Couple Q's on repeat-ability and desired tolerances...

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SIMJOSH1
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Couple Q's on repeat-ability and desired tolerances...

Post by SIMJOSH1 »

I've been loading for a short time.. (6 months).

I've been focused on 300 blackout and 223 so far. Moving onto some 270 Win next week..

My issues for the moment is loading consistently and to ensure I have a small or negligible tolerance between rounds.

IE COAL -Ojive to base.. / Headspace

I've got powder loads finalized and started paying a bit more attention to the COAL / Ojive differences between rounds..
- - My subsonic bullet is a 190gn Maker - These bullets expand like crazy but have horrible consistency issues.. Some noses are too proud, some sit back and all in-between.

I currently use a Hornady Die set with (i believe) the eld seat stem. It rides very high up on the maker 190's so I'm getting inconsistent coal / ojive numbers.. Out of 50 rounds loaded I get about 5-10 within 1-3 thousandths of desired set. All others are way over or under.

What seat stem do you use if something different and what do you do to fight this inconsistency? You got a better bullet / design recommendation?

With regards to some Barnes 110tx I get better consistency with my ojive to base measurements but end up with around 10 out of 50 with ojive to base irregularities ..


Do you measure bullets first with ojive comparator and separate accordingly?
(This makes the most sense for Barnes bullets but not for the Maker since they are SOOO bad [bad as in each bullet seems to have a different shape above the ojive])

Thanks! Any recommendations are appreciated.. or constructive criticism...
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rebel
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Re: Couple Q's on repeat-ability and desired tolerances...

Post by rebel »

When making match ammunition, I tend to measure, base to ogive, each bullet in a box and sort by size. Then you'll have to decide which is more important, relationship to lands( ogive ) or relationship to powder. ( base )

Conventional supersonic match ammunition tends to be more concerned with ogive to lands consistency. However, as dellet has proved countless times with 300 BLK, depending on the powder used, how that powder is being touched is every bit as important.

As far as consistent headspace, good brass helps and a high quality die, which yours is. I have made custom seaters with hot melt glue. Apply a gob of glue to the seater, press desired greased bullet nose in place. Trim and use. A more permanent solution would be epoxy.
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SIMJOSH1
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Re: Couple Q's on repeat-ability and desired tolerances...

Post by SIMJOSH1 »

Thanks for reply. Headspacing is some what controlled - I sort sub rounds vs super - this was a single step that made the biggest impact.

I use all Lapua brass with annealing every other firing. I'm getting around 1-2 thou consistency on average with a couple 3-4ish out.

I believe I've read some that H110 (powder I'm using) is one such powder that likes to be slightly compressed...

I'll have to play around with bullet seating depth on the tac-tx's.

I read maybe a Dellet post saying he takes a fired case and fills with powder - then slides the bullet on top to get case fill in relation to bullet seat depth. I'll run a couple tests to see where I'm at on case fill. I wish more mfg's produced case fill % on their load data!
(to use as a rough estimate if nothing else...)

Thanks again!
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Re: Couple Q's on repeat-ability and desired tolerances...

Post by rebel »

SIMJOSH1 wrote: Wed Oct 02, 2019 10:27 am Thanks for reply. Headspacing is some what controlled - I sort sub rounds vs super - this was a single step that made the biggest impact.

I use all Lapua brass with annealing every other firing. I'm getting around 1-2 thou consistency on average with a couple 3-4ish out.

I believe I've read some that H110 (powder I'm using) is one such powder that likes to be slightly compressed...

I'll have to play around with bullet seating depth on the tac-tx's.

I read maybe a Dellet post saying he takes a fired case and fills with powder - then slides the bullet on top to get case fill in relation to bullet seat depth. I'll run a couple tests to see where I'm at on case fill. I wish more mfg's produced case fill % on their load data!
(to use as a rough estimate if nothing else...)

Thanks again!
Yes, dellet has used that method with H110 for a long time. It works well. In my experience, H110 and W296 get a bit unpredictable when compressed.
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BoomerVF14
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Re: Couple Q's on repeat-ability and desired tolerances...

Post by BoomerVF14 »

My load data also shows W296's best range to be 97-100% fill to get the lowest variance in MV. I determine case fill by taking a fired case, filling it with increasing weights, plopping the bullet on top and measuring COAL, about five times at each charge weight. Then I plot the averages in Excel. (I got a little nerdier and derived the y=mx+b constants to make a solver where you can input either a charge weight or a COAL and get what the other variable has to be to make 100%). 8)
Image

I'm not confident in my measurements though, because a fired case is naturally going to have more volume than a re-sized case. I just WAG an extra percent or two because I don't have a case mouth expander to do it right. That, and I'm using 1F 5.56 FC stamp re-man cases and don't have the dedication you guys do when it comes to sorting and measuring brass. :oops:
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Re: Couple Q's on repeat-ability and desired tolerances...

