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Rimfire accuracy affected by rim thickness
- Thread starter Wodan
- Start date
If it makes you happy, enjoy y'erself.
If you expect sorting by weight or different cartridge dimensions,
to improve results on target, you likely are an optimist.
Which portion of the rim do you measure?
The part where the firing pin impacts, correct?
Do you think the rim is the same thickness the entire circumference?
Might want to verify that.
Do you think the brass thickness that forms the rim
is the same on every cartridge? How about brass hardness?
Will measuring the rim affect powder or primer chemistry or amounts?
Will the rim dimension affect bullet weight/shape?
How will the rim relate to assembly variations?
How many cartridges will be needed to be measured,
to prevent normal variations in cartridge quality
from skewing the conclusion?
These are all questions that bother me when sorting by any methods.
If you expect sorting by weight or different cartridge dimensions,
to improve results on target, you likely are an optimist.
Which portion of the rim do you measure?
The part where the firing pin impacts, correct?
Do you think the rim is the same thickness the entire circumference?
Might want to verify that.
Do you think the brass thickness that forms the rim
is the same on every cartridge? How about brass hardness?
Will measuring the rim affect powder or primer chemistry or amounts?
Will the rim dimension affect bullet weight/shape?
How will the rim relate to assembly variations?
How many cartridges will be needed to be measured,
to prevent normal variations in cartridge quality
from skewing the conclusion?
These are all questions that bother me when sorting by any methods.
Go your own path.
When I was traveling 12hours to compete, I did as much as I could to sway things in my favor, including sorting ammo. You’ve gotta test things yourself and draw your own conclusions.
You have to be mental to shoot, err, I mean Shooting is a Mental game, so believing in your gear may be just as important as it’s inherent performance.
When I was traveling 12hours to compete, I did as much as I could to sway things in my favor, including sorting ammo. You’ve gotta test things yourself and draw your own conclusions.
You have to be mental to shoot, err, I mean Shooting is a Mental game, so believing in your gear may be just as important as it’s inherent performance.
This comes up every few years. Many of us have tried it. I did so long ago.
IIRC the consensus was that it does seem to help with low to mid quality target ammo but not at all at the top end.
All the points Justin brings up are valid and he likely missed a few. Rimfire precision is insanity so take your own path to the destination.
IIRC the consensus was that it does seem to help with low to mid quality target ammo but not at all at the top end.
All the points Justin brings up are valid and he likely missed a few. Rimfire precision is insanity so take your own path to the destination.
I went down this particular rabbit hole a couple times when I was younger. I weighted shells, I sorted by rim thickness and lot tested. in the end I found that for me I just switched to Lapua which in practice I found to be the most consistent. I just decided that one load that works the best most of the time and not spending hours sorting and measuring and grouping rounds would be a better use of my limited gun time.
Buying quality ammo is a better use of your time.
I used to shoot with an old retired guy that rim and weight sorted CCI standard. When he died there were about 30000 rounds of sorted ammo in his own lots. He only shot the stuff in the middle, the rest just made his house look like an episode of hoarders. (Seriously, he had a recliner, a coffee can for an ash tray next to it, and the rest of the house was ammo stacks that would make army Jerry jealous).
He never could outshoot me, yet called my spending money on SK or Lapua wasteful.
He could have just bought cases of x-act for what he spent on CCI, nevermind the time invested in ammo he wasn't going to ever shoot.
But, he was old, never married, no kids, plenty of money and free time. His hobbies considered of sorting 22s, loading for his arsenal, and shooting occasionally.
I used to shoot with an old retired guy that rim and weight sorted CCI standard. When he died there were about 30000 rounds of sorted ammo in his own lots. He only shot the stuff in the middle, the rest just made his house look like an episode of hoarders. (Seriously, he had a recliner, a coffee can for an ash tray next to it, and the rest of the house was ammo stacks that would make army Jerry jealous).
He never could outshoot me, yet called my spending money on SK or Lapua wasteful.
He could have just bought cases of x-act for what he spent on CCI, nevermind the time invested in ammo he wasn't going to ever shoot.
But, he was old, never married, no kids, plenty of money and free time. His hobbies considered of sorting 22s, loading for his arsenal, and shooting occasionally.
