Loading the 129SST

[skyfish]

Do any still use AA2520 powder with the 129SST, I have a lot on hand and several hundred bullets. Since my Creedmoor shoots 130gr Bergers so well, these are Grendel bullets now.

Have 2520 on hand as well as TAC and XBR, looks like velocity may be best with 2520 but sounds like case volume is issue. Going to use these up this January antlerless and maybe on my March hog hut. Should be fun.

[LRRPF52]

Hornady lists A 2520 with a mild start load of 23.7gr behind the 129gr SST, going up to 28.2gr for max.

TAC behind the 129gr SST starts at 23.0gr, up to 27.5gr max. You might consider starting between there.

8208 XBR is 22.3gr start, 26.6gr max.

All listed C.O.L.'s for that data was with their 14.5" test carbine, with a Grendel chamber.

My .260 Rem gas gun also shoots the 130gr Bergers very well, and I haven't even tuned the seating depths with them.

[skyfish]

Thanks, tested some loads with AA2520. Wanted a reference for comparison with the 123 SST's. Out of AA's 18" barrel, theses shot about as good as anything I've put through the pipe. Do have a Saturn on order. Some numbers if people are interested.

2.320 COL to touch rifling. Measure with Comparator 1.706
Loaded at 2.250(+-.005) COL
At 27.5 gr 2250fps under one inch, actually about .250 except for one that took it to .8"
At 28.0gr 2275fps about an inch
At 28.5gr 2290fps about an inch

I am going to a farm in Texas in March, always thought I'd just use a Amax, but having second thoughts. Figure the SST would be better.

Also, I do get a large point-of-impact change from 115 Berger, 123 Amax, and 129 SST. 2-3 inch vertical change from each.

[LRRPF52]

I see no reason to use the 129gr SST now that we have the 123gr SST made for the Grendel. You should be able to get 2500fps from an 18" barrel with the 123gr SST, which also has a .510 G1 BC, versus the 129gr SST's .485 BC.

I'll be using all the 129gr SST's in my .260 Rem.

[bobke]

Does anyone have a sense of the velocity parameters the 123 SST was designed to expand within? Hadn't seen it here as yet, and wondered if it's set up for lower Grendel velocity, while still retaining controlled expansion. Certain Hornady has the answer, but is also looking to us to vet their design with field experience.

[KentuckyBuddha]

I think the company guessed something under 1600 fps would still do it bobke.

[LRRPF52]

Even at an 1800fps expansion threshold, that gives you 475yds from a 16" barrel with a 2460fps mv. How many of you feel comfortable taking a shot on game at 475yds? If you can place it in a 10" vital zone with confidence, let her fly.

1600fps expansion threshold takes you out to 675yds from a 16". For most of us who will use this bullet within 300yds, we're more than good-to-go. For those that want to push it, you have another great pill as well.

At 300yds, we only have 6" of wind drift with a 10mph full value wind. That .510 BC is hard to beat.

[JASmith]

Hornady indicates they are reasonably sure of good expansion at 1700 to 1800 ft/sec, and that some shooters may see expansion as low as 1600.

We members of the Horde will probably need to get shots at water, gel, and d hogs at ranges where the bullet velocity has dropped to under 1700 and see what happens.

Then we will know.

[skyfish]

I agree, now with the 123gr, the 129 seems obsolete for the Grendel. I was just getting a base line for comparison. I only have 100, now less. I will use on hogs if POI is close to the 123 SST. But trends show it will be significant higher.