.270 Win and 150 gr. Partitions

[Silentstalker]

I am starting some load development for my Partitions. In your experience, should I load them at Magazine length or do they typically shoot better at SAAMI spec? This is for hunting but I would like the best accuracy possible from a factory rifle.

I am going to start with my old stand by H4831sc and go from there.

Thanks again for all the help!

 

[Sas874runner]

IMO Parts tend to shoot better closer to the lands. I like to start .010" off the lands

 

[Silentstalker]

Cool. I am limited by my mag length but I will start long as possible and go from there as a starting point! Thanks!

 

[SJB358]

IMO Parts tend to shoot better closer to the lands. I like to start .010" off the lands

I agree alot with that.. .010-.025" off seems to work the best in my rifles.

 

[DrMike]

Despite having the Partition, the bullet acts as a cup and core bullet. Consequently, the advice you've received generally holds true: loading closer to the lands tends to give a greater degree of accuracy. Best of luck as you work up this load.

 

[bobnob]

I load the 160 grain Partitions in my 270 Win, as long as the mag box allows which is 3.34in. They shoot well with 58g H4831 for 2830fps in a 24 inch barrel.

They work well on game too!

 

[Silentstalker]

So I went out and shot today despite it being in the high 40's and a mild head wind. I shot 3 shot groups of H4831sc with Win Brass, Win Primers, and 150 gr. Partitions. I was very happy with the results!

Started out with 53 gr. and shot a nice tight group. Adjusted 1" to the left on my scope and shot the rest of the groups with out adj. The final group I aimed at the intersection of the horizontal line and where the fat outer circle intersects it. I went all the way to 55.5 grains which is 1/2 a gr. over the "max" listed on the Nosler website for H4831. I found no signs of pressure so far. I am sure I could push this a bit more but not sure if its necessary. The Website lists this at an approx. velocity of 2950. I do not have a chrono to verify or check. What do you all think of that estimate and these groups? Any advice?

This rifle has really struggled with the 150 ABLR but sure loves these 150 gr. Partitions and 150 gr. BT's. I am thinking to load up the 55.5 gr. load for verification and then using it on elk and big mule deer in the future.

Thanks for all the help and advice! You guy's are all great!

 

[DrMike]

Any velocity data? I agree that the 55.5 grain load merits a verification. That will likely give you more than enough "oomph" to down elk and large mulies.

 

[Silentstalker]

Unfortunately I don't own a chrono. Nosler lists the 55 gr at around 2850fps??

 

[DrMike]

QL projects ~2762 fps with a 55.5 grain IMR 4831 load. You likely do have quite a bit of room to charge the case, still.

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 150, Nosler PART SP 16323
Useable Case Capaci: 60.130 grain H2O = 3.904 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : Hodgdon H4831 SC

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 79 44.40 2181 1584 28633 9311 83.5 1.545
-18.0 81 45.51 2237 1667 30531 9656 84.9 1.507
-16.0 83 46.62 2294 1753 32559 9998 86.3 1.468
-14.0 85 47.73 2351 1841 34728 10334 87.7 1.431
-12.0 87 48.84 2409 1933 37045 10664 89.0 1.395
-10.0 89 49.95 2467 2027 39525 10986 90.2 1.350
-08.0 91 51.06 2525 2124 42179 11299 91.4 1.308
-06.0 93 52.17 2584 2224 45024 11602 92.5 1.268
-04.0 95 53.28 2643 2327 48074 11894 93.6 1.229
-02.0 97 54.39 2702 2432 51351 12172 94.6 1.192
+00.0 99 55.50 2762 2540 54869 12436 95.5 1.156
+02.0 101 56.61 2821 2651 58662 12685 96.3 1.121 ! Near Maximum !
+04.0 103 57.72 2881 2765 62744 12917 97.1 1.087 ! Near Maximum !
+06.0 105 58.83 2941 2881 67136 13131 97.8 1.054 !DANGEROUS LOAD-DO NOT USE!
+08.0 107 59.94 3001 3000 71851 13326 98.3 1.022 !DANGEROUS LOAD-DO NOT USE!
+10.0 109 61.05 3061 3121 76941 13500 98.8 0.992 !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 99 55.50 2909 2819 65687 12569 99.4 1.069 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 99 55.50 2575 2208 44891 11709 87.8 1.266

 

[Sas874runner]

The ablr seems to need a long mag well inorder to get the bullet far enough out to get the accuracy out of them. But that looks like it will do the job! Good shooting. Verify and commence killin

 

[Silentstalker]

My rifle has a 24 inch barrel will that change that chart at all? I think I will load some more at 55.5 and then work up from there based on your chart watching for pressure. I would like to see closer to 2900 fps if I can get it. If not I know the lower velocity would work too! Thanks all!

