Conflicting Load Data?

Interestingly enough. Sierra's start load for the 270 wsm with H1000 is lower than the start charge they list for 270 win. Using same powder and bullet weight.
 
With those starting loads. The 270 win gets 2700 FPS with 54.4 grains of h1000.

270 wsm start load is 52.2 at 2800 FPS. Seems like that info is odd. The 270 wsm has a higher case capacity. How do you use less powder in a larger case to get more velocity than you did in a smaller case with 2 grains more powder....

I will call Sierra tomorrow and try to verify that data.
 
Sounds like a plan. it is almost certain to be true that different lots of powder were used in developing loads for the two, so the WSM could have had the faster burn rate lot. The short case probably lights a little more powder initially, so it's possible to get those results. Double-check that the guns used had the same barrel length. It would be interesting to run the two with the same lots of powder and primers side-by-side in same-length barrels.
 
If I can manage to get the Labradar, that is a test I can run in the 7.5 Swiss vs the 30-06.

It seems the 7.5 shorter and fatter does burn a bit more efficiently, will have to do some cross checks there as well.
 
Sierra uses different start loads. The loads for 270 started 2700fps and when to 3000fps and loads for 270WSM started 2800fps to max of 3250fps.

In Sierra manual for those 140gr bullets in 270 which included 140gr HPBT and 140gr SBT they started @ 2600fps max @ 3000fps Same bullets for 270WSM they started load @2800fps max @ 3100fps.

Why should they put more low end loads for Mag?
 
Old Roper,

At first I used a different manual to start. And found that Sierra data is waaaaay lower than all of the others I can find. My starting load is a full 5 grains heavier than their max load. It's also a load that's ibhavr already fired without issue with another 140 grain bullet.
 
In case anyone was interested I downloaded the Sierra Data for the game changer and posted the PDF in the online load data sources thread.
 
Something else to consider is that the load manuals from specific manufacturers are created using the bullets THEY make. As a result, a 150gr .30 caliber bullet made by Sierra may be just barely different than a bullet with the same spec that is made by Hodgdon which is just a little different than the bullet from Nosler, etc.

Add to that the different rifles they use and the other unknowns between them all as listed above and you can't say that there is consistency between them at all, SAAMI notwithstanding.

--Wag--
 
Add to that the different rifles they use and the other unknowns between them all as listed above and you can't say that there is consistency between them at all, SAAMI notwithstanding.
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Powder lots as well.

Like most things, you can get a good idea of the range and make a decision accordingly.

If you see a high outlier, throw it out or work up slowly to it.
 
I feel like Sierra is the outlier here. Comparing other starting load data for even heavier bullets. with H-1000 is higher than sierras max loads for the 140 grain. Hodgdon shows starting loads of H-1000 with 150 and 160 grain bullets at or higher than sierras max load for 140 grain.

Nosler's Data also shows much higher charges of H-1000 with heavier bullets than sierra does for this cartridge.

I get it. Different materials cause different drag factors, and different lots of powder have different burn rates. But calling for a 20 percent plus reduction in powder charge?

For me to start at Sierra's start load and work all the way up to where I feel like I am gonna be with this rifle will take me several boxes of bullets and pounds of powder.

I will reduce the hodgdon data by 12 percent, but not by 26 percent. especially when I have fired other 140 grain bullets in the same cases, same lot of powder, same rifle seated deeper into the case. With no pressure signs. Not even a flat primer or ejection marks.

Even Barnes Data for 150 grain TSX bullet is heavier than the sierra with a 140 grain game king with H-1000.

Sierra is considerably lower than everywhere else that I can find reasonably comparable data. That was the purpose for this thread. I already knew the direction I was headed. This is for conversation mostly
 
For me to start at Sierra's start load and work all the way up to where I feel like I am gonna be with this rifle will take me several boxes of bullets and pounds of powder.
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not necessarily, like I suggested in my first thread do one or two rounds from low to high for a pressure test working your way up. Start the load development in the range where the velocity is where you want it once you are sure the charge range is safe. I have been getting some great results from what I call the 55 round load test. I just made a thread on it, you might want to give it a try. It's worked twice in a row for me
 
hounddawg said:
not necessarily, like I suggested in my first thread do one or two rounds from low to high for a pressure test working your way up. Start the load development in the range where the velocity is where you want it once you are sure the charge range is safe. I have been getting some great results from what I call the 55 round load test. I just made a thread on it, you might want to give it a try. It's worked twice in a row for me
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Yeah I will have to check that out.
 
with that bullet I can get 1350 @ 1000 using the minimum charge, in the test I went up to 39.5 and found a couple of other promising nodes but I doubt I will do any further testing. Same with the 120 SMK in the .260 test. If it works, don't mess with it and keep it simple. Only idiots overly complicate something that works fine as is. 18 rounds at a 95% CEP of less than a half MOA is good enough for me
 
Worked up to 68 grains h-1000. No pressure signs, but it doesn't shoot that well. This gun really likes Magpro better with 140 grain pills.
 
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