.375H&H Viht N540 reloading: early results

[Alistair]

I, on the other hand, have a 300gr SPBT load with some N150. Trundles along at 2400 or so. I'm in the process of working up a load, again with N150, for a 300gr TSX.

If you want velocity though, RL-17 would be an interesting option, especially if you're not shooting much volume.

 

[zambezi]

Yoday's testing continued to show a slow and semi-linear increase in MV as I nudged the N540 charge weight closer to the maximum value suggested on the Viht tables [73.4gr].

In summary, 72gr N540 gives me 97% of the 2600fps target I am seeking. The reason for that target MV is in the OP.

All spent cases are free of any over-pressure indicators, there is no headstamping and accuracy through all charge weights [65gr up to 72gr] has been superb.

With one exception: 71gr N540 felt "lively" on release and the POI was well away from the rest of the otherwise tight group. Not sure why that might be. Once again case extraction was easy, spent case was visually fine, and later the case length and obturation found to be same as all others [regardless of charge weights]. ho hum

 

[zambezi]

Today's testing was pretty frustrating and srvet's post below is starting to sound likely:

possibility is that you may have identified a wide node where variation in charge weight doesn’t cause much change in velocity

Charge weights of 65 - 69gr N540 deliver around 2400fps. There is a step up in MV around 69.7gr. But this powder [pushing the Barnes 270gr TSX] seems to have a peak MV sub 2600fps in my rifle. Plotting the sample data I have gives the following graphic:




The extracted cases still look remarkably free of over-pressure issues, so I might try one more load increment. Viht suggest 73.4gr N540 as a max load. But I am now wondering if RL-15 may be a better fit for this caliber.

 

[Selous]

It does look like a wide node. This is great for accuracy as minor changes in charge weight, seating depth, case capacity should make little difference to pressure and therefore velocity. If you have no pressure signs then increasing charge weight might be possible but bear in mind the change in environment temperature between the UK and Africa might increase pressure further.

 

[Selous]

I have just done a quickload simulation trued to the 70 g charge weight. I have had to assume case capacity is as on QL, a barrel length of 24 inches and also that the cartridge OAL is 3.700 as the program wont cope with measurements to ogive. If you can measure these things and get back to me then I can rerun the numbers and get it hopefully more accurate. As you will see below the N540 seems to be maxing out just below the 2600fps that you desire.

Cartridge : .375 H.& H. Mag.
Bullet : .375, 300, Barnes 'TSX' 30491
Useable Case Capaci: 77.097 grain H2O = 5.006 cm³
Cartridge O.A.L. L6: 3.700 inch = 93.98 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Vihtavuori N540 *C ?, Temperature: 46 °F

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 77 55.20 2059 2825 32210 6513 97.8 1.594
-18.0 79 56.58 2104 2949 34105 6669 98.3 1.558
-16.0 81 57.96 2148 3075 36115 6817 98.8 1.522
-14.0 83 59.34 2193 3202 38246 6956 99.2 1.488
-12.0 85 60.72 2237 3332 40504 7086 99.5 1.454
-10.0 86 62.10 2280 3463 42898 7206 99.8 1.422
-08.0 88 63.48 2323 3596 45435 7316 99.9 1.390
-06.0 90 64.86 2366 3730 48125 7416 100.0 1.359
-04.0 92 66.24 2409 3866 50979 7508 100.0 1.329
-02.0 94 67.62 2451 4003 54006 7597 100.0 1.296 ! Near Maximum !
+00.0 96 69.00 2493 4141 57219 7684 100.0 1.263 ! Near Maximum !
+02.0 98 70.38 2535 4280 60632 7769 100.0 1.231 ! Near Maximum !
+04.0 100 71.76 2576 4421 64260 7853 100.0 1.200 !DANGEROUS LOAD-DO NOT USE!
+06.0 102 73.14 2617 4563 68118 7934 100.0 1.171 !DANGEROUS LOAD-DO NOT USE!
+08.0 104 74.52 2658 4706 72226 8013 100.0 1.142 !DANGEROUS LOAD-DO NOT USE!
+10.0 106 75.90 2699 4852 76604 8090 100.0 1.114 !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 96 69.00 2567 4391 67139 7443 100.0 1.186 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 96 69.00 2381 3777 47445 7911 99.0 1.356

