I just got my custom 700 7mm rem mag with 26" varmint contour douglas barrel back from the gunsmith and I'm working up a load for the 168 gr VLD. Berger gives 65 gr RE22 as max load @2994 fps from a 26" barrel.

I barely get 2900 fps from that load - seated touching the rifling - and have signs of excessive pressure (blown out rimer pocket and split neck) and horrible accuracy. After tinkering I ended up at 65.5 gr RE22 seated 0.080 back @ 2850 with decent accuracy.

66.0 gr splits the case neck half of the time but gives about 2900 fps and good accuracy. What is going on, Why cant I get better velocities out of a magnum cartridge with a new barrel and why the excessive pressure? I contacted Berger and they said their load data is conservative.

Cartridge          : 7 mm Rem. Mag.
Bullet             : .284, 168, Berger VLD #28501
Useable Case Capaci: 72.308 grain H2O = 4.695 cm³
Cartridge O.A.L. L6: 3.290 inch = 83.57 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : Alliant Reloder-22

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.769% 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

-07.7   89    60.00   2768    2858   45896  11291     98.7    1.455
-06.9   90    60.50   2790    2904   47036  11367     98.9    1.438
-06.2   91    61.00   2813    2951   48205  11440     99.1    1.422
-05.4   91    61.50   2835    2998   49401  11511     99.3    1.405
-04.6   92    62.00   2857    3045   50627  11579     99.4    1.390
-03.8   93    62.50   2879    3092   51882  11644     99.5    1.374
-03.1   93    63.00   2901    3139   53167  11705     99.6    1.359  ! Near Maximum !
-02.3   94    63.50   2923    3187   54484  11764     99.7    1.343  ! Near Maximum !
-01.5   95    64.00   2945    3235   55833  11820     99.8    1.329  ! Near Maximum !
-00.8   96    64.50   2967    3283   57215  11872     99.9    1.314  ! Near Maximum !
+00.0   96    65.00   2989    3332   58632  11921     99.9    1.299  ! Near Maximum !
+00.8   97    65.50   3010    3380   60083  11967    100.0    1.285  ! Near Maximum !
+01.5   98    66.00   3032    3429   61570  12010    100.0    1.271  ! Near Maximum !
+02.3   99    66.50   3053    3478   63093  12050    100.0    1.257  !DANGEROUS LOAD-DO NOT USE!
+03.1   99    67.00   3075    3527   64655  12088    100.0    1.243  !DANGEROUS LOAD-DO NOT USE!
+03.8  100    67.50   3096    3576   66257  12126    100.0    1.229  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 3% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 3% relative to nominal value:
+Ba     96    65.00   3030    3424   62161  11775    100.0    1.267  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 3% relative to nominal value:
-Ba     96    65.00   2942    3229   55125  12014     99.5    1.334  ! Near Maximum !

Looks like you are dead on with predicted velocity. (100 fps low in cold November temperatures is not suprising)

What brand of brass are you using?
What is the history of your brass?

Touching the rifling can add 8K to your pressure.

i would think you are pretty much there.
what twisst is the barrel?
i have 1:9.5 and I use H4831 64grs and H1000 upto 70grs 168smk without any pressure issues.
With the vld bullets and the length the only way I could get the pressured down was with moly coat. ended up at 63grs for a load accuracy was ok velocity around 2875
Dave

I'm using winchester WW Super brass fired 3-4 times(FL). The brass has an odd factory crimp around the mouth of the case and most of the splits occur at the edge of one the crimp indentations. It's not the best brass and I suspect it's weak at the crimp but It shouldn't be splitting like that at those velocities.

With 61.0 gr RE22 @ 2700 fps I get a nice clover-leafed 3 shot group fitting inside of a dime @ 100 yds. I'm still under 1/2" @ 2850 but 2 groups I shot at 300 weren't very impressive at 1.5" & 2". I'm afraid to adjust my seating depth too close with 65 gr b/c seated at the rifling was excessively hot.


Barrel twist is 1:9, but from what I hear Douglas isn't very accurate with their twist reate.

I have owned several rifles with douglas barrel and I have no complaints.
As far as the brass goes 3 or 4 loadings especially if you are full length resizing will use up the brass the necks get thin and work harden and will split. i usually anneil after 2 firings and may only use the brass one or two more time.
I partial resize and only set the sholder back enough to chamber the case. watch for thinning just a head of the belt.
Dave

Antelope Sniper, what does quickload say for H4831?

Thanks,
Jeff

Here you go!