 

[DrMike]

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 150, Nosler PART SP 16323
Useable Case Capaci: 60.130 grain H2O = 3.904 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Hodgdon H4831 SC

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 79 44.40 2240 1671 28633 8561 84.9 1.621
-18.0 81 45.51 2297 1757 30531 8868 86.3 1.580
-16.0 83 46.62 2355 1847 32559 9170 87.6 1.540
-14.0 85 47.73 2412 1938 34728 9466 88.9 1.501
-12.0 87 48.84 2471 2033 37045 9755 90.2 1.463
-10.0 89 49.95 2529 2130 39525 10036 91.4 1.416
-08.0 91 51.06 2588 2231 42179 10309 92.5 1.373
-06.0 93 52.17 2647 2333 45024 10570 93.6 1.332
-04.0 95 53.28 2706 2439 48074 10820 94.5 1.292
-02.0 97 54.39 2765 2547 51351 11058 95.4 1.253
+00.0 99 55.50 2825 2658 54869 11282 96.3 1.215
+02.0 101 56.61 2884 2771 58662 11491 97.0 1.179 ! Near Maximum !
+04.0 103 57.72 2944 2887 62744 11684 97.7 1.144 ! Near Maximum !
+06.0 105 58.83 3004 3005 67136 11860 98.3 1.110 !DANGEROUS LOAD-DO NOT USE!
+08.0 107 59.94 3063 3126 71851 12018 98.8 1.077 !DANGEROUS LOAD-DO NOT USE!
+10.0 109 61.05 3123 3249 76941 12156 99.2 1.046 !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 99 55.50 2969 2937 65687 11312 99.7 1.126 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 99 55.50 2638 2318 44891 10702 89.0 1.330

 

[Silentstalker]

Thank you Dr. Mike!

 

[SJB358]

That 150 PT shoots super in my 270. Seems like 4831 is clicking pretty well with your rifle. Great shooting.

 

[Silentstalker]

Yeah 4831 seems to work great for me. One day I will try more powders but for now im pretty happy!

 

[bobnob]

My 270 with 24 inch barrel has I suspect a kinda loose bore and the chamber is slightly commodious,with 69.2g water capacity of fired brass.

With 150g bullets I have to pump up to 59g of H4831sc to get over 2900fps. As above, with 58g and the 160g NPT I am only getting a bit over 2800fps. With 130 grainers I am using 62.0g to get to 3100fps which is a generally accepted standard speed for that bullet.

The thing is very accurate for a hunting rifle though, 10 shot groups hovering right about 1.3 moa at 100y, even when shooting without letting the barrel cool.

But the need for my rifle to have more of that powder than most shows loading manuals and software can take you only so far before you need a chrony.

By the way SilentS, that load looks like a keeper! Those 150 NPTs should do the business nicely.

 

[Silentstalker]

Good info bobnob! Sounds like your gun shoots awesome! I loaded more today with hopes to get out Wednesday to try them again working up to higher est. velocities. I loaded up to 57 gr. starting at my previous 55.5 gr. load for confirmation. Pretty excited to see how she shoots! That 150 gr. Partition will handle anything I am currently going to hunt nicely!

 

[Antelope_Sniper]

With WIN brass I've loaded all the way up to 59gr of H4831. It's on the warm side, and DON'T TRY THAT LOAD WITH REM BRASS.

 

[SJB358]

Good info bobnob! Sounds like your gun shoots awesome! I loaded more today with hopes to get out Wednesday to try them again working up to higher est. velocities. I loaded up to 57 gr. starting at my previous 55.5 gr. load for confirmation. Pretty excited to see how she shoots! That 150 gr. Partition will handle anything I am currently going to hunt nicely!

I have 50 of the PT Golds loaded up for my 270WSM. They shoot really well and I think they'd handle everything pretty well. They are penetrating little missiles. I love the way they shoot in my 270.