Been working on determining OAL for each bullet plan on loading and testing.
With XTP 124gr I’m getting .0005” clearance at 1.063” OAL which just so happens to be the OAL of Hornady factory loaded ammunition.
Current safety recommendations are a set back of .015 which would create an OAL of 1.048 which would require lighter starting load to ladder up.
When Reloading ages ago I would have used a 1.06-1.059” OAL for the 124gr XTP based on my current measurements. Which would also require lighter starting load.
What are the cons of a .003-.004” set back versus the .015”?
3-4 thousandths set back was fairly common among those who helped me learn >30 years ago so just trying to understand updated parameters.
Load data: 😖
How good is VV/Hornady load data?
Hornady load data is over a grain lower for all bullets on both minimum and maximum charge weights than VV for the same powder.
I know I’ll have to cautiously work up my own loads, but good grief the more books I get in the more variances in load data. Seeing so many typographical errors in other fields now days makes me nervous.
Doesn’t make sense if VV N300 powders aren’t supposed to create as much chamber pressure.Who said that? If the bullet is traveling the same speed, then it must have nearly equal Chamber Pressure pushing it. Otherwise it would defy the Laws of Physics. Newton's Second Law says for every force there is an action. If the resulting actions of 2 separate forces are equal, then the forces themselves must be equal.
A Solution
Brother Dave, what I suggest is that we develop this load together, from the very beginning. You tell me all the components you have, the pistol you are using, and what your goal is. We will work through every step together. Step by step. I'll even do the chrono work for you. How's that sound ?
Regards
One big factor I rarely see mentioned when determining max OAL for pistol cartridges is the length of the case being used for the test.
Dave -What’s the determining factor for starting load?
Here's the steps in order...
• Berry recommends a velocity of 1050 to 1150fps for this bullet. This data is from the bullet maker's web site. That means we are searching for a specific velocity in order to make the bullet work optimally.
• Next do the "push test" to determine the Max OAL for this bullet in your barrel. Yours and mine came out just under 1.050", so that is a useable number. Not too short; not too long; very easy to measure.
• Next we look at the Max Velocity for the HHP in the VihtaVuori online data. We see the Max Velocity listed as 1115fps. Thus we know we cannot use any N340 load that generates more than that velocity. To do so would also generate the maximum Chamber Pressure, which is a no-no. We are always watching the Chamber Pressure !!
• We can also see that the Vit recommended loads are 4.2 to 4.9gr, but this is at a much longer OAL of 1.126". So we can't use any of these loads. We must find our own, and the way to do that is by using Velocity.
• The only thing to do is try some (1, maybe 2) shots across the chrono, while we keep working the load up toward the "magic" velocity of 1100fps. We'd be using gross incremental steps of (maybe) 0.3gr as we work our way up.
(Note: At this point we are changing ONLY 1 variable: the amount of N340. The primer, powder choice, bullet, OAL, etc are all firmly fixed and unchanging.)
• I have this data already recorded in my notebook
Using N340 @ OAL 1.050" with Federal primers
As fired in a P10c
Average of 8 rounds over a chrono
4.9gr 1086fps
5.0 1101
5.1 1121
5.2 1135
5.5 1178
• Based on these results, your choice MUST BE 4.9 or 5.0gr because anything higher violates Vit's Max Velocity finding.
• So in the end, the load was defined by a combination of Berry's and VihaVuori's recommended velocities.
Hope this helps.
What’s the determining factor for starting load?
Did you start with the lightest load even with shortening of OAL?
Edit:
Or Reduce by certain percentage?
Reloading in 1990’s I didn’t have to worry about a shorter OAL cause every OAL could be lengthened as long as staying in max parameters for the caliber.
The P10c barrel is about 1/2" shorter than the 75. I will try the ammo in an SP01 for a velocity check tomorrow.It's been too overcast to get a reading here.
Loaded 2 Berry's 124gr HHP with 4.2 grains VV N340 @1.050 just to test.So your results are roughly matching my data. 4.2gr is way too low. We need to be up around 1100fps.
Clocked at average 1035fps. 10fps difference between the 2 rounds.
Since it’s supposed to be a while before we have any days with Sun, after today, I sat out with chrono and waited for break between clouds today. [emoji23]Loaded 2 Berry's 124gr HHP with 4.2 grains VV N340 @1.050 just to test.So your results are roughly matching my data. 4.2gr is way too low. We need to be up around 1100fps.
Clocked at average 1035fps. 10fps difference between the 2 rounds.
So we are working toward higher velocity loads, and also getting better "case fill" as a free side benefit.
Still no sun down here.
Are you using mixed brass for your testing ? If so, fish through your collection and dig out 25 that are the same brand. Use those matching for your testing.I’m Using All new Starline brass.
There is always variation in manufacturing (meaning reloading)....The best you can hope for is a low (possibly single digit) SD number. But you can't even go by that until you start measuring at least 8 rounds, and hopefully 10 or more.
But in the end what you really care about is how it performs on target correct? That should be the ultimate arbiter.Agreed. Accuracy is King in my book.
I’m Using All new Starline brass.That's about as consistent as you can get.
Thinking I had to have gotten one of longer bullets in the mix resulting in couple seated deeper eating up a few thousandths of cartridge space.By "longer bullets in the mix" I hope you don't mean that you have 147gr mixed in with your 124gr.
Dillon thanks.
I Found one in stock.
So, may I ask, what dies are you using ?
Dillon, Hornady, Redding... you might look at those 3. Dillon and Hornady have a seating anvil that is exchangeable... that is, you can swap it out to get the best seating with different shaped bullets. Redding has a very good "universal" shape.
The conical shapes from Hornady and Precision Delta can be the hardest to seat correctly. Since the seating anvil is removeable, that allows you to make your own for special bullets. Such as these I make for the PD 124gr JHP....
In that regard, I'll be glad to help you anyway I can.
Main issue is with the Berrys. Had a few issues seating the Sierra Vcrown using it.
Berry’s recommends rounded seating anvil, but search algorithms weren’t helping me find one.
It took a long time, but I finally got you on my to-do list....Loaded half a dozen with it tonight.
(https://i.imgur.com/PNOqThRl.jpg)
These fit pretty darn good, if I do say so myself. Maybe this will help your seating dilemma.
(https://i.imgur.com/Jc3vtiwl.jpg)
I started with the standard Hornady flat anvil. If you'll contact me, we can simply swap flat anvils via the mail.
This anvil isn't much help with 30° bullets, like XTP and PD JHP, but it does fit the 158gr for 38/357.
Just remember folks.... You saw it first here !!
I had to take it down to 1.047 to accommodate my M&p, now I’m thinking about getting quick loads just to see how much that .070 increases my pressure .. that’s the part that kind of stinks as you have to go as short as your Tws barrel if you’re going to shoot the same load in multiple guns