Bullet Seating

[ratrod54]

If this is in the wrong section, I will remove.

Looking to improve my reloads and have recently come across the Bullet Jump testing Mark Gordon @ SAC did. He also did a pod cast a few days ago where this was also discussed and now I am curious. I am not challenging the data, I like what the data says. Taking that into consideration, I have a few questions.

First, what are some general thoughts about this topic?

In the Podcast, It sounded like Mark mentioned that charge weight wasn’t quite as important as possibly finding the appropriate bullet jump when beginning a load workup.

• Does that previous statement sound accurate?
• Should someone focus on a bullet jump ladder test first, where would someone start with regards to the charge? Is it best to go into a reloading manual and just start with a safe charge for the particular round and then fine tune the charge once the bullet jump has been settled on?

In this day and age, components aren’t easy to come by, so to be able to do load workup with the use of consumables kept to a minimum would be ideal.

I have been reloading for about 6 years, but I don't do it a lot. I still have a lot of questions and my inexperience with reloading shows, so I apologize if this question is "stupid".

 

[Dthomas3523]

You’ll find people on both sides the aisle. Some who find charge weight first and others who find seating depth first.

Neither way seems to be wrong as both sides show good results. And when neither is wrong, that means neither is right. And that also means that neither is most important. For example, Erik Cortina finds his powder charge first without any regard to seating depth. Then finds his seating depth

I personally have interpreted his jump data that if you don’t want to mess with things often, use his method of testing to find the widest jump node possible.

I personally use a tuner and regularly run test to find tuner setting before matches. So, I don’t worry with any of the jump stuff for prs/nrl.

 

[samb300]

If this is in the wrong section, I will remove.

Looking to improve my reloads and have recently come across the Bullet Jump testing Mark Gordon @ SAC did. He also did a pod cast a few days ago where this was also discussed and now I am curious. I am not challenging the data, I like what the data says. Taking that into consideration, I have a few questions.

First, what are some general thoughts about this topic?

In the Podcast, It sounded like Mark mentioned that charge weight wasn’t quite as important as possibly finding the appropriate bullet jump when beginning a load workup.

• Does that previous statement sound accurate?
• Should someone focus on a bullet jump ladder test first, where would someone start with regards to the charge? Is it best to go into a reloading manual and just start with a safe charge for the particular round and then fine tune the charge once the bullet jump has been settled on?

In this day and age, components aren’t easy to come by, so to be able to do load workup with the use of consumables kept to a minimum would be ideal.

I have been reloading for about 6 years, but I don't do it a lot. I still have a lot of questions and my inexperience with reloading shows, so I apologize if this question is "stupid".

What podcast was this? I'd like to check it out.

In the data SAC has published and the podcasts I've listened to with Mark, he says each bullet design has a jump node (not sure if that's his exact wording), so once you select a bullet you can use his data to test and verify that jump, and go from there. So if you have something like a 105 Hybrid, you know it will shoot good at 0.020" jump like it always has, but it might be more "set it and forget it" at 0.060"-0.075" as the throat wears.

In my last barrel I shot 6GT with 110 A-Tips, and after I found my charge weight and shot a few matches, I played around with jumps and found the bullet was very insensitive to jump, meaning groups and POI were essentially the same from 0.020 - 0.100" jump. In my next barrel I might do the opposite order as I break the barrel in, test the jump with a random charge weight and see if it yields the same result.

You might be somewhat limited to how much you can jump by your cartridge selection and chamber freebore. Something like a 6BR and a 0.104" freebore you have tons of neck to seat bullets deep in order to test long jumps. But on a short neck like a Dasher with a 0.104" freebore, jumping a bullet 0.080" will likely have the bullet seated deep past the neck/shoulder junction.

One other thing I found really interesting was the thought put into this subject by Hornady. Mark said he tested the 108 ELDM and got something like a 0.035" jump as being ideal. Which ended up being exactly the jump of a 108 factory loaded 6 Creed round in a SAAMI 0.183" freebore chamber.

