A couple load development questions

1

10ring

Member
My first attempt at developing a load for my short range benchrest rifle went well. I used Tony Boyer's approach as described in his book step by step using a 68 grain Hottenstein and N133 for the 6PPC. This was for a used barrel that came on the rifle I bought used.

I had a barrel chambered with a slightly different reamer and I want to try a 65 grain bullet. Is it best to start at square 1 with the Tony Boyer approach or are there any pieces of information I can use from the first load development experience?

If I develop a load during the winter months in, say, 30 - 50 degree F temps, will I need to do it all over when the temps are much warmer, like 80 - 95 F?
 
start over tho you have some idea what the powder does.
yes temp affects ....br is constantly adjusting for changes
 
Up Down Round and round

Here in the Gulf Coast region temperature and humidity vary a lot. It may start in the morning about 55F with 80% humidity. By the afternoon it is 90F and 35%. Most are using Vit. 133. Most also go up in powder charge as the temp. goes up reasoning that the powder loses moisture and weighs less per volume. I am not sure that this change is necessary if you use a charge master but may be necessary if you use a powder measure. I have had less then stellar luck varying my load as the temp./humidity changes. Sometimes it helps. Sometimes it hurts. Probably it is my ignorance as to what to do and by how much to do it. Keeping a rifle in tune, for me, has always been very difficult. I hope you have better luck than me.
 
Tim Oltersdorf said:
Here in the Gulf Coast region temperature and humidity vary a lot. It may start in the morning about 55F with 80% humidity. By the afternoon it is 90F and 35%. Most are using Vit. 133. Most also go up in powder charge as the temp. goes up reasoning that the powder loses moisture and weighs less per volume. I am not sure that this change is necessary if you use a charge master but may be necessary if you use a powder measure. I have had less then stellar luck varying my load as the temp./humidity changes. Sometimes it helps. Sometimes it hurts. Probably it is my ignorance as to what to do and by how much to do it. Keeping a rifle in tune, for me, has always been very difficult. I hope you have better luck than me.
Click to expand...

Thank you for sharing your experiences Tim. What size are your 5-shot groups when things are working right? The load I ended up with is consistently in the 1's with an occasional 0's when the wind isn't crazy. The load development was done in September and it's still providing 1's in the cooler temps. (I'm in CO) I've been concentrating on technique and reading wind so I haven't been concerned about consistently smaller groups yet. -- Todd
 
Time to test again

I would test again, the 65's will have less bullet in the neck, thus less neck tension, may have a different ogive and contact the lands differently and along with it's lighter weight you will be building pressure differently. The way a case builds pressure more than likely will produce different harmonics in the barrel and finding the correct harmonics is what tuning is all about. You don't know until you see it on paper!
 
hayscott said:
I would test again, the 65's will have less bullet in the neck, thus less neck tension, may have a different ogive and contact the lands differently and along with it's lighter weight you will be building pressure differently. The way a case builds pressure more than likely will produce different harmonics in the barrel and finding the correct harmonics is what tuning is all about. You don't know until you see it on paper!
Click to expand...

Thanks for your thoughts. Those are good points.
 
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