Tuning for a new lot of Powder

[TikkaSporter]

So somehow my six 1lb containers of H4350 in a matching lot withered down to less than one. I figured I should check velocities before switching to a new 8 lb container to make sure it would remain in the 'node'. Just got back from the range and didn't like what I saw.

The running velocity that matches drops for this load out to 1200 yards is 2860 fps (41.6 gr H4350 with 130 Norma Golden Targets)

Tonight:

5 shots with 41.6 gr of the old lot of powder:
Average = 2876, SD = 2, ES = 1

3 shots with 41.4 gr of the new powder lot:
Average = 2845 SD = 4, ES = 8

5 shots with 41.6 gr of the new powder lot:
Average = 2847, SD = 4, ES = 10

So what should I do here? Keep adding powder until I get up to my original velocity range (2860 - 2875) and call it good. Start over again on load work-up?

This load was developed with two side-by-side ladder tests that showed essentially the same result, followed by a seating depth tune for optimal grouping (and a stable POI) at 100 yards.

 

[savagedasher]

Mix the one pounder with the 8# and Check the results you have 9# to work with .
Larry

 

[dmoran]

My own practice and experience is to adjust the charges to match the barrel speed. Typically pressure will not be an issue, but do keep an eye on pressure signs for that possibility. 30-fps spread from H4350 between Lot's isn't to bad (seen a lot worse from it).

Good report.... nice to see others data.
Thanks for sharing !.!.!
Donovan

 

[TikkaSporter]

I guess I should mention that this is for a 6.5x47 Lapua with a short freebore (0.050"). My only concern with adding more powder to match barrel speed is that it is already a compressed load, so hoping that I don't run out of room in the case.

 

[TikkaSporter]

Mix the one pounder with the 8# and Check the results you have 9# to work with .
Larry

Haha, I actually have a 2 or 3 more one pound stragglers of H4350 from different lots that I picked up when it was 'unobtanium'. How many do you think I could fit in the 8 lb container? How do I mix them well enough to ensure that I don't increase my ES/SD?

 

[JAlfred]

I use a huge ceramic bowl my wife bought to make large batches of bread (Bed , Bath, and Beyond) and mix it clean hands till I am sure that I have gone beyond thorough and entered ridiculous. I think I got more the listed weight in a 5 lb Alliant powder container. Your milage may vary.

 

[gotcha]

Haha, I actually have a 2 or 3 more one pound stragglers of H4350 from different lots that I picked up when it was 'unobtanium'. How many do you think I could fit in the 8 lb container? How do I mix them well enough to ensure that I don't increase my ES/SD?

Wait a minute! You're changing the rules in the middle of the game I'll bet your wife/Lady friend has a cooking container that's just the right size for mixing. Like a good Gin Martini stir don't shake

 

[JAlfred]

Wait a minute! You're changing the rules in the middle of the game I'll bet your wife/Lady friend has a cooking container that's just the right size for mixing. Like a good Gin Martini stir don't shake

I should have included a statement about adding the powders from different lots in layers, a little at a time till everything is added in. In my crazy little mind, that helps with mixing.

 

[savagedasher]

Wait a minute! You're changing the rules in the middle of the game I'll bet your wife/Lady friend has a cooking container that's just the right size for mixing. Like a good Gin Martini stir don't shake

Garbage bag Bucket with s lid shake and tournament . I have two and one Half 8# that all shoot rhe same . Nobody ask to buy because I had mixed Larry

 

[JRS]

Just throw it in an empty tumbler for a few hours and let it run...I don't suggest mixing powder lots but that's just me.

That would not be a wise thing to do

 

[dmoran]

Just throw it in an empty tumbler for a few hours and let it run...

^^^^ WARNING ^^^^
Highly advise to NOT do this !.!.!
( Static + Propellant = BOOM )

 

[Eddie Harren]

Garbage bag Bucket with s lid shake and tournament . I have two and one Half 8# that all shoot rhe same . Nobody ask to buy because I had mixed Larry

Once again the translator is needed!

 

[JimPag]

Once again the translator is needed!

Or as my ancestor's would say Eddie, no capisci.

 

[rifleman700]

So somehow my six 1lb containers of H4350 in a matching lot withered down to less than one. I figured I should check velocities before switching to a new 8 lb container to make sure it would remain in the 'node'. Just got back from the range and didn't like what I saw.

The running velocity that matches drops for this load out to 1200 yards is 2860 fps (41.6 gr H4350 with 130 Norma Golden Targets)

Tonight:

5 shots with 41.6 gr of the old lot of powder:
Average = 2876, SD = 2, ES = 1

3 shots with 41.4 gr of the new powder lot:
Average = 2845 SD = 4, ES = 8

5 shots with 41.6 gr of the new powder lot:
Average = 2847, SD = 4, ES = 10

So what should I do here? Keep adding powder until I get up to my original velocity range (2860 - 2875) and call it good. Start over again on load work-up?
This load was developed with two side-by-side ladder tests that showed essentially the same result, followed by a seating depth tune for optimal grouping (and a stable POI) at 100 yards.

You can determine how much more powder you will need by figuring this.

Velocity increases by the square root of the percent of powder increase.

 

[dmoran]

Or as my ancestor's would say Eddie, no capisci.

Like Eddie; me no capisci jibber.... !.!.!

 

[TikkaSporter]

I've been a bit leery in the past about mixing lots of powder with different burn rates with concern that unless its mixed perfectly (or even if it is) that it could adversely affect my ES/SD...

In this case I had time on my hands and went for it. I kept my last 1 lb bottle of the 'old lot' out of the mixing process. It's enough powder in a known lot (with excellent ES/SD) to load for one or two local matches, plus I have it if I need to re-test my new lot against it again for any reason.

I mixed two new 1 pounders (different lot numbers) with the new 8 lb jug, using some big salad bowls, a funnel, plastic spoons, etc to mix. I probably went overboard in my efforts to ensure that they were as evenly mixed as possible. I was able to fit just shy of 10 lbs into the 8-lb jug (the rest went into the powder dispenser hopper).

Todays Test Summary:

- Conditions = Colder than yesterday (~ 40 F vs ~ 55F). Lightly raining, but shooting under a covered bench. Care was taken to keep ammo and everything else dry.
- Increased C.O.A.L by 0.002" on these rounds for estimated throat erosion since developing the load/seating depth testing...

Results:

3 shots with 41.6 gr of the old (known) lot:
Average = 2861 fps, SD = 5, ES = 11

3 shots with 41.9 gr of the new (mixed) lot of powder:
Average = 2868 fps, SD = 7, ES = 14

3 shots with 42.2 gr of the new (mixed) lot of powder:
Average = 2883 fps, SD = 2, ES = 5

Thoughts/Comments/Questions:

- Did adding the two 1-lb'ers to the 8lb jug increase the overall burn rate?
- Thinking of going with 41.8 gr of the new mixed lot powder and calling it good?
- Were 3-rounds of each charge weight enough to be valid for this purpose?
- Groups from all of these velocity tests were in the 0.3 - 0.7 MOA range (averaging about 0.5), but since they were shot with a Magneto that may not mean much.

 

[CharlieNC]

What constitutes a "lot" when it comes to powder? Does it mean made the same day but across multiple batches, is it just the same raw ingredients made across multiple batches, same ingredients on one batch, ???? I have worked in or with manufacturing for 45 years, and have never seen a common definition for a lot for a given industry. As a result I do not trust that any 1lb jar with the same lot number is the same as another, so I always maintain a running blend within a lot number and when changing lots.