 

[TheOfficeT-Rex]

RE: Seating first or charge weight first - neither is right or wrong, but preference. I have seen seating depth affect my average velocity readings, 30fps over a 45k change, with shorter being faster. Is some of that because of shooting the shorter depths later (barrel heat, sunny day warming up), possibly, but going forward I'm going to start with seating depth before powder charge.

 

[PinesAndProjectiles]

RE: Seating first or charge weight first - neither is right or wrong, but preference. I have seen seating depth affect my average velocity readings, 30fps over a 45k change, with shorter being faster. Is some of that because of shooting the shorter depths later (barrel heat, sunny day warming up), possibly, but going forward I'm going to start with seating depth before powder charge.

I'd be willing to guess that a bullet seated deeper in a case allows less case volume for the powder, which causes higher pressures and thus, higher velocity.

 

[clcustom1911]

I'd be willing to guess that a bullet seated deeper in a case allows less case volume for the powder, which causes higher pressures and thus, higher velocity.

Yes, especially if you are almost full. Like 98% or so. But, IMO once you are compressed, then seating depth won't really have a whole lot of effect on case capacity because, well, there isn't amy more volume to take away from moving the bullet in further.

 

[ratrod54]

What podcast was this? I'd like to check it out.

 

[ratrod54]

You’ll find people on both sides the aisle. Some who find charge weight first and others who find seating depth first.

Neither way seems to be wrong as both sides show good results. And when neither is wrong, that means neither is right. And that also means that neither is most important. For example, Erik Cortina finds his powder charge first without any regard to seating depth. Then finds his seating depth

I personally have interpreted his jump data that if you don’t want to mess with things often, use his method of testing to find the widest jump node possible.

I personally use a tuner and regularly run test to find tuner setting before matches. So, I don’t worry with any of the jump stuff for prs/nrl.

I agree that there seems to be a thought process for both options and can see what you mean by either/neither is "right".

I want to start from scratch on a new load for a 7mm08 and my question came from being puzzled as to where i should start with charge weight if I was going to do a jump test first. During the podcast, it appears as though he says that charge weight doesn't have that much effect and he follows up with an example of three different loads (same bullet, primer and brass & jump). He mentioned that the end result are nodes which are similar for all three, regardless of the charge.

So if I were going to start with jump, I guess I am okay to pic a charge between the start load and max load for the Berger bullet I want to use. Find my jump during a ladder test and then start working up the charge? I am probably over thinking this. Only difference I see that could be interesting is guessing the jump (if starting with the charge weight) could be less hazardous than guessing the charge (if starting with the jump).

I appreciate all the responses here. I enjoy reloading and honestly like the "if you don't want to mess with things often, use his method" idea for the moment.

 

[Dthomas3523]

I agree that there seems to be a thought process for both options and can see what you mean by either/neither is "right".

I want to start from scratch on a new load for a 7mm08 and my question came from being puzzled as to where i should start with charge weight if I was going to do a jump test first. During the podcast, it appears as though he says that charge weight doesn't have that much effect and he follows up with an example of three different loads (same bullet, primer and brass & jump). He mentioned that the end result are nodes which are similar for all three, regardless of the charge.

So if I were going to start with jump, I guess I am okay to pic a charge between the start load and max load for the Berger bullet I want to use. Find my jump during a ladder test and then start working up the charge? I am probably over thinking this. Only difference I see that could be interesting is guessing the jump (if starting with the charge weight) could be less hazardous than guessing the charge (if starting with the jump).

I appreciate all the responses here. I enjoy reloading and honestly like the "if you don't want to mess with things often, use his method" idea for the moment.

Shouldn’t be any “guessing.” Most everything out there has published data. Be loading manuals or on forums like this. And most any wildcat is going to have enough similarities to known cartridges.

So, you shouldn’t be starting anywhere near “hazardous” area.

 

[TheOfficeT-Rex]

So if I were going to start with jump, I guess I am okay to pic a charge between the start load and max load for the Berger bullet I want to use.

Pick a moderate charge from the book and you should be good to go. It's ok to be too slow, but you don't want to be on the upper end of pressure.

Once you have seating depth, go back and work charge weight to get the speed/es/node that you want (whatever method you subscribe to). There's a lot of info in the reloading depot forum and you might get more traffic if you ask specific questions there once you get started.