Trying to identify other powders that may be of use gives some useful options. It looks like a slightly slower powder might be worth trying. I have seen some excellent velocities with RS60 in other calibres which came out top of the list. This data is based on charge weights calculated to give maximum safe pressure for each powder up to a maximum of 105% case fill

Cartridge : .375 H.& H. Mag.
Bullet : .375, 300, Barnes 'TSX' 30491
Useable Case Capaci: 77.097 grain H2O = 5.006 cm³
Cartridge O.A.L. L6: 3.700 inch = 93.98 mm
Barrel Length : 24.0 inch = 609.6 mm

Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 54570 psi, or 376 MPa
or a maximum loading ratio or filling of 105 %
These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.
USE ONLY FOR COMPARISON !

46 loads produced a Loading Ratio below user-defined minimum of 90%. These powders have been skipped.
Powder type Filling/Loading Ratio Charge Charge Vel. Prop.Burnt P max P muzz B_Time
% Grains Gramm fps % psi psi ms
--------------------------------- -----------------------------------------------------------------
ReloadSwiss RS 60 *T 97.7 72.8 4.72 2599 100.0 54570 8681 1.243 ! Near Maximum !
ReloadSwiss RS 70 *C 103.9 78.7 5.10 2581 97.9 54570 9346 1.244 ! Near Maximum !
Alliant Reloder-17 *T 96.7 72.1 4.67 2580 100.0 54570 8632 1.250 ! Near Maximum !
Elcho 17 96.7 72.1 4.67 2580 100.0 54570 8632 1.250 ! Near Maximum !
Alliant Reloder-26 *C 105.0 80.2 5.20 2569 99.0 49362 9674 1.293
Somchem S365 104.1 73.6 4.77 2564 100.0 54570 8242 1.259 ! Near Maximum !
Alliant Reloder-16 *C *T 101.4 70.2 4.55 2560 99.8 54570 8581 1.250 ! Near Maximum !
ReloadSwiss RS 62 100.5 74.8 4.85 2554 99.5 54570 8703 1.268 ! Near Maximum !
PB Clermont PCL 518 102.3 75.1 4.86 2542 98.2 54570 8805 1.261 ! Near Maximum !
PB Clermont PCL 511 98.2 74.3 4.82 2541 98.5 54570 8761 1.262 ! Near Maximum !
Ramshot Hunter 101.4 74.4 4.82 2540 98.5 54570 8749 1.262 ! Near Maximum !
Hodgdon H414 95.6 71.9 4.66 2528 97.8 54570 8679 1.268 ! Near Maximum !
Winchester 760 95.6 71.9 4.66 2528 97.8 54570 8679 1.268 ! Near Maximum !
Norma URP *C 100.8 70.8 4.59 2524 99.5 54570 8430 1.272 ! Near Maximum !
Bofors RP19 ~approximation 100.8 70.9 4.59 2524 99.5 54570 8428 1.272 ! Near Maximum !
Norma MRP *C 105.0 77.9 5.05 2524 96.5 49165 9416 1.303
Accurate 4350 100.3 71.3 4.62 2523 99.6 54570 8427 1.287 ! Near Maximum !
