Playing With Center-X

[USMCDOC]

So i am sure, that you know that i have been playing around with some inserts that i made for my Stoney Point. Well this morning, i decided to take it a bit further.. taking a small sample of about 150 rounds.. i first separated them by rim thickness, then took the largest pile of that and separated them by base to driving band..

So the first pic shows the division by rim thickness

Then the division by base to driving band of the 0.039 rim thickness pile.
This is just the beginning of a my lil experiment..

 

[kzin]

subscribed

 

[JoeMcNeill]

USMCDOC,
I'm interested to see how this turns out. I'm shooting more RF BR now that my local club has stopped shooting monthly
CF BR matches.I find that "playing around" with $17.00 a box of center x , well I like someone else doing the playing. (lol).
Regards,

Joe McNeill
SW Arkansas

 

[USMCDOC]

Ok. the very top row is the ammo separated by rim thickness as we have already noted.. the second row with the 700 series numbers under them is the 0.039 pile of ammo separated by base to driving band. The next row under the 700 series numbers is the 0.0385 pile and the row under them are the 0.0395 pile.. and they are 764, 7645, 765, 7655, and so forth.. there is a lone one not in the picture way to the right that was 770..

i wonder if anyone has figured out already where i might be going with this..

 

[USMCDOC]

USMCDOC,
I'm interested to see how this turns out. I'm shooting more RF BR now that my local club has stopped shooting monthly
CF BR matches.I find that "playing around" with $17.00 a box of center x , well I like someone else doing the playing. (lol).
Regards,

Joe McNeill
SW Arkansas

If you are paying that much for a box of Center-X.. let me know and i will put you on a better source!

 

[USMCDOC]

Ok.. so the idea is, if the rim thickness is close in variation in a 0.041 head spaced rifle.. and this does not seem to effect accuracy in a negative way. And we know that many in RF world are more concerned about where on the driving band the throat engages them. Then it makes sense to me that if you sort by rim thickness first.. then by base to driving band.. then we should be able to presume that rounds that are 0.0390 rim thickness with a BTDB distance of say .7670 and say another round that is 0.0385 and is .7675, should be in the same contact point on the throat.. this is my thinking.. please help me if i am wrong in my thinking! Thanks

 

[USMCDOC]

That first pic the lot on that was a 29551 series lot, this pic above is a 28551 series lot.. Notice that in the rim thickness, there are less outliers.. and the stacks appear to be more evenly distributed.. this is 100 pcs. Now to see how they stack up.. i mean separate up base to driving band.

 

[Sundown]

Doc, It's fun to see someone else go through what I did. I did all the measuring and recorded all my findings. I found the ammo that did the best for me was Fed Ultra Match. I did sighting in for 50 to 200 yards...this was fun. On one day I would get 50 yard 5 shot groups of .27"...the next time I went out I would get terrible groups. It all depended on Temp and Humidity for that day, wind was mild in all cases. I shot a CZ455 22RF Trainer (standard sporter barrel). I don't believe a heavy barrel would have changed anything. We don't have any competitions in this area so I just gave up and went back to centerfire. Good luck on your journey!! It's all fun

 

[USMCDOC]

Doc, It's fun to see someone else go through what I did. I did all the measuring and recorded all my findings. I found the ammo that did the best for me was Fed Ultra Match. I did sighting in for 50 to 200 yards...this was fun. On one day I would get 50 yard 5 shot groups of .27"...the next time I went out I would get terrible groups. It all depended on Temp and Humidity for that day, wind was mild in all cases. I shot a CZ455 22RF Trainer (standard sporter barrel). I don't believe a heavy barrel would have changed anything. We don't have any competitions in this area so I just gave up and went back to centerfire. Good luck on your journey!! It's all fun

Thanks.. i am getting into it.. i am trying to decide if i want to shoot the tests all in the 10X-III or in the 10/22 or take one lot and shoot it in one rifle and the other lot in the other rifle.. or take the ones that are the same length and shoot them in one and the.. well you know what i am getting at! Decisions!

