Question on bullet seating.

Alaskaman11

Alaskaman11

Gunny Sergeant
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Jan 21, 2009
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#1
Question guys.
Does bullet seating effect std dev?
The issue I’m getting, with my dasher and 308, I get a std dev in the single digits, my 223 bolt gun is getting around 25 to 30 std Div. My process is the same on all, but the difference is I use LW Wilson seating die for the dasher and the 308 and a standard rcbs for the 223. It’s the only difference I can find. Thoughts?
 
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#4
Lots of threads and at least as many opinions...

First will be the faux statisticians...how many rounds are you evaluating and that is not enough unless you shoot 6000 rounds...not 100% incorrect but missing much.

I support the theory that the smaller the case volume, the more influence vary small variations contribute to things such as velocity...and, by extension, SD of that velocity.
 
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#6
Alaskaman11 said:
Question guys.
Does bullet seating effect std dev?
The issue I’m getting, with my dasher and 308, I get a std dev in the single digits, my 223 bolt gun is getting around 25 to 30 std Div. My process is the same on all, but the difference is I use LW Wilson seating die for the dasher and the 308 and a standard rcbs for the 223. It’s the only difference I can find. Thoughts?
Click to expand...

OK : Take #5 closest matched cases in .223 ,that have been fired from YOUR weapon . Clean and prep identically . Then reload as near as accurately and identical as you can including OAL . Take those #5 test group to the Range ,with a CLEAN bore fire #2-3 any old rounds for fouling .
Now fire the #5 test group for accuracy as well as Measurement within 1 minute . Post YOUR results .

This is from Ballistics POV :

Statisticians have determined that values no greater than plus or minus 2 SD represent measurements that are are closer to the true value than those that fall in the area greater than ± 2SD. Thus, most QC programs require that corrective action be initiated for data points routinely outside of the ±2SD range.

I've been pulling the handle closer to 60 years now and I've NEVER gotten 2 SD !.

I have on #3 occasions placed two 7.62X51mm and four 5.56X45mm into the same hole at 100 yd. and 200 yd.
I'm NOT talking about a ragged hole group but the exact .308" and .224" hole diameter . Had there been No backer change ,I'd not have been credited with the hits .

Fyi : One of MY personal best groupings of #15 shots averaged 87 SD and a Dime covered the entire group with change at 200 yd. . So go figure and that Rifle is MY 1990's 20" ES2 A2 AR 15 Bushmaster bone stock ,with MY handloads (y)
 
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#8
Ex E6 said:
OK : Take #5 closest matched cases in .223 ,that have been fired from YOUR weapon . Clean and prep identically . Then reload as near as accurately and identical as you can including OAL . Take those #5 test group to the Range ,with a CLEAN bore fire #2-3 any old rounds for fouling .
Now fire the #5 test group for accuracy as well as Measurement within 1 minute . Post YOUR results .

This is from Ballistics POV :

Statisticians have determined that values no greater than plus or minus 2 SD represent measurements that are are closer to the true value than those that fall in the area greater than ± 2SD. Thus, most QC programs require that corrective action be initiated for data points routinely outside of the ±2SD range.

I've been pulling the handle closer to 60 years now and I've NEVER gotten 2 SD !.

I have on #3 occasions placed two 7.62X51mm and four 5.56X45mm into the same hole at 100 yd. and 200 yd.
I'm NOT talking about a ragged hole group but the exact .308" and .224" hole diameter . Had there been No backer change ,I'd not have been credited with the hits .

Fyi : One of MY personal best groupings of #15 shots averaged 87 SD and a Dime covered the entire group with change at 200 yd. . So go figure (y)
Click to expand...
I’ll do this. As for your last point on the FYI, all 5 groups were a ragged hole. Maybe I should just stop worrying about it
 
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#10
Alaskaman11 said:
I’ll do this. As for your last point on the FYI, all 5 groups were a ragged hole. Maybe I should just stop worrying about it
Click to expand...


I did this off the dirt NO mat at a LEO BBQ/Picnic Accuracy demonstration one afternoon ,so as to demonstrate the benefit of loading your own . With BLC-2 Bulk bullets with cannelure no less and 1990 LC cases . Note the classic Paper BBQ plate target ;)
Back then MY Bushmaster wore a Simmon AETEC 2.8X10 44mm scope ,not exactly a precision piece of glass but did well enough on 6 power at 200 yd. .
 

