extrapolating load data

[JonB_in_Glencoe]

Are you looking for cast boolit Data that seemingly doesn't exist?

this post is primarily for newbies who can't find published data for a specific boolit...because it doesn't exist, due to many of the new molds available from the many mold makers that have started up businesses since the turn of the Century.
...But I also would like input from those seasoned boolit casters if you have experience with the two powders that I'd like to use for this project. Hodgdon HS7 and Vihtavuori N110.

I am planning to load some full-house 357 Mag loads (1600+ fps) for the NOE 358-128-SWC (plain base) cast with a strong alloy, and I have two different powders in my stash that I have never used and there is a few lbs of each (mentioned above) and I'd think each one might work well, but there isn't a great amount of data from my usual sources, and of course there is no specific data available for the NOE boolit. The following is my process (extrapolate) to come up with a place to start to work up a load.

As I thumb through my paper manuals, I see some instances where these powders are used in similar loads but not exactly the info I would want to see, if I was looking for specific data. Also, my favorite manual "Lyman Castbullet Handbook 4th Ed" did NOT have any relate-able data, and that is the reason I decided to make this post.

======================================
Here is what I found for HS7:

Lyman 49th
120gr Lead RN (linotype alloy) mold 356242
Start 10gr 1050fps
Max 13.2gr 1436fps

Lee Manual 2nd ed.
125gr jacketed
start 11.5gr 1511fps
MAX 12.5gr 1604fps

Nick Harvey's reloading Manual (I really like this manual because he "independently" developed his own data)
110gr JSP
start 12gr 1570fps
MAX 13gr 1650fps

=====================================

Here is what I found for N110

Lee Manual 2nd ed.
124gr Lead (COAL-1.614)
start 15.7gr 1546fps
MAX 17.4gr-c 1699fps

Lee Manual 2nd ed.
145gr Lead
start 14.0gr-c 1475fps
MAX 15.3gr-c 1591fps

Lyman 49th
150gr Lead (linotype alloy)mold 358477
start 13.2gr 1152fps
MAX 14.7gr 1374fps

Gun-Guides "reloading guide for 357 Mag Revolvers"
I rarely use these little blue booklets you see at gunshows, but I do have a few and this one had Vihtavuori data, also they credit Vihtavuori and other powder manufacturers in the forward
124gr LSWC Intercast (COAL-1.614)
start 17.1gr 1673fps
MAX 18.7gr 1813fps
I included COAL because it matches the Lee data for 124gr and it's a specific unique length, as I suspect Lee got this data from Vihtavuori, but it's interesting that the charges and speed is different

Vihtavuori website
They don't list the 124gr LSWC for some reason, but they have a couple Jacketed loads that are fairly similar.
125gr JHP, Sierra [I](COAL-1.575)[/I
start 16.3gr 1783fps
MAX 18.5gr-c 1811fps

================================================== ===

So after comparing all these charges and knowing my target is around 1600fps or a bit more,
I have extrapolated that if I use HS7, I'll start at 11.0gr and work up to 12.5gr.
OR
If I use N110, I "might" start at 15.0gr and work up. But first I need to investigate case capacity, especially since I suspect N110 prefers a full case much like H110...of course I do not know that, I only suspect it from the narrow data on Vihtavuori's website.

If anyone knows for sure about N110, please comment, because they don't go into much detail on their website.
https://www.vihtavuori.com/powder/n110-rifle-powder/

[JimB..]

I’d calculate powder case capacity based on the seating depth of the bullets for which you have data and decide from there. Just a guess, your SWC is going to be seated no deeper than the Sierra 125gr JHP, which is seated a little shallower than the hornady xtp, if thats all true I’d feel really comfortable starting at 16.5gr VV N110.

[JAC43]

I agree with JimB, seating depth is maybe the most important variable when comparing data. It makes a big difference in pressure. For me, QuickLoad has been very valuable in estimating starting points for various cast bullets not used in manuals. NOE is kind enough to offer for free a QuickLoad bullet file with dimensions and weights for their designs. I use it often.

