Vo vs. Powder Charge & Type

Discussions of powders, bullets and loading information.

Moderators: Kirk, Lucinda

User avatar
Raven
Posts: 63
Joined: Thu Apr 23, 2020 5:18 pm
Location: Scottsdale AZ

Vo vs. Powder Charge & Type

Post by Raven »

I am experimenting with known bullets vs. Powder type (1.5FG to 2F) to attain the same accurate Vo.

Any experience with this logic. I am guessing that if you use the same bullet that gives accuracy with a specific powder at a specific Vo, then using a different powder grain size (1.5FG to 2F) that gives the same Vo would give similar accuracy.?

I am going to test this next range time.
martinibelgian
Posts: 1610
Joined: Thu Oct 26, 2006 1:20 pm

Re: Vo vs. Powder Charge & Type

Post by martinibelgian »

Dream on! 😁 If it only were so simple....
User avatar
desert deuce
Posts: 3845
Joined: Mon Apr 14, 2008 10:51 pm
Location: Rio Rico, Arizona

Re: Vo vs. Powder Charge & Type

Post by desert deuce »

Presume you mean volume when you write Vo ? Yes, volume has proven the best place to start with a new lot of swiss powder of the same granulation. Different granulation maybe not.

I just cracked a new case of 3f Swiss. The old lot of 3f swiss weighed 73.0 grains for a set volume, the new lot of same volume weighed 67.5.

Last case of 1.5 varied almost two grains and last case lot of 2f varied almost 3 grains.

If you are looking for accuracy you may find 2f swiss requires more volume and more compression that 1.5 swiss to obtain similar accuracy.

It all depends on you, your rifle and your load. Accuracy should be the goal, the only goal and that is determined by the target.
Sometimes you get the chicken, and sometimes you get the feathers!
User avatar
Raven
Posts: 63
Joined: Thu Apr 23, 2020 5:18 pm
Location: Scottsdale AZ

Re: Vo vs. Powder Charge & Type

Post by Raven »

Sorry No; Vo is muzzle velocity in this case.
User avatar
Distant Thunder
Posts: 882
Joined: Sun Apr 09, 2006 11:46 am
Location: NE Wisconsin

Re: Vo vs. Powder Charge & Type

Post by Distant Thunder »

So you're thinking that if powder X drives bullet Y accurately at Vo Z then powder B driving bullet Y at Vo Z would also do so accurately?

Could be! Good luck!

I would just use powder X with bullet Y at Vo Z and be happy.
Jim Kluskens
aka Distant Thunder
rdnck
Posts: 1885
Joined: Tue Oct 29, 2002 9:33 pm
Location: Woodlawn,Texas

Re: Vo vs. Powder Charge & Type

Post by rdnck »

I think I remember someone saying something about a horse and water sometime back. Shoot straight, rdnck.
Chairman, Phd
Caddo Lake Chapter
FES
Charter Member FBASS

Charter Member OGANT
Clarence
Posts: 2167
Joined: Tue Dec 24, 2002 7:38 pm
Location: Hill Country, TX

Re: Vo vs. Powder Charge & Type

Post by Clarence »

I shot 2-3 cases of Swiss 1.5 using the same volume as produced the best accuracy in the first case (0.060" compression). But, more recent lots/cases have been lighter and produced mediocre accuracy with that volume. The lot I'm finishing now requires ~0.170" compression to get the accuracy my .40-65/Money bullet combo is capable of. Perhaps coincidentally, the weight of powder and velocities are reasonably close to the original charge. That may possibly indicate that there is more inert material or less active material in the ingredients that makes the powder less dense, but the active ingredients produce roughly the same energy from the larger volume???

In any case, there is no shortcut to working up a load when changing powder lots or bullets. For a change in either powder lot or bullet, I load a series of loads, beginning with little compression and working up to ~0.200" compression. I do, in most rifles, find that an overall length that produced good accuracy with one lot of powder will do the same when the powder charge is adjusted.

YMMV.

Clarence
beltfed
Posts: 1962
Joined: Sun Jun 03, 2007 10:07 am
Location: Central Wi

Re: Vo vs. Powder Charge & Type

Post by beltfed »

Back in 2008, "PRE-Paper Patch days" , I did parallel Load Ladder test of loads with KIK 2F compared to my Swiss 1.5 in my 40-65/Lyman Snover bullet in my Brg 40-65
My basic accurate match load was 62 gr Weight Swiss 1.5, The friend who provided the KIK 2F had a 56 g Weight load KIK 2F shooting at matches in TX.
His rifle was also a Brg 40-65.
I checked the bulk density of both powders: 62 gr Swiss, weight of equivalent volume of KIK2F is 58 gr KIK 2F "These Lots, of course"
Then I loaded 56,57,58,etc. thru 62 grains of the KIK2f into RP cases, compressing to the same depth of the 62 gr load of Swiss 1.5.
Shot over the Ohler 33, and targeted at the same time.
Velocity of the 62 gr swiss load was 1260fps, ES 6,SD 2
Velocity of the Equivalent Volume, 58 gr KIK2F was 1207fps, ES13,SD 5
Velocity of the 62 grain Weight of KIK 2F was 1259fps, ES8,SD3.
So, the Same Weight of KIK 2F shot to about the same velicity as the Swiss 1.5 load.
And the 62 grain weight load of the Less Dense KIK 2F
Compressed to the same volume, grouped very close to the 62 gr Weight of Swiss 1.5.
Bottom line was that the KIK 2F appears have the same Energy Weight for Weight, to give
the same velocity as the Swiss 1.5. And the accuracy was very close, to the extent that I did this comparative test.
Oh, obviously the Swiss 1.5 was at that time, the "good old" dense stuff.
Recently, I have had similar comparative results in my 38-50 comparing Same Weight charges
of Swiss 3F, 2F, and an older lot of Swiss 1.5.
Bottom line: I like to compare SAME WEIGHT charges in my load work ups.
beltfed/arnie
bruce m
Posts: 3350
Joined: Tue Aug 04, 2009 5:25 am
Location: australia

