7mm Rem Mag and RL23

[308 5R]

Good evening all,

I recently began to load for a 7 mag and have decided to start with the following recipe for my father in law's 26" browning A-Bolt Medallion.

160 NAB
RL 23
Rem brass
CCI 250
3.290" oal

I've looked at Alliant's data which shows 65.1/3000fps with a Speer 160 (24"bbl)as max albeit with different components. I loaded groups of 3 starting at 63.2. I fired one of the starting loads at this charge weight across a chrony and measured 3069fps. Looking at QL I should've been at approx 2880 (I understand the limitations of the program) .
My chrony is nothing special, an old pro chrony, but has matched QL within 15fps for my 308 with Varget so I doubt it completely out in left field.

I understand the difference in components from published data, but exceeding a max load by 70 fps while being down 2 full grains of powder seems odd. Even with an extra 2" of barrel.

-Charges weighed on a calibrated A&D FX 120
-Eastern NC 85* humid/overcast
-All input data on QL verified (I had to adjust the burn rate to essentially RL16 values 0.5 BA to match my observations)
-Any "dumba$$" possibilities have been eliminated.
-unsure of distance to the lands at this point but the cbto measurements I have are less than some factory 150 core lokts that were sent with the rifle. So definitely jumping.

Any thoughts would be appreciated.

S/F
Ryan

 

[ShootDots]

It does not sound odd to me.. RL-23 has proven over and over again to exceed expectations, as far as velocity goes. One other thing of major importance: it has been my experience with the "new" i.e. RL-16 and RL-23, that the correlation between QL and "reality" leaves one to believe that the info that Alliant gives to QL is W-A-Y off base! So as far as QL is concerned with RL-23>>>just forget it. Believe your chronograph and the groups you are getting or are going to get. If you are getting good e.s.s and good groups without any noticeable pressure signs, just go with it and don't look back!

 

[308 5R]

Good to know. I was starting to get some anxiety over reading of lot to lot variances of RL series powders. I have recently invested in some decent amounts of various offerings from Alliant given some of the results I have heard of.

I have zero pressure signs right now. Looks like I will proceed with caution as always. Thanks

S/F
Ryan

 

[Zero333]

I have the same problem with QL and RL-33.

To match QL with a chronographed RL-33 load I have to adjust the Burn Rate Factor Ba from 0.2670 to 0.2800 !!... The difference is 150 fps.
I use RL-33 for only one load, so I don't know how much the barrel is to blame for the huge velocity discrepancy.