I think I realized something tonight

Status
Not open for further replies.
vaalpens

vaalpens

Member
Joined
Aug 14, 2014
Messages
2,618
I re-load 4 pistol cartridges which I test for accuracy using the same testing method.

It is/was always baffling to me why it was so easy to find very accurate loads in 357sig and 40S&W, but in 45ACP and 9mm, not that easy.

In 9mm specifically I probably have 1 very accurate load, where the rest are much lower in the ranking. The very accurate load I always thought was probably when all the stars lined up the one time, since I have never been able to duplicate it.

My normal process for creating loads to be tested, is to pick a beginning and end powder range, use the same headstamp brass, and sort the brass by length. This I thought will remove or minimize some of the variables I deal with.

Tonight I was preparing for some 9mm loads that will be tested for accuracy, picked a headstamp FC, and started sorting the brass by length. One thing that caught my attention was that length of the cases were spread very evenly over 6 thousandths of an inch. Normally by headstamp the lengths fall mostly within 2 thousandths or 3 thousandths of an inch.

This made me scratch my head a little bit, until I realized that this is 9mm, and they have not been resized yet. So the length of the case was probably determined by the actual length and the pressure of previous load.

So the next thing I did was resize the cases of the same length and measured them again. After the resizing of the cases I probably had 5 different lengths from a previous same length.

Now I wonder that since I measured the lengths of the cases for accuracy loads previously before resizing, that it was probably just luck when I found a very accurate load.

For the next time when I create loads to test accuracy, I will definitely resize the cases first before sorting them by size. Hopefully with the next test I'll be able to determine if this makes a difference or not.
 
Last edited:
vaalpens said:
I re-load 4 pistol cartridges which I test for accuracy using the same testing method.
Click to expand...

What is your method? How many shots, at what distance, and off a bench or standing?

vaalpens said:
Tonight I was preparing for some 9mm loads that will be tested for accuracy, picked a headstamp FC, and started sorting the brass by length. One thing that caught my attention was that length of the cases were spread very evenly over 6 tenths of an inch. Normally by headstamp the lengths fall mostly within 2 or 3 tenths.
Click to expand...

Tenths of an inch? No way.
 
I hope you mean 2 to 6 thousanths (.002-.006) rather than 2 to 6 tenths (.2-.6) or restated is 2 hundred thousandths to 600 thousanths (.200-.600).

9mm and 45 get a taper crimp so case length, as long as it fits your gun chamber isn't as critical as a cartridge requiring a roll crimp like a .38. Uneven lengths wll result in inconsistent roll crimp.
 
fxvr5 said:
What is your method? How many shots, at what distance, and off a bench or standing?

Tenths of an inch? No way.
Click to expand...

I test at 15 yards from a bench using a pistol rest. Each of these guns also has teh same scope attached to them.

Sorry, my mistake. I am talking thousandths of an inch. I was probably thinking about my powder charges while writing about the case lengths. Thanks for the correction.

PWC said:
I hope you mean 2 to 6 thousandths (.002-.006) rather than 2 to 6 tenths (.2-.6) or restated is 2 hundred thousandths to 600 thousandths (.200-.600).

9mm and 45 get a taper crimp so case length, as long as it fits your gun chamber isn't as critical as a cartridge requiring a roll crimp like a .38. Uneven lengths wll result in inconsistent roll crimp.
Click to expand...

Thanks for the correction. Yes, I was talking about thousandths of an inch.

Matt Dillon said:
That’s why the only pistol cartridges I trim are .38 Special and .357 Magnum, for uniform crimps.
Click to expand...

Thanks for the comments. I do not trim, but I try to sort by case length for certain loads. My 357sig cases go through a resize before I measure the case lengths.
 
Thanks for all the comments and corrections. I have corrected my original post to read thousandths instead of tenths. I must be getting old.
 
Why not trim all of the cases to your shortest length and have all exactly the same lenght cases. Then go from there.
 
I can’t say I sort 9mm by case length or even headstamp very often.

How much of a difference in group size are you seeing at 15 yards?

I have found that what bullet I use makes a huge difference in accuracy but I also don’t test quite that close, if I am looking for accuracy.

