need help reducing ES and SD

[lablover]

I know reducing ES is king for 1000 yards. That being said. Took the new rifles out this morning to do the break in and here is what I noticed.

I made up 3 different loads that I will list below. Before, I do want to say what my brass prep and reloading procedure was.

6mmBr Lapua Brass new out of the box. Being a newbie at this case I read it was best to leave it alone. So, that being said I did nothing but size the new brass. ,Might be my first problem) Primed the cases with 450 primers and topped em off with Sierra 107’s

The only nit picking I did was trim the meplats with a Montour trimmer.

Here’s where it gets fun.

Load 1
29.0 Gr of Varget
cci 450 primer
COAl to ogive 1.790 ,I zero my calipers with the stoney point on )
Used a Redding f/l bushing die Loaded was .269 Sinclair recommended .268 bushing.
Velocity from oehler 35 P
Hi- 2685
Lo- 2594
ES- 91
Avg- 2656
SD – 30

OK…YUK on the SD and ES only 5 rounds Best group was .841 YUK

Load 2
29.5 gr Varget Same as everything else above
Hi – 2723
Lo – 2637
Es – 86
Avg – 2699
SD – 35

More yuk

Load 3
30.0 gr Varget Same as everything else above
Hi – 2765
Lo – 2683
ES – 82
Avg. – 2742
SD – 34

Still not the greatest. Best group on the last load was .421 Better but the numbers stink.

So, that all being said here’s where I need the help.

Could the numbers being caused by not enough neck tension? Maybe go to a .267 bushing?

My Oehler has only the 2 foot rod for screen spacing plus I had to set it out to around 10 yards in front of me due to the range I was at.

As far as I can tell..I’m seating .015 into the lands.

Why the low Velocity on 30.0 gr of varget? Slow barrel? These ar the first 30 rounds thru her!

What is the safe max for the 6mm BR??

Is Varget a good choice? Primers, bullets??

Should I debur the flash holes and clean p the primer pockets? I have Sinclair tools for both but the special flash hole tool for small flash holes seems a bit snug..Not super tight but tight enough to have to push a bit to get it thru the flash hole! ,Did one)


Any help would be great. Again, being very new to Benchrest and loading for Benchrest I can use all the help I can get. Part of me feels I should of left the Oehler at home for breal in.

Last but not least. Should I do my next loads with the once fired brass I now have or try again with the rest of the new stuff I have. And can I trim..debur etc with the once fired brass now that it has been fired.

Change to CCI BR primers?

Thank you very much for talking the time to read all this mess

Joe

 

[lablover]

Promise this is the last thing.

I use the RCBS hand priming too. When I seat primers...I seat till the handle bottoms out...Thus flatening the primer,I think) a little bit...Is this a no no

Joe

 

[Forum Boss]

It's a good idea to expand the necks of virgin brass before loading. I've found that, with one pass with a K&M Expander, there is still enough tension to hold the bullet.

I don't normally size the brass before firing the first time, but that's not a bad idea, provided the case is lubed properly.

Did you inside and outside chamfer the necks before loading? That is one bit of case prep we recommend.

What is the outside neck diameter of a loaded round? That helps us gauge what neck tension you need.

I suspect you may want to add some more powder. Seems some recent lots of Varget have been a little slow. Still, some barrels max out around 2800. What is your barrel brand, length, and groove configuration?

 

[lablover]

loaded no turn neck come out at .269 I used a .268 bushing.. Did chamfer the inside of the necks as well.

Broughton 5C 28"

 

[Forum Boss]

OK,

If the loaded round is .269", a .268" bushing will give you pretty minimal tension, because there is some springback. Try a .267.

Jason also has a Broughton 5C 28" and it's a running a little slower than we expected also, but it is wicked accurate. You're probably going to need to hot up that load. Try 0.2gr increments up to 31.0gr Varget. I also suggest you get a pound of RL15 and try that.

Do you know the freebore on your chamber? And what's the loaded length from case base to the bullet tip. That will help me know where you are relative to the lands. A couple of smiths are building 6BRs with super-long throats and this means you need to add quite a bit more powder to get "up to speed."

 

[lablover]

Great tips

Do you think I need to mess with the primer pockets at all? Or flash holes. I don't want to mess with to many things at once.

Also..I'll get the free bore Monday if I can. My loaded base to bullet tip is 2.347 Now..That's with around 7 thou of the meplat trimmed off if that makes any diff? I may just try to load some without touching the meplat...Wait one...I'll go seat one with out the meplat trimmed and give you a number...tic toc tic toc

OK 107 sierra with no meplat trimming is 2.354 I think I can jam it into the lands a bit more.

