Quickload and 6.5SS

[jb1023]

Just curious if anyone has used Quickload for the 6.5SS. I ask because I'm a pretty novice user of QL and the numbers I am seeing just don't seem possible. I went through and "built" a new case using the 6.5 RSAUM as the base and changed all the specs to match a fired case, Norma brass. It calculated that I should have 70.49 gr of H2O when I actually have 71.1, so pretty close. Fyi, I used both numbers and my predicted velocity did not change at all. When I put in the bullet/powder (147 eld-m/58.0gr RE26) it says I should have a velocity of 2928 and have a psi of 56730. When I correct the ba (default of .3397 to .4180) to match my actual velocity, 3140, it says my psi is 86786. Brass just shows just a slightly flattened primer and a hint of an ejector mark but nothing major and no heavy lift. My question is, can I really be running that much pressure?

 

[Hawk in WY]

I agree that looks odd.

More than 10% powder burn rate change is unusual. That makes me question your actual velocity.

COAL also a significant impact on pressure and velocity.

 

[adam32]

Yes make sure your COAL is correct and also you will have to fudge the "weighting factor" to match your velocity.

 

[can1010]

your imputs are definitely screwed up. I don't change the ba any more than +/- .005 on any of my powders including RL-26 and not having worked with his cartridges cant give you any changes but bore cross section, weighting factor, bullet average length, seating depth, and shot start pressure all need to be addressed before you go and change powder burn rates

 

[Doublezranch]

I think if you had 86k psi, you would have some sort of catastrophic failure.

When you built your case, did you also do the bore measurements as well?

 

[jb1023]

Thanks guys. When I get home I will pull the break and measure my bore cross section and verify other measurements as well.

How do you know what number to use as the Weighting Factor, .5 being default, or do you just play with it till the numbers line up after you have adjust the BA by up to 10%.

 

[lancetkenyon]

58.0gr RL26 w. 147 ELD-M @ 3140 sounds about right.
I got 3156 with the same powder charge under a 150 SMK in my 26" Bartlein 1:8". Slight ejector marks with Norma brass, primer was round but had the normal R700 bolt "crater" around the edge due to firing pin hole needing bushing. This was at temps under 84°F. Once it hit 90°+, pressure went up to unacceptable levels. It was great from 14° to 84° however.
Now, with the new ADG brass, no ejector marks at all.

 

[Doublezranch]

I used my surgical loupes and a caliper to measure my grooves and lands. I'm not sure if you can get a absolute perfect measurement due to the size of everything, but it really helped me solidify the numbers on the 375 Zayne, 340 Zaylea Ann, and the Texan.

 

[KMG]

Just curious if anyone has used Quickload for the 6.5SS. I ask because I'm a pretty novice user of QL and the numbers I am seeing just don't seem possible. I went through and "built" a new case using the 6.5 RSAUM as the base and changed all the specs to match a fired case, Norma brass. It calculated that I should have 70.49 gr of H2O when I actually have 71.1, so pretty close. Fyi, I used both numbers and my predicted velocity did not change at all. When I put in the bullet/powder (147 eld-m/58.0gr RE26) it says I should have a velocity of 2928 and have a psi of 56730. When I correct the ba (default of .3397 to .4180) to match my actual velocity, 3140, it says my psi is 86786. Brass just shows just a slightly flattened primer and a hint of an ejector mark but nothing major and no heavy lift. My question is, can I really be running that much pressure?

Wow, I surely hope those numbers aren't correct. I ran the 147's with 60.5 grains of RL26 with only slight flattening of the primer in Norma brass. I'm currently running 66 grains of RL33 & the 147's @ 3130. It's slower than RL26 but the pressures are lower too.

 

[jb1023]

Just a quick update on my findings. I have not measured my cross-sectional bore area and at this point I don't plan to. I played with some different measurements and it has very minimal impact on vel or psi so I don't think it is worth the effort, the default should be close and quite frankly I don't have the tools to get anymore precise. I pulled an unfired bullet from the same batch that my actual velocity was measured from and these are the measurements:
Barrel:
Mark Chanlynn
Barrel length: 24"
4 groove cut rifling
lil beast 3 port break

Round:
COAL: 2.925
Hornady ELD-M 147
Bullet length: 1.439"
Bullet weight: 147.22gr
Case length: 1.950"
RE26: 58.4gr
***Might need a new scale as the original loaded weight was 58.5 but the pulled weight was 58.4 and I'm pretty sure .1gr did not just vanish.

Average velocity from 5 fired rounds over Labradar: 3187
***Different from yesterdays post because I pulled a 58.5 round apart whereas yesterday I used 58.0 data for the post.

So the base Velocity (with all physical measurements input that I am capable of inputting) is: 2938
and the base PSI is: 55705

I decided I would change the Ba by a maximum of +/- 10% as that is the number that is displayed in the notes at the bottom of the QL graph. So for RE26 the default is .3397, I added 10% to that and got .3737 (rounded up as QL will only accept 4 digits).
New velocity is: 3057
New PSI is: 68979

I found out that the weighting factor is a guestimate of how much powder is expelled from the case into the barrel where it subsequently burns, or doesn't. A 0.0 would mean no powder gets expelled and it all remains in the case. The default for the 6.5 RSAUM is .5. If I dropped that to .18.
New velocity is: 3164
New PSI is: 61009

This combo puts my predicted velocity within the average I actually saw on the range. In my head I am able to justify the Ba adjustment because that is clearly listed on the QL graph so it is a variable. The weighting factor makes sense, in my simple mind, because the SS is more efficient than the SAUM. Another factor that makes sense to play with is the Shot Start PSI. I opted not to change this though because I am loading .020-.040 off the lands and am not using any sort of lubed projectiles.

Thoughts on my new thinking?