Cartridge          : 7 mm Rem. Mag.
Bullet             : .284, 168, Berger VLD G7 #28501
Useable Case Capaci: 72.308 grain H2O = 4.695 cm³
Cartridge O.A.L. L6: 3.290 inch = 83.57 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : Hodgdon H4831 SC

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.769% 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

-07.7   89    60.00   2752    2826   48133  10762     97.5    1.414
-06.9   90    60.50   2775    2872   49332  10844     97.7    1.398
-06.2   91    61.00   2797    2918   50560  10923     98.0    1.382
-05.4   91    61.50   2819    2965   51819  11000     98.2    1.366
-04.6   92    62.00   2841    3012   53110  11074     98.4    1.351  ! Near Maximum !
-03.8   93    62.50   2864    3059   54433  11146     98.6    1.336  ! Near Maximum !
-03.1   93    63.00   2886    3107   55790  11216     98.8    1.321  ! Near Maximum !
-02.3   94    63.50   2908    3154   57182  11283     99.0    1.306  ! Near Maximum !
-01.5   95    64.00   2930    3203   58609  11348     99.1    1.292  ! Near Maximum !
-00.8   96    64.50   2952    3251   60073  11410     99.3    1.277  ! Near Maximum !
+00.0   96    65.00   2974    3300   61576  11469     99.4    1.263  ! Near Maximum !
+00.8   97    65.50   2996    3349   63117  11525     99.5    1.249  !DANGEROUS LOAD-DO NOT USE!
+01.5   98    66.00   3018    3398   64698  11579     99.6    1.235  !DANGEROUS LOAD-DO NOT USE!
+02.3   99    66.50   3040    3447   66321  11630     99.7    1.222  !DANGEROUS LOAD-DO NOT USE!
+03.1   99    67.00   3062    3497   67987  11677     99.8    1.208  !DANGEROUS LOAD-DO NOT USE!
+03.8  100    67.50   3084    3547   69698  11722     99.9    1.195  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 3% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 3% relative to nominal value:
+Ba     96    65.00   3015    3390   64940  11396     99.9    1.234  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 3% relative to nominal value:
-Ba     96    65.00   2929    3201   58232  11488     98.5    1.294  ! Near Maximum !

Very few rifles I have ever come close to book vel.

quote:

case and most of the splits occur at the edge of one the crimp indentations. It's not the best brass and I suspect it's weak at the crimp but It shouldn't be splitting like that at those velocities.

One more thing. If the brass is only splitting on the edge it may not be a pressure sign. Sometimes with shot up brass that has not been TRimmed thatcan happen. My .264 win is good for that.
Dave

I'd say you were ball park with velocity. Maybe the rifle just doesn't like the bullet. Have you tried anything else.

My 700 REALLY likes the 168VLD with 64.5g of RE19.

It is over book, but no pressure signs, very accurate and I can reload brass 10 or more times.

I use W-W brass, 215ms.

2990FPS


.

I'm at 2830 fps over 65 gr RE22 and I split 4 out of 20 cases. Is my brass just junk or what b/c according to quickload and every book I've read thats not a hot load?

Would a slower burning powder help?

I've never loaded that bullet but according to the 48th Lyman book you can go up another grain for max. I wouldn't angst over 100fps myself. The point is rather moot anyway if the accuracy isn't there. Within reason, I'll take accuracy over velocity any time.

I shot a 3 shot group today @ 421 yds that measured 1.625". The bullet drop was 24.5" @ 12.1 degree uphill angle - both ballistic programs I have (KAC Bullet Flight & Ballistic for iOS) indicate that is a 2960 fps muzzle velocity.

Is it more likely that my chronograph is reading 130 fps low?

My semi custom 7mag from HCR with the 26" barrel loves 71.5 gr of Retumbo. Average velocity for several strings is right at 3060. Super accurate, no signs of pressure.

Gilk, did you chronograph the group you shot? It's not unusual to get different results on differnet day, especially if the temperature is different.

We you move out of the classroom, and into the real world, you will find some variance. Integrating all the different data requires a degree of art....

The most important result is 1.625" at 421 yards. If those results are consistantly repeatable, the game in your area should be very scared.

No, I didnt chronograph those shots.

I like to chronograph the same load at different times and temperatures. It will give you a better idea how the load will perform over a variety of conditions.

Here's my rule of thumb:

For a load chronographed at 70 degrees, expect to add 100 fps at 100 degrees, and subtract 100 fps at freezing.