Re: Vo vs. Powder Charge & Type

Post by bruce m »

good post arnie.
bruce.
ventum est amicus meus
User avatar
Raven
Posts: 63
Joined: Thu Apr 23, 2020 5:18 pm
Location: Scottsdale AZ

Re: Vo vs. Powder Charge & Type

Post by Raven »

rdnck wrote: Fri Aug 28, 2020 7:28 pm I think I remember someone saying something about a horse and water sometime back. Shoot straight, rdnck.
I got it. But experimenting is part of the fun and I will learn something along the way as I have from your input.
User avatar
Raven
Posts: 63
Joined: Thu Apr 23, 2020 5:18 pm
Location: Scottsdale AZ

Re: Vo vs. Powder Charge & Type

Post by Raven »

beltfed wrote: Sat Aug 29, 2020 4:46 pm Back in 2008, "PRE-Paper Patch days" , I did parallel Load Ladder test of loads with KIK 2F compared to my Swiss 1.5 in my 40-65/Lyman Snover bullet in my Brg 40-65
My basic accurate match load was 62 gr Weight Swiss 1.5, The friend who provided the KIK 2F had a 56 g Weight load KIK 2F shooting at matches in TX.
His rifle was also a Brg 40-65.
I checked the bulk density of both powders: 62 gr Swiss, weight of equivalent volume of KIK2F is 58 gr KIK 2F "These Lots, of course"
Then I loaded 56,57,58,etc. thru 62 grains of the KIK2f into RP cases, compressing to the same depth of the 62 gr load of Swiss 1.5.
Shot over the Ohler 33, and targeted at the same time.
Velocity of the 62 gr swiss load was 1260fps, ES 6,SD 2
Velocity of the Equivalent Volume, 58 gr KIK2F was 1207fps, ES13,SD 5
Velocity of the 62 grain Weight of KIK 2F was 1259fps, ES8,SD3.
So, the Same Weight of KIK 2F shot to about the same velicity as the Swiss 1.5 load.
And the 62 grain weight load of the Less Dense KIK 2F
Compressed to the same volume, grouped very close to the 62 gr Weight of Swiss 1.5.
Bottom line was that the KIK 2F appears have the same Energy Weight for Weight, to give
the same velocity as the Swiss 1.5. And the accuracy was very close, to the extent that I did this comparative test.
Oh, obviously the Swiss 1.5 was at that time, the "good old" dense stuff.
Recently, I have had similar comparative results in my 38-50 comparing Same Weight charges
of Swiss 3F, 2F, and an older lot of Swiss 1.5.
Bottom line: I like to compare SAME WEIGHT charges in my load work ups.
beltfed/arnie
Perfect. Just the kind of experience I was looking for.
bruce m
Posts: 3350
Joined: Tue Aug 04, 2009 5:25 am
Location: australia

Re: Vo vs. Powder Charge & Type

Post by bruce m »

raven,
i don't know if it applies here, but if fclass rifles go off the boil, bringing back the accureate shooting velocity will return them to the node.
not sure if that same velocity works with different powders, or just the same powder.
bruce.
ventum est amicus meus
User avatar
Raven
Posts: 63
Joined: Thu Apr 23, 2020 5:18 pm
Location: Scottsdale AZ

Re: Vo vs. Powder Charge & Type

Post by Raven »

bruce m wrote: Mon Aug 31, 2020 4:16 am raven,
i don't know if it applies here, but if fclass rifles go off the boil, bringing back the accureate shooting velocity will return them to the node.
not sure if that same velocity works with different powders, or just the same powder.
bruce.
That is exactly what I was after. Logic says if you use The same bullet that is accurate with say 1.5 Fg at a given V0 (Muzzle velocity) then it seems logical that that bullet, pushed to the same V0 with say 2fg powder would also be as accurate.

I’ll test that theory this week.
semtav
Posts: 2880
Joined: Wed Feb 03, 2010 3:21 pm
Location: Montana

Re: Vo vs. Powder Charge & Type

Post by semtav »

Just a SWAG, but i think you are forgetting about harmonics.
bruce m
Posts: 3350
Joined: Tue Aug 04, 2009 5:25 am
Location: australia

Re: Vo vs. Powder Charge & Type

Post by bruce m »

the fclass technique is all about harmonics.
mostly it is used when changing lot nos of powder if the burn rat varies a little, or as the throat wears, allowing velocity to drop off.
it is amazing how groups tighten up again when coming back to the accurate velocity.
a lot of work goes on shooting various types of ladders and chronographing to get a good harmonic node at low std deviations.
bruce.
ventum est amicus meus
Post Reply