Need help with with loading data for 30-06, 22" barrel, 1 in 10 twist, using Vihtavuori N550 powder, Hornady165Gr SST

[CharlConradie]

Hi Guys

I am currently doing load development for my 30-06

I don't have the equipment so a friend has is helping me out

There is no load data for N550 powder in Hornady's 10th edition handbook for the 165Gr SST

The 165Gr SST is also not listed on Vihtavuori website (Only 165gr GMX)

I have read that the 165Gr GMX load data is interchangeable with the 165Gr SST, can someone confirm that this is true?

Vihtavuori Load data suggests starting load of of 45.2 Grains of N550, with a max load of 48.3Gr (For the 165Gr GMX variant)

This seems extremely low given the velocities, and the fact that others on this forum are loading up to 56Gr of N550 for 165Gr bullets.

Also, the 150Gr SST can load up to 55.2 Gr according to Vihtavuori

I am concerned about barrel pressure, My friend runs 52Gr of N550 in his CZ 30-06 with 165Gr SST's with no issues.. anything lower just does not group

I was hoping I can get data from someone in the line of the table below

Will below mentioned data also apply die the 165Gr SST?

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Based on 22" barrel and COAL of 3.340 and (I'd load it a bit shorter to get more shank in the neck maybe). Will vary with your individual brass dims and capacity etc, but an idea

Cartridge : .30-06 Spring. (SAAMI)
Bullet : .308, 165, Sierra SPBT 2145
Useable Case Capaci: 62.446 grain H2O = 4.055 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : Vihtavuori N550

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 78 45.60 2227 1817 27867 8365 88.9 1.498
-18.0 79 46.74 2282 1909 29715 8643 90.2 1.459
-16.0 81 47.88 2338 2002 31688 8914 91.4 1.422
-14.0 83 49.02 2393 2099 33795 9176 92.6 1.385
-12.0 85 50.16 2449 2198 36022 9431 93.7 1.350
-10.0 87 51.30 2505 2299 38371 9675 94.7 1.312
-08.0 89 52.44 2560 2402 40865 9908 95.6 1.273
-06.0 91 53.58 2616 2507 43521 10130 96.4 1.236
-04.0 93 54.72 2672 2615 46348 10339 97.2 1.200
-02.0 95 55.86 2727 2724 49360 10534 97.8 1.166
+00.0 97 57.00 2782 2836 52570 10715 98.4 1.133 ! Near Maximum !
+02.0 99 58.14 2837 2949 55993 10880 98.9 1.101 ! Near Maximum !
+04.0 101 59.28 2892 3064 59646 11029 99.3 1.070 !DANGEROUS LOAD-DO NOT USE!
+06.0 103 60.42 2946 3181 63546 11161 99.6 1.040 !DANGEROUS LOAD-DO NOT USE!
+08.0 105 61.56 3001 3299 67715 11276 99.8 1.011 !DANGEROUS LOAD-DO NOT USE!
+10.0 107 62.70 3055 3419 72175 11372 100.0 0.983 !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 97 57.00 2915 3113 63150 10492 100.0 1.047 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 97 57.00 2602 2481 42303 10367 92.4 1.245"
=====================================================================================================


Thank you in advance

 

[1894]

GMX being mono metal with no grooves causes more pressure. The equivalent nosler. e tip data stresses ‘ always start at minimum’ so I suggest you do too. In addition I thought viht data for 06 quite hot so I suggest you don’t exceed their data

 

[CharlConradie]

GMX being mono metal with no grooves causes more pressure. The equivalent nosler. e tip data stresses ‘ always start at minimum’ so I suggest you do too. In addition I thought viht data for 06 quite hot so I suggest you don’t exceed their data

Thanks a mil. Hornady basically gave my the same answer

 

[CharlConradie]

Thank you

I emailed Hornady directly and this was their answer:

"Thanks for writing in to us. Unfortunately we do not have any data for N550 and a 165 gr bullet at this time. You might consider using data for the 165 Swift they have or the 167 Lapua and start low and work your way up checking for pressure signs."
==========================

Then I asked them the following:

"Thank you so much for the response

I did indeed look at the load data for the 165 swift as well as the lapua
167gr

The reason I am concerned is because the N550 Gunpowder charge for the
165Gr Hornady GMX is much lower than that of the Swift or Lapua.

Can you explain the reason for this?

If I can understand why two bullets (GMX and SWIFT) weight, have vastly
different min and max loads according to Vihtavuori, it would be great.

Thank you in advance"
==========================

To which Hornady replied:

"The GMX is a lead free all copper bullet. Because of that it is much longer in length and has more bearing surface to create pressure. The Swift bullet is a copper jacket with a lead core, just like the SST."

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