Quickload and RS60

[Davee]

Both of these are new to me. I have been constantly questioned about why I don't use RS60 in my 6.5x55, it was mainly trying to source some without a 2 hr drive. My local RFD now stocks it so I bought some, I also treated myself to QL. There seems to be few recommended loads for Sierra 130GK -1728-, RS60 and 6.5x55, so to QL. Firstly I entered my data for N550, way off of any nodes. Started looking harder and realised that the QL data for 1728 dimensions is different to the bullets I have, Measured 20. took the mean, entered that into QL and was 20fps away from the node and where I get the best grouping, Marvellous!! I had entered case length, capacity etc and made the temperature selections. Now to RS60, using the previous data - only changing the powder- and a couple of hours I had load data for 3 OBT nodes. Loaded 5 of each and off to the range, group wise the best were at the loads for nodes 6 and 7, with the latter being smaller. BUT the fps were nowhere near what was expected being 222 and 329 fps slower. The fps's were closer to nodes 7 and 8 than those predicted. I went to RS web page, downloaded their data for QL and compared it with those QL already had , identical.
Questions, 1. why was the 1728 data wrong? 2. Why are the barrel times so far out? 3. What should I modify to get a better result? 4. Should I forget OBT and do more work with tuning the better load?
KBC don't bother to try to score points, informative responses would be greatly appreciated.

 

[Yorric]

If your velocity isn't as high as QL predicts, you may have a "slow" large diameter barrel or one with a low friction bore surface. All barrels are not the same quality & diameter in bore & grooves.
I use HBN coating on bullets & bores. This drops pressure & velocity in the real world so I need to up the charges to compensate. My QL has a setting "friction proofed" & I use that & it calculates accordingly.
Not sure how to tweak QL beyond that.
Having had an experience with a friend's Weatherby Vanguard 308 which has a barrel that develops high pressures needing up to four grains less powder than other 308 rifles I've had to shoot good groups, I'm accutely aware of this syndrome & will now always fully work each new load up from scratch!

Ian

 

[NigelM]

I use QL and OBT. I only found OBT a few weeks back but have been using QL for a number of years. Spookily enough my accuracy nodes developed independently matched OBT nodes, so I'm now a convert.

A few less obvious things with QL that make a big difference. You have already accurately measured your bullet and presumably seating depth, but have you measured the H2O capacity of your brass? If not take 5 fired cases with primers still in place, weigh all 5 empty, then weight them again full of water and subtract. Enter this capacity of water in grains into QL. Makes a big difference to pressure.

Secondly you need to get the powder temperature right for the day. Especially with temperature sensitive powders like RS60 it can make a big difference. Picture of a thermometer next to the case fill % in the right hand box. Click it and enter the temperature in degF. Default is 70F which is too high most of the time and results in over optimistic velocities and pressures. When I have a load I always revisit it at 70F to ensure it will not be over pressure on a hot day.

When I get all the detail right QL is surprisingly close to measured velocities in all my rifles.

 

[Davee]

Sorry, maybe I was not clear about what I did, measured cases (10) length and capacity, measured bullets (20), measured temperature, and throat length, and barrel length, entered all this into QL. To check I entered the data for a known good load using N550 -same bullet-, got a result that was 23 fps slower than that measured -node 7. Ergo in my estimation everything works as it should. I then changed the powder to RS60, all the other data remained the same other than the quantity of powder. The 3 nodes -8, 7 and 6- gave me -154 fps,-222 fps and -329 fps, the two latter groups where of a similar size but the last had a lower vertical component and the lowest ES -not enough data for a valid SD. The RS60 node 6 gave me a smaller group than the N550 node 7. Same gun, same batch of cases, neck turned and sized, same batch of primers, same batch of bullets, same point of aim, and similar points of impact -except the node 8-, the only other variable was the wind -at 12 o'clock but variable. OK so I have a load to fine tune, what I find odd is that the QL prediction was so far out with RS60 -the prediction was for node 6 but the measured velocities where closer to node 7. Is the data for RS60 ultra conservative?

 

[mealiejimmy]

Try changing the burning rate factor (Ba) for the powder until it matches you measured MVs.

Cheers

Bruce

 

[NigelM]

Sorry, maybe I was not clear about what I did, measured cases (10) length and capacity, measured bullets (20), measured temperature, and throat length, and barrel length, entered all this into QL. To check I entered the data for a known good load using N550 -same bullet-, got a result that was 23 fps slower than that measured -node 7. Ergo in my estimation everything works as it should. I then changed the powder to RS60, all the other data remained the same other than the quantity of powder. The 3 nodes -8, 7 and 6- gave me -154 fps,-222 fps and -329 fps, the two latter groups where of a similar size but the last had a lower vertical component and the lowest ES -not enough data for a valid SD. The RS60 node 6 gave me a smaller group than the N550 node 7. Same gun, same batch of cases, neck turned and sized, same batch of primers, same batch of bullets, same point of aim, and similar points of impact -except the node 8-, the only other variable was the wind -at 12 o'clock but variable. OK so I have a load to fine tune, what I find odd is that the QL prediction was so far out with RS60 -the prediction was for node 6 but the measured velocities where closer to node 7. Is the data for RS60 ultra conservative?

Tough one.

I'm using RL17/RS60 and QL is predicting velocities reasonably accurately, to within 30fps, and it's consistent.

Just talk us through how you are deciding on a charge weight for a specific node?

 

[Davee]

I obtained the fps using
from the OBT table, ie for my 23.5 inch barrel
Node 5 6 7 8 9
1.215 1.295 1.419 1.499 1.623 msec
From QL 46.6 44.6 41.8 39.4 36.8 gr RS60 at 54F
1.220 1.297 1.415 1.495 1.624 msec barreltime
2900 2793 2617 2500 2315 f/sec theoretical
OK so the table gets reformatted when posted! Apologies
Another query if I may, does one use the thermometer reading or the Apparent temp? Because on Sunday the apparent temp was 44F.
I'm inclined to reload two sets of cartridges one from 41.5 to 43.5 and the second from 44.5 to 46 grains and repeat the exercise to gain more data.