XBR8208, 6BR, 95gr SMK

[Rtheurer]

I did a search for some load data on the new XBR 8208 and came up with squat in the 6BR. Is it to fast of a burn rate? I purchased a pound and some 95gr SMK and tested it myself. My intent was to see if would be a viable 200 Yard 300 yard XTC NRA highpower bullet and powder combo. This would give me a powder that pours like water through a powder measure and pushes the 95gr Sierra accurately enough for the short line Rapid fire portion of High power.
Let me first say I am NOT a Benchrest shooter nor am I looking to put them all in the same hole at 300 yards. A good 1/2MOA load is more than adaquate for what we do.
Ellisio Tube gun R5 Bartlein 1/8twist .272 NK Norma Brass all fifteen thousandths off the lands.CCI 450
Shot off a Sinclair rest with round foregrip rolling around in the rest. ( again im not a bench rest shooter)
26gr.. ES 67Fps SD 25.5 2650fps About 3/4MOA
27gr ES 20FPS SD---- 2702fps .368 @100
28gr ES 36fps SD---- 2767fps .323 ( 4 into.118) Worth testing again
29gr ES 22fps SD7fps 2849fps .683 @100
29.5gr ES 28fps SD10.2 2878fps About 1 MOA
30gr ES 24fps SD ---- 2930fps Same
30.5grES ------------ 2953fps 1 MOA +

Do NOT attempt without reducing loads to what your loading manual recomends. These loads where safe in my rifle but may not be in yours.

RussT

 

[Rtheurer]

Goal Met?

Yes. Im not exactly looking for speed. Im looking for a accuracy and low recoil to get back on target after the shot is taken. 2700 to 2800fps is plenty fast for my aplication. A retest to see if its all repeatable is next but looks very promising with an easy to pour powder. At 30 and 30.5gr Id say that is about max for my gun. Primers where still rounded but the Bolt had the slightest bit of resistance right at the very top. Temp was 61* and 73% Humidity.

Russ T

 

[RonAKA]

Hodgdon does have the powder listed in their on line data for the 6BR. They show a max of 28 for 90 grain and 27 for 100. About 27.5 and a velocity of about 2720 for a 95 would be close. You are a fair bit beyond that, so some caution is advised.

 

[Heavies]

I worked up to 30 grains with 105's and 107's. I had slight bolt lift at 30 grains with the heavies.
I only worked up to 29.8 grains with 95 SMK's, and I had no pressure signs whatsoever. YMMV.
I have a sweeet load for these 95's at 29.4 grains of IMR 8208 XBR with CCI 450 primers. I am about .023-.020 off hard jam, and .002 tension on the neck. (Any less or more neck tension and the groups opened up a bit.)

Three different days; all different conditions. This is a Very consistent load! (for me anyway. ) I have not had a chance to try these at any matches yet, but at 100yards these are great. I hope to try these at 200 and 300.
Hope it works out for you! ;D ;D ;D

 

[Rtheurer]

Ron
Thanks for the info. And yes this is above the recomended MAX charge in the book. So please people, dont be THAT GUY. Work into it and know how to read for signs of pressure. Again this load was safe in my barrel, action, brass, bullet, chamber, primer combination but certainly may not be even close with yours. : )

Russ T

 

[Forum Boss]

Off-topic, but we saw extremely good accuracy with the Berger 95gr VLDs about .010" into the lands (ten thou past initial) contact, with a stout load of Varget. We achieved almost 100% case fill and that was probably one reason for the accuracy. Velocity was slightly over 3000 fps.

NOTE: you can not substitute a Berger 95 VLD load for the Sierra 95gr MK. The Berger bullet is a very unusual design with an extremely short bearing surface. A "practical max" load for the 95gr Berger would almost certainly be too hot for the 95gr Sierra, given its greater bearing surface. If our 6BR is did not like jumping.

 

[swehrman]

A few questions for you Russ,

If you do end up using 8208 for your 200 and 300 yard loads, what will you shoot at 600? If not 8208 do you have any concerns with powder compatibility?

What length is your barrel?

How would you compare the bolt lift of the 28 or 29 grain loads to your current rapid fire load?

-- Scott

 

[Steve Blair]

Best 6BR load for my Stiller Viper SS with 30" Bartlein 5R 8" twist:

WARNING--MOLY Load--Reduce for naked bullets

Lapua case, 38.9 g H2O
CCI 450
Sierra 107 MK moly, seated 2.380, -.010
31.1 8208 XBR for ~2930

Last chrono on a breezy 75° day:
Max Min Mean ES SD
2935.80 2925.90 2930.10 9.90 4.65

This load has produced several groups between .100 and .125 at 100. It groups pretty well at 300 provided the wind leaves me alone.

As our Forum Boss noted above, this load uses moly bullets, which produce less starting and peak pressure than naked bullets. My action is a very stiff Stiller Viper SS Drop Port with no ejector. The bolt has a very small firing pin diameter and the CCI 450 primers are hard. The short answer is to reduce the given load by 10% and work up in 1% increments, watching for pressure signs. Thanks for the reminder.

 

[Rtheurer]

Hi Scott

This rifle has been a prone rifle from day one. Been shooting Service rifle and have been getting a itch to try Match Rifle or at least get ready to shoot match rifle at a later date. So right now the barrel is 30" Bartlein 1:8. Put a new Elisio R5 stock on it.

MY normal load at 600 yards is Varget with 105Berger VLD's soft seated. I did do a prelime test of shooting two 5 shot groups after the 95gr SMK/8208 test and nothing looked out of place. Of course testing at distance with 66 rounds of 95grSMK/8208 then my normal Varget/105VLD load to conform all are going to play nice with each other still need checking.


Bolt lift was like no case was in the chamber with the 27 and 28gr load. Again this was in my rifle and I would suggest anyone reading this,best WORK up YOUR own load.

Russ T