Both of these 10 shot 9mm groups were using mixed brass at 100 yards from a bagged rifle. The only difference between them is one used plated RN bullets, the other a decent JHP.

EE3868C9-9EA2-4703-82F9-34D983C0852D.jpeg

D3319E1C-7BB4-4B1C-B177-D637899B43F2.jpeg

At 15 yards the difference between the two is insignificant, the further away from the muzzle, the more pronounced the difference gets.
 
You didn't mention what bullets you are using, either.

I see questions now and then about 'good accuracy with 55grn FMJ bullets in .223,' which I used to ask, too... until I realized that bullet, generally speaking, is not necessarily an accurate bullet... it's a mass-produced bullet made as cheaply as possible. If you were to compare any cheapo 55grn bullet to a 69grn SMK... I'd wager that the SMK would beat it every time, and twice on Sunday.

Same-same with handgun bullets. If you are looking for 'inth degree accuracy from your 9mm, you are going to have to use better bullets. Further, it also matters what pistol you are shooting these in. I don't have what I would call a 'target' 9mm... mine are all carry self-defense pistols. Even something like the Browning HiPower, which is indeed a fine pistol, but the lower-end versions are service pistols, and I would only expect 'reasonable' accuracy out of them, not target-level accuracy.... and that's not saying you won't find an exception to the rule, either in a handgun, or a handload.

I recently was testing some new powders in both my 9mm's and my 4" Kimber .45's. 10 rounds at 21' was my barometer... I did not measure groups, I just picked the smallest one for each, after running them over the chronograph. I don't shoot those pistols for absolute accuracy, but finding the most reasonably accurate load that produces velocity within the range I wanted it was my goal (along with other things, like lower flash, and no cycling issues, etc., of course.) This was using generic plated RN bullets, not Hornady XTP's, for example, which have produced very good accuracy in everything I've tried them in. If I had used XTP's, I would have been looking for a higher level of accuracy, but probably less of an emphasis on FPS.

If you expect target- or match-grade accuracy out of your handloads and handguns, you need to use components that would produce that, and handguns that are likely to produce the results you are looking for.
 
fxvr5 said:
How many shots in your group?
Click to expand...

For my standard testing I do 5 shots at 15 yards. My expectation for a very good grouping load with my current setup is to have a few tested loads in the .5" or below grouping. I will test the same load on later dates to confirm that the good grouping was not a fluke.
 
Jmorris: You remember what brands of bullets hit those targets? Just curious.

BTW, I've never seen a Starrett adjustable square like that before. Super cool antique! Still useful too.
 
jmorris said:
I can’t say I sort 9mm by case length or even headstamp very often.

How much of a difference in group size are you seeing at 15 yards?

I have found that what bullet I use makes a huge difference in accuracy but I also don’t test quite that close, if I am looking for accuracy.

Both of these 10 shot 9mm groups were using mixed brass at 100 yards from a bagged rifle. The only difference between them is one used plated RN bullets, the other a decent JHP.

At 15 yards the difference between the two is insignificant, the further away from the muzzle, the more pronounced the difference gets.
Click to expand...

Thanks for sharing your test results. The plan is to test my better loads at 25 yards, which should probably identify the most accurate load between all my loads. for normal shooters like me, I think pistol accuracy I think is more affected by the shooter than rifle accuracy.
 
vaalpens said:
I will test the same load on later dates to confirm that the good grouping was not a fluke.
Click to expand...
And increase the shot group from 5 to 10, preferably 20+ to verify the accuracy of load.

I used to use 5 shot groups but when jmorris pointed out that 5 shot groups are subset of 10 shot groups and 10 shot groups are subset of 50 shot groups, etc. I saw the light and started using 10 shot groups for initial accuracy testing with 20+ shot groups for repeated verification.

