Load Data and OAL

[JFrank]

@BJung I have started several charge test with tangent ogive bullets on the touch point or (my zero ) although they always seem to end up with a jump .015 -.026 ish shooting best.
Secant ogive/ vld bullets seem to really shoot small inside the lands so that where I start them.

 

[HowieG]

Benchrest shooters are a completely different ballgame, for a number of different reasons. For the average reloader, it's unlikely they would take the steps (and investment) to prep their handloads like a BR shooter.

I do agree... 'consistent' is a better term, and is actually what I meant. Proper sizing, annealing, and other things like neck turning can get you there.

Frankly, you don't even have to be that consistent depending on what you are doing. I load survival 30-30 using mixed brass, a starting load, and a cheap bullet and they shoot plenty good enough for 30-30 purposes.

 

[kalielkslayer]

IMHO seating depth varies depending on what you’re loading for.

My big game rifles, I’m just off of the lands. I realize this can cause pressure issues so I start 2 full grains below max, sometimes more. Go up 1/3 a grain at a time, look for pressure signs, group size and velocity. I don’t even measure OAL except to endure my rounds are consistent.

I’ve been known to ream out magazines with a dremel tool to allow the OAL that shoots best in that gun, to be able to feed those rounds.

For anything I’m loading in an auto loader, functionality is my primary concern. OAL is one of my primary concerns. It needs to feed every time!

 

[redcon1]

Tip off came the other day when I was assessing load data for 150 grain Hornady Interlock in 308 Win using Varget powder.

Found 4 or 5 load data sources that listed max powder charge of Varget at 47 to 48 grains.......but with OAL of 2.800 or 2.810......(seating depth of bullet to achieve over all length).
The outlier was the Hornady data (I have developed habit of going to bullet maker data to get their recommendation for powder and OAL). Hornady topped out the powder charge at 44.5 grains......but had bullet seated deeper at 2.735 OAL.

Hornady 9th ed lists 44.9 grains as max with 150 grain pills at 2.735". I used to load 42 grains of Varget over a 168 grain AMAX for my AR10 and Recon (2 grains below 44 grain max per Hornady 9th ed) but then the bolt catch broke on the AR10 and the hammer actually broke on the Recon so I dropped down to the next lowest node, 40.8 grains. My 40.8 grains was still beating their 41.7 grains. They listed 2,500 fps for 41.7 gr out of a 22" barrel and I got 2,567 fps with 40.8 grains with my 24" of barrel. It was real cold out when that hammer broke. It could have been poor MIM and brittle fracture or it could have been too much powder in lake city brass. It was warm out when the bolt catch broke though. I'll never know but I'll never stuff any kind of published max load into 7.62 lake city brass again. as far as COL goes, I never seat deeper than published COL but I'm loading for semi-autos so I'm looking at magazine lengths first and then the published data.

 

[JFrank]

Harold Vaughn did an investigation of pressure vs. seating depth several years ago. The short version is that when the bullet is deeply seated, pressure is high. As the bullet is seated farther out, pressure diminishes. As the bullet is seated yet farther out, proximity to the rifling starts to take over, and as OAL is increased, pressure again increases.

Which makes perfect sense.

Even though it makes sense, try to pick up the changes in fps on a chronograph and you may quickly find that the differences are so small they can get lost in the white noise and won’t be able separate primer crush variations from seating pressure or charge variations of minor amounts effecting ES

 

[Charlie98]

Frankly, you don't even have to be that consistent depending on what you are doing.

It also depends on what you expect out of your handloads, too.

I'll never know but I'll never stuff any kind of published max load into 7.62 lake city brass again.

I've never understood why most, if not all, of the published service rifle data is worked up with commercial cases, not surplus. It would seem a given...

 

[BJung]

I think I started taking the original question off topic so I'll open a new thread. Returning to the original question, I'd say the charge weight range depends on the components and the gun. I look for range that fits in all of them as a safety range. For recommended loads, look at what firearm was used. For example, I looked at two cartridges that Ken Waters' tested. He used the same model rifles as mines. It turns out that in both instances, my discovered accuracy load was almost the same as his. I think this is because of the consistency of mass produced items.

 

[HowieG]

Even though it makes sense, try to pick up the changes in fps on a chronograph and you may quickly find that the differences are so small they can get lost in the white noise and won’t be able separate primer crush variations from seating pressure or charge variations of minor amounts effecting ES

Yep. The only way to really track this stuff is with equipment to gather pressure data. I actually do have a rifle that likes the bullet touching the rifling. I stay away from max loads with that one.

 

[HowieG]

IMHO seating depth varies depending on what you’re loading for.

My big game rifles, I’m just off of the lands. I realize this can cause pressure issues so I start 2 full grains below max, sometimes more. Go up 1/3 a grain at a time, look for pressure signs, group size and velocity. I don’t even measure OAL except to endure my rounds are consistent.

I’ve been known to ream out magazines with a dremel tool to allow the OAL that shoots best in that gun, to be able to feed those rounds.

For anything I’m loading in an auto loader, functionality is my primary concern. OAL is one of my primary concerns. It needs to feed every time!

That's why I like my Tikka. I converted it from a short action to a long action just so I could use a longer magazine and load longer bullets out to the rifling.