Data when there is no data?

[Leo_B]

I have .32 cal 78gr. RN hard cast coated bullets I plan to use for my .327 Fed Mag Ruger 3" SP101. Probably mostly in .32 H&R Magnum level loadings. Hopefully that covers all info needed, probably too much. Anyway, my Lyman Cast Bullet Handbook has data for 75gr. and 85gr. RN Lyman bullets but nothing in between. Hodgdon adds data for a 77gr. LFN, almost correct weight but wrong profile. Hornady nothing. So what do you do for data when there is only "close" but not exact? Thanks again in advance for so far always excellent and helpful responses.

 

[Orr89rocz]

Interpolate and software like quickload or GRT for me

 

[Mark611]

JMO, 5grns of bullet weight doesn't make that much difference, in load data unless you're trying a max load, bullet designs do, I would start in the middle of the load data for the load data of the 77gn and work your way up.

 

[PhilC]

Use the 75gr starting charge weight data for your 78gr bullets. Not like you're pushing them real hard and +3gr bullet weight difference isn't going to matter a whole lot anyway.

Alternatively, you could halve the starting charge weights for 75 & 85 and use that. I've done that many times for a starting charge with a bullet weight between two published values.

 

[Leo_B]

The numbers are interesting depending on powder. Of the powders I have:
Accurate No 5, 75gr 5.4/6.1, 85gr 4.0/5.4
Alliant Unique, 75gr 4.0/4.5, 85gr 3.0/4.5
Hodgdon HP38, 75gr 3.9/4.4, 85gr 2.0/3.5
Hodgdon TiteGroup, 75gr 3.2/3.6, 85gr 3.1/3.5

The No 5 starting load for 75gr is the max for 85gr
Unique has the same max for both but big difference in starting load
HP38 is two totally different ranges with no overlap or even touching
TiteGroup is almost identical

I've got a LOT to learn and comprehend on this reloading business.

 

[nmkid]

I've got a LOT to learn and comprehend on this reloading business.

Take your time...you will never learn it all!

 

[PhilC]

Which Lyman cast bullet manual are you getting that data from? Lyman #4 does not show Acc 5 nor HP38, at all, and min/max charge weights for Titegroup and Unique are significantly different than your data.

75gr bullet data min/max
Titegroup - 5.0/6.0
Unique - 5.5/6.6

Edit to add: The data I posted is specifically for 327 Federal Magnum. The data you posted is for 32 H&R Magnum and not interchangeable.

 

[Leo_B]

Lyman Cast Bullet Handbook 4th Edition 13th Printing September 2024 pages 240/241 .32 H&R Magnum.
Oh, sorry, I'm looking at the .32 H&R loadings but will shoot them in the (presumably) much stronger .327 revolver.

 

[Krogen]

In my mind, it's simple. (hah, no simple minds comments please!)

Just use data for the next lighter bullet. It doesn't usually matter much, but going with data for the next heavier bullet means pressure tends to increase. Again, probably not much but it's going in the wrong direction.

Also keep an eye on seating depth, specifically how much of the bullet's shank is in the case. If you seat two bullets with different profiles to the same COAL one may intrude deeper into the case, reducing available capacity and increase pressure. Smaller cases with faster powders are affected more.

 

[kenhwind]

This is an interesting topic because we have all been there. "What data to use when there isn't any?"
I agree that a few grains difference isn't going to be an issue as long as you are not loading max data.
Bullet profiles can but do not always make a difference.

Sierra published load data for the .38 Super, the data was the same for their 125 grain bullets, as well as their 130.

Speer lists the same data for several different 9mm bullets.

When in doubt I look at all the data I can find for a particular load, bullet profile, etc.

Try to match the components as close as you can, it is possible to create a bad combination. In low pressure round like a .38 Special or .45 ACP this isn't an issue, but it can be in a .38 Super, 10mm, etc.

 

[Leo_B]

My current thought is to use the Lyman Cast Handbook data for when I do .32 H&R cases with the slightly lighter 75gr RN bullet. I'll start with the lowest charge plus 0.1gr. for the heavier bullet. I'll use my powder that's giving the lowest pressure among their loadings, in this case Unique 4.0gr. 1068fps 14,400psi. I'll start at 4.0gr. on my 78gr RN also. Max load on the 75gr RN is 4.5gr. Interestingly enough, for their 85gr RN they show a starting load of 3.0gr at 10,800psi and it also tops out at 4.5gr max.

I'm not sure I can use the .327 load data as that makes 1585fps which may be too fast for this bullet. I've emailed the company to ask what max. velocity for the bullet should be.

 

[charlie b]

Revolvers are very forgiving given that too light a load won't hurt anything.

As noted above, use data from lighter bullets and go from there. 3-5gn bullet weight won't make that much difference since the load data may be +/- 10% anyway. Heck, difference in bullet shape and construction will give more difference. A chronograph is a great tool for load development, if not just to keep velocities in sane territory.

If you get flattened primers you are in magnum territory and need to be careful, if not back off entirely. Same with sticky cases.

FWIW, plain base powder coated bullets are good for velocities approaching 2000fps, but, I liked to keep them in the 1500fps range or less. I believe HiTek will go a bit higher but have never used it. Above that and I used gas checks.

 

[thatguyshm]

It can be extra confusing with so many different sources, including revisions you can get online that we used to have to wait until the next loading manual came out for to get updated data.

I ran in to exactly this this morning. Finally found Barnes data on the 280 AI and 145 LRX. I checked the new data against what I had loaded up by pulling a bullet. I had loaded 57.0gr staball 6.5, new data said 53.5 was max. Velocity given for max new data is the velocity I'm getting with 57gr. Went and checked Hodgdon, see that the 150 TTSX is loaded to 58gr max, which is how I extrapolated in the first place.

Ever since getting a Garmin Xero, I let my velocity speak to me just as much as the load data when trying to come up with data on my own. Start low, go slow and be safe, you'll get there.

 

[Leo_B]

Revolvers are very forgiving given that too light a load won't hurt anything.

As noted above, use data from lighter bullets and go from there. 3-5gn bullet weight won't make that much difference since the load data may be +/- 10% anyway. Heck, difference in bullet shape and construction will give more difference. A chronograph is a great tool for load development, if not just to keep velocities in sane territory.

If you get flattened primers you are in magnum territory and need to be careful, if not back off entirely. Same with sticky cases.

FWIW, plain base powder coated bullets are good for velocities approaching 2000fps, but, I liked to keep them in the 1500fps range or less. I believe HiTek will go a bit higher but have never used it. Above that and I used gas checks.

That is good to know. The load data for .327 shows the 78gr RN at 1585fps starting load up to 1761fps max load. I don't plan on ever going beyond 50% and probably not nearly that, so 1585-1620fps is likely my only velocity range loading those. And more of them will be loaded .32 H&R than .327 so 750-850fps mostly.

I'm putting a Xero on my wish list. Not sure when the jolly fat guy will come through on something that big though.

 

[bobcat93]

Brother, all it takes is a call to Sierra bullet. talking to them its fantastic, and they are here to help, you can also ask a member who has quickloads to look something up for you, and compare the data from Sierra
That is what ive done in the past.
Also check pick up those data books when working with spicific cartridges with hard to find data..
One of these will have load data your looking for
This is a link below to load book..even if it doesnt look like it..haha..weird internet

Amazon.com