Vihtavuori N550 *C 97.7 71.0 4.60 2522 99.4 54570 8528 1.278 ! Near Maximum !
Hodgdon CFE223 *C 91.1 70.6 4.58 2520 99.6 54570 8351 1.269 ! Near Maximum !
ADI AR 2209 104.9 74.2 4.81 2520 95.7 54570 8747 1.255 ! Near Maximum !
Alliant Reloder-19 *C 105.0 74.6 4.84 2508 95.7 53227 8778 1.274 ! Near Maximum !
SNPE Vectan SP 11 93.8 68.9 4.46 2506 99.9 54570 8107 1.274 ! Near Maximum !
ReloadSwiss RS 52 91.4 67.1 4.35 2506 100.0 54570 7867 1.280 ! Near Maximum !
Bofors RP4 ~approximation 103.5 73.5 4.76 2502 95.7 54570 8569 1.264 ! Near Maximum !
Raufoss RA4 103.5 73.5 4.76 2502 95.7 54570 8569 1.264 ! Near Maximum !
Norma 204 *C 100.2 73.5 4.76 2502 95.7 54570 8569 1.264 ! Near Maximum !
Ramshot Big Game 90.8 68.8 4.46 2500 99.9 54570 8017 1.275 ! Near Maximum !
Hodgdon Hybrid 100V 103.7 71.3 4.62 2499 100.0 54570 7789 1.268 ! Near Maximum !
IMR 4831 105.0 71.5 4.63 2491 99.5 53220 8221 1.296 ! Near Maximum !
IMR 4895 90.1 64.0 4.15 2489 100.0 54570 7977 1.288 ! Near Maximum !
Bofors RP4 NT *C ~approximation 101.0 72.8 4.72 2488 97.4 54570 8354 1.278 ! Near Maximum !
Winchester Supreme 780 104.4 78.2 5.07 2483 95.6 54570 8388 1.265 ! Near Maximum !
Bofors RP14 ~approximation 105.0 74.6 4.84 2483 95.4 52038 8651 1.287
IMR 7828 SSC 105.0 76.7 4.97 2482 92.7 50228 8982 1.295
Norma 203B *C 91.4 64.9 4.21 2480 100.0 54570 7896 1.289 ! Near Maximum !
Bofors RP11 ~approximation 90.9 64.6 4.19 2480 99.8 54570 7947 1.289 ! Near Maximum !
Alliant Reloder-15 *C 90.9 64.6 4.19 2480 99.8 54570 7947 1.289 ! Near Maximum !
Raufoss RA11 90.9 64.6 4.19 2480 99.8 54570 7947 1.289 ! Near Maximum !
Bofors RP3 93.0 66.8 4.33 2478 100.0 54570 7799 1.301 ! Near Maximum !
Norma 203 old 93.0 66.8 4.33 2478 100.0 54570 7799 1.301 ! Near Maximum !
Hodgdon H380 92.4 67.1 4.35 2473 99.3 54570 8052 1.293 ! Near Maximum !
Rottweil R903 95.1 66.8 4.33 2472 100.0 54570 7733 1.301 ! Near Maximum !
Lovex S070 99.8 70.2 4.55 2471 97.9 54570 8205 1.293 ! Near Maximum !
Somchem S385 105.0 75.4 4.89 2471 96.6 52448 8437 1.303
IMR 4320 92.9 65.0 4.21 2468 99.9 54570 7669 1.272 ! Near Maximum !
Rottweil R904 103.9 72.8 4.72 2467 94.4 54570 8260 1.272 ! Near Maximum !
Hodgdon H4350 *T 102.4 71.2 4.62 2466 97.0 54570 8120 1.276 ! Near Maximum !
IMR 4350 100.5 71.1 4.60 2466 97.1 54570 8108 1.276 ! Near Maximum !
Somchem S355 94.9 66.0 4.28 2465 100.0 54570 7729 1.297 ! Near Maximum !
Bofors RP7 NT *C ~approximation 94.2 67.5 4.38 2460 98.0 54570 7910 1.265 ! Near Maximum !