I sorted 4 boxes of Lapua Long Range into 4 groups. I them shot 25 from each group and 25 from a box picked at random. My conclusion it didn't make a difference
Measure the rim thickness on 50 rounds and record it. Then fire those fifty rounds thorugh a chronograph. You don't even need a target, just do not hit your chronograph. Then do a correlation plot of the rim thickness versus the velocity for all 50 rounds and show me a correlation factor of 90% and them I'll believe that rim trhickness has something to do with where the bullet ends up on the target
What means did you use to sort by length? and from where did the gauge take the measurements?
I sort by OAL as taken from the rim face to the ogive and it makes a difference. this is based off the same CFBR reloading knowledge of bullet land engagement. the advantage I found is that knowing what lengths shoots best in a particular barrel helps with lot selection. I also see where longer lengths shoot lower POI and shorter higher.
Lee
I sort by OAL as taken from the rim face to the ogive and it makes a difference. this is based off the same CFBR reloading knowledge of bullet land engagement. the advantage I found is that knowing what lengths shoots best in a particular barrel helps with lot selection. I also see where longer lengths shoot lower POI and shorter higher.
Lee
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I sort by base to ogive the same as Lee .I also only use centrex and eley match.I also put a .004 thou shim in my bolt when i shoot the eley as the rim thickness is .0375 thou and the lapua is .040 thou. This method is working well for me. Scott.
IIRC they tested mean value rim thicknesses fairly extensively over the past 50 years, and alot is known about this subject. Noboody is really going crazy with this since simply sourcing good quality lots seems to be much more important, at least as a starting place.
Might be for me since my barrels are all chambered with a Nevius reamer which gives about a 0.030 engagement I can see the difference. what measuring gauge did you use? I use the G3 MKII been using one since 2013. unfortunately, they are no longer available. very valuable with the current ammo shortage.
FYI, a pallet of ammo? maybe ELEY since none of the top RFBR shooters are shooting the current stuff.
Lapua is the ammo you want
Lee
FYI, a pallet of ammo? maybe ELEY since none of the top RFBR shooters are shooting the current stuff.
Lapua is the ammo you want
Lee
My issue with the sorting of rimfire by any measurement
is that we are attempting to solve a multivariable equation
by quantifying a single variable. It just doesn't work.
Given that: A + B + C + D + E = X
If A = 1, but no idea what B, C, D and E are
you can't determine what X is, can you?
Rim dimension, cartridge length, brass thickness
brass hardness,
case volume, bullet weight, cartridge diameter, crimp tension,
seating depth, brass length, primer chemistry/amount,
powder chemistry/amount, bullet asymmetry
all affect muzzle velocity and bullet trajectories.
If y'er thinking only the thickness of the rim varies during cartridge production
while everything else is manufactured identical, y'er an optimist.
is that we are attempting to solve a multivariable equation
by quantifying a single variable. It just doesn't work.
Given that: A + B + C + D + E = X
If A = 1, but no idea what B, C, D and E are
you can't determine what X is, can you?
Rim dimension, cartridge length, brass thickness
brass hardness,
case volume, bullet weight, cartridge diameter, crimp tension,
seating depth, brass length, primer chemistry/amount,
powder chemistry/amount, bullet asymmetry
all affect muzzle velocity and bullet trajectories.
If y'er thinking only the thickness of the rim varies during cartridge production
while everything else is manufactured identical, y'er an optimist.
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No, I am using a special gauge that was made by G3 unfortunately the maker I believe has passed away. no attempt to contact him has been successful. I know checks sent for payment have gone uncashed.
Lee
Lee
Justin, do you reload CF? same principle is being applied. two wins this year in ARA UL using untested lot of CX sorted by OAL. plus, last 5 years using OAL sorted CX of again untested lots produced 5 consecutive club UL championships. my best match score of 250-21X was done shooting sorted Lapua Pistol King and it was the first time that rifle shot it in a match. for me if the A equation is correct, I don't need to know what B, C, D & E are my match results the X equation end result are proof enough.
