely touching breech face? 6-7 thou is not very much. just thinking out loud.
ever think of reaching out to them to see if that is where they set all of them ?

 

[Tim7139]

So it’s your way only. Adding you to my list.

 

[Gleedus]

That ‘s odd. Somewhere down the line measure how much recess is in the bolt nose.
have you ever set it where the extractor is barely touching breech face? 6-7 thou is not very much. just thinking out loud.
ever think of reaching out to them to see if that is where they set all of them ?

My bad the gauge is 0.050". I can "force" the bold closed but barely... has to spotless clean and any tighter it wouldn't go so I'm under the 50 with no tension.
Bolt recess is 0.043"

The rifle shoots good as is so I didnt concern myself with checking further at this point.
I'm using this barrel to test different lengths for optimal velocity spreads etc. Maybe once its short I will set the head space as tight as I can and see what happens? Its shouldered so I cant play with it. I guess I could thread for a nut...

 

[Tim7139]

sounds like you’d have to really screw with it. I doubt aI would frankly if it performs.Out of curiosity I’d ask them about it.....what the hell.
Guess I learned something tonight.

 

[grauhanen]

That ‘s odd. Somewhere down the line measure how much recess is in the bolt nose.
have you ever set it where the extractor is barely touching breech face? 6-7 thou is not very much. just thinking out loud.
ever think of reaching out to them to see if that is where they set all of them ?

According to @Zermatt Arms "Minimum [headspace] for the RimX will be .0455" with a maximum of .0500"."

The explanation:

Yes, we know this is a bit shocking to some people familiar with rimfire chambers. The reasons behind the higher minimum headspace are derived from the geometry of our fixed extractor bolt head. In our design, the extractor controls the round throughout the entire feeding, chambering, firing, and extracting cycle. There is not a time in the bolt cycle of our design that the round is not being controlled by the bolt head and extractor. In the typical claw extractor, extractor slot/reverse cone chamber setup, the extractor lets go of the round while it's chambered creating the ability for the round to move fore and aft if the headspace is not set much closer to the minimum. That's why you see other designs with that claw extractor and timed extractor slots using a much smaller minimum headspace (somewhere in the .0410" - .0430" range).

See post #352 here (1) NEW From Zermatt Arms - RimX Actions | Sniper's Hide Forum

 

[Tim7139]

Yep, Read it although a big part of their explanation is fundamentally wrong, at least as far as precision rifles.
There are zero actions I own, used, or heard of where the extractor "releases" upon chambering. Once they snap over rim, they stay until hit by the ejector. Makes zero difference as to cone breech or traditional extractor slots.
One little detailing adjustment is to maybe file the very end if it hits case wall creating lateral pressure.
I did see the range goes down to .0455", so that's interesting.
Good luck with the rig.

 

[308pirate]

Does barrel polishing occur shooting rimfire ammunition,
does it improve accuracy over time, if polishing does occur
how many shots does it take to show that improvement?

Polishing is an industrial process that I have more than a passing experience with.

Lead will not polish steel in the absence of an abrasive.

The question to answer would be, what kind of abrasives are introduced by the combustion process. Interested in where this goes.

 

[Tim7139]

Tim, I knew you were going to point out my cleaning technique.
That's why I added the note regarding how it was cleaned.

That's not leading of the rifling. It was cleaned with solvent and a bronze brush.
That is the actual steel finish of the barrel...that's some seriously poor rifling.
I do know how to clean a barrel. Not a totally ignorant amateur on this side of the keyboard.

Since when does bad rifling have deposits ON TOP of the underlying metal ? Any crap barrel fish yields tool marks, inclusions, rough finish INTO the steel, not on top of the steel and since it's probably lead, you can brush it until your freaking arm falls off without much improvement when it gets bad. That's why they make specific lead remover like No Lead. Different approaches for different issues.
Youse gots lots of learning to do.