 

[Ledzep]

IME the things that have the biggest influence, in order;
1. Powder type (i.e. H4350 vs. Varget vs. RL-16 vs. H4831sc, etc.)
2. Powder charge in large increments (1-1.5gr). Everything I've seen so far says milder charges are more accurate.
3. Bullet type (140 hybrid vs. 140 ELDM vs. 135 A-tip-- Different barrels like different things)
4. Seating depth. Most stuff seems to work best from .020 to .050 jump. Anymore I set it to .035 and forget it.

Case mfg. and primer mfg. or type (BR/match vs. 'normal') hasn't really amounted to much of anything. Lapua, alpha, etc.. are stronger and handle high pressure loads (over 65ksi) better, but again, I've seen decreased precision capacity with higher pressure loads across the board. I have not found any evidence of 'nodes'. Changing powder charge has negligible effect on ES/SD, and minor changes-- mind you across the entire spread from book min to book max-- in accuracy which trends better slower.

Seating depth will affect ES/SD. I haven't tested jamming because it spikes chamber pressure, but touching the lands produces some of the worst ES/SD results I've seen. Things are usually pretty happy from .020 to .050 jump, and some bullets then exhibit a loss in precision when you jump them long.

Obviously every barrel is different but those are some trends that have stuck out to me.

 

[Ledzep]

I'd be willing to guess that a bullet seated deeper in a case allows less case volume for the powder, which causes higher pressures and thus, higher velocity.

It's a hump. Super close to the lands spikes pressure because the bullet doesn't get a running start into the rifling, which then increases velocity. As you back away from the lands pressure and velocity drop, then start to rise again when you rob case capacity.

 

[TheOfficeT-Rex]

Super close to the lands spikes pressure because the bullet doesn't get a running start into the rifling, which then increases velocity.

What do you consider "super close to the lands?" I saw no appreciable change in velocity using a 223 that was 5k jammed, at touch, and 5k off. It was a stout, but not compressed load (52 berger at 3340 or so)

 

[ratrod54]

Shouldn’t be any “guessing.” Most everything out there has published data. Be loading manuals or on forums like this. And most any wildcat is going to have enough similarities to known cartridges.

So, you shouldn’t be starting anywhere near “hazardous” area.

Agreed. I meant "Guessing" within the Start and Max loads that are published. Poor wording on my part.

 

[ratrod54]

Pick a moderate charge from the book and you should be good to go. It's ok to be too slow, but you don't want to be on the upper end of pressure.

Once you have seating depth, go back and work charge weight to get the speed/es/node that you want (whatever method you subscribe to). There's a lot of info in the reloading depot forum and you might get more traffic if you ask specific questions there once you get started.

I have a load for the 6.5 CM that's on the slower end. Its amazingly accurate, but I have been wanting to speed it up some. Along with working up a new load, I was going to play around with it as well but I will likely start over and play with jump a little too.

I was going to place in there and then felt maybe here was better. I likely derailed the post a bit with my response and realize it would have been a better fit in the reloading depot. I appreciate the reply though, thank you!

 

[ratrod54]

IME the things that have the biggest influence, in order;
1. Powder type (i.e. H4350 vs. Varget vs. RL-16 vs. H4831sc, etc.)
2. Powder charge in large increments (1-1.5gr). Everything I've seen so far says milder charges are more accurate.
3. Bullet type (140 hybrid vs. 140 ELDM vs. 135 A-tip-- Different barrels like different things)
4. Seating depth. Most stuff seems to work best from .020 to .050 jump. Anymore I set it to .035 and forget it.

Case mfg. and primer mfg. or type (BR/match vs. 'normal') hasn't really amounted to much of anything. Lapua, alpha, etc.. are stronger and handle high pressure loads (over 65ksi) better, but again, I've seen decreased precision capacity with higher pressure loads across the board. I have not found any evidence of 'nodes'. Changing powder charge has negligible effect on ES/SD, and minor changes-- mind you across the entire spread from book min to book max-- in accuracy which trends better slower.