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#12
Neck tension can cause irregular pressure ,thus effecting velocity .

There are SET variables which NONE of us can account for or compensate . Powder same lot same canister can vary 3 +% ,Primers 2 +%

Those two factors alone make 2% SD ; IMPOSSIBLE .
 
#14
Ex E6 said:
OK : Take #5 closest matched cases in .223 ,that have been fired from YOUR weapon . Clean and prep identically . Then reload as near as accurately and identical as you can including OAL . Take those #5 test group to the Range ,with a CLEAN bore fire #2-3 any old rounds for fouling .
Now fire the #5 test group for accuracy as well as Measurement within 1 minute . Post YOUR results .

This is from Ballistics POV :

Statisticians have determined that values no greater than plus or minus 2 SD represent measurements that are are closer to the true value than those that fall in the area greater than ± 2SD. Thus, most QC programs require that corrective action be initiated for data points routinely outside of the ±2SD range.

I've been pulling the handle closer to 60 years now and I've NEVER gotten 2 SD !.

I have on #3 occasions placed two 7.62X51mm and four 5.56X45mm into the same hole at 100 yd. and 200 yd.
I'm NOT talking about a ragged hole group but the exact .308" and .224" hole diameter . Had there been No backer change ,I'd not have been credited with the hits .

Fyi : One of MY personal best groupings of #15 shots averaged 87 SD and a Dime covered the entire group with change at 200 yd. . So go figure and that Rifle is MY 1990's 20" ES2 A2 AR 15 Bushmaster bone stock ,with MY handloads (y)
Click to expand...
Hmmm??? "NEVER gotten 2 SD" in that time :eek:
Having been precision reloading for ~ 9 years now, my .308 has given me several SD's of 2 or less (all 5 shots or less). One 3 shot with an SD of 1.0 . And only once I got a 1.7 SD with 5 shots out of my 6.5 PRC. ;) LOL, yeah . . . I know, that statistical thing, and that 1.0 SD group I got wasn't particularly good and didn't go with that load because of the poor mean radius number. In fact, I've had a 5 shot SD of 2.0 and the group size was over 1 MOA. But, most of my low SD's I've recorded have had very good groupings. For sure, a low SD just does not guarantee a small group. 😵‍💫
Alaskaman11 said:
I’ll do this. As for your last point on the FYI, all 5 groups were a ragged hole. Maybe I should just stop worrying about it
Click to expand...
Low single digit SD's are a good thing to strive for, but what count's is what you get on target. I simply look at SD's as measure of how well I'm putting together my cartridges. . . . consistency with all the elements matters! :giggle:
 
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#16
Alaskaman11 said:
Question guys.
Does bullet seating effect std dev?
The issue I’m getting, with my dasher and 308, I get a std dev in the single digits, my 223 bolt gun is getting around 25 to 30 std Div. My process is the same on all, but the difference is I use LW Wilson seating die for the dasher and the 308 and a standard rcbs for the 223. It’s the only difference I can find. Thoughts?
Click to expand...
To answer you're question, IMHO, yes. . .but to the extent of how much variation there is in the seating. You need substantial variation to see it in the SD's. Probably the biggest factor here is, the difference in cartridge selection, which often is THE major factor. For example, a Dasher is one of the cartridges that's much easier to get good performance on paper and in terms of consistency. A 223 is much tougher to get the kind of performance one can get out of a Dasher or a .308.

Don't know if you saw this in another thread, but the graph produced by Little Crow Gunworks should give you some idea as to the relationship of things that effect things like SD's and precision the most:

1746380322937.jpeg
 
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#17
Are you using 223 components that are of equivalent quality as the dasher brass?
The answer will 95% be “no.”

Crap components, that much of 223 is, won’t ever shoot well. Get lapua brass, anneal it, mandrel it, develop a good load and you should be able to get it below 10. An sd below 10 on a 223 is pretty dang good.

“Bullet seating” alone won’t affect crap. You need to get more specific with your queries to get good answers.
 