Vihtavuori N560 *C 105.0 76.2 4.94 2460 91.5 47315 9137 1.328
Elcho TR140 - preliminary data 91.9 67.5 4.37 2459 99.3 54570 7835 1.289 ! Near Maximum !
ReloadSwiss RS 50 92.2 68.2 4.42 2453 98.2 54570 7948 1.289 ! Near Maximum !
Lovex S065 98.4 68.4 4.43 2452 98.7 54570 7932 1.296 ! Near Maximum !
IMR 3031 90.2 59.9 3.88 2452 100.0 54570 7046 1.292 ! Near Maximum !
ADI AR 2213 105.0 75.4 4.89 2451 92.2 49252 8804 1.307
ADI AR 2208 93.1 64.2 4.16 2447 99.8 54570 7654 1.282 ! Near Maximum !
Hodgdon VARGET *T 93.4 64.2 4.16 2447 99.8 54570 7654 1.282 ! Near Maximum !
Bofors RP5/NP ~approximation 105.0 75.4 4.89 2447 94.1 46697 8941 1.338
Alliant Reloder-22 *C 105.0 75.4 4.89 2447 94.1 46697 8941 1.338
Raufoss RA15 *C 105.0 75.4 4.89 2447 94.1 46697 8941 1.338
IMR 4451 Enduron *C*T 95.6 67.1 4.35 2446 97.5 54570 7937 1.280 ! Near Maximum !
Accurate 4064 92.3 64.1 4.16 2445 100.0 54570 7236 1.327 ! Near Maximum !
Bofors RP3 NT *C ~approximation 95.9 67.7 4.39 2444 98.7 54570 7756 1.279 ! Near Maximum !
Bofors RP7 97.1 67.7 4.39 2444 97.1 54570 7987 1.293 ! Near Maximum !
Rottweil R907 97.1 67.7 4.39 2444 97.1 54570 7987 1.293 ! Near Maximum !
IMR 4007 SSC 94.1 67.8 4.39 2443 97.1 54570 7981 1.293 ! Near Maximum !
Hodgdon H4831 SC *T 105.0 75.4 4.89 2443 92.4 51543 8395 1.294
Lovex S062 91.8 63.5 4.11 2441 100.0 54570 7382 1.302 ! Near Maximum !
IMR 4064 94.0 63.1 4.09 2439 99.8 54570 7496 1.288 ! Near Maximum !
Somchem S361 102.9 77.9 5.05 2436 93.3 54570 8073 1.285 ! Near Maximum !
Vihtavuori N150 *C 100.1 67.1 4.35 2434 100.0 54570 7270 1.294 ! Near Maximum !
Vihtavuori N540 *C 90.6 65.1 4.22 2434 100.0 54570 7244 1.296 ! Near Maximum !
Accurate MAGPRO 105.0 79.3 5.14 2428 88.9 45975 9033 1.346
Rottweil R902 90.6 62.1 4.02 2422 100.0 54570 7245 1.310 ! Near Maximum !
IMR 4166 Enduron *C*T 94.7 64.4 4.18 2421 97.7 54570 7662 1.289 ! Near Maximum !
Ramshot Magnum 105.0 81.3 5.27 2408 94.0 46469 8621 1.337
Vihtavuori N140 *C 90.3 62.9 4.08 2405 100.0 54570 6809 1.299 ! Near Maximum !
IMR 4955 Enduron *C*T 105.0 72.6 4.70 2400 92.7 50813 8067 1.314
Vihtavuori N135 *C 96.1 61.9 4.01 2400 100.0 54570 6619 1.308 ! Near Maximum !
Accurate 2700 94.1 69.8 4.52 2400 96.8 54570 7516 1.300 ! Near Maximum !
Alliant Reloder-23 *C *T 105.0 73.0 4.73 2390 98.9 42561 8416 1.388
Rottweil R905 105.0 74.1 4.80 2379 90.9 45297 8419 1.362