So are left two smaller groups reflective of accuracy or larger two groups on the right?

index.php


In the two "Real World" 22LR 20+ brand/weight ammunition comparison threads where brand new 10/22 Collector and T/CR22 were tested with every 10 shot groups fired captured and documented (To follow effects of trigger break-in and barrel rifling wear over several thousand rounds), I found drawing accuracy conclusions based on a few 5 shot groups don't reflect the composite of thousands of rounds fired as many of my 10 shot groups started out as smaller 5 shot groups but "flyers" opened up the 10 shot groups and composite of hundreds of 10 shot groups opened up the extreme boundaries even more - https://www.thehighroad.org/index.p...lector-3-break-in.859106/page-2#post-11405547

Take a look at below 50 yard target shot with 10/22 Collector #3. "Real" accuracy of the barrel/ammunition is not the smallest 5 shot groups rather composite of all the groups which is larger. So instead of claiming accuracy of sub 1" 5 shot groups, it's more like around 1" 10 shot groups. And composite of 60 shot group is more like 1.5".

index.php
 

Attachments

  • 5-10 shot.jpeg
    5-10 shot.jpeg
    13 KB · Views: 363
Last edited:
Match grade guns will benefit from brass of the same lot, fired the same amount of times, with the same load. (50 yards Bullseye Pistol.)

The longer the brass, the better. Note SAAMIs maximum brass trim length & minimum chamber lengths. In 9 or 45 acp, they are the same.

Any time end play is reduce, accuracy is better with good bullets.

45 acp brass gets shorter the more its fired.
 
243winxb said:
The longer the brass, the better.

Any time end play is reduced, accuracy is better
Click to expand...
Yes, I think in terms of longer resized brass being able to seal with chamber walls better as shorter resized brass will move back to contact the breech wall face and likely leak more gas as case mouth no longer headspaces on the chamber.

And to some extent, shorter resized brass will likely produce less neck tension due to less bullet base seated in thinner case wall portion of case neck.
 
Lennyjoe said:
I’ve never taken the time to trim any 9mm or .45 case in over 15 years of reloading.
Click to expand...
As 243winxb pointed out, for straight walled semi-auto calibers that headspace on case mouth, you want the resized case length to be long as possible as repeated reloading will shorten resized case length over time.

While same resized case length will produce more consistent amount of taper crimp, I believe there are many other reloading variables that will readily overshadow taper crimp variable.

Instead of trimming cases, sorting by resized case length of same headstamp would be better, which is what the OP is doing.
vaalpens said:
For the next time when I create loads to test accuracy, I will definitely resize the cases first before sorting them by size. Hopefully with the next test I'll be able to determine if this makes a difference or not.
Click to expand...
It is my opinion that consistency of resized case length of same headstamp will likely be overshadowed by headstamp case that produces less or no bullet setback.

I know, I know ... Another myth busting thread coming for the THR peanut gallery. :D
 
Charlie98 said:
You didn't mention what bullets you are using, either.

I see questions now and then about 'good accuracy with 55grn FMJ bullets in .223,' which I used to ask, too... until I realized that bullet, generally speaking, is not necessarily an accurate bullet... it's a mass-produced bullet made as cheaply as possible. If you were to compare any cheapo 55grn bullet to a 69grn SMK... I'd wager that the SMK would beat it every time, and twice on Sunday.

Same-same with handgun bullets. If you are looking for 'inth degree accuracy from your 9mm, you are going to have to use better bullets. Further, it also matters what pistol you are shooting these in. I don't have what I would call a 'target' 9mm... mine are all carry self-defense pistols. Even something like the Browning HiPower, which is indeed a fine pistol, but the lower-end versions are service pistols, and I would only expect 'reasonable' accuracy out of them, not target-level accuracy.... and that's not saying you won't find an exception to the rule, either in a handgun, or a handload.

I recently was testing some new powders in both my 9mm's and my 4" Kimber .45's. 10 rounds at 21' was my barometer... I did not measure groups, I just picked the smallest one for each, after running them over the chronograph. I don't shoot those pistols for absolute accuracy, but finding the most reasonably accurate load that produces velocity within the range I wanted it was my goal (along with other things, like lower flash, and no cycling issues, etc., of course.) This was using generic plated RN bullets, not Hornady XTP's, for example, which have produced very good accuracy in everything I've tried them in. If I had used XTP's, I would have been looking for a higher level of accuracy, but probably less of an emphasis on FPS.