You also have to understand I am using a tuner, and the rifles are tuned at their optimum settings. so, some of the velocity variables are negated by matched bullet exit timing for each barrel. there is a window you can time a bullet's exit from the barrel with differing velocities. some may call it positive compensation; I do not as I don't think there is the ability to achieve 100% PC.
don't take this in the wrong way but till you shoot a rifle setup for RFBR shooting and I mean for UL you won't really see what I just stated as believable. your issue of not believing a single variable in the equation of being capable of rendering the others as less in the equation is due in part of the equipment limitations you are using.
Lee
You also have to understand I am using a tuner, and the rifles are tuned at their optimum settings. so, some of the velocity variables are negated by matched bullet exit timing for each barrel. there is a window you can time a bullet's exit from the barrel with differing velocities. some may call it positive compensation; I do not as I don't think there is the ability to achieve 100% PC.
don't take this in the wrong way but till you shoot a rifle setup for RFBR shooting and I mean for UL you won't really see what I just stated as believable. your issue of not believing a single variable in the equation of being capable of rendering the others as less in the equation is due in part of the equipment limitations you are using.
Lee
@Hi-NV Shooter
Lee are you shooting the Mini Palma type matches or the BR type matches? Do you shoot outside Vegas or just local matches? Just curious and I know a couple of guys up in northern Nevada that shoot these rim fire matches.
Lee are you shooting the Mini Palma type matches or the BR type matches? Do you shoot outside Vegas or just local matches? Just curious and I know a couple of guys up in northern Nevada that shoot these rim fire matches.
Not sure but looks to use the same principle on measuring. I plan to make a gauge using my current one as a model. the challenge will be the spring used for the cup that bears against the bullet's ogive. since RF bullets are rather soft would defeat the purpose if it damages the bullet.
Lee
Lee
Hey Lee, F-Class 223.
H322, Lapua brass, Hornady ELD 73 grain at 0.016 off the lands.
I get that bullet jump is a thing with centerfire.
I've found that engraving 22lr produced my best results.
I also found that I have to get everything else right
or my results aren't good enough for centerfire competition.
Brass, bullets, primers, powder amount, seating, neck size and crimp,
all have to be as close to identical as I can get.
Yes I crimp 223, it improves my velocity consistency.
Sorting doesn't fix cartridge problems.
You can measure all the external dimensions,
but it won't allow you to quantify the unseen variables.
H322, Lapua brass, Hornady ELD 73 grain at 0.016 off the lands.
I get that bullet jump is a thing with centerfire.
I've found that engraving 22lr produced my best results.
I also found that I have to get everything else right
or my results aren't good enough for centerfire competition.
Brass, bullets, primers, powder amount, seating, neck size and crimp,
all have to be as close to identical as I can get.
Yes I crimp 223, it improves my velocity consistency.
Sorting doesn't fix cartridge problems.
You can measure all the external dimensions,
but it won't allow you to quantify the unseen variables.
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I didn't say it would fix bad ammo. bad will still shoot bad.
the OP question was sorting by rim thickness did it or has it been seen to improve accuracy. the improvement is slight in most cases as you know and not meaningful to do.
couple of posters said it doesn't work regardless of what you sort by. I know for a fact from experience it does work if you know what to look for. in my example I know the engraving my barrels are set up for. so, going off my best shooting lot, I can match OAL for each barrel and pretty much see how sorting to within 0.015 of each round will give predictable results. my match records of both unsanctioned and sanctioned performance are all the quantification I need.
you reload so you understand why it is important to know engagement length for best performance. I will be surprised if you are shooting the same load in a multiple of rifles/barrels unless each barrel was setup the same. no different with RF, but if you are shooting multiple rifle/barrels which are all different you will see different results.
IME if you have a lot of engraving then the lots will need to be really good and lot selection is imperative to get the best accuracy. perhaps this is where the labeling of imperfect cartridges is what you believe to be the culprit for results that are not similar from one rifle to another shooting the same lots. I don't have this problem.
