Wondering about pressure

338 Ultra

Beginner
Aug 14, 2011
113
0
Well here is a question for you fine fellows on here about pressure.

I have just worked up a load recently in my 300 win mag,( last sunday to be exact) and I have worked beyond listed max data by 3 grains and have no pressure issues or any signs that you would normally see. I was hoping to get my hands on some of the LRAB's but have not seen any in my neck of the woods yet. Did get my hands on some Berger 185 classic hunters though from one of my friends in a trade for .224 ballistic tips so I figured why not give em a try.

Well these bullets are made to shoot in standard factory rifles with sammi spec throats and mag's and still give improved drops and wind drift. I have shot quite a few Bergers when I was shooting matches and always shot the target vld's either jammed or within a couple of thou of the gears with great results. With a purpose built rifle this is not an issue nor is single loading as we all know. I fooled around a little bit with hunting Berger vld's in hunting rifles working on jump and had some ok results but nothing close to having them up tight to the lands but if you can't load the mag they don't seem very attractive.

I started working up using the data from Berger's new load manual with 3 cases to see what would happen during load work up. The first loads were on brand new cases, after that they were resized in lee collet dies with primer pockets cleaned and such and measured for stretch each time. So this worked out to six loads per case once I found the tighest shooting load. No extractor marks, nice round primers with no cratering, no issues with bolt lift and after the 6th load the cases needed to be trimmed to get back into proper spec but only 5 thou so I could have still probably got another load or two before I had to bump the shoulder's back and trim.

I am scratching my head a wee bit as to where I am at pressure wise. I have to shoot 3 more cases at this load level a few times to see what is going on for sure. I am getting one eggshaped hole at 100 yards with this load so I am really happy with the accuracy in a rifle that is proven to be fussy in what it likes to shoot. It is not a finished load yet but I think it is where it needs to be. This rifle has been pretty much right on with listed data in every combo I have tried in it over the years I have had it. My 10 year old chroney packed it in and won't read anything but error so I will have to wait till I get a new one to see what speed is which is not too big of a deal as I am just tinkering and have lots of accubonds loaded for hunting with just need to re-zero and I am good to go.

Here is what I have for a load and what the Berger Manual lists as thier max.

300 Win mag
Win Brass
CCI-250 primer
77 grains IMR-7828
Berger 185 classic hunter
loaded to 3.34" oal

Berger manual lists 74 grains and a bit as their max ( sorry dont have the book with me right now) The rifle in question is a Ruger Hawkeye stainless "plastic fantastic" 24" tube with a timney trigger nice rifle to carry in the field not to heavy and accurate enough to knock down any moose or elk I would think about shooting with it and cheap enough that I don't worry about rough treatment.

The bullet does have a shorter bearing surface than what I would normally shoot but I did not think that would give the results I am seeing, this rifle has been pretty much in line with published data and pressure signs when I went above said data. So I thought I knew this rifle on an intimate basis with a few different combo's and now I am learning that I don't quite know what I thought I knew and that it sure is fun to try some different things from time to time just to break up the boredom.

Sorry Nosler that I strayed from my tried tested preferred bullets but when I can't buy an AccuBond or a longrange version in my area and I can trade 200 55 grain Btips for 200 185's I just have to give em a try for curosity sake.



Going to shoot this load again this weekend with 3 once fired cases and see how they hold up with pockets sizing trimming and such. Hopefully my buddy will make it down to the farm with his gong and his 338 lapua and we can do some reaching out and I can see what this bullet will do when the range gets long.
 

DrMike

Ballistician
Nov 8, 2006
35,024
1,423
Before they released the Berger Manual, Walt Berger sent QL sheets whenever people requested load data.

This is a QL projection, indicating that you are just now at maximum pressure in a standard chamber.

Code:
Cartridge          : .300 Win. Mag.(W)
Bullet             : .308, 185, Berger VLD G7 #30513
Useable Case Capaci: 82.085 grain H2O = 5.330 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length      : 22.0 inch = 558.8 mm
Powder             : IMR 7828

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   84    61.52   2341    2250   31039  11283     87.2    1.510
-18.0   86    63.06   2403    2372   33172  11694     88.7    1.471
-16.0   88    64.60   2466    2498   35457  12094     90.2    1.433
-14.0   90    66.13   2530    2629   37904  12481     91.6    1.391
-12.0   92    67.67   2593    2763   40528  12854     92.9    1.346
-10.0   94    69.21   2658    2901   43342  13210     94.0    1.303
-08.0   96    70.75   2722    3043   46353  13547     95.1    1.261
-06.0   98    72.29   2786    3189   49608  13864     96.1    1.221
-04.0  100    73.82   2851    3338   53100  14158     97.0    1.182  ! Near Maximum !
-02.0  102    75.36   2915    3491   56859  14427     97.8    1.145  ! Near Maximum !
+00.0  105    76.90   2980    3647   60911  14670     98.5    1.109  ! Near Maximum !
+02.0  107    78.44   3044    3807   65281  14886     99.0    1.074  !DANGEROUS LOAD-DO NOT USE!
+04.0  109    79.98   3108    3969   70009  15071     99.4    1.041  !DANGEROUS LOAD-DO NOT USE!
+06.0  111    81.51   3173    4135   75124  15225     99.7    1.008  !DANGEROUS LOAD-DO NOT USE!
+08.0  113    83.05   3236    4303   80664  15346     99.9    0.977  !DANGEROUS LOAD-DO NOT USE!
+10.0  115    84.59   3300    4473   86685  15432    100.0    0.946  !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    105    76.90   3131    4026   74151  14303    100.0    1.021  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    105    76.90   2774    3161   49222  14138     91.9    1.222
 

338 Ultra

Beginner
Aug 14, 2011
113
0
Thanks Dr Mike I never even thought about Berger having a match or custom chamber that their data came from. Working too many hours I guess so the old melon is getting soft in the middle now I feel somewhat stunned that I could not figure that out myself

Thanks again Doc Mike
 
Top