Pure lead boolit velocity results part 4

[Lead melter]

Well gang, here are the results of today and yesterday's [in a terrible wind] experiments using Hodgdon's H-4198.

Testing parameters can be found in my post dated 2/20/08 titled "Testing tomorrow".

Some interesting results in comparison with previous powders used.

14 grains H-4198
Group 1-.533"
Group 2-.953"
Velocity group 1-1121 fps
Velocity group 2-1135 fps
Group average-.743"
Velocity average-1128 fps

15 grains H-4198
Group 1-.711"
Group 2-.749"
Velocity group 1-1206 fps
Velocity group 2-1194 fps
Group average-.730"
Velocity average-1200 fps

16 grains H-4198
Group 1-.940"
Group 2-.372"
Velocity group 1-1292 fps
Velocity group 2-1282 fps
Group average-.656"
Velocity average-1287 fps

17 grains H-4198
Group 1-.946"
Group 2-.876"
Velocity group 1-1377 fps
Velocity group 2-1378 fps
Group average-.816"
Velocity average-1377 fps

18 grains H-4198
Group 1-1.389"
Group 2-1.191"
Velocity group 1-1442 fps
Velocity group 2-1450 fps
Group average-1.290"
Velocity average-1446 fps

These groups were all fired in a ferocious windy condition, but they looked so good I decided to take it a step farther in powder charge and fire at 100 yards. The results were better and worse than I expected.

19 grains H-4198
Group 1-1.942"
Group 2-2.950"
Velocity group 1-1423 fps
Velocity group 2-1416 fps
Group average-2.446"
Velocity average-1419 fps [Strange that the velocity decreased while the charge increased. Has anyone ever seen this situation before? There were no spikes, nor lulls in velocity readings, all just lower.}

20 grains H-4198
Groups 1 and 2 were 6-8", too large for test parameters
Velocity group 1-1529 fps
Velocity group 2-1533 fps
Velocity average-1531 fps

Everything looked really good for a while, but as you can see, I reached a peak and then overran it with velocity.

Summary tabulations will follow.

[cbrick]

Lead melter,

I went back to the first thread and found out your using the Lee 150 gr RN but in pure lead what does this bullet weigh? Is it near 160 grains?

One of the pressure indicators I use in load work ups is for every 0.5 gr powder charge increase there should be 50 fps increase in velocity. It may be 40 fps or 65 fps but it'll be right around 50 fps. Your data follows this up to a point, it says a velocity increase of 90 fps for a full grain charge incease from 16 to 17 grain (or 45 fps per 1/2 grain). Then from 17 gr to 18 grain an increase of 69 fps for a full grain (or 34.5 fps per 1/2 grain). Then 18 to 19 gr there is a net loss of 27 fps. Between 18 grains and 20 grains there is an increase of 85 fps for two full grain increase in charge weight (21 fps per 1/2 grain powder, remember, you had 90 fps velocity increase for one grain in charge weight). In other words the velocity gains stopped following the charge increases starting between 17 and 18 grains.

Been my experience with mid capacity cartridges that once this point is reached the only gain to be had from more powder is more pressure, almost always with a loss of accuracy and usually a velocity loss. This is the point I back off a 1/2 grain. I take this as a sign that in this cartridge, with this powder and this bullet weight, style, alloy that this is the point of no gain and a pressure max.

From IMR (Hodgdon) online load data, it says min/max charge of IMR 4198 for 160 gr cast FP is 15 gr. to 17.0 gr. Your velocity gains stopped right after 17.0 grains and your groups opened up by 1/3 at this point. After this point groups got worse quickly and velocity increased very little.

Same Hodgdon source also says min/max charge of IMR 4198 for a 170 gr Sierra (jacketed) FP is 21.0 to 22.3 gr.

I have no experience with pure lead at the upper end of listed loads (why do you think I'm so interested in your results? :mrgreen:) so I don't know how much or even if the soft lead will increase pressure, even bullet style/alloy could affect this. I've always used WW and HT WW and for the most part (within velocity limitations) have used jacketed data with no problems.

Just a little something for your brain to chew on.

Rick

[Leftoverdj]

I think you transposed the group average and the second group numbers for the 17 grain charge. Doesn't make much difference, though.

The accuracy difference between the groups with the 14, 15, 16, and 17 grain charges is so small as to be meaningless. Sheer chance could give that spread on two five groups. interesting that you kept accuracy to 1377 fps, though. I'd expect pure lead to expand pretty good at anything close to that if the bullet has much of a meplat.

