Pressure build near max for ball powders

[Tac-O]

I thought I'd read in my loading manuals somewhere that ball powders will build pressure very quickly when you get near max, ie they have a steeper pressure curve than extruded powders. I looked and can't find that statement in them though. Maybe I read it on here or in a reloading video, but I can't find it in the search here.
So, specifically for Ramshot Hunter and Staball 6.5, but also for ball powders in general, do you start seeing larger jumps in velocity when doing a pressure ladder with ball powders when you get close to pressure?

Here's my pressure ladder data from last weekend. It is an AI case, so I assume that it is masking some pressure signs. I can't believe that I'm not at max pressure with the higher end charges of staball.

185 juggernauts
Cci200
30-284AI (68.75gr H20 cap, use 30-06 data)
Peterson brass
24" 10twist 4 groove
Temperature 32F, although cartridges were stored in my house overnight

All recorded with a Caldwell chronograph. It was in the shade, so it should have read these accurately.


Hunter - *1gr charge jump from 58-59
56.5 - 2798
57 - 2795
57.5 - 2793
58 - 2809
59 - 2874
59.5 - 2857
60 - 2873
60.5 - 2917 full case

Staball - *1.5gr charge jump from 56-57.5
54.5 - 2708
55 - 2700
55.5 - 2732
56 - 2732
57.5 - 2862
58 - 2881
58.5 - 2906
59 - 2942

No definitive pressure signs but a very slight ejector mark on the highest hunter charge.

For a follow up, I want to shoot 10 rounds each of one charge of each powder, but not sure which one to pick. I don't want to base that on any kind of apparent "node", but want to pick a charge that is 1-1.5gr below max. I'm thinking maybe 59-59.5 for hunter and 57.5 - 58 for staball.

Thoughts and experiences?

 

[Seabeeken]

Have you tried more or less neck tension or even a crimp or a magnum primer? I had similar results with ball powders. IME, they can vary speeds like that but give me very good groups. I've found Hunter an excellent powder.
Recently I experimented with my 6XC and 69 gr AH. I could not find a single single base stick powder that it liked. I was shocked. I went to ball powders and things improved as far as groups but ES wasn't that great. I tried other ball powders and found TAC and A2520 shot single hole groups and ES 10-15. With that said, I was working with my 243AI several years ago with H-414 and got pressure spikes at several charge weights and then the next increment would show normal. Haven't seen that before or since. Probably not much help with this but ball powders can be strange but I often get excellent accuracy.

 

[Tac-O]

For these, I haven't tried crimps, mag primers, or different neck tension.

I would bet there is some noise in there for my velocity measurements. I don't think I've ever had better speed ES than probably 25. So the shape of these particular curves might not be able to tell me anything as far as coming up on pressure.

I will likely pick one of these in the upper half for each powder and see how they group.

 

[Tiny Tim]

I've used Staball 6.5 in my 243 AI with Hammer Hunter bullets. Es was horrid until I started crimping. Accuracy was always good (short range). But yes, I definitely noticed a large jump when near max load. .5 grain increase went from acceptable pressure to yikes! 80-90fps increase. Not locking up bolt or piercing primers, but significantly hotter. Many other experience the same with Staball. Have no experience with Hunter so cannot speak to that.

 

[Ol' Red]

Last weekend I was testing some H380 ball powder in a .308. I was increasing .5 grain between loads. Velocity increase was fairly even, but did have a jump at about the mid-point. Temperature was in the high teens, so I want to duplicate those loads and retest in warmer temps. My spike was not like your Staball between 56 gr and 57.5 gr. I think you are on track to with your suggested start point to start tuning for accuracy.

 

[3800fps]

Working up loads for 22-250 …H414 and WW760 (the same powder)
40.5grains with 55gr bullets is the load that works in many guns with no pressure signs….
41grs loosened primer pockets…. I saw similar powder behavior with H380…. I'd find a load within 1gr of the "book" max and .5 grs up gave all the pressure signs at once.

also these ball powders left a durable carbon-like fouling in the barrel not present with stick powders, seems to need a little more effort to clean out.

 

[Bubbize]

I didn't have any luck with Staball 6.5 in my 6.5 Creedmoor. SD was off the chart, mid 20's-low 40's, accuracy was still good at a 100yd but the further out you go the worst it gets. But that was my experience. Every rifle is different.

 

[cape cove]

I have used quite a bit of ball powders over the years with mag primers and never experienced much of a spike near max other than with StaBall 6.5. This powder set me back on my heels. With one grain I went from what I would consider normal to pierced primers and expanded primer pockets. This was in my 7/08. I still use it in my 22/250 but keep a sharp eye out for pressure and what the manuals print. JME

 

[SSgt G Cody]

I've had incredibly good response from H414, H4350, and W760 with Mag primers in .243AI. I keep my loads at .030" off lands. Groups at 300 yards with 100gn bullets are .58", and no pressure signs.

 

[SSgt G Cody]

I had a question for more info on previous comment. Barrel is an 8-twist, 26" light Sendero, trued, as is action, a Rem 700. Polished Rem trigger, 2 lbs., Modified wood stock. 43-45gn H414 usually, WinMag primers. Very good shooter. It's taken many deer.

 

[Mike Matteson]

If you are starting to show ejector marks, you are at the pressure signs of high pressure. I could be your brass at the same time too. Need to look at your primers at the same time.

 

[doggonner]

Staball 65 is a hot powder be careful, I tried some and you have to take the charge up slowly, it's sitting in the back row of powders I will not use it no more, I think it would be a great powder for 308, it seems to just suddenly cause pressure issues..but it could be me not paying attn

 

[Tac-O]

Staball 65 is a hot powder be careful, I tried some and you have to take the charge up slowly, it's sitting in the back row of powders I will not use it no more, I think it would be a great powder for 308, it seems to just suddenly cause pressure issues..but it could be me not paying attn

I have heard that about staball and hodgdon 100v in some cartridges, but I think it happened at warm to hot temperatures outside. Not sure if it's also common at cold temps

 

[cape cove]

I have used a good amount of H100V and never found it any different than other powder ball or stick. StaBall was different and when I ran into pressure with it the outside temp was at appx 70F. Temp wasn't a factor in my case. JME