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Discussion in 'Reloading' started by 270Weatherby, Mar 27, 2010.
Anybody have a starting point for RL 17
120gr Barnes TTSX
I see 180gr Bergers maxed at 53gr
Related to the last sentence. I have no clue who claims to be pushing 180 Bergers with 53g of RL17 in a .284 Winchester but I sure wouldn't do that. My QuickLOAD model says that's a 96,000 psi load which is 33,000 psi "over" max. That probably is way over the factory proof load. I don't see how that could be a good thing.
FWIW: QuickLOAD says 52.4g @ ~3,240 fps, 55,700 psi is max or close to it for the 120g Barnes TSX in a .284 Winchester. There isn't a TTSX bulle tin the library and since I don't have one to measure I can't enter it but I'd not expect it to be much different than the TSX. I'd back off to 49 or 50 grains, work up carefully keeping an eye on the chronograph readings, brass, and group size.
Could you do us a favor and run 67.5 gr of RL17 in a 300 WSM (24 3/8" barrel) with 180 E-Tips and 55.5 gr of RL17 in a 25-06 (26' barrel) with 115 Ballisitc Silvertips? I am very curious to see what the program says vs what my chrony is telling me.
Sure, with a disclaimer - I've not ever used RL17 - I'm planning to get a pound of it to try but I don't have any "real world" experience with it yet.
Results would be more accurate if I knew the COL of the loads in question and the H2O capacity in grains of the fired, unsized, brass. Small changes in COL and brass capacity (which reflects chamber size) make significant changes in pressure because they affect the initial volume.
The E-Tip bullet isn't in the QuickLOAD library and I don't have one to measure so I can add it, but if you can tell me the length of the bullet I can get pretty close by assuming it is the same shape as the 180g BT and adjusting the length.
With the data you gave me for the .300WSM, assuming a max for the cartridge COAL and using the library value for brass capacity, and a 180 NBT in place of the E-Tip I get the following results:
Input: 180g NBT, 2.860" COL, 81.3g H2O capacity, 67.5g RL17 (99.1% fill ratio), 24.375" barrel.
Results: 3,188 fps, 79,601 psi.
I don't really trust that answer because there are so many unknowns that can have a significant effect. To illustrate the sensitivity of the results to COL and H2O capacity, if the COL is 2.9", pressure drops 2,000 psi. If the water grain capacity is two grains more (fairely common) the pressure drops 5,000 psi.
For the .25-06.
Input: 115g Ballistic Silver Tip (which is in the QL library - I think it is a moly coated bullet so I adjusted the start pressure to 2400 psi), 3.25" COL, 26.0" barrel, 65.8g H2O capacity, 55.5g RL17 (95.5% fill).
Results: 3,446 fps, 81,848 psi.
These look high to me, but RL17 seems to have a reputation for modeling a little higher than it runs. QL isn't usually "that" far off though. The load that models at 90ksi in the original post is an over pressure load, I'm pretty sure of that. These may be just pretty stout if the right water grain capacity data is used.
So, how does this compare with what you are seeing at the range and in the brass? And can you get H2O capacity data on your brass?
If this is significantly different from what you expected and you have data for some other powders in these rifles I'd like to model that data as well to see if the issue is the QL model of RL17.
Thanks for the help Fitch. I'll start at 48 or 49 and work up until I see pressure and back off 10% or 1/2gr.
You are welcome.
I'd sure appreciate it if you would post your results so I can get a better handle on RL17 in QuickLOAD.
will do as soon as i get some good info
According to Nosler, the 180 E-Tip's length is 1.464"...
Nosler - Bullets, Ammunition, Rifles, Brass, and Reloading Data.
My measurement is 1.475". I don't have any 180 AB's (1.38") or BT's (1.36") to compare it with, but Nosler lists a slightly higher BC for the E-Tip (.523) vs the AB and BT (.507) I'm sure the bearing surface of the E-Tips is longer, as the bullet itself is longer by about .1"
The Ballistic Silvertip has a lubalox coating which is an oxide, not a moly. I had a chat with a Nosler tech on the subject and he told me it was quite different. It's meant to reduce fouling which I haven't really seen any evidence of. It (like the AB) is basically the same as BT in design and structure.
Your velocites are close to what I'm getting but hopefully your pressures are not. With the E-Tips, I'm getting 3193 from one chrony and about 30 fps less with the other (slower) chrony. In looking at all the evidence, the faster chrony appears to be more correct. My COAL was 2.93" (subtract .1" to use the AB in it's place for case capacity). Brass was neck sized only and therefore slightly swollen. Primers were somewhat flattened but not crater and bolt lift was easy, slighty stiff at 1/2 gr higher charge.
The velocity for the 115 BST's was about 3405 (with the slow chrony) and Win brass. Recently I treid the same load in Rem brass and got about 30 fps more velocity. Pressure signs similar as those reported for the 180 E-Tips.
Just to humor me, could you run the 300 WSM data for the E-Tips and 65.5 gr of H4350?
Input: 180 Nosler E-Tip @ 1.475” bullet length, 2.93” COL, .300WSM CIP nominal case capacity of 81.3 H2Og, 24.38” barrel, 65.5g H4350 (102.8% compressed load), normal 3625 psi start pressure.
Results: 3080 fps, 68,855 psi.
I see a lot of loads in this pressure range. They are stiff but not causing bad things to happen to the brass. H4350 and IMR4350 usually model within a couple of percent in QuickLOAD if I get the bullet data, COL, and water grain capacity input correct.
If you would take a piece if fired, still primed, and unsized brass and weigh it on your powder scale, then fill it level full of room temperature water, weigh it again on your powder scale, subtract the two numbers and let me know that number for each piece of brass (the water grain capacity) the answers will be quite a bit more accurate in terms of pressure. I'm expecting the brass to have anywhere from 1 to 4 grains more capacity than the CIP brass volume (chambers are always a little bigger so the brass will always fit).
I've seen quite a few RL17 loads on the internet where I could duplicate the MV, or at least get close, but the pressures QL predicted were inconsistant with the brass as read by the shooter. It may be that RL17 has a lower peak pressure and holds it longer. If that is in fact what it does, then Alliant is onto a real feature for their powders. The VV N5xx series is supposed to have the same properties - higher average pressure for the same peak pressure as the 1xx series. N570 and N560 are usuallly the powders that give the best results in cartridges like 7mmMAG, .300WM, and .338WM. I'd have to see results from pressure test equipment before I'd be ready to sign up for RL17 being that much better in terms of pressure, but it could be.
But then according to QuickLOAD, the best easily obtainable powder for your .300WSM is IMR7828SSC. Nosler has a max load of 70g of IMR7828 in their manual for the nominal 180g category of bullets. If I use IMR7828SSC (which allows a less compressed load but burns almost the same), I get 3,049 fps at 62,563 psi. That looks like a reasonable result and is comparable to their predicted 3,037 fps.