Longshot failed with the 125gr Barnes TAC-XP and G29
I had great hopes for Longshot. I have searched for the best 125gr Barnes TAC-XP load, and I had previously found that 11.4gr of 800-X got them to 1460fps, with room to spare (pressure wise). That load (CCI 300, COAL 1.260"), produced VERY mild case expansion, on the order of.432-.433", which is well below my max. However, the load was heavily compressed, and there likely was not much more room. In my search for 1600fps out of my G29, I decided to try Longshot. Power Pistol had already failed me, even when pushed a whole grain beyond Barnes's data. I gained no velocity over the Barnes max. Unique gets you as much velocity as Power Pistol in the G29, and has EXCELLENT accuracy and standard deviation (single digit).
I thought Longshot would be the answer. Longshot has usually proved to be very similar to 800-X in power, but much more dense. I figured I could get enough Longshot into the case to get the TAC-XP really moving. On Mudrush's suggestion, I loaded Longshot 1:1 with 800-X, and started at 10.7gr. I worked all the way up to 13.0gr with very disappointing results. Like with Power Pistol, I didn't get much beyond 1300fps. I did see an interesting trend (though I admit my sample sizes were small, but these things are EXPENSIVE, and I only had 20 left). The velocity seems to decrease, then starts to increase again. Maybe I need to keep pushing higher.
Here is the data:
Competition Electronics Digital, 85*F, 77% humidity, 495ft ASL
All loads used: CCI 300s, 125gr Barnes TAC-XP, new Starline nickel, Longshot, COAL 1.260"
Gun used was a G29 with 21lb Wolff spring
Maximum case expansion of the 13.0gr load was only .433", so it appears I could push some more. Mudrush says he's gone to 15gr or so (with 135gr bullets). The 13.0gr load was lightly compressed, so I'm not sure how much more room there is. When I get another box of them, I'll go a little further. I still want to see at LEAST 1500fps. I think 800-X will end up being the better powder. I will push both powders until pressure stops me. I'm not close with either. I will likely run out of room with 800-X first, and I hope I can even go further than 11.4gr. I'm thinking I can get at least 12.0gr. I will report back when I do the next batch of testing.
I expect these loads would gain a LOT in a G20 barrel. I'm guessing this 13.0gr load would produce nearly 1500fps or more in a G20. I believe Longshot is just not very efficient in the short barrel. With the 135gr Nosler JHP, it maxed out at 1382fps with 12.5gr. 12.7gr dropped to 1365fps (10 shot strings). So, like Power Pistol, I think there's a point with Longshot (in short barrels), where more powder does not equal more velocity. It just amazes me that 800-X does not seem to obey this rule. Even though the burning rates for the two powders are similar, 800-X just seems to keep climbing in velocity. Fun stuff.
Last edited by 21Carrier; 09-23-2011 at 16:50..