Accurate 3100 105.0 74.6 4.84 2376 96.8 46010 8115 1.381
Bofors RP15 105.0 73.8 4.78 2376 92.5 42990 8674 1.386
Winchester WXR 105.0 73.8 4.78 2376 92.5 42990 8674 1.386
SNPE Vectan SP 12 105.0 79.7 5.16 2350 89.9 42526 8726 1.384
PB Clermont PCL 517 105.0 79.7 5.16 2345 89.6 42309 8710 1.387
Hodgdon H4831 *T 105.0 72.5 4.70 2340 90.3 45375 8016 1.366
IMR 7828 105.0 72.5 4.70 2331 89.4 41988 8396 1.396
Bofors RP5 NT *C ~approximation 105.0 76.1 4.93 2329 87.3 44512 8165 1.374
Alliant Reloder-25 *C 105.0 74.2 4.81 2324 95.2 39068 8645 1.432
Vihtavuori N165 *C 105.0 73.8 4.78 2323 93.8 44168 7797 1.386
Vihtavuori N160 *C 105.0 71.5 4.64 2315 91.7 45726 7638 1.375
ADI AP 2214 105.0 77.5 5.02 2312 88.9 42851 8259 1.388
Vihtavuori N565 *C 105.0 76.7 4.97 2304 88.6 38873 8567 1.444
Lovex S071 105.0 70.6 4.57 2237 94.5 38349 7686 1.487
Bofors RP30 105.0 74.6 4.84 2228 87.1 35082 8334 1.498
Norma MRP 2 *C 105.0 74.6 4.84 2228 87.1 35082 8334 1.498
IMR 7977 Enduron *C*T 105.0 73.8 4.78 2209 80.5 44390 6989 1.406
ReloadSwiss RS 80 *C 105.0 81.0 5.25 2186 81.6 33862 8418 1.518
Vihtavuori N570 *C 105.0 78.7 5.10 2179 77.1 34117 8315 1.516
ADI AR 2217 105.0 73.8 4.78 2175 85.3 36362 7653 1.488
Hodgdon H1000 *T 105.0 73.8 4.78 2175 85.3 36362 7653 1.488
ADI AR 2225 105.0 75.0 4.86 2125 86.4 31735 8021 1.564
Hodgdon Retumbo 105.0 75.0 4.86 2125 86.4 31735 8021 1.564
Alliant Reloder-33 *C 105.0 81.0 5.25 2104 75.1 31854 7928 1.563
Lovex D100 105.0 80.3 5.20 2078 72.9 35598 6806 1.522
Vihtavuori N170 *C 105.0 73.8 4.78 2059 77.0 32493 6960 1.580
Vihtavuori 24N41 *C 105.0 79.5 5.15 2046 68.6 33515 6864 1.553
Norma 217 *C 105.0 73.5 4.76 2035 82.3 27424 7763 1.654
ADI AR 2218 105.0 79.5 5.15 2033 68.4 31551 7262 1.583
Hodgdon H870 105.0 77.1 4.99 2000 74.0 27910 7359 1.651
Alliant Reloder-50 *C 105.0 80.7 5.23 1930 68.3 25129 7226 1.757
Bofors 12,7mmRA NC1214 Lot20115087 105.0 78.9 5.11 1922 63.3 26125 6749 1.750
Hodgdon 50BMG 105.0 75.8 4.91 1905 60.9 27813 6204 1.675
Hodgdon US 869 105.0 79.5 5.15 1899 64.0 27436 6248 1.686
Somchem 12.7-0 105.0 77.1 4.99 1888 61.2 28938 5780 1.664
SNPE Vectan SP 13 105.0 76.2 4.94 1865 68.5 25069 6262 1.741
Accurate 8700 105.0 77.9 5.05 1825 65.0 24930 5948 1.753
PB Clermont PCL 513/520/9520 105.0 76.2 4.94 1814 65.0 23867 5957 1.780
Vihtavuori 20N29 *C 105.0 80.3 5.20 1796 61.7 23614 5937 1.836
NC A3502 ,test only 105.0 73.0 4.73 1699 44.4 23842 4240 1.864