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#19
straightshooter1 said:
Hmmm??? "NEVER gotten 2 SD" in that time :eek:
Having been precision reloading for ~ 9 years now, my .308 has given me several SD's of 2 or less (all 5 shots or less). One 3 shot with an SD of 1.0 . And only once I got a 1.7 SD with 5 shots out of my 6.5 PRC. ;) LOL, yeah . . . I know, that statistical thing, and that 1.0 SD group I got wasn't particularly good and didn't go with that load because of the poor mean radius number. In fact, I've had a 5 shot SD of 2.0 and the group size was over 1 MOA. But, most of my low SD's I've recorded have had very good groupings. For sure, a low SD just does not guarantee a small group. 😵‍💫

Low single digit SD's are a good thing to strive for, but what count's is what you get on target. I simply look at SD's as measure of how well I'm putting together my cartridges. . . . consistency with all the elements matters! :giggle:
Click to expand...

Not that I was aware of . ANY SD in single digits is what I'd consider a WIN . Loads that are in single digit SD's will in theory group together better ,as obviously velocity dictates POI . Lessen the charge and impact becomes lower ,increase it climbs .

ALL depending upon bullet aerodynamics and distance to impact . Loads for LR shooting at 100 yd.-300 yd. makes little difference but at a K yd. is where it really shows up .
 
#20
Ex E6 said:
Not that I was aware of . ANY SD in single digits is what I'd consider a WIN . Loads that are in single digit SD's will in theory group together better ,as obviously velocity dictates POI . Lessen the charge and impact becomes lower ,increase it climbs .

ALL depending upon bullet aerodynamics and distance to impact . Loads for LR shooting at 100 yd.-300 yd. makes little difference but at a K yd. is where it really shows up .
Click to expand...
Just before I started precision reloading I read that it was difficult to get .308 cartridges into single digit SD's, especially compared to the likes of 6ppc's or Dasher's. But, I was determined to see just how low I could get them, especially using a factory gun like an RPR (I think maybe the Krieger barrel helps a little ;)). My hope then was to just get an SD of 9. . . even for just 5 shots. I've come a long ways and typically get in the low 6's for a large series of shots (like 40 and 50 shots recorded). Last year I procured a box of Alpha brass and a fire forming session of 80 rounds, the SD was 6.5 and the 5 shot groups were good, but not great.

Now, if I don't get single digit SD's I know there's something not working, like I tried out some Remington 9.5's and 45 shots gave me an SD of 20.4 and groups were over 1 MOA. It wasn't one of my best loads I was playing with, but it should have been much lower than that. Tried another 10 rounds with one of my better loads that typically works well and still didn't get a good results with those primers (SD of 14.4).

And yes, you're right on. . . SD's can really show up in vertical dispersion on target at distance. (y)
 
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#22
straightshooter1 said:
Just before I started precision reloading I read that it was difficult to get .308 cartridges into single digit SD's, especially compared to the likes of 6ppc's or Dasher's. But, I was determined to see just how low I could get them, especially using a factory gun like an RPR (I think maybe the Krieger barrel helps a little ;)). My hope then was to just get an SD of 9. . . even for just 5 shots. I've come a long ways and typically get in the low 6's for a large series of shots (like 40 and 50 shots recorded). Last year I procured a box of Alpha brass and a fire forming session of 80 rounds, the SD was 6.5 and the 5 shot groups were good, but not great.

Now, if I don't get single digit SD's I know there's something not working, like I tried out some Remington 9.5's and 45 shots gave me an SD of 20.4 and groups were over 1 MOA. It wasn't one of my best loads I was playing with, but it should have been much lower than that. Tried another 10 rounds with one of my better loads that typically works well and still didn't get a good results with those primers (SD of 14.4).

And yes, you're right on. . . SD's can really show up in vertical dispersion on target at distance. (y)
Click to expand...

To make good ammunition component selection is crucial ,to make Fantastic Ammo requires the Key component ; The Correct Powder , bullet weight and sound cases regardless of brand name ( partial annealed necks definitely help ) .

Now will run of the mill Military expended cases make the best ammo ?. Probably not and it most certainly makes a difference WHERE those cases came from !. A well worn M60 or a 249 SAW ISN'T gonna be a great starter base cartridge decision .

