QuickLoad H20 case fill question

[TackDriver284]

I am stumped with a reading on QL for my 7mm Mag. I used the Berger 140 grain VLD under 66.7 grains for a chronograph reading of 3250 fps this morning. I have a 25.5 inch barrel.

The QL program default reading for H20 is 82 grains, so I changed it to 88 after the average of using 5 cases. I weighed each unsized fired empty brass ( 5) for a final weight of 219.5 grains and 5 fired unsized cases of H20 and ave weight is 307.8 and final weight after calculations is 88.4 grains of H20, so i entered that in the tab in place of the program's reading which was 82 grains. Now I added the charge weight, and other data.

Now my velocity is way lower by 220 fps slower than my chrono reading and 100 fps slower than the program's 82 H20 reading. I tried the same method with my 6.5 Creed and 6.5 x 284 and reading is just off by .4 to .6 grain of H20 which is normal. Why is the 7 Mag reading off by 6 grains? Could someone help me with this issue? Thanks

 

[kraky1]

To me worrying about case capacity is kind of a waste of time. I would never use quick load to predict a maximum load and then go right to that maximum loaD. I try to start my first load at 55k to 58k pressure using reloading manuals and quick load as a guide. Once I get a chronograph reading on those numbers I adjust quick load to match what actually happened. Quick load cant take into account variations in Chambers and Freebore. Some Remington's Tikkas and of course wby have a lot of this. And to me ql way over reacts on seating depth situations.
It's fun when quick load comes up with the right predictions but it certainly doesn't happen all the time!

 

[Wyo7200]

7mm rem mag is an overbore Caliber- If you change the weighting factor to .33 it will be more accurate in you QL.

 

[TackDriver284]

7mm rem mag is an overbore Caliber- If you change the weighting factor to .33 it will be more accurate in you QL.

Yes Sir I had already done that last night, changed from .5 to .33 and increased velocity from 3187 to 3240. One problem still exist that I am still confused with is the H20 weighing factor. Program's reading is 82 grains on H20 while my fired case / with spent primer in it, and weighed at 88 grains. so its off my 6 grains. After changing H20 factor from 82 to 88 ( my reading ) and the velocity drops dramatically from 3240 to 3125. But my problem is I do not understand the editing on Ba factor to make the velocity match. RiverRider has explained to me on that but I am still clueless. :?

 

[kraky1]

Geez... I never noticed the weighting factor adjustment! I always change to case capacity ba.
Here's a good read....

http://forum.accurateshooter.com/thread ... r.1645308/

 

[TackDriver284]

I think I may have a understanding what you are trying to explain. I have the sheet with the OBT vs Barrel Length with 7 nodes on them, example if my QL velocity currently says 3175 and my chrono velocity is 3280, then I change the Ba number , let's say 0.5187 to 0.5390 until my QL velocity is 3280 , the same as my chrono speed, then I look at the Barrel Time 10% PMax to muzzle on QL, and let's say it is 1.3442 on QL and my Excel sheet says on node #6 is 1.883, then I increase my powder charge weight on QL to increase the OBT from 1.3442 until it gets to 1.883 ish?? I hope this is how its done, let me know. Thanks for your help.

 

[kraky1]

All I can say is that's how I do it...lol.
Now....all that said..... don't necessarily expect Magic on your Barrel just because a sheet of paper says it matches a node.
I have to say when all this node stuff appeared on the internet I went back through a lot of my very accurate loads..... I did find a lot of them seemed to be close to nodes..... but certainly not always.
Most of us reloading people are optimistic tinkerers...... it doesn't take a lot of development to get our guns near A node..... and it certainly is as good a place to start as any where! Tinker onward....lol.

 

[TackDriver284]

All I can say is that's how I do it...lol.
Now....all that said..... don't necessarily expect Magic on your Barrel just because a sheet of paper says it matches a node.
I have to say when all this node stuff appeared on the internet I went back through a lot of my very accurate loads..... I did find a lot of them seemed to be close to nodes..... but certainly not always.
Most of us reloading people are optimistic tinkerers...... it doesn't take a lot of development to get our guns near A node..... and it certainly is as good a place to start as any where! Tinker onward....lol.

Am I going in the right direction?

 

[Wyo7200]

I think you are- another limitation of QL (ime) is estimating ball type powders in large quantities. You wouldn't happen to be using ball powder?

It does make sense for the velocity to decrease when you add more capacity to the case but do not add any more powder to it.

There is an excel workbook on Chris's longs site that contains formulas for obt so you can enter a barrel length and node # to see the nodes past 7.

 

[TackDriver284]

I think you are- another limitation of QL (ime) is estimating ball type powders in large quantities. You wouldn't happen to be using ball powder?

I am using Reloader 19

 

[kraky1]

Well I'll throw a little mud in the water and stir it. One bench rester wrote a pretty compelling article that finding the mode where your Barrel wasn't moving might actually not be the most accurate. It was his theory that you might actually want to find a node where your Barrel is on a slightly upward movement. That way if a bullet came out a little slow your Barrel was at a higher point and the two would self-correct. If your bullet came out on the faster side of es your barrel would be at a lower point and those two would self-correct correct. So if you ever find yourself at longer range with some ES and still have amazingly consistent point of impact you may have found such a load!

 

[RiverRider]

I was taught the same theory, and I think it holds water...BUT, I was also told that a load that works at 100 yards may not work so well at 200 yards.

 

[kraky1]

My 1:12 308 throws amazingly tight clusters with 208 Amax at 100 but they fall apart very quickly soon after.
On the other hand my older 300 Weatherby Alaskan with Barnes 180 xbts didn't do really good at 100 yards but was consistently under moa at300.
All this is why we get to have fun when we go to the range and see what the real world is like....LOL!