Home Forums Reloading Big Game Rifles Solve this riddle

I've worked up a load for the 110AB in the 257WBY using Ramshot Magnum. I have made my way up to 77.0gr with no pressure signs. All info I have gathered says this should be a dangerous load but it hasn't been for me. The bullets have been moly coated and the bore has recieved the UBC treatment. Chronograph has been checked and double checked with other guns and everything is checking like it should velocity wise, except for this particular load. All data I have gathered shows this load should be clocking in the 3500's going damn near 3600fps. It's checking 3285 at the muzzle for me. Primers-CCI250's,Norma brass(virgin),OAL 3.200.
What's going on?


Nail

my guess would say powder/scale is suspect.. chrono says slow, pressure signs say slow.. either the scale is lying or the powder isn't bringin' the poop..... any other powder to try for the AB?

woofer

slow barrel?

.264 barrel?

The scale thing crossed my mind too. It's a new Lyman DPS3, doesn't mean something can't be wrong though. I'm pretty sure it's close,if not exact, as 77.0gr charge fills the case to just below the neck. An ultra slow batch of Magnum...maybe,but I suspect it's something more to it than that.


Nail

What does factory ammo clock?

I bet you have a bad powder lot, Have you had similar situations with the same rifle ? ...tj3006

I haven't checked this gun with factory ammo for velocity. I just took another gun to shoot across the chrony to see if it was reading correctly or not. All signs say the chrony is right on. I will contact Ramshot about what's going on if no one can come up with other possible issues.

I just went back and read the other post again. Yes, I had this discrepency once before on another load work-up, forgot about it though as it was "just for giggles" to see what it would do. That was a 75gr V-Max pushed with RL-19. Velocities were not where they should be that time either but none of 'em shot worth a damn and I put that idea to bed. Very strange.


Nail

I went back and looked over the numbers for another rifle I load for and everything checked good as far as where it should be velocity wise. So it seems to be confined to 257WBY.


Nail

Shoot some factory stuff over the chrono and it will tell you a bit about the particular rifle involved. Bear

Like what exactly? It's already established it's slower than it should be.


Nail

Possible problem with the chronograph. Some of them read slow under certain lighting conditions.

It's not the chrony. I even shot a group at moderate range and another at 300yds, checking for drop at extended range. I then went to the JBM calculator and entered the data from the chrony and it checked almost exactly(within 0.2in) with the results I got.


Nail

We don't know if there is a problem with the powder, or possibly undersize bullets, or any number of things.
If you shoot some factory stuff, and it too is real slow, then it is a characteristic of the rifle and not the load, or the loads componants.

FYI

Cartridge : .257 Weath. Mag
Bullet : .257, 110, Nosler AccuBond 53742, Friction Proofed
Cartridge O.A.L. L6: 3.170 inch or 80.52 mm
Barrel Length : 26.0 inch or 660.4 mm
Powder : Ramshot Magnum (Big Boy)

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 82 61.60 2826 1951 32747 12357 92.5 1.583
-18.0 84 63.14 2910 2069 35488 12758 94.1 1.523
-16.0 86 64.68 2994 2190 38471 13129 95.5 1.466
-14.0 88 66.22 3079 2315 41715 13468 96.7 1.411
-12.0 90 67.76 3163 2443 45275 13770 97.8 1.359
-10.0 92 69.30 3247 2574 49154 14033 98.6 1.308
-08.0 94 70.84 3330 2708 53394 14254 99.3 1.260
-06.0 96 72.38 3413 2845 57993 14430 99.7 1.214 ! Near Maximum !
-04.0 98 73.92 3495 2983 62995 14560 100.0 1.169 ! Near Maximum !
-02.0 100 75.46 3576 3123 68445 14643 100.0 1.126 !DANGEROUS LOAD-DO NOT USE!
+00.0 102 77.00 3656 3265 74394 14710 100.0 1.085 !DANGEROUS LOAD-DO NOT USE!
+02.0 104 78.54 3736 3409 80898 14771 100.0 1.046 !DANGEROUS LOAD-DO NOT USE!
+04.0 106 80.08 3815 3554 88026 14825 100.0 1.008 !DANGEROUS LOAD-DO NOT USE!
+06.0 109 81.62 3893 3702 95857 14871 100.0 0.972 !DANGEROUS LOAD-DO NOT USE!
+08.0 111 83.16 3971 3852 104484 14909 100.0 0.937 !DANGEROUS LOAD-DO NOT USE!
+10.0 113 84.70 4050 4006 114019 14939 100.0 0.903 !DANGEROUS LOAD-DO NOT USE!

Results caused by � 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 102 77.00 3809 3543 92021 14128 100.0 0.996 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 102 77.00 3422 2860 57519 15090 97.8 1.208 ! Near Maximum !

Just to clarify, this is the second time this has happened. The first time involved RL19/75gr.VMax/Fed215, low velocities for charges loaded. The second time the load involved Ramshot Magnum/110grAB/CCI250,low velocities again. Different components, very similar results.

Pop, yeah I know. That's why I'm posting the situation here. Not that I don't appreciate it, I have that info as well. One of the reasons it's got me so puzzled.

Edited to add that OAL for the 75gr load was 3.140(as best I remember) and for the 110gr it was 3.200. Barrel length 24in.

Nail

so all loads fired in this gun have been running terribly low? i am assuming the vmax and the AB are the only loads fired?

factory stuff has some poop.. if it is slow in your rig then your done looking at the load components...

woofer

I shot some factory stuff when I first got the gun last year but I didn't have access to a chrony so I can't say if it was slow then or not. I hate to drop 50-60 bucks just to find out when I have two different loads/components doing the same exact thing.

Does anyone else here run moly in a UBC treated barrel? If so, have you ran any loads over the chrony and what were results like?


Nail

Not that you shouldn't care, but every gun is different. A friend of mine ordered two identical rifles and with identical loads in each his rifle averages around 70-75fps faster. This may not be as extreme as your case but something to think about.

Could it be that the moly and the bore slickum keep the pressure from rising as it should? Seems I've read about that with moly coated bullets. Anyone ever hear about that? I've never fired moly stuff so haven't chronographed any.