If you expect target- or match-grade accuracy out of your handloads and handguns, you need to use components that would produce that, and handguns that are likely to produce the results you are looking for.
Click to expand...

Thanks for all the information. I am not looking for match accuracy, but rather just trying to find the most accurate loads per gun an cartridge.

I test all different bullets, but lately I have been using the RMR 124gr FMJ TCFP bullets. I use the same bullet in 357sig. In 357sig the best grouping load with this bullet is Unique .478". Even the RMR 147gr FP bullet groups very well in 357sig: CFE Pistol .500"

The best 9mm grouping with this bullet so far is a .650" using Power Pistol.

It just seems I have more difficulty finding a very good grouping load in 9mm. It could be the gun also and maybe I am just chasing my tail. I know the bullet is very important, but in 40S&W I see very good groups using pulled FMJ bullets.
 
vaalpens said:
It just seems I have more difficulty finding a very good grouping load in 9mm. It could be the gun also and maybe I am just chasing my tail. I know the bullet is very important, but in 40S&W I see very good groups using pulled FMJ bullets.
Click to expand...
Your experience is not isolated and shared by many, including me.

Difficulty in developing accurate 9mm loads could be from the reasons that 9mm being smaller internal case volume caliber with shorter bullet base producing less neck tension can be more susceptible to greater swings in chamber pressures from small changes in bullet seating depth variance or bullet setback after being fed from the magazine.

For these reasons, I now use shorter OAL to improve neck tension and headstamp brass that won't produce bullet setback (Or least amount) for my accuracy testing.

This may be why Atlanta Arms Elite 115 gr FMJ Match AMU which used to be loaded shorter at 1.130" OAL is now loaded even shorter at 1.105" OAL - https://atlantaarms.com/products/elite-9mm-115gr-fmj-match-amu.html

vaalpens said:
CFE Pistol
Click to expand...
Have you tried BE-86 or WSF?

And if you are not pushing high to near max load data, you will likely obtain greater accuracy from faster burning than W231/HP-38/W244/Sport Pistol powders.
 
mdi said:
In normal machinist/precision measurements terminology, "tenths" refers to ten thousandths of an inch (.0001"). Perhaps the OP meant that?
Click to expand...

Thanks for trying to help me out of the embarrassment hole, but I just made a mistake. Probably thinking about the powder weight when writing about the case length.

SAAMI max min are .754" - .010".

When I was measuring the case lengths, most were around .740" to .745". This when I realized that I should probably resize them before sorting by length.
 
LiveLife said:
Your experience is not isolated and shared by many, including me.

Difficulty in developing accurate 9mm loads could be from the reasons that 9mm being smaller internal case volume caliber with shorter bullet base producing less neck tension can be more susceptible to greater swings in chamber pressures from small changes in bullet seating depth variance or bullet setback after being fed from the magazine.

For these reasons, I now use shorter OAL to improve neck tension and headstamp brass that won't produce bullet setback (Or least amount) for my accuracy testing.

This may be why Atlanta Arms Elite 115 gr FMJ Match AMU which used to be loaded shorter at 1.130" OAL is now loaded even shorter at 1.105" OAL - https://atlantaarms.com/products/elite-9mm-115gr-fmj-match-amu.html


Have you tried BE-86 or WSF?

And if you are not pushing high to near max load data, you will likely obtain greater accuracy from faster burning than W231/HP-38/W244/Sport Pistol powders.
Click to expand...

Thanks for the excellent information. So far I have tested loads with power Pistol, BE86, HP38, W244 and Sport Pistol with the 124gr FP match winner bullets. The COL I am using is 1.065".
 
Status
Not open for further replies.

Similar threads

R
  • Locked
45 ACP Brass Length
Replies
2
Views
387
ReloaderFred
ReloaderFred
M
  • Locked
.075" ???
Replies
2
Views
404
ReloaderFred
ReloaderFred
R
  • Locked
how short is too short?
Replies
10
Views
856
roval
R
U
  • Locked
Using a Case Length Comparator
Replies
2
Views
461
Ol` Joe
O
G
  • Locked
9mm brass problem
2
Replies
35
Views
2K
Walkalong
Walkalong
Back
Top