 

[USMCDOC]

As you can see, with this lot, for instance the 0.0395 rim thickness has a wider spectrum of base to driving band lengths.. This might be one factor why some lots are better than others.. whereas the base to driving band lengths are more consistently closer together.. another thought is the measurement of the cases themselves.. has anyone ever checked fire cases for base to mouth lengths? Just being curious out loud here with my fingers.. since you can't hear me speak!

 

[USMCDOC]

Ok.. i moved the 0.0395 group above the 700 series of numbers.. then checked the 0.390 group.. the spread was from .7675 to .7735 (that one alone way out to the right!)..

 

[aussiepowderburner]

But..... how do they perform on paper please??!!

 

[USMCDOC]

But..... how do they perform on paper please??!!

i won't know till prob this coming friday, due to the weather not agreeing here..

 

[USMCDOC]

Ok.. so a case of SK Standard Plus came in yesterday.. i picked a brick out from it and separated it.. it is the first outcome to that.. you should notice a significant difference from the Center-X here..

As you can see, i separated by rim thickness first, then i measured the base to driving band length. Big difference..

 

[USMCDOC]

Here is a pic of a round of Center-X and Standard Plus.. can you tell the difference?

 

[Tim s]

Not for nothing but since your OAL specs go down to 1/2 a thou, exactly how precise do you think you might be without wiping the lube off the end of the ogive/top of drive band ? Half your varience is likely lube.
Measure one and then remove the lube with acetone, etc and re measure it. .0005-.001 is pretty damn small.

 

[USMCDOC]

Not for nothing but since your OAL specs go down to 1/2 a thou, exactly how precise do you think you might be without wiping the lube off the end of the ogive/top of drive band ? Half your varience is likely lube.
Measure one and then remove the lube with acetone, etc and re measure it. .0005-.001 is pretty damn small.

Not trying to start something.. how do you know that i haven't done that? Plus.. you have no idea of how i made the insert. To assume,, well we know what to assume means.. Your post comes off as being negative.. maybe if you approached in a different manner.. ??

 

[Rsadams]

Here is a pic of a round of Center-X and Standard Plus.. can you tell the difference?

View attachment 1024174

I have never really looked at a close up picture of .22 like this .. very interesting really.. the one one the right appears to have a thicker rim , crimped more and altho it's probably not , the bullet appears smaller in diameter...Is all of this an optical illusion??

I have been watching this thread I love shooting .22...

 

[Ggmac]

There is so much more than looks when it comes to the 22 . It's a round we can't reload , it's a round that has very small differences that mean so much . They can have identical components but make the grade by a measurement we may /may not be able to measure , those that make the manufacturers specs are boxed a certain way and those that don't get a lower sale point . Hope this makes sense .

Yes , been there done that . Went a little further . Removed bullets , weighed ( 100 each ) averaged , used the Lee lead hardness tester on the bullets , cut cases and wall thickness measured . Size of heel was measured . Yes that's got your head scratching , how did you do that ? Measure a loaded round , measure the case thickness , subtract . Do it about 20-25 X to get a decent average . Measure powder , 100 cases and average .
Use the Hawkeye to view primer compound , and compare its location an if a 360 rim coverage . Section cases and measure the base brass thickness . I TRIED to weigh the cases minus powder but with primer compound , then remove primer ( both by firing and by scraping residue ) not good results .
All this got me was a very expensive headache . Too many variables with achieving accurate repeatable groups with any of the most equal weight , length , diam , etc bullets . It would be good /great then after the same cleaning and fowling regiment , it would be crappy the next . Same poi just larger groups . Wind was measured , flags were used bench and prone with seb rest front and gator back .
Have fun and keep us posted . At least the ammo is available now !
Keep going , love the process .

 

[Ggmac]

Here is a pic of a round of Center-X and Standard Plus.. can you tell the difference?

View attachment 1024174

im only looking at a pic but the case on the right seems to have a taper crimp and a rounded lead band above it . The left case seems to have a straight case ( juncture ) with a bullet dia band of lead above the brass .