wildcatter
Silver $$ Contributor
Approx .670" from where the bullet contacts the lands front at the ogive to the where the boatal end contacts them. The OAL of the bullet is 1.393". It is almost the same OAL as the Nosler 225 AB.What is the length of the bearing surface on those bullets?
woops, that was a fat finger mistake! I had less than .0015'' expansion at the case head, actually .0012". But have reshot the the H4350 loads and taken them to 64.0 grains, and more like .0007 to .0003 expansion on those three cases. But velocity was great 2867 fps, and only 13 fps es! I will reshoot these and the 63.0gr load which was best at 2804.Where are you measuring this .0025" expansion?
Well I have had to stop and rethink the 210 Sirocco's as I was loading them. Firs off the design causes deep seating issues. No doughnut, and the full diameter of the bullet still in the case neck above the shoulder anyways.
I set this chamber up to seat Nosler 180 grain AB at the least seating depth I am comfortable with if just contacting the lands. This allowed descent seating for 200 grain SST's, 200 grain AB's, and 225 grain AB's seated the same way, and can work away from there. But the if I seat more than .020" off the lands, with the Sirocco's, I am collapsing the shoulder, and bulging the case right at the beginning of the shoulder.
When I go .030" to .040" of the lands It is more like 2 collapsed for every properly seated round. Most recommended starting .050" off the lands and work in .003" at a time. I was going to work .005" in at a time.
So today after much aggravating neck cleaning, dri lubing with Mica powder, brushing heavy, and still shoving the shoulders back completely collapsing it on some cases. I may get about 3 or 4 cases seated fine then, it happens.
So after tearing my dies down, micing inside neck mandrells and finding both only running .335.1" to .335.3 on both the FL die, I use and the neck die the Redding deluxe set came with, I broke out the K&N neck expanding mandrel I bought to neck the Lapua 30/06 cases up to 338 with. It measures right at .3368". Now with the unturned necks this does make for some spring back when running them thru the necks. So I still have secure neck tension for hunting rounds.
So today working with the fl sized cases, and using Mica, I ran three cases that had collapsed the shoulder, by pulling the bullets, extreme force was needed and hard crimps on the bullets with vise grips to pull them using the rockchucker press, pulled the shoulders back out, as well as the sides of the case at the shoulder junction as I was pulling them, I don't think a collet puller would have enough grip to get them out.
Then using the same 63.0 grain load of H4350, and seating them to .050" off the lands, I got 100% success with the three compromised cases, and all are withing .002" on headspace after reseating with new 210's.
I really want to have a load with about 50 of these on hand if I ever headed to big bear country or for Moose hunting. Highly unlikely @ my age that would be needed, but, that is what this rifle was built to handle if it ever did happen. After all, my grandson has plenty of time to make that happen, and this is probably going to be his someday? So I'll restart my efforts to get a load with this bullet that shoots under .75 moa or move on.
The other possibility is, maybe these Sirocco II's won't need more .010 or .015 off the lands to shoot, to soon to tell. But at .030" off the lands I had 2 in nearly the same exact barely able to see it was enlarged slightly, with the 3rd shot making it 1 1/8" group. It seems to shoot 1 flyer with 2 very close, under 1/2" appart. with the 4 or 5 3 shot groups it has shot so far.
But at over 1 dollar a shot, I am not spending 200 rounds looking for a load, if one box isn't enough to find a load, I'll be moving on. I have already ruined 7 trying to seat them deeper. and 30 rounds shot so far. I have ran them from 2750 to 2836 fps. I have not tried Varget yet either, and that is what shot so good and consistent with the 200 SST's when I was fireforming the new cases.
So should I expect to need to run them so far off the lands to make them happy. I'll load these 3 3 shot different loads to try, using the neck mandrel as a secondary neck sizing step after running thru the FL die and mandrel. It is more work but not rely a big deal if I need to for no more than I would shoot of these bullets. After seated this way I get about a .003" expansion on the neck with the bullet seated, and it makes a huge difference in seating, and is enough tension to assure a firm hold for positive OAL in tougher hunting conditions and abuse of my ammo if roughly handled.