[uscra112]

Extrapolating from paper manuals has been acknowledged to be extremely dangerous practice for over 100 years.

[John Boy]

I’ve been known to do math calculations for same powder and different bullet weights but then I back down the powder charge by 10%, do a chrono and readjust. This is not recommended for smokeless powders in high pressure capability firearms or without a chronograph

[Hick]

I do very much he same thing, and agree with where you are headed. For those who think extrapolating is wrong-- it is important to note that there is a huge difference in working between published values and starting low, which is safe, compared to extrapolating outside the range of published values-- which can indeed be a very bad idea, especially on the high end.

[Norske]

I use Quickload, but since it's predictive, I search for published, pressure-tested data in my collection of reloading manuals to verify. A really useful bit of data from Quickload is muzzle pressure. Change to a completely different load with similar muzzle pressure, and it will commonly group similarly. POI will differ, but group size will be similar.

[JonB_in_Glencoe]

I appreciate the input so far.
Glad I posted this before I got to far into the planning, because between suggestions here and another forum, I got some things to thing about. I have a large pile of the NOE boolits cast up, using them for 9mm...so that's why I thought about using some in 357 Mag, now I'm reconsidering that, and maybe using a longer/heavier boolit...maybe even using a GC style boolit. There is no shortage of full-house data for the standard 158gr boolits.
Thanks...

[JimB..]

Extrapolating from paper manuals has been acknowledged to be extremely dangerous practice for over 100 years.
It’s perhaps an issue of misusing language. We say that we smelt lead, but we don’t really smelt lead. In this case we’re saying extrapolate but we’re really talking about interpolate.

[uscra112]

I use Quickload, but since it's predictive, I search for published, pressure-tested data in my collection of reloading manuals to verify. A really useful bit of data from Quickload is muzzle pressure. Change to a completely different load with similar muzzle pressure, and it will commonly group similarly. POI will differ, but group size will be similar.

Just fooling around in QL this morning, working loads for my 4 inch S&W 626. Looks to me that 1600 fps puts the pressure into the red zone no matter what powder I try. Is the O.P. using a longer barrel?

[meh]

If I use N110, I "might" start at 15.0gr and work up. But first I need to investigate case capacity, especially since I suspect N110 prefers a full case much like H110...of course I do not know that, I only suspect it from the narrow data on Vihtavuori's website.

If anyone knows for sure about N110, please comment, because they don't go into much detail on their website.
https://www.vihtavuori.com/powder/n110-rifle-powder/

I think N110 safe to download, but it likes to be loaded at nearly full case capacity or somewhat compressed for clean and consistent burn. As with most magnum handgun powders, just because you can download N110 doesn't mean that you will be happy with it. In a relatively high pressure magnum cartridge (> 30K PSI max pressure), a 95% case-filling load is where I usually start. Obviously that will depend on how deeply the bullet is seated. The maximum load will be a compressed one. However, I like to go a little easy on my guns, and I choose a more moderate load that gives me the best standard deviations and accuracy. My .357M loads with N110 are also a little on the light side because I saw some cratering and backed off from there. It was probably not indicative of over-pressure, but I just had no reason or desire to push it over an additional, say, 5% velocity increase.


Just fooling around in QL this morning, working loads for my 4 inch S&W 626. Looks to me that 1600 fps puts the pressure into the red zone no matter what powder I try. Is the O.P. using a longer barrel?

I don't know what the seating depth and overall length is for this bullet, but I had no difficulty using similar weight bullets and 5.7" for the barrel length. The correct input for QL "barrel length" includes the whole of the cylinder.

[uscra112]

I don't know what the seating depth and overall length is for this bullet, but I had no difficulty using similar weight bullets and 5.7" for the barrel length. The correct input for QL "barrel length" includes the whole of the cylinder.

