Friday, I received my 8lb jug of IMR 8208 XBR. Yahoo! Tried to get out yesterday but family emergency precluded that; too bad as the wind was only about 3-4 mps. Today, I did even though the wind was much worse. Decided to shoot a pressure/ladder.

Surgeon 591 (smithed by Chris Matthews of Longshot rifles)
26" Krieger 1:8.5 MTU contour (600 round count). No one's yet explained to me what MTU stands for.
AICS 1.5 stock
NF 5.5-22x50mm w/ NP-R1
6.5x47 Lapua, original throat .104" now .146". No turn .294" neck.
130 Berger VLD Hunting, .010" into lands
CCI 450 primer
Redding Type-S FL w/ .289" bushing
Redding comp seater, seated to OAL 2.760"
Just completed my load development for 40.24 gr H4350, .010" into lands, CCI450, 2800 fps, ES 24, SD 9, .25 to .6 MOA.

Harris 6-9" swivel bipod
CED M2 chrono with center of screens @ 13.5' from muzzle, sun light from my 9pm. Shot between 11 am and 1 pm today.
65'F @ start, 77'F at finish
47.47 Baro
Wind, 3 to 15 mph, average 9mph from 11 am to 1 pm direction.
Sunny

I started off by shooting 5 sighters into a group @ 385 yds. 33.5 gr = 2597 fps AV - 11 ES - 3 SD. Four shots into 1.5" with 5th out to 3". That's .389 MOA or .78 MOA. Looks promising as far as accuracy and good ES/SD. At least for me. Oh, and I shoot off a portable fold-up picnic table so with the wind, the rifle was not still. One of my favorite spots is a sort of bowl where I can shoot in a near 180 deg direction so I can keep the wind pretty much between 11 and 1; in my face.

31 gr to 36 gr in .5 gr increments. Three shots each shot at 385 yds. Used my VIC 123 elec scale to keep powder charges to with in +/- .02 gr.

31 gr/ 2436 - 2435 - 2454 / ES = 19
31.5/ 2474 - 2462 - 2445 / ES = 29
32 gr/2496 - 2504 - 2498 / ES = 8
32.5 /2522 - 2528 - 2523 / ES = 6
33 gr/2534 - 2548 - 2536 / ES = 12
33.5 /2599 - 2612 - 2616 / ES = 17
34 gr/2632 - 2634 - 2626 / ES = 8
34.5 /2643 - 2648ej-2641shiny/ES = 7
35 gr/2649ej-2657shiny-2650ej/ES = 8
35.5/2728ej-3734ej -2728 / ES = 6
36 gr/2768ej & stiff - 2762ej - 2780/ES = 18

ej = ejector mark on brass
shinny = shinny smear on brass
stiff = stiff bolt lift

ES 335 fps

Really haven't had a chance to eval the target which was a 3" circle. I color coded each 3-shot group of bullets with perm marker; green, red, black, blue, then repeating the same four colors again. Works great because my Zeiss spotter @ 45x had too much vibration from the wind to tell all the impacts. Thanks Jason Baney!

I'll try and post pics later.

For now, I'm impressed with the accuracy potential, ES and SD but not the velocity. I saw a post here on Snipershide where someone witnessed a chrono printout of something around 3000 fps. Must have been a looooong barrel and loooots of pressure.

Alan

Very thorough post!

Sounds like you've found a great load! Are you shooting matches or using it to hunt with? Just wondering why you chose the Berger "hunting" bullet instead of a target bullet.

I shoot the Lapua Scenars.

Currently it's just for tactical practice and matches but am thinking about lugging it along this fall. I say "thinking" because it weighs 16-17 lbs. I originally went with the "hunting" version because that's what I was able to obtain and just decided to keep it so come hunting season I would have to take the chance of needing to tweak the load if necessary.

Alan

Can you describe your change of the throat.

At 17 pounds, it would be a good truck gun if you happen to see a giant muley at 750 yards!

I believe he did that to be able to use the longer VLD bullets to their max.
Butch

Your velocity seems awful slow. Should be around 2950 I think. You may need to try some slower powder. The 8208XBR is not working as well as I would like in the cooler weather. I think it may come into its own at 80deg and above.
Butch

Was able to run back out this morning and check out something that looked promising for accuracy and ES/SD.

Both the 32.5 gr groups (the first was the sighter load and then the next was within the ladder) ran .4 MOA'ish with low ES/SD. So, I loaded up 10 rounds each of 32.4/32.6 and 32.8 gr. I can't verify these exact weights because I "threw" my charges with my Harrell's Premium powder meter to see what sort of accuracy/numbers would present themselves. I was quite pleased.

Groups ran .36 to .69 MOA @ 360 yds SD's ran 5, 9 , 9 respectively. Something else. Velocity was a solid 70 fps slower when I dipped the bearing surface in some Sinclair's powdered graphite; 2530 vs 2600 ish.

So, again, not great velocity but very good accuracy, ES and SD's. Good enough to practice with.

Alan

PS:

Nordic,

When I first took possession of my rifle back on 24 Dec (Santa was good to me this year) I immediately took various makes and weights of bullets and figured out the OAL for each via seating them up against the throat. I kept these same bullets for future throat measurements. The first time I checked for throat wear was around 400 rounds and it had increased .029", then again at 600 rounds for it's current .042".

Butch,

Totally agree that their are other slower powders out there which will get my MV going faster. As I'd heard before over on Snipershide.com, I read where some guy witness a chrono printout @ 3000'ish along with an accompished F-class shooter over on accurateshooter.com.

Just didn't pan out for me, though the consistency is there with the powder. Also, from what I've read IMR 8208 is extremly temperture resistant so I sure won't expect much of an increase in 80+ temps.