 

[zambezi]

...bear in mind the change in environment temperature between the UK and Africa might increase pressure further.

Agree. In fact Viht declare only one of their 500 series powders to be insensitive to ambient temperature: N555.

So I think I will now tinker with N540 loads in the 69-71gr range and fine tune accuracy with CBTO tweaks.

 

[zambezi]

QL...the N540 seems to be maxing out just below the 2600fps that you desire.

Hi srvet, much appreciated.Do the QL figures look same for N540 if we enter the parameters specific to my case?

Barrel length: 600mm
CBTO=2.999"/COAL=3.518",
Barnes 270gr TSX [30489]

 

[zambezi]

Trying to identify other powders that may be of use gives some useful options

Thanks srvet, the powder options are a useful guide. I imported that data into a spreadsheet and re-ordered by MV. As you say, RS60 looks to be a top contender per QL. Worth noting is that my experience of N540 at around 65gr broadly agrees with QL.

I am tempted to try N160 in the .375 [because I already have some] and see how that compares.




The Nosler reloading manual [citing scenario where 260gr projectiles are used] suggests that RL15 is the accuracy sweet spot and also indicates a higher MV at lower density than does QL:




I am looking to avoid buying half a dozen [expensive] powders only to discover they do not quite pass muster...

 

[Selous]

I have tweaked burning rate of the powder to meet your velocity figures and adjusted the COAL and barrel length. Case volume would be useful if that is possible.

Cartridge : .375 H.& H. Mag.
Bullet : .375, 270, Barnes 'TSX' 30489
Useable Case Capaci: 77.768 grain H2O = 5.049 cm³
Cartridge O.A.L. L6: 3.600 inch = 91.44 mm
Barrel Length : 23.6 inch = 600.0 mm
Powder : Vihtavuori N540 *C ?

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 77 56.00 2061 2547 28104 6471 93.0 1.575
-18.0 79 57.40 2108 2665 29783 6662 94.0 1.539
-16.0 81 58.80 2156 2786 31566 6848 94.9 1.505
-14.0 83 60.20 2203 2909 33466 7028 95.7 1.471
-12.0 85 61.60 2250 3035 35466 7201 96.5 1.438
-10.0 87 63.00 2297 3164 37571 7367 97.1 1.406
-08.0 89 64.40 2344 3295 39788 7525 97.8 1.374
-06.0 91 65.80 2391 3428 42138 7675 98.3 1.343
-04.0 93 67.20 2438 3563 44637 7816 98.8 1.313
-02.0 95 68.60 2485 3701 47294 7947 99.2 1.284
+00.0 97 70.00 2531 3840 50121 8069 99.5 1.256
+02.0 99 71.40 2577 3982 53130 8179 99.7 1.226 ! Near Maximum !
+04.0 100 72.80 2623 4126 56334 8279 99.9 1.194 ! Near Maximum !
+06.0 102 74.20 2669 4271 59750 8368 100.0 1.163 ! Near Maximum !
+08.0 104 75.60 2715 4418 63395 8445 100.0 1.133 !DANGEROUS LOAD-DO NOT USE!
+10.0 106 77.00 2760 4567 67286 8518 100.0 1.105 !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 70.00 2633 4156 59299 7821 100.0 1.174 ! Near Maximum !
Data for burning rate decreased by 10% relative to nominal value:
-Ba 97 70.00 2388 3420 41120 7961 95.1 1.358

 

[zambezi]

I have measured empty case volume using water and found that to weigh 86gr. After conversion, that corresponds to 5.57cm³.

With a bullet inserted into the water filled case [simulating a cartridge COAL of 3.578"] , the measurable water volume drops a full 10gr to 76gr. In short, available case volume for QL calculation is measured to be 4.93cm³. But I am aware that some water was retained in the case after tipping onto the scales, and also clinging by capilliary action to the extracted bullet, so your working assumption of 5.049cm³ is probably correct.