Seating depth will affect ES/SD. I haven't tested jamming because it spikes chamber pressure, but touching the lands produces some of the worst ES/SD results I've seen. Things are usually pretty happy from .020 to .050 jump, and some bullets then exhibit a loss in precision when you jump them long.

Obviously every barrel is different but those are some trends that have stuck out to me.

This was the reason for the post originally. I don't disagree with your 1-4 above, but based on the study that Mark Gordon has done, its possible the order doesn't necessarily follow this path and long jumps aren't as bad as once thought for some bullets.

He fond sweet spots for some bullets in the .050 to .080 ranges regardless of charge weight. Each bullet seems to have its own likings, but outside of the bullet itself, the rifle didn't matter as much. I am not saying that it doesn't at all, but if you watch the pad cast above and listen to his commentary, he has some compelling information in there to suggest otherwise. I thought it was good for conversation.

 

[Ledzep]

I'll watch the podcast tonight in its entirety and see what I think.

@TheOfficeT-Rex less than .010 jump. I've found issues with ES especially under .010 jump. Jammed will be the high velocity/pressure. Jump about .030-.050 will usually be the bottom (obviously this is very cartridge/chamber dependent), then after that it will start to rise again.

 

[Ledzep]

This was the reason for the post originally. I don't disagree with your 1-4 above, but based on the study that Mark Gordon has done, its possible the order doesn't necessarily follow this path and long jumps aren't as bad as once thought for some bullets.

He fond sweet spots for some bullets in the .050 to .080 ranges regardless of charge weight. Each bullet seems to have its own likings, but outside of the bullet itself, the rifle didn't matter as much. I am not saying that it doesn't at all, but if you watch the pad cast above and listen to his commentary, he has some compelling information in there to suggest otherwise. I thought it was good for conversation.

Watched the video. ES/SD does not correlate with dispersion with powders that are a good fit for the cartridge. I have found that to be true. I have found 'happy spots' in jumping from the lands, too. However, in my testing the change from best to worst dispersion from adjusting jump is smaller than from adjusting powder charge... However, I adjusted over a pretty wide range of powder charge (several grains). If a guy wanted to stick towards the top end of the powder charge, then seating depth may cut you some slack (assuming you're out of the happy spot to begin with).

 

[fx77]

Secrets of the Houston Warehouse recommends just touching the lands to start (marks are 1/2 wide as long)
One can then use the Euber method of getting your best group by varying the charge.
Then with the latter back off from the lands in fixed increments until your group gets better or worse.
Then stop when it is best.
The charge and jump are determined.

 

[Sogan]

Jump discussion Starts at 44:00

 

[47guy]

IME the things that have the biggest influence, in order;
1. Powder type (i.e. H4350 vs. Varget vs. RL-16 vs. H4831sc, etc.)
2. Powder charge in large increments (1-1.5gr). Everything I've seen so far says milder charges are more accurate.
3. Bullet type (140 hybrid vs. 140 ELDM vs. 135 A-tip-- Different barrels like different things)
4. Seating depth. Most stuff seems to work best from .020 to .050 jump. Anymore I set it to .035 and forget it.

Case mfg. and primer mfg. or type (BR/match vs. 'normal') hasn't really amounted to much of anything. Lapua, alpha, etc.. are stronger and handle high pressure loads (over 65ksi) better, but again, I've seen decreased precision capacity with higher pressure loads across the board. I have not found any evidence of 'nodes'. Changing powder charge has negligible effect on ES/SD, and minor changes-- mind you across the entire spread from book min to book max-- in accuracy which trends better slower.

Seating depth will affect ES/SD. I haven't tested jamming because it spikes chamber pressure, but touching the lands produces some of the worst ES/SD results I've seen. Things are usually pretty happy from .020 to .050 jump, and some bullets then exhibit a loss in precision when you jump them long.

Obviously every barrel is different but those are some trends that have stuck out to me.

just a question and im not trying to be a dick but how long have you been reloading and how long have you been doing all this testing you talk about?

 

[Ledzep]

Reloading ~15 years, for precision rifles for 8, large sample testing over the last year and change.