Maybe you'd like to share the details? I used the Sierra JHC 8320 125 grain, for which the QL database sets seating depth of .229. And the barrel length input for the S&W 626 is a measured 5.5". Every powder I tried, when loaded to give 1600 fps, generated a calculated pressure at or above 35000 psi. Which is why i asked about barrel length. If you assume a 6" barrel on the gun, (7.5" in the model), you can get there (barely) without exceeding 35kpsi.

Until the barrel length is specified, not much we say is of any value.

n.b. We single-shot rifle cranks shooting plain base bullets at paper use magnum pistol powders at pressures of 10k to 12k psi with great success. I've never tried N110, but 2400, Blue Dot, AA#9, 4100, all do quite well. Some of our better benchrest types are shooting groups well under 1 moa at 200 yards.

[meh]

Maybe you'd like to share the details? I used the Sierra Sierra JHC 8320 125 grain, for which the QL database sets seating depth of .229. And the barrel length input for the S&W 626 is a measured 5.5". (This ain't my first rodeo using QL.) Every powder I tried, when loaded to give 1600 fps, generated a calculated pressure at or above 35000 kpsi. Which is why i asked about barrel length. If we assume a 6" barrel on the gun, (7.5" in the model), we can get there without exceeding 35kpsi.

Until the barrel length is specified, not much we say is of any value.

Well, as I said, I used 5.7", and the reason I did so was because most 629 cylinders are about 1.71" long, and the standard barrel length of the current circa-4" model is currently 4.125". I don't know what models measure out at 5.5". Seems like that couldn't be a 4" model because the cylinder has to be longer than 1.6".

The Sierra JHC is a very hard, jacketed bullet with a hollow nose and high initiation pressure. I just picked a .358" 125 grain RNFP bullet instead, Lee. With these two modifications, I trust that details are not required. Yes, 1600fps is certainly an aggressive goal for a 5.7" QL "barrel length", and it may not be attainable in the real world under 35K psi with a 4" or 4.125" barrel, either one. As you say, knowing what barrel length the OP will be using will clear up how attainable the goal is.

[meh]

n.b. We single-shot rifle cranks shooting plain base bullets at paper use magnum pistol powders at pressures of 10k to 12k psi with great success. I've never tried N110, but 2400, Blue Dot, AA#9, 4100, all do quite well. Some of our better benchrest types are shooting groups well under 1 moa at 200 yards.

I've heard of success when using these powders at lower pressures behind heavy bullets for caliber. Is that the context there?

[uscra112]

No. Example load in the .25-20 Stevens is 6.2 grains 2400 (or AA#9) behind the canonical 86 grain cast bullet. Or 5.5 grains Blue Dot behind the common 257420 bullet which checked and lubed weights 74 grains. The .32 Ideal likes 11-12 grains of 4100 with the 32360 (8mm) bullet weighing 150 grains. In the .30-40 Krag I've shot the old Lyman 311041 bullet weighing 181 grains with Blue Dot loads ranging from 14 to 18 grains. I've even used Blue Dot in the 7.5x55 Swiss with a 160 grain Eagan MX-3 for a 2000 fps load, although that one approached 30kpsi.

Your 629 is a .44, is it not? Not a .357.

[black mamba]

I don't use QL, but in GRT you have to also put in the cylinder gap and any porting, which both greatly reduce the velocity. When I plug in the OP's numbers of 18.5gr. of N110, Sierra 125 JHC @ 1.575" with a .006" cylinder gap and 4 inch barrel, I get:
MV = 1491 fps @ 39.8 kpsi with a load ratio of 107.7%. That's about as compressed as you can safely get, and still nowhere near 1600 fps.

[uscra112]

Yes, cylinder gap is something QL doesn't have in the model. I'm not concerned - revolvers are a pretty small segment of the reloading universe.

[meh]

Your 629 is a .44, is it not? Not a .357.

LOL. I have no idea why I got on to the 629. I should probably not post so late at night.

[meh]

Yes, cylinder gap is something QL doesn't have in the model. I'm not concerned - revolvers are a pretty small segment of the reloading universe.

