Reloader-17 and 4350

[Mustang]

I've begun experimenting with Reloader-17 in 7.5 x 55. Yesterday I tried several loads with Nosler Custom Competition 175's (practically a clone of the 175 SMK.) with decent results. I used charges of 48.5, 48.8 and 49.2 grains of RE-17, with my best results being with the 49.2 gr load. I got no obvious signs of excess pressure with the 49.2 load, but am somewhat concerned by data in the reloading manuals.

I've found no published data for reloader-17 reloading in the 7.5 x 55 cartridge. A call to Alliant confirmed that they had no such data, but advice that RE-17 had a similar burn rate to IMR 4350. I've checked my reloading manuals for IMR 4350 and found that 49.2 grains is over the limit in both the Sierra and Hornady manuals for 175 grain bullets and 4350 powder.

My questions...

-Is anyone using a load of reloader-17, either at 49.2 grs or above, with 175 grain bullets in 7.5 x 55 and if so, have you seen any signs of excess pressure?
-Is the burn rate of RE-17 different enough from 4350 that I shouldn't obsess about this load exceeding the max for 4350?
-Anyone have any thoughts on this load?

Thanks.

[milotrain]

If it shoots good and you don't see signs of over pressure you are GTG. Check for flowing to flattened primers, stiff bolt lift and excessive base expansion of the brass (with a mic).

What is the action? The older military actions you need to be more careful with.

[Mustang]

Thanks, train.

It is amazing how much difference a few .1's of a grain of powder can make.

I used this target to test the loads at 100 yards.

[

I set the sights of the K31 to 200 and fired the upper left hand (8") target with 4 rounds of 48.5 grains of RE-17 and was aiming with a 6 o'clock hold on the small (5.5") just beneath it. I then fired 5 rounds of 48.8 grains of RE-17 at the right hand 8" target, again with a 6 o'clock hold on the 5.5" target just below it.

I then moved the sights on the K31 to "100" and fired 4 rounds of 49.2 Re-17 with a 6 o'clock hold on the 5.5" target at the bottom left, getting a group just to the left of my aim point. That was the best group of the test.

[krwada]

Only 0.5 grains will make a significant difference in group size.

[milotrain]

One way to test without a chronograph is to shoot a known good pressure load with a known FPS (a 4350 max load for example) and see where it lands on the target. Then you can work up a RL17 load to POI of the 4350 load. At that point you know that the RL17 load is moving about as fast as the 4350, and in your case specifically that should be nearly the same pressure curve. Pressure is not linear nor does it match velocity typically but if Alliant said to start with 4350 data then it might be a decent correlation.

[allenj]

A good article on RL17 is here: http://www.6mmbr.com/reloder17.html

What signs are you using to check pressure?