Went to the range today so I ran a quick OAL ladder for you.
None of the loads are MAX or close to MAX (light to medium), no powder compression.
I would speculate if you were loading MAX loads the numbers would look different, OAL changes would be more pronounced. Powder compression due to a shorter OAL would have an effect as well. (or heaiver charge)
But for what it's worth
Springfield XD 4" Once fired WIN Brass S+B SP
Charges as thrown by Lee Auto Disk
Bullet Extreme 124 (125?) RNs
Lee FCD used lightly
String: 7
Date: 4/23/2017
Time: 12:57:46 PM
Grains: 124
Hi Vel: 947
Low Vel: 920
Ave Vel: 933
Ext Spread: 16
Std Dev: 10
Xtreme 124 RN 3.8 AA2 OAl 1.155
Velocity Power Factor Ft/Lbs
920 114.08 233.023
947 117.428 246.901
936 116.064 241.199
928 115.072 237.093
936 116.064 241.199
String: 9
Date: 4/23/2017
Time: 12:59:43 PM
Grains: 124
Hi Vel: 950
Low Vel: 931
Ave Vel: 943
Ext Spread: 19
Std Dev: 7
Xtreme 124 RN 3.8 AA2 OAl 1.14
Velocity Power Factor Ft/Lbs
931 115.444 238.629
945 117.18 245.859
950 117.8 248.468
943 116.932 244.82
948 117.552 247.423
String: 1
Date: 4/23/2017
Time: 1:00:56 PM
Grains: 124
Hi Vel: 959
Low Vel: 943
Ave Vel: 952
Ext Spread: 16
Std Dev: 5
Xtreme 124 RN 3.8 AA2 OAl 1.13
Velocity Power Factor Ft/Lbs
952 118.048 249.515
954 118.296 250.565
943 116.932 244.82
959 118.916 253.198
955 118.42 251.09
String: 2
Date: 4/23/2017
Time: 1:02:04 PM
Grains: 124
Hi Vel: 966
Low Vel: 936
Ave Vel: 952
Ext Spread: 30
Std Dev: 10
Xtreme 124 RN 3.8 AA2 OAl 1.11
Velocity Power Factor Ft/Lbs
936 116.064 241.199* This one skewed the numbers but charges as thrown I didn't weigh every one
955 118.42 251.09
951 117.924 248.991
955 118.42 251.09
966 119.784 256.908
-----------------------------------------
String: 1
Date: 4/23/2017
Time: 12:50:35 PM
Grains: 124
Hi Vel: 1065
Low Vel: 1038
Ave Vel: 1056
Ext Spread: 27
Std Dev: 11
Xtreme 124RN 5.0 BE86 OAl 1.155
Velocity Power Factor Ft/Lbs
1038 128.712 296.632
1064 131.936 311.678
1065 132.06 312.264
1062 131.688 310.508
1055 130.82 306.428
String: 2
Date: 4/23/2017
Time: 12:52:05 PM
Grains: 124
Hi Vel: 1084
Low Vel: 1061
Ave Vel: 1072
Ext Spread: 23
Std Dev: 9
Xtreme 124RN 5.0 BE86 OAl 1.14
Velocity Power Factor Ft/Lbs
1071 132.804 315.793
1079 133.796 320.528
1067 132.308 313.438
1084 134.416 323.506
1061 131.564 309.923
String: 3
Date: 4/23/2017
Time: 12:53:05 PM
Grains: 124
Hi Vel: 1092
Low Vel: 1056
Ave Vel: 1072
Ext Spread: 36
Std Dev: 15
Xtreme 124RN 5.0 BE86 OAl 1.13
Velocity Power Factor Ft/Lbs
1058 131.192 308.173
1084 134.416 323.506
1056 130.944 307.009
1070 132.68 315.203
1092 135.408 328.298
String: 4
Date: 4/23/2017
Time: 12:54:31 PM
Grains: 124
Hi Vel: 1089
Low Vel: 1052
Ave Vel: 1076
Ext Spread: 37
Std Dev: 14
Xtreme 124 RN 5.0 BE86 OAl 1.11
Velocity Power Factor Ft/Lbs
1089 135.036 326.497
1076 133.424 318.748
1084 134.416 323.506
1052 130.448 304.688
1080 133.92 321.123
In hindsight I should have weighed all the charges. A couple of the BE86 #s in the 1.13 and 1.11 groups look low.