[Lead melter]

cbrick,

You called that one pretty close. The boolits, lubed and checked average at 160 grains.
Interesting observation about powder charge/velocity increase tabulations. This has probably been noticed by a lot of folks, but I just never picked up on it. The data does seem to bear that out.
Inductive reasoning would tell me that it happened once, therefore will happen again. Your findings are deductive reasoning. That it happens repeatedly and therefore will happen again. Both methods point to the same conclusion, and so that seems good enough for me.
I'm glad you caught this. It will answer several questions in the future.

Leftoverdj,
The actual figures were 1387, 1372, 1384, 1380, 1363, average 1377.2 fps group 1, and
1380, 1389, 1346, 1396, 1381, average 1378.4 fps group 2. Average of the 2 groups was 1377.8, but it's close enough I think. I like to err on the side of conservativism.

Keep in mind that these were all thrown charges. No individual weighing of powder. Ambient temperature, barometric pressure, powder position, shooter error, and many other factors could well have played a part in these results.

I tried to keep everything possible at a baseline for the tests. All powders were from the same lot, primers from the same lot, checks from the same lot, boolits from the same cast, etc. There are just the occasional gremlins who decide to show up sometimes.

Thanks for checking me out guys, it helps a lot.

[cbrick]

cbrick, Interesting observation about powder charge/velocity increase tabulations. This has probably been noticed by a lot of folks, but I just never picked up on it. The data does seem to bear that out.
Inductive reasoning would tell me that it happened once, therefore will happen again. Your findings are deductive reasoning. That it happens repeatedly and therefore will happen again.

Whether I am working up a standard cartridge with a book load or working with a wildcat this has always applied for me. With book loads it’s very common for the powder/velocity to suddenly show little or no gains very close to book max. Lots of variables involved so it’s not always exact but it’s usually pretty close.

Its one of the great advantages of using a chrono in load development, it can't tell you what the pressure is but it can sure raise your eye brows and get you thinking. Since almost all of my load work is for long range handgun (revolver mostly these days) accuracy it’s fairly easy to watch this and see the accuracy drop off at the same time, sometimes radically.

I don’t know the correct name for this is or even if there is a correct name, I’ve always just called it the point of no gain. You can still raise pressure after this point but if its not getting a velocity increase and accuracy is dropping off that’s “NO gain”.

Rick

[Lead melter]

Whether I am working up a standard cartridge with a book load or working with a wildcat this has always applied for me. With book loads it’s very common for the powder/velocity to suddenly show little or no gains very close to book max. Lots of variables involved so it’s not always exact but it’s usually pretty close.

That helps explain why I've never noticed that. I try never to push max on anything I load. I apply what Richard Lee wrote that if a powder charge is reduced just 5% of maximum, the performance {velocity, trajectory, etc.} reduces about the same amount, but barrel wear reduction is more than 10 %.

On the flip side, I know one fellow who starts at book max and goes up from there. He has a 243 shooting 85 grain jackets at 3800 fps from a 20" barrel Model 70. Too much for my blood!

[cbrick]

It's not the max load I'm looking for. Normally when starting low and working up in half grain increments as long as it is or could become a decent, balanced load that groups well the groups will shrink as you approach the optimum charge for that cartridge, powder, bullet combination. Pass the optimum and groups start getting larger, sometimes slowly, sometimes dramatically. It's not surprising that this often happens at the same time the velocity increases stop following the charge increases.

It's the most accurate load I'm looking for and I have never seen the flat out hottest load as the most accurate load. I suppose that could happen but it hasn't happened to me yet.

Rick

[Bass Ackward]

Boy I sure have. But not with lead in handguns.

Hardness is the key there. OF coarse, every bullet design has a different point for this based upon band width, unsupported nose weight or lack of bearing area. This is why guys that use the same mix often find certain bullet designs that work better for how they want to shoot them. There is a discussion going on right now on another thread of Semis vs RNFPs. (Sounds like a horror movie huh?) And others that perform poorly for them, simply because they don't want to adjust for conditions.

Accuracy improves along with ignition. When accuracy peeks and begins to degrade, no matter handgun or rifle, you need a slower powder or a harder bullet to go on up. Eventually you will go so slow in burn rate that poor ignition is always the case.

That's why they say match hardness to your pressure. But there are always exceptions.

Occasionally, and I am a big proponent of softer for hunting, I use softer stuff and play around with it to get it to do what I need done and this often exceeds what the hardness chart says is possible. Elmer was famous for this using his 10 or 11 BHN mix depending on the tester, to go 34,000 psi when clearly the hardness chart says that is only possible for linotype and harder.

That is why I am interested in Lead Melters conclusions.