Lee
the OP question was sorting by rim thickness did it or has it been seen to improve accuracy. the improvement is slight in most cases as you know and not meaningful to do.
couple of posters said it doesn't work regardless of what you sort by. I know for a fact from experience it does work if you know what to look for. in my example I know the engraving my barrels are set up for. so, going off my best shooting lot, I can match OAL for each barrel and pretty much see how sorting to within 0.015 of each round will give predictable results. my match records of both unsanctioned and sanctioned performance are all the quantification I need.
you reload so you understand why it is important to know engagement length for best performance. I will be surprised if you are shooting the same load in a multiple of rifles/barrels unless each barrel was setup the same. no different with RF, but if you are shooting multiple rifle/barrels which are all different you will see different results.
IME if you have a lot of engraving then the lots will need to be really good and lot selection is imperative to get the best accuracy. perhaps this is where the labeling of imperfect cartridges is what you believe to be the culprit for results that are not similar from one rifle to another shooting the same lots. I don't have this problem.
Lee
I hear ya' Lee.
I can see lot selection being critical not only by cartridge uniformity,
but by the uniformity of the muzzle velocities
and how the average mv fits the exit timing/barrel harmonics.
If you can find high quality cartridges, with a minimum of factory defects,
could dimension sorting improve results? I don't know.
But in top level competition I have to think that any edge you can apply
even if it's miniscule, has to increase y'er confidence
which can make a difference in the mental portion of the game.
Could be the difference between first and second at the end.
I can see lot selection being critical not only by cartridge uniformity,
but by the uniformity of the muzzle velocities
and how the average mv fits the exit timing/barrel harmonics.
If you can find high quality cartridges, with a minimum of factory defects,
could dimension sorting improve results? I don't know.
But in top level competition I have to think that any edge you can apply
even if it's miniscule, has to increase y'er confidence
which can make a difference in the mental portion of the game.
Could be the difference between first and second at the end.
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If you don't have 100% confidence in your rifle/ammo there is chance of doubt entering into your mental game. which in turn can cause a shooter to not try 100% to not give 100% in a competitive match will always have less than stellar performance.
IMO make the other shooter(s) work to finish on the top, don't give anything away. self-doubt is certainly providing an edge to your competitor.
Lee
IMO make the other shooter(s) work to finish on the top, don't give anything away. self-doubt is certainly providing an edge to your competitor.
Lee
Rim thickness has to do with headspace, which can affect accuracy.
I have taken bulk .22 ammo and separated it in batches by rim thickness in 4 categories, with the Neil Jones rim gauge.
Each batch grouped more consistent within its own category.
The disadvantage is that it is a boring past time, but hen I find a lot of reloading chores boring too. However, the difference is noticeable.
I have taken bulk .22 ammo and separated it in batches by rim thickness in 4 categories, with the Neil Jones rim gauge.
Each batch grouped more consistent within its own category.
The disadvantage is that it is a boring past time, but hen I find a lot of reloading chores boring too. However, the difference is noticeable.
Reading all the replies on my post, I agree that purchasing quality Eley, SK or Lapua beats separating federal or Winchester cheap bulk ammo, which I use for gophers. It would be a waste of time as I found out a couple of days ago. Although I noticed a difference, it is really not meaningful when shootings 20-60 yard gophers with my CZ 455
I Even tried bullet pulling 100x rounds of various brands and type of ammo to see which one has the most consistent powder amount, and also weighed bullets and measured brass length.
I found no statistical difference in ANYTHING. Rim, weights, concentricity,. Nothing.
The ONLY thing i found to increase performance was a hollowpoint "re-expander" which was a tiny pin mandrel which was used to open up the little cavity on winchester hollow point ammo. It made it slightly more destructive / reliable on things.
Dont waste time or money, just do a group test, find ammo your gun likes, and buy a HUGE batch of it.
TL;DR - go practice more. Better value.
I found no statistical difference in ANYTHING. Rim, weights, concentricity,. Nothing.
The ONLY thing i found to increase performance was a hollowpoint "re-expander" which was a tiny pin mandrel which was used to open up the little cavity on winchester hollow point ammo. It made it slightly more destructive / reliable on things.
Dont waste time or money, just do a group test, find ammo your gun likes, and buy a HUGE batch of it.
TL;DR - go practice more. Better value.
