Is finding the powder load which fills the case "always" right?

22 April 2002, 09:33

Okay, so I've got several powders which are new to me (Vectan SP7, TU2000 and TU3000).

The manufacturer's data for one in particular offers a load range in the mid 20's of grains for driving a 55gn bullet in .22/250. As I'm used to using 38.4gn of H380 I initially dismissed this new load as too light. Howver I've just weighed out 27gn and find that it does indeed almost fill the .22/250 case and on that basis, I'm considering loading some up to see how they perform.

I know that all the perceived wisdom generally points to optimal loads as the ones where the case is full, but how watertight a rule is this? Is it one of those "usually but with exceptions" rules?

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tikka 3 barrels

21 April 2002, 23:40

Eddie

quote:
Is it one of those "usually but with exceptions" rules?

I can't comment on bottle-necked cases, but, in my experience, some straight-walled cases are the exception. I use magnum primers in some light loads to get a complete burn, but they are very accurate.

Eddie

22 April 2002, 01:42

<green 788>

As a rule, you'll get your best burn consistency with a near full case. Gerard Schultz of GS Custom bullets http://gscustom.co.za/ recommends that the powder charge be *almost* touching the base of the bullet.

I believe the reason that such powder charges give better consistency is that the powder column is always basically intact. There is no room for it to pour forward or rearward.

Imagine that your in the field, and carrying your rifle with the muzzle down, as many folks do. The powder in the cartridges in that rifle pours to the front of the case. This leaves an area near the case head and primer where there is space, with no powder. When you pull the rifle up to shoot, some powder pours back toward the primer. The various ways that the powder column can get distorted in a 60% full case are near limitless. This affects the consistency of the burn, and of course, accuracy.

Check out www.snipershide.com, click forums, and then handloading. I have a more detailed account of my OCW (Optimal Charge Weight) load development plan there. By following such a plan you can find just the right amount of powder for a given set of load components.

Dan Newberry
green 788

22 April 2002, 01:47

<.>

There's the possibility of "flash over" in light loads. The primer flashes across the top of the powder, and it detonates rather than burns. This can spike pressures dangerously.

Some powders are less dense than others. So, 30 gr. of one powder may fill the case while 30 gr. of a different powder may not. BL C2 is apparently less dense than H-335 although the two are very similar otherwise.

I wonder about the effects of compressed loads on ignition.

Magnum primers can give you faster velocities at lower peak pressures -- in SOME applications. Again I think this is a part of burn rate and bbl length.

Work up data with a chrony. (Mine is being shipped.) I don't think there's any other way to figure out what's going on.

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.223 Ackley Improved Wildcat Forum:
http://www.hotboards.com/plus/plus.mirage?who=223ackleyimproved

22 April 2002, 01:47

Alex Szabo

Pete,

Unless one has significant experiance with 'a load' then conventional wisdom dictates to use the load data [presumably] obtained from the powder vendor.

My high-level approach has always been to start with the low-end forumla; test and repeat until accuracy is achieved. If you are looking for 'power' or 'speed' vs. accuracy, then perhaps your approach is viable considering it meets the maximum safe standards established by whomever you subscibe to (as we use SAMMI).

Be safe in the meantime Pete.

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Best regards,
Alex

Democracy is two wolves and a lamb voting on what to have for lunch.
Liberty is a well-armed lamb contesting the vote! - Benjamin Franklin 1759

22 April 2002, 03:03

<Don Martin29>

That "flash over" term is a new one. I have never heard of dangerous pressures with fast burning powders unless it's a over load or a double load. I have heard of dangerous pressures with light loads and slow burning powders.

I have found that using high bulk powders such as imr 4759 and say imr 3031 in a case that's ideal for imr 4350 as an example that the accuracy is just as good as a full case of slow burning powder. The velocity is not as high of course. Magnum primers are what I use also for such loads.

22 April 2002, 03:07

Pete

Guys, thanks for the input so far;

Green,

I couldn't contact the server for www.snipershide.com - any ideas?

Genghis,

I'm with you on the chrono - all that stuff about "just work up the load until it groups optimally" always feels like groping around in the dark to me.

Alex,

You're right about starting light and working up with powder weight. This particular powder looked like such a light load on paper that I needed to see how it actually filled the case before believing it might have potential. Sure I'll start with a lesser load but had the manufacturer's recommended top weight only half-filled the case I wouldn't have bothered testing it.

cheers guys

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tikka 3 barrels

22 April 2002, 03:44

<Daryl Elder>

I read an article recently where tests were conducted using 'light' charges with the powder against the primer, away from the primer, etc.. There is a dramatic pressure increase when the powder is not against the primer; accuracy is also adversely affected. One reason I like to use a powder that basically fills the case is it prevents double charging. Close to 100% load density is much preferred. FWIW.

22 April 2002, 04:07

<green 788>

Pete,

Try the link again. I just tested it and it works. Once there, go to "forums," then to "handloading." You'll see some threads on OCW load development there.

Good luck, and let us know how things go.

Dan Newberry
green 788

22 April 2002, 05:43

DannoBoone

Pete - Somewhere last year I read about a
guy who often used loads in which the
powder didn't fill the case. When using
these loads, he would chamber a round, point
the rifle straight up, and slowly put it
back down to the rest so that the powder
would always be to the back of the case. I
tried it in my 25-06 in which practically
all loads do not fill the case and it helped
for very consistant groups. For those who
hunt with the barrel pointed towards the
ground, this would be another matter,
entirely!

22 April 2002, 05:43

<.>

Ya gotta drop the period at the end of the sentence in the link in order to get to the URL.

http://www.snipershide.com/

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.223 Ackley Improved Wildcat Forum:
http://www.hotboards.com/plus/plus.mirage?who=223ackleyimproved

22 April 2002, 06:12

Pete

I'm in, and I'm tikkatikkatikka (can you guess what kind of rifle I shoot mostly?)

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tikka 3 barrels

22 April 2002, 11:51

stronics

When I go here it locks up Netscape

www.snipershide.com - any ideas?

David

22 April 2002, 23:30

1894

Pete,

I think it's a question of balance. Some of the compressed loads list those charge weights not because of pressure but because above that and either the bullet starts to move out or the case expands and chambering is difficult.

You might be surprised how well the faster powders work - I still cannot beat VVN120 in my 222 try as I might!