.243 load ladder questions

[CATM15]

I loaded up 15 or so rounds for a load ladder in my .243win Accuracy International.

Powder IMR 4831
Bullet 105 nosler RDF
SIG brass sized
CCI LR primer

Nosler reloading manual says max is 41gr at 3007fps

Started my test at 39gr in .1gr increments up to 40.5
All shots were shot suppressed with a magnetospeed attached.
Problem I’m running into is that it’s slow....like super slow.
40.5gr load clocked in at 2665fps. Wayyyyy off the reloading manual. Has anyone had this problem or suggestions? I want to try to use this powder but obviously if I can’t get the speed it’s not worth it.

 

[Dthomas3523]

What’s the length and twist rate of your barrel?

 

[Kevins750]

I am shooting 40.5gr of H4350 with 107 SMK in lapua brass at around 2970ish.
26" 8 twist shillen match savage. 4831 is quite a bit slower

 

[Cascade Hemi]

If you look at Nosler's load data they list case capacity as 48.0gr of water. I don't have any Sig brass but I'd bet it is more like 53.0gr or 54.0gr of water. Nosler's load data is notoriously conservative, I'd run your pressure ladder up to 42.6gr of IMR4831.

 

[CATM15]

I forgot to mention barrel length and twist.
24” 1-8 twist
I was really just mystified that I have the same on paper spect as the test rifle in the manual and I’m seeing such different data

 

[PowellSixO]

You need to find some H4350, which is hard as hell to find. If you can't find that, get some RL16, which is the next best thing. Great accuracy, and you should gain some fps.

 

[CATM15]

I’ve got about 11lbs of H4350 but I was reserving it for other loads. I’ll work up a test to see how it does in the .243 but again I’m just bewildered that the book is off by over 200+ FPS for the charge. My buddy has quickload so I’ll ask him to plug in some info and see what that comes up with. I may just start loading to the moon fitting as much as I can before I see pressure. (IMR4831 is stupid cheap and easy to find so I wanna try me best to make it work) lol

 

[Cascade Hemi]

I ran it through QL and that is what I based my post above on. I used 2.80" with a 62K ceiling. I used 62K so you can run single shot pressure ladders until you find signs.

Here is the actual output:

Cartridge : .243 Win.
Bullet : .243, 105, Nosler RDF HPBT 53410
Useable Case Capaci: 48.531 grain H2O = 3.151 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : IMR 4831

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0 89 38.34 2716 1719 44966 9704 99.7 1.370
-09.0 90 38.77 2743 1754 46406 9770 99.8 1.350
-08.0 91 39.19 2769 1788 47891 9831 99.9 1.330
-07.0 92 39.62 2796 1823 49419 9887 99.9 1.311
-06.0 93 40.04 2822 1857 50995 9939 100.0 1.293
-05.0 94 40.47 2849 1892 52617 9986 100.0 1.274 ! Near Maximum !
-04.0 95 40.90 2875 1927 54289 10030 100.0 1.256 ! Near Maximum !
-03.0 96 41.32 2901 1962 56012 10074 100.0 1.239 ! Near Maximum !
-02.0 97 41.75 2926 1997 57787 10117 100.0 1.222 ! Near Maximum !
-01.0 98 42.17 2952 2032 59617 10160 100.0 1.205 !DANGEROUS LOAD-DO NOT USE!
+00.0 99 42.60 2977 2067 61503 10202 100.0 1.188 !DANGEROUS LOAD-DO NOT USE!
+01.0 100 43.03 3003 2102 63448 10243 100.0 1.172 !DANGEROUS LOAD-DO NOT USE!
+02.0 101 43.45 3028 2137 65453 10284 100.0 1.156 !DANGEROUS LOAD-DO NOT USE!
+03.0 102 43.88 3053 2173 67520 10323 100.0 1.140 !DANGEROUS LOAD-DO NOT USE!
+04.0 103 44.30 3078 2208 69652 10362 100.0 1.125 !DANGEROUS LOAD-DO NOT USE!
+05.0 104 44.73 3102 2244 71851 10401 100.0 1.110 !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 42.60 3074 2202 72947 9850 100.0 1.106 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 99 42.60 2831 1869 50095 10545 98.9 1.299

 

[MakeSawdust]

It is likely you have a longer freebore with more case capacity than the manual. It is also possible you have a slow lot of powder. It looks like the oal of the load from noslers manual is pretty short.

I would work up in small increments until you find pressure and then back off to test for a good load. If your buddy has quickload, adjust the inputs to match your brass, chamber, and lot of powder, and you will have a better idea where your load is in regards to pressure and velocity.

 

[Dobbs02si]

I'm not familiar with the imr, but h4831 at 46gr and h1k at 47gr will get what your after. Mag primers with both of course. As always, work up and be safe.

Edit: These are 105 amax loads. I haven't ran through my stash to try the rdfs yet.