I use both tools now, and I normally don't even bother putting the cylinder gap into the model with GRT. It's pretty seldom that predicted velocity coming out of a revolver is something I care very much about, and when I do, it's usually a situation where I'm designing a load to be subsonic or something, not a situation that has anything to do with maximum charges/pressures. In that context, rather, it's always a "get what you get" situation.

It seems like the OP has altered his plans, but returning to the gist of the post, I don't know why one would come at the problem with a velocity target, anyway. You've got a powder and a bullet. If you have reason to believe they should work well together, the first order of business is to predict a safe starting charge. Some idea of the safe maximum charge helps maximize the information gained from the first test firings and to avoid making test rounds that will have to be disassembled. The velocity you get on the high end after working up the load is what you get.

[JonB_in_Glencoe]

I think N110 safe to download, but it likes to be loaded at nearly full case capacity or somewhat compressed for clean and consistent burn. As with most magnum handgun powders, just because you can download N110 doesn't mean that you will be happy with it. In a relatively high pressure magnum cartridge (> 30K PSI max pressure), a 95% case-filling load is where I usually start. Obviously that will depend on how deeply the bullet is seated. The maximum load will be a compressed one. However, I like to go a little easy on my guns, and I choose a more moderate load that gives me the best standard deviations and accuracy. My .357M loads with N110 are also a little on the light side because I saw some cratering and backed off from there. It was probably not indicative of over-pressure, but I just had no reason or desire to push it over an additional, say, 5% velocity increase.

I should have thanked you earlier, this was precisely the info I was asking for.



It seems like the OP has altered his plans,
Yep, I surely did post that. Heavier boolit, maybe GC'd...and there is better data available.



but returning to the gist of the post, I don't know why one would come at the problem with a velocity target, anyway.
Maybe my OP was unclear, my target was "full-house 357 Mag loads", I only mentioned speed as the Data I found for those powders and similar projectiles seemed to max out in that 1600 range, so I put that number in parenthesis, and in hindsight it appears to have given the readers the wrong impression.


You've got a powder and a bullet. If you have reason to believe they should work well together, the first order of business is to predict a safe starting charge.
I believe I clearly stated that in the OP...and it appears I misused the term extrapolate, my bad.

The following is my process (extrapolate) to come up with a place to start to work up a load.



The velocity you get on the high end after working up the load is what you get.
I regret not clearly stating this in my OP, but I tried to imply just that.


As to barrel length. I have several different 357 Mag revolvers and didn't think mentioning them was important, still don't. But Likely most of them would be fired in my 4" GP-100 or my Buddies 6" GP-100 for plinking fun. I prefer not to punished my collectable S&W revolvers with such a load.

[Char-Gar]

I have been reloading since the late 50s. If we didn't extrapolate data back in the day, there would be precious little shooting. Bullets of a similar weight were considered fungible...IF... we used the starting loads and worked up. Nobody in their right mind would start with Max loads!!! Still works the same way today.

[meh]

Maybe my OP was unclear, my target was "full-house 357 Mag loads", I only mentioned speed as the Data I found for those powders and similar projectiles seemed to max out in that 1600 range, so I put that number in parenthesis, and in hindsight it appears to have given the readers the wrong impression.


To be honest with you, I didn't pay any attention to it to begin with, and I didn't really understand why velocity was worth discussing. If I had been thinking more clearly at the time, I would not have responded on that subject at all, but in for a penny... Tangents happen.

[meh]

I have been reloading since the late 50s. If we didn't extrapolate data back in the day, there would be precious little shooting. Bullets of a similar weight were considered fungible...IF... we used the starting loads and worked up. Nobody in their right mind would start with Max loads!!! Still works the same way today.

