Load Data for 338 WM - 250 gr Nosler Partition & N560

[JPP]

Hi to all from SA, new to this forum but new to the reloading diction.
I'll be grateful if some one can give me some guidance for loads on the above.
I did a quick search and found some data for the AccuBond but unfortunately not the Partition

My setup as follow:
Rifle - Howa 1500 in 338 WM
Barrel Length - 605 mm
Twist 1:10
Case - Norma, trimmed @ 63.15 mm
H2O volume on fired case - 89.7 gr
For 250 gr Nosler Partitions
I measured the Partitions at 35.12 mm with an approximate bearing surface 19.30 mm
Cartridge Max OAL - 84.60 mm
Loaded Cartridge OAL - 83.85
Powder - Vihtavuori N560
Will be using CCI 250's primers but also have BR2's & 200's available

Just for info - my highest save node predicted by QL, for loads with S365 Lot 89, seems to be at about 2595 fps @ +/- 5500 psi and 65.4 gr powder.... if this can help any, but groups are horrible and I experiencing pressure spikes

 

[OU812]

Welcome. You can use the same data for the 250 Partition as the AccuBond. As always start low and work up to max powder charge for your rifle. H4831sc always worked well for me in a 338wm. I think N560 might be on the slow side for the 338wm.

 

[DrMike]

Glad to see your post, JPP Always pleased to see new people posting. Sounds as if you have already consulted QL, so additional review won't likely prove that helpful. With the data you provided, I would expect that you have quite a bit of room to increase your charge of S365. Generally speaking, slower powders give the best results with full charges. A quick review would suggest that you can increase your charge by up to five grains. When you say you're experiencing pressure spikes, are you basing that on sticky bolt lift, measured velocities, or some other criterion

OU812 gave you good advice concerning H4831SC and using the same data you have for the AB. I will say that I like VN560 in many of my rifles. My instinct is that this would be a good propellant for your 338WM with the 250 gr PT. A double base powder would give the extra kick in the pants as you initiated the firing sequence which could move you along. Also, it will give good case fill with a full charge (77 grains).

 

[JPP]

Welcome. You can use the same data for the 250 Partition as the AccuBond. As always start low and work up to max powder charge for your rifle. H4831sc always worked well for me in a 338wm. I think N560 might be on the slow side for the 338wm.

Thank you, appreciate the replay.
I'm not chasing speed on this one as this is for a bush load, say up to 200m. Ideally I hope to achieve the slower node with reasonable case fill %
Will definitely give H4831sc a shot or two as an alternative.

 

[JPP]

Glad to see your post, JPP Always pleased to see new people posting. Sounds as if you have already consulted QL, so additional review won't likely prove that helpful. With the data you provided, I would expect that you have quite a bit of room to increase your charge of S365. Generally speaking, slower powders give the best results with full charges. A quick review would suggest that you can increase your charge by up to five grains. When you say you're experiencing pressure spikes, are you basing that on sticky bolt lift, measured velocities, or some other criterion

OU812 gave you good advice concerning H4831SC and using the same data you have for the AB. I will say that I like VN560 in many of my rifles. My instinct is that this would be a good propellant for your 338WM with the 250 gr PT. A double base powder would give the extra kick in the pants as you initiated the firing sequence which could move you along. Also, it will give good case fill with a full charge (77 grains).

Thank you for the worm welcome DrMike
Regarding pressure spikes: Yes, sticky bolt lift and I can see some impressions of the bolt face on the case. I have a suspicions that this might be as a result of secondary ignition as the case might not create a proper seal with the "low" load. I am a bit weary of S365 though, due to its temperature sensitivity. I have tried the S365 with a couple of different primers for this load but they just do not seem to be friends.
Ideally I would like to reach a 105% case fill but I suppose even 97% fill would be acceptable at a 100% burn rate.

The S365 does work well with 210 & 215 gr's giving me 18mm groups on average

I do not have QL and basically have to ask chaps on forums like these. Hope the chaps here can help out

 

[DrMike]

N560 will give you 106% case fill, which is just about ideal. Again, I like the double base powder with the bigger bullets in cases that hold as much (or more) as does the 338 WM.

Cartridge          : .338 Win Mag.
Bullet             : .338, 250, Nosler PART SP 35644
Useable Case Capaci: 76.973 grain H2O = 4.998 cm³
Cartridge O.A.L. L6: 3.301 inch = 83.85 mm
Barrel Length      : 23.8 inch = 605.0 mm
Powder             : Vihtavuori N560

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   85    61.68   2196    2678   30842   9025     87.1    1.641
-18.0   87    63.22   2255    2822   32988   9342     88.6    1.596
-16.0   89    64.76   2313    2971   35298   9651     90.0    1.551
-14.0   91    66.31   2372    3125   37774   9950     91.3    1.507
-12.0   94    67.85   2432    3283   40436  10238     92.5    1.458
-10.0   96    69.39   2491    3445   43299  10513     93.6    1.412
-08.0   98    70.93   2551    3612   46383  10774     94.7    1.367
-06.0  100    72.47   2611    3784   49706  11021     95.7    1.324
-04.0  102    74.02   2671    3959   53292  11250     96.6    1.282  ! Near Maximum !
-02.0  104    75.56   2731    4139   57169  11462     97.3    1.242  ! Near Maximum !
+00.0  106    77.10   2791    4323   61363  11654     98.0    1.203  ! Near Maximum !
+02.0  108    78.64   2851    4511   65909  11826     98.6    1.165  !DANGEROUS LOAD-DO NOT USE!
+04.0  111    80.18   2910    4702   70844  11976     99.1    1.129  !DANGEROUS LOAD-DO NOT USE!
+06.0  113    81.73   2970    4898   76211  12103     99.5    1.094  !DANGEROUS LOAD-DO NOT USE!
+08.0  115    83.27   3030    5096   82054  12206     99.8    1.060  !DANGEROUS LOAD-DO NOT USE!
+10.0  117    84.81   3090    5299   88394  12283     99.9    1.027  !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    106    77.10   2932    4773   75204  11377    100.0    1.108  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    106    77.10   2598    3746   49212  11240     91.2    1.325

 

[JPP]

Great ! thank you

 

[JPP]

just some feed back after shooting a couple over the chrony

Case - Norma @ trimmed to 63.0 mm
H2O for fired case 90.4 gr
Max O.A.L. - 84.60 mm
N560
Primer - CCI-250
Chrony @ 5m

Temp 24°C
O.A.L = 83.85
69.5 gr @ 2597, Es=31
71.5 gr @ 2663, Es=11

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