Excessive Pressure XBR 8208 help please

[ih784]

[A5BLASTER]

That powder is know to spike with 123 or heavier bullets when at are a hair past 28 grains.

If 27.5 gives you the groups you want use it.

Me personally I would order up some leverevolution,cfe223 or maybe some power pro varmint.

[ih784]

[A5BLASTER]

I was thinking the leverevolution or ar comp. I put 5 shots in 7/8” using 27.5 grains of xbr and 7.5 primers. This was with a Ballistic Advantage barrel. I load for .308,300 wsm and 5.56. Is there a powder you think may work well in the Grendel and one of those other calibers?

Honestly I have no clue. I only load for the grendel. It's what I started learning how to load on.

I think I have seen others post that cfe223 works good for 223/556 and 308 but I'm not sure.

[Bfglowkee]

If you want temp stable then stick with XBR or AR Comp, if speed is your game then cfe223, leverrolution or accurate 2520. AR Comp is a solid compromise and will get good speeds and stability across temps without the pressure spikes

[ih784]

[Klem]

8208 is a single-based powder. Single-based powders are more temperature stable than double-based. Your difference of temperature with your 27.5 will not be a pressure concern, but you will probably see a difference on the target so need to adjust your scope.

If your primers came from the same box with the same load then they should all look exactly the same after firing. For the higher pressure case I can only imagine that bullet may have drifted forward on being loaded (inertia as it comes to a sudden stop) and was closer, or touching the throat when it went off. Or maybe the bullet was pushed back in before firing.

[Popeye212]

I could not get CFE to work. I load a bit of 8208xbr but when you get up toward 28.0 you have to be careful. It tends to as others have said spike quickly but in my experience that is where my best groups come at near max. I have some 123 cc's I loaded for the Creedmoor. I will try to duplicate your load but what seating depth are you using. I noticed in the Creed I had to abandon the book OAL because their seating depth was too far out. According to this You are above their max by .5 grains, at a seating depth of 2.250. I will let you know what I get.

65grendelNosler123data.pdf

[StoneHendge]

If you like your 27.5 XBR load, I have had fantastic success with XBR with 77s in 223 in 3 barrels from 3 different manufacturers.

[Gusmeister]

ih,

My experience is limited but I have been bitten by pressure spikes with 120gr bullets and 8208. IME 8208 is a wonderful, fast and accurate powder that can be temperamental. But the issue so far has only been to back away from a pressure and velocity spikes and 8208 is easy going and accurate (I took a dumb shortcut). In my case the chrono was spiking velocity and the 120gr bullets were going "too fast" compared to the 123's I'd been shooting. So the powder charge was cut back .7 gr, velocity matched the 123 gr (running .7 gr more powder) and I ended up with a wonderful load for slapping steel out to 700 yards. So all I am saying is 8208 demands respect.

I don't think you'll have an issue going from 40 deg to 90 deg with your load but really don't know. Summer is coming. Let us know how it's turns out.

[ih784]

[Popeye212]

Here's what I got I could have gone to 28.0gr. but ran out of bullets.

2019-02-21 12.28.33 (2).jpg

From bottom row to top row 26.8,27.2,27.5,27.7

This 27.2
2019-02-21 12.25.36 (2).jpg

2019-02-21 12.26.04 (2).jpg

Gotta work on pic posting skills...

Synced on: 2019-02-21 10:21:42
Series Nos123268xbr Shots: 5
Notes 26.8 8208xbr
Min 2368 Max 2396
Avg 2386 S-D 12.2
ES 28

Shot Speed
1 2396 ft/s
2 2394 ft/s
3 2380 ft/s
4 2395 ft/s
5 2368 ft/s
---- ---- ---- ----

Synced on: 2019-02-21 10:28:41
Series 2019-02-21_10_28_41 Shots: 5
Notes 27.2gr 8208xbr
Min 2400 Max 2430
Avg 2414 S-D 10.8
ES 30

Shot Speed
1 2412 ft/s
2 2418 ft/s
3 2430 ft/s
4 2400 ft/s
5 2414 ft/s
---- ---- ---- ----

Synced on: 2019-02-21 10:35:05
Series 2019-02-21_10_35_05 Shots: 5
Notes 27.5gr 8208xbr
Min 2423 Max 2452
Avg 2444 S-D 12.2
ES 29

Shot Speed
1 2451 ft/s
2 2444 ft/s
3 2451 ft/s
4 2452 ft/s
5 2423 ft/s
---- ---- ---- ----

Synced on: 2019-02-21 10:43:31
Series 2019-02-21_10_43_31 Shots: 5
Notes 27.7gr.8208xbr
Min 2455 Max 2480
Avg 2463 S-D 10.8
ES 25

Shot Speed
1 2455 ft/s
2 2469 ft/s
3 2480 ft/s
4 2457 ft/s
5 2456 ft/s
---- ---- ---- ----

Seating Depth 2.250

Disclamer: No excuses but these might have been tighter if my shooting was a little better. Trying to get these in before the next rain shower. Could have gone to 28.0 but would stop there maybe 28.2 to get over 2500 but 28.5 would have been a stretch IMHO Ymmv

[Jetpig]

You may want to try and stretch the OAL out just a tad bit more. Pressure should go down a bit 2.260 ish if you are still looking to get over 28 g.

[OpFor1]

Nice grouping!
I have the same troubles with pictures on this and other forums. I have not figured out why.

[Popeye212]

May get some more of those if I catch them on sale and test on a better day. Probably will use this data later on when the weather warms up and see what they chrono at. Creed didn't like these at all. OAL in that Elander was pushing it a bit. Need to get some more C products mags. Had I taken a little more time might have gotten better results these were run through fairly quickly.