This. But I do find it annoying that manuals will tell me the COAL (usually) but not bother to mention the length of the bullet they used. Who hasn't substituted bullets? But the single biggest factor with a given powder charge isn't the bullet composition, rather the seating depth. If I just knew the seating depth they used, I'd have better insight into whether my maximum charge would likely to be less than, or more than, their maximum. I was recently developing some loads for WST (the pandemic having pushed me to try something new), and I wasted some time because my initial trial loads were all very light. The reason for that was using a 200 grain RNFP, and their data was for a 200 grain SWC. In .45 ACP, there's more than the average difference between the length of these two bullet shapes, and the SWC is seated substantially deeper. I still wouldn't have seated my RNFPs as deep, but at least I'd have then known that I was loading to shallower seating depth and to expect lower pressures. If it had been the other way around, published load data with an RNFP and I had SWCs, I'd have known not to bother loading any at, or very close to, their published maximum charge. I would just find it helpful.

[uscra112]

I have been reloading since the late 50s. If we didn't extrapolate data back in the day, there would be precious little shooting. Bullets of a similar weight were considered fungible...IF... we used the starting loads and worked up. Nobody in their right mind would start with Max loads!!! Still works the same way today.

Heck, ,that's how Elmer did it. Increase the load until the cylinder blew out.

[Char-Gar]

Heck, ,that's how Elmer did it. Increase the load until the cylinder blew out.

For the record: I have never destroyed or damaged in the slightest any firearm by handloading.

[ddixie884]

Heck, ,that's how Elmer did it. Increase the load until the cylinder blew out.

I'm sorry sir, but your information is not correct. Elmer Keith only ever blew one cylinder and it was with Kings Semi-Smokeless Powder. If you have any documentation to prove your assertions, please post them with dates and publications. This kind of baseless allegation is the beginnings of internet gossip.

[uscra112]

And that was my intention......../sarc

[1006]

Regarding HS7 data: I believe HS7 was previously sold as Winchester W571. You might find more cast data for W571.

Also, the Laser Cast reloading manual has some HS7 data.

[JonB_in_Glencoe]

I appreciate the input so far.
Glad I posted this before I got to far into the planning, because between suggestions here and another forum, I got some things to thing about. I have a large pile of the NOE boolits cast up, using them for 9mm...so that's why I thought about using some in 357 Mag, now I'm reconsidering that, and maybe using a longer/heavier boolit...maybe even using a GC style boolit. There is no shortage of full-house data for the standard 158gr boolits.
Thanks...

Yesterday, I shot some loads using N110 and a NOE 160gr SWC.
The 13.3gr load did what I was looking for. More accurate than a load I worked up a few years ago, using H110 with the same boolit. The N110 sure metered nice.

[Conditor22]

IF I could find ball/flattened ball powders that gave great results in ALL my guns I'd be happy to get rid of all my flake and stick powders.

Just finished doing load workups for 55grn and 62 grn swaged bullets for 3-223's using BL-C(2) ( flattened ball). Dial-in the powder dropper and the charge never changes :bigsmyl2:


Jon, at the price Brownells, is selling N110 for it should load itself :)

[JonB_in_Glencoe]

Yeah, I know. I got these 2 lbs of N110 for a very good price a few years ago...and just want to use it.

[justindad]

I record the bullet length and OACL for all of my hand loads, and interpolate load data based on case volume. Keeping the record of bullet lengths & OACL has been useful.

And to beat a dead horse - I’m comfortable interpolating, but not extrapolating.

[MT Gianni]

To interpolate is to go between a start and max charge. To extrapolate is to assume that since a Speer 150 gr bullet is listed as a max with XX gr of XYZ powder a Hornaday 150 gr is also safe. i suspect most of us do that. It would also be assuming that since 7 gr of powder Q is listed at 700 fps and the table tops out with 10 gr of powder Q at 1000 fps that 11 gr gives you 1100 fps. I hope that none of us does that.

I would start with measuring of the bullet bearing surface and comparing it to the one listed. I believe that is as important with cast as weight is do jacketed due to ogives, tapers and jacket thickness.
i have never shot and of the VV powders and consider HS7 to be at the top of the medium powders. In a perfect world this would be where we tell you to go buy some 2400/296/H110/AA9 and go to work.
If I chose to do this, I would look at each fired case with a magnifying glass at each progression, including the start.