These differences are negligible in comparation with small variations of powder charge, bullet tolerances etc
I'll have to call you on this one. It has been proven that head spacing has very little if any effect on accuracy until you get to the point of FTFs or hard bolt closure. Consistent pin strikes from shot to shot is what you want no matter what pin strike depth, Measuring minor differences in rim thickness is simply a waste of time. What you need to be measuring is pin strike depths to determine how consistent your ignition is. If your into sorting 22lr ammo then OAL is what I would look at.
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Crimp and bullet seating depth do have effects on max pressure profile, and to internal ballistics overall. Consequently the muzzle velocities can be affected. That's much more important than slight change of head space due to slight change of rim thickness. Consistent pin to pin strikes assumed. Perhaps it has more to do with firearm than with rim thickness?
I had a problem with measuring strike depths.
The thickness of the brass that forms the rim varies also.
During the cupping and heading process, brass is stretched and shaped
and the machine tolerances along with the properties of the brass being used
can produce rims/heads/case walls that are not uniform in thickness.
I've had pin strikes that were barely deep enough to be measurable.
Cartridges did not fire. Disassembled the cartridge and there was no cup in the rim.
No hollow for primer to fill, solid brass from sidewall to head.
Another of those variables that affect results.
The thickness of the brass that forms the rim varies also.
During the cupping and heading process, brass is stretched and shaped
and the machine tolerances along with the properties of the brass being used
can produce rims/heads/case walls that are not uniform in thickness.
I've had pin strikes that were barely deep enough to be measurable.
Cartridges did not fire. Disassembled the cartridge and there was no cup in the rim.
No hollow for primer to fill, solid brass from sidewall to head.
Another of those variables that affect results.
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Then the problem can be formulated in terms of presence of the primer and its quality in order to reliably ignite powder.
I don't have the tools and I guess the ability to measure pin strike depth with any amount of reliability. It can be done and is the basis of opinions as to which style ignition is the most consistent. SAP or PAS.
G'day to those interested in home tools to measure rim and base to ogive. The empty case has been belled to fit over the lead projectile.Scott
Quite a few years ago I experimented with measuring rim thickness on lower priced ammo to see just what it would produce. It was the middle of summer with temperatures in the 100 degree range so I killed some Sunday afternoon time under the air conditioner experimenting. I made a clamp on holder that mounted on the moving jaw of a dial indicator, zero the dial, drop in a round, and measure. I segregated the rounds into groups with no more than 2 thousands of an inch difference. This usually resulted in four groupings. The only thing I saw was that the fliers didn't fly as far out of the group as when not sorted. Conclusion was it was a waste if time. Want better groups buy better ammo. Rim thickness is only one of several variables found with rimfire ammo and the cheaper the ammo the wider the variables.
If I want to plink with the grandkids I buy cheap ammo. If I sit down at a bench and want to see just how good a particular rifle will shoot I spend more money. I only compete with myself. The only competitive thing here is rimfire chickens and I am far too old and shaky for that. My problem is that no one stocks anything except lower tier ammo and I have to order it making it even more expensive. Because of that I shoot a lot of CCI-SV.
If I want to plink with the grandkids I buy cheap ammo. If I sit down at a bench and want to see just how good a particular rifle will shoot I spend more money. I only compete with myself. The only competitive thing here is rimfire chickens and I am far too old and shaky for that. My problem is that no one stocks anything except lower tier ammo and I have to order it making it even more expensive. Because of that I shoot a lot of CCI-SV.
G'day all, bought 4000 rounds of 1067 speed eley match 1023-06124 and ran 300 rounds for base to ogive measurement. 150 at .760 45 at .758/59 9 at .757 36 at .753 60 at.751/52 I will not be shooting these until the new year. Matches are 60 scoring shots , 3 cards plus sighters(average10/15). After you start your business shots you are not allowed to return to sighters so you have to remember conditions.Our matches are at 20 metres/50 metres and 90 metres outdoors at 2week intervals. Scott.
.The key to shooting benchrest is consistency and repartition and i follow this from setting up the bench to breaking the shot.I have been sorting my ammo for over 10 years and am confidant every time i squeeze the trigger. I am 79 years young ,use 2 rifles ,an Anschutz 54.30 and a Diana820s both in home made stocks by myself. I also shoot " head up "/ set the scope on the target,wait for my condition,squeeze the trigger. 2023 season is over trophy's awarded .Scott.