I've had some of the best groups I've produced with lousy SD #'s but compensated with KEY components including decent cases .

Norma , FN , LC , PPU even S&B ( Yeah go figure ) . Yes I've got and also use Lapua . What I've found out over the years is , a PPU can be just as accurate as a Lapua case . Having been in a few Ammunition factories ,including Lapua and Norma , I've found things very similar and both had stringent QC . Sellior & Bellot ( Pronounced correctly is Sell-er Bel -lot ) accent on the B & L not on the t . When a Czech says it in English , it's nearly identical to Sailor Below . Just to clarify that .
Point is Seller & Bellot produces some of the BEST factory made ammunition in the World ,Bar None . NO company allowed behind the scenes analytical analysis of their components ,including Brass and it's % trace elements .

MY personal opinion , as I said having been to a few factories , Brass rolls looked nearly identical in the Nordic Factories ,so ??.
One is not permitted to view puck to cartridge draw process but all other operations were open to view . With any and all questions answered cheerfully . A Very Close Long time Friend ,was in charge of Norma up until about 4 years ago ,when He retired .
Just in case anyone wondered How I was able to visit those facilities .

I also batched Industrial explosives as well as Smokeless powder ,way way way back for Hercules Powder . So less than a handful of related industry people are left ,around various manufacturing facilities which I still remain in touch with .

Some of the very best 7.62X51mm cases I still retain are , FN and groups from when I fired factory Military rounds proved it and reloads are super accurate . MY Favorite Powder these days is VV for MANY of My reloading choices . IMO ; VV is holding some of the strictest tolerances that I've access too . (y)
 
#23
Ex E6 said:
To make good ammunition component selection is crucial ,to make Fantastic Ammo requires the Key component ; The Correct Powder , bullet weight and sound cases regardless of brand name ( partial annealed necks definitely help ) .

Now will run of the mill Military expended cases make the best ammo ?. Probably not and it most certainly makes a difference WHERE those cases came from !. A well worn M60 or a 249 SAW ISN'T gonna be a great starter base cartridge decision .

I've had some of the best groups I've produced with lousy SD #'s but compensated with KEY components including decent cases .

Norma , FN , LC , PPU even S&B ( Yeah go figure ) . Yes I've got and also use Lapua . What I've found out over the years is , a PPU can be just as accurate as a Lapua case . Having been in a few Ammunition factories ,including Lapua and Norma , I've found things very similar and both had stringent QC . Sellior & Bellot ( Pronounced correctly is Sell-er Bel -lot ) accent on the B & L not on the t . When a Czech says it in English , it's nearly identical to Sailor Below . Just to clarify that .
Point is Seller & Bellot produces some of the BEST factory made ammunition in the World ,Bar None . NO company allowed behind the scenes analytical analysis of their components ,including Brass and it's % trace elements .

MY personal opinion , as I said having been to a few factories , Brass rolls looked nearly identical in the Nordic Factories ,so ??.
One is not permitted to view puck to cartridge draw process but all other operations were open to view . With any and all questions answered cheerfully . A Very Close Long time Friend ,was in charge of Norma up until about 4 years ago ,when He retired .
Just in case anyone wondered How I was able to visit those facilities .

I also batched Industrial explosives as well as Smokeless powder ,way way way back for Hercules Powder . So less than a handful of related industry people are left ,around various manufacturing facilities which I still remain in touch with .

Some of the very best 7.62X51mm cases I still retain are , FN and groups from when I fired factory Military rounds proved it and reloads are super accurate . MY Favorite Powder these days is VV for MANY of My reloading choices . IMO ; VV is holding some of the strictest tolerances that I've access too . (y)
Click to expand...
Likewise, I've found PPU cases to produce quite well, even as a mix of lots. What I have of them is a collection from range brass that I picked up as I collected various brands of cases to compare when I first started precision reloading. I also collected a LOT of FC brass that also performed quite well and have fired a lot of them as I developed my reloading procedure. These days, Lapua is my main choice. The Alpha brass, a rather recent purchase, performed great initially, but haven't shot them a lot yet as I'm still waiting for my Lapua brass to give up the ghost before I do.

I really like the VV powders that I've used for my 6.5 PRC. I just wonder how affordable they might be in the near future given current political environment.
 
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