What is reassuring is that my field testing, QL and the Viht tables appear to agree on the safe use of a 70gr N540 charge and that it will produce 95%+ of the MV I sought [2600fps]. I will probably make that the weight around which I now tinker with CBTO to deliver optimum accuracy.

 

[Vortex2019]

Just a quick one on powder as you were saying you don’t want lots of expensive powder.
Norma 203-B is the same as RL-15. It’s cheeper as well.

 

[zambezi]

During the .375 and 6.5x55mm load development I have been doing, I have been using a Chrony F-1 to verify MV. It has worked well, but can [like any optical system] suffer if light conditions are not optimum. I have had it throw some "err" readings. Which is fine if you are set up on a range where you are at liberty to move forward of the shooting bench to fettle the Chrony. That is not the case at my club once a course of fire has commenced.

Also, I do not want to build huge batches of ammo, so really want a valid chrono reading for every shot I take. So I bit the bullet and bought myself a magnetospeed V3. What the V3 brings to the table is the ability to run a chronograph from the firing point. In any lighting conditions. And more specifically, the V3 bayonet fits my chunky .375 moderator!

Cannot wait for lockdown to be lifted and get back to this development

 

[Namman]

on a more simplistic note.
Some years ago!! I was loading 235 gr speer hot cors in a .375 H&H using 83 grains Nobel no O rifle powder for I recall 2850fps , a compressed load . I remember increasing the charge in increments to max charge of 85 grains ( the most the case could handle) and now this heavily compressed load showed no increase in velocity over the 83 grains. I came to the conclusion that the cartridge just could not burn any more of that powder, as it is not a particularly overbore cartridge.
That was in the simplistic days of reloading without all the technical spiel and gizmos I hear about today. I think we had more time to shoot then and with certainly a wider variety of firearm types!
Good luck with your testing, it is a fine and versatile cartridge.

 

[Namman]

I should have said there were no indications of excess pressure.

 

[sh1kar]

My 375 270g load is

Magnum CCI Primer
270g Hornady RN interlock
82g N160 (compressed)
COAL 3.6”
2580 FPS
3/4 “ group at 100

For 300g I use 80g. Runs at 2525fps

S

 

[thegreg]

For 300g I use 80g. Runs at 2525fps

Interesting. I use 77gr of N160 under a 300gr Hornady RN to produce 2490fps. I've found that's the absolute limit before powder compression and I always try to avoid that if I can.

Cheers
Greg

 

[zambezi]

Today was a good day... Magnetospeed seems to indicate slightly faster MV than did the Chrony F1 for same loads. Regardless, today I was able to deliver a tight group using 70gr N540 behind a Barnes 270gr TSX in once-fired Sako brass with no ill effects.

Magnetospeed pegs factory ammo at 2680fps. My load above gives 2612fps which is to say 97% of target MV. Given the accuracy, I will probably tinker very little with that.

EDIT: that group achieved with a 4x scope. The red dot covers all the rings in view on this target,

 

[A Guy Out West]

Great hand loading and shooting.

 

[Selous]

Today was a good day... Magnetospeed seems to indicate slightly faster MV than did the Chrony F1 for same loads. Regardless, today I was able to deliver a tight group using 70gr N540 behind a Barnes 270gr TSX in once-fired Sako brass with no ill effects.

Magnetospeed pegs factory ammo at 2680fps. My load above gives 2612fps which is to say 97% of target MV. Given the accuracy, I will probably tinker very little with that.

EDIT: that group achieved with a 4x scope. The red dot covers all the rings in view on this target,


View attachment 161732

Would be interesting to see what groups were like with higher magnification. Great result though!!

 

[zambezi]

Would be interesting to see what groups were like with higher magnification.

I am pretty certain group would be very tight if I dropped my Z6 onto the .375. But even the Z4 [4x] result is sufficiently accurate for any large-bodied plains game out to 175m