Post by dellet »

BoomerVF14 wrote: Wed Oct 02, 2019 6:46 pm My load data also shows W296's best range to be 97-100% fill to get the lowest variance in MV. I determine case fill by taking a fired case, filling it with increasing weights, plopping the bullet on top and measuring COAL, about five times at each charge weight. Then I plot the averages in Excel. (I got a little nerdier and derived the y=mx+b constants to make a solver where you can input either a charge weight or a COAL and get what the other variable has to be to make 100%). 8)


I'm not confident in my measurements though, because a fired case is naturally going to have more volume than a re-sized case. I just WAG an extra percent or two because I don't have a case mouth expander to do it right. That, and I'm using 1F 5.56 FC stamp re-man cases and don't have the dedication you guys do when it comes to sorting and measuring brass. :oops:
I do this a bit different, and i don't really need a ton of math.

To get actual density with this cartridge, it take way too many numbers and equations, or something like Quickload that does it for you. With a long bullet that goes halfway into the case, you can't get a 100% case fill, but you can compress powder. There will still be an air gap between the case body and bullet.

So for 296/H110 starting loads are touching the powder COL +/- .010".
Something like 1680 it's touching +.010-.020" into the powder or compression.

A handy tool to have if you do this is a body only sizing die. One die will do all cartridges based on the same parent case. You can size the body while leaving the neck and shoulder in place.
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Re: Couple Q's on repeat-ability and desired tolerances...

Post by SIMJOSH1 »

I can run the dies through a 223 die to body size without mucking about at the neck..

Nice excel chart.. that "lessons learned" tabs got me intrigued !

What's ya'lls acceptable headspace tolerance? +/- .001-2?
What are you specifically calling acceptable?
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Re: Couple Q's on repeat-ability and desired tolerances...

Post by Dolomite_Supafly »

Uniform and deburr the flash holes. That is one thing I still do to every case. Doing it made the single biggest difference when I used to shoot groups.

Case fill is also very important because powder position can impact velocity. I tested loads by first loading then pointing the muzzle at the ground then firing across a chronograph. I did the same except pointed to the sky first and there was a detectable difference in velocity based on whether the powder was mostly at the front of the case or rear. So choosing a powder that gets slightly compressed when seating the bullet eliminates that variable.

Neck tension and case capacity are variables that the 300 Blackout suffers from more than most because most people use lake city brass which vat vary widely depending on year. And neck tension changes based on how many times the brass has been sized because of work hardening.
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SIMJOSH1
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Re: Couple Q's on repeat-ability and desired tolerances...

Post by SIMJOSH1 »

Dolomite_Supafly wrote: Thu Oct 03, 2019 1:24 pm Uniform and deburr the flash holes. That is one thing I still do to every case. Doing it made the single biggest difference when I used to shoot groups.

Case fill is also very important because powder position can impact velocity. I tested loads by first loading then pointing the muzzle at the ground then firing across a chronograph. I did the same except pointed to the sky first and there was a detectable difference in velocity based on whether the powder was mostly at the front of the case or rear. So choosing a powder that gets slightly compressed when seating the bullet eliminates that variable.

Neck tension and case capacity are variables that the 300 Blackout suffers from more than most because most people use lake city brass which vat vary widely depending on year. And neck tension changes based on how many times the brass has been sized because of work hardening.

I got a Redding primer pocket uniformer and K&M shooting premium carbide flash hole uniformer... Very nice tools..

I also run all 300 blackout through a lee neck collet die to ensure proper neck tension. Only thing I've yet to attempt / measure is neck thickness uniformity. Just with rudimentary digital calipers I'v measured but I want the I-gaging ball micrometer that measures to the .00005

When you were testing your case fill / powder location vs speed... What were you testing and what differences did you notice?

Thanks!

Josh
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Re: Couple Q's on repeat-ability and desired tolerances...

Post by SIMJOSH1 »

Loaded up some more 110 Barnes Tac-TX's this morning

15 @ 19.7gn h110
15 @ 20.3gn H110...

Tried a couple different seating depths in groups of 5ea..

One thing to note which - hasn't happened - basically ever...

Rounds seated a tad deeper than published COAL - (2.25)
2.2 to 2.24 end up slipping in and out of my slotted Sheridan gauge easily.. Most rounds always got stuck..

I've got the Hornady runout tools so I know bullets are straight but at 2.25 coal they'll get jammed up in the sheridan.
huh!

I'm going to try and get some more groups shot weekend after next. Waiting on Labradar to send me a new external microphone adapter... Last one was nonworking for whatever reason.

So we'll also see if ES/SD is any better with different seating depths.

Thanks!
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