124 gr RN vrs 124 gr HBRN powder charge

[MR40]

I have been shooting 115 GR LRN with IMR 700-X and like my results.

Now I am looking to load 124 GR RN Plated with IMR 700-X but looking for load data all I can find is Hollow back 124gr RN information on both the Load Data website and Hodgdon site.

What has perked my questions is the starting load listed for the 124 gr HBRN Plated is 3.7 to 4.2 and the max load for the 115gr LRN is 3.7.

Thus the heavier bullet is using a larger charge?

Now I know LRN is not the same as plated and the LRN is .356 & the plated is .355 also the noted COL is longer for the 124 than the 115.

But since the 124 gr RN plated I will be loading is flat back and not hollow back I was looking for any input for direction on this before I load up some rounds.

thanks again for all your input

Tom

[MT Gianni]

Cartridge?

[tazman]

It isn't uncommon for plated bullets to require a larger charge than a cast boolit. I had the same thing happen with the plated bullets I used a while back. I loaded what would have been a midrange load for a similar weight cast boolit under a plated bullet and got extremely dirty cases and chambers since the case didn't seal properly.
I had to up the charge significantly to get them to work right.

[MR40]

I am loading 9mm handgun rounds

[Virginia John]

Plated bullets usually require a heavier load than the lead boolits. What you are seeing is not unusual.

[MR40]

It isn't uncommon for plated bullets to require a larger charge than a cast boolit. I had the same thing happen with the plated bullets I used a while back. I loaded what would have been a midrange load for a similar weight cast boolit under a plated bullet and got extremely dirty cases and chambers since the case didn't seal properly.
I had to up the charge significantly to get them to work right.

Thanks Tazman?

I do see that in the loading profiles that plated and or jacketed run higher loads than cast lead. Been loading (2) basic loads with a single FMJ bullet for almost 2 years, the press was at a friends so it was preset I just brought the raw materials and someone else set me up to run and I just made sure the loads stayed the same, I didn't even have load books till recently.

So I consider myself a newbie because the only thing I really did before was pull the handle.

So back in August I setup my own equipment and are trying to expand my knowledge by using different powders and different bullet combinations to see how they work.

Or more simply expanding my loads beyond 1 preset load. Since powder is cycling whats on the shelf, I thought trying different powders and comparing was prudent.

This has lead me in to reading a bit more, but I am finding that with the amount of information getting to what I am really looking for is not that easy to find.

does anyone know of a good site, post or book that explains how bullet differences affect load and pressure? In other words, how does a 124 gr LRN with a flat back compare to a 124 gr HBRN Plated bullet and explain or provide theory on why and how the loads differ?

What I have seen or found, seems to just say they need different loads, but does not breakdown the theory behind it, also does anyone know were I can read up on metering chamber pressure in more detail.

Hence, testing for it and more in depth with comparing Crono reads with chamber pressure.

Thanks for any help in direction

[tazman]

Pressure testing requires some very specialized equipment. I don't have any experience with that. When I am working up a load, I keep an eye out for badly flattened primers. The 9mm runs high enough pressure that you will get some flattening at standard working pressure. Just watch out for anything excessive.
A chronograph is your friend here. When you are using powders known to work in your cartridge, and you reach what would be normal velocities, you are usually near max loads. If you get sudden spikes in velocity with small changes in powder, you have reached the danger zone.
As far as theory on why the differences in loading between cast, jacketed, and plated, you can search this site and get a lot of opinion. I haven't seen any published theory on why this is so. I have just found it to be true by loading and watching results. Different brands of plated react differently just as different styles of boolits and different manufactures jacketed bullets react differently even though the all weigh the same.
I know this wasn't as helpful as you would like. A lot of what we do as handloaders is somewhat uncharted territory because every gun is different and every bullet style, case brand, and powder type is a different combination. You need to find what works in your pistol through starting with lowered charges and working up your loads until you find the combinations that work best.
There is a lot of information detailed in various places on the web about proper, safe loading techniques and procedures, including how to develop a load with a powder you haven't used before.
Your loading books usually have much of this data in them.
Study, research, and safe experimentation are the keys to success here.

[MR40]

Thanks for the reply Tazman,

My Crono is due in this week, but I have to work with indoor lighting so I needed to order the indoor kit.

I have to schedule my range time for late Friday's because of setup, they don't want crono's on the range during busy times and I fully understand.

But do check my primers and cases for deforming closely since I don't have a crono yet.

The slower burn of the 700-X is a softer shot than Power Pistol, but the power pistol load I have has been using is fine turned by others I shoot with and works well, but I am trying other powders and like the 700-X so far, but I need to dial it in more for accuracy.

Thanks for your response.