Est on freebore off the top of my head is 90-100 thou...Now that's a precise guestimation hehehehee

Thanks a million for the help

Joe

 

[sparker]

Hi,

Your ES and SD #s seem uniform regardless of load density or velocity. This implies that there is a systimic error that is causing the velocity spreads. If you are throwing charges without weighing each one, that would cause it. Also, if your chronograph is too close, that might cause the readings that you are seeing.

Scott Parker

Bakersfield CA

 

[Forum Boss]

I would inspect the flash holes. On maybe 1 or 2 cases per box you'll see a little chip on the inside--though usually this will come out when depriming. I don't think you'll need to uniform anything yet. Jason is getting well under 1" of vertical at 500 yards and he doesn't ream or uniform his primer pockets.

If you're at 2.354 OAL,before meplat trimming), you're probably not .015" into the lands with a 0.100 freebore. 2.355 is my load length with Lapua 105s and I have about a .080 freebore. Of course the lead angle makes a difference too. Best thing is to use a Stoney Pt. gauge,or equivalent tool) to know for sure.

I think once you tweak neck tension a bit and increase the charge some you'll see the ES drop. N540 and H4895 are other powders worth trying, but RL15 would be my first suggestion after Varget.

 

[lablover]

Just got lucky and Got the freebore number 98 thou. Hope that helps.

I weigh evey charge. The Oehler is out at about 10 yards or better because the range I shoot at has a safety pavillion in front of the firing line. So I have to set it out a ways. I think makin the bar that holds the sky screens longer may help. I heard 8 foot bar is best.

I can't wait for the freebore explination. Being so new at this..I have no clue what that number means or how it's used to determine OAL

Thanks a million guys

Joe

 

[Asa_Yam]

At 10 feet from the muzzle, the chronograph may be too close. The precursor wave,gas expelled from the muzzle) is triggering the start screen, giving you the low velocity readings. Move the screens to 12 - 15 feet from the muzzle to give the precursor wave time to dissipate.

Other things can give you erratic readings. Information about troubleshooting chronographs can be seen at http://www.shootingsoftware.com/CEDMQA.htm

Also, shoot strings of 10-20 shots to get a better idea of the ammo's quality. 5 Shots isn't enough to form a statistically valid sample.

Good luck, and keep us informed as to your progress.

 

[lablover]

Asa

My Chrono was at 10 YARDS! Not feet. I wish I could get it dialed in closer.

Thanks for the links as well

Joe

 

[lablover]

NOTE:

I just used the barrel drop my smith made for me using the same reamer than the rifle. Boy, that makes things easier. Anyway as far as I can tell My OAL base to bullet tip is 2.370...thats with .020 into the lands.

Used the drop and kept smokin the bullet and seating deeper until the bullet no longer stuck into the lands and made no marks. The backed out my seater plug to hit .020 I think I'm right on the money.

Will be interested to see Mods comments.

 

[jb1000br]

Joe I am 20thou in and running 31.4 varget...which has developed vertical recently for some reason...after shooting incredibly to 500 just a couple weeks ago...I am confused too :,

Not much to add, but i would definitely go higher...I hav a .113 FB, so you might even go over 31gns if the pressure isnt too bad.

10yds...hmmm...that might make things spread out a bit, but i wouldnt expect that much.

might also be a bad lot of varget?!?

using "from the factory neck tension" may not be a good idea either, though with the BR brass, those neck dims are a little more user friendly than some other lapua stuff.

can you shoot past 300yds?

JB

 

[lablover]

200 max around here. Gonna try next weekend as well. Might be better hopped up a bit varget wise. As well as with once fired brass. Groups are pretty good though!

Joe

 

[Forum Boss]

Gunamonth--Good tips. Likewise, I don't normally full-length size virgin brass. In fact all I do is run an expander down the neck and chamfer the mouth inside and outside. After the expander, there is still enough residual neck tension.

 

[lablover]

All great info..Thanks a million

MOD...What is your thoughts on my freebore..I was waitin on that one. OAL etc

Joe

 

[Forum Boss]

All great info..Thanks a million

MOD...What is your thoughts on my freebore..I was waitin on that one. OAL etc

Joe

If you are at 2.370" case OAL base to bullet tip +.020 into lands, I think your freebore is about .100",using Kiff-style measurement), which is just about right for your intended purpose. You might play with seating depth from 2.360-2.370. Also, some guys prefer to jump their bullets, .015-.020. Simple matter of seating 5-10 rounds .035 deeper into the case to try that.

 

[lablover]

Thanks a million guys!

 

[lablover]

BTW with that freebore...What is the lightest bullet I can get away with and still be accurate