748 vs 8208XBR, and primer Q

[Redleg11B]

I went by a LGS that had some XBR when I was in there Sat. I didn't have the $ or I would have picked up the 2# they had. Went in today and it was gone, but they had a lot of 748. I've heard 748 is a decent powder as well. What differences can I expect? I know XBR is temperature insensitive, 748 not as much but not terrible. Will mostly be used with 123SST.

Does SRM make a difference, or are regular SR (CCI 400) adequate? I just can't find any SRM locally. It will be a couple months before I actually start testing loads, just trying to get everything together now.

[Harpoon1]

The typical “Magnum/Military” SRP have a thicker cup to prevent slam fires with the AR platform. The CCI 400 are generic SRP with a thinner cup and more suitable for bolt actions.

[lazyengineer]

748 is actually a pretty good powder in terms of accuracy and velocity in general. Be aware that it is pretty crazy-T sensative. In High Power we laugh that you need come-ups in 10 degree temperature increments, if you run it. And in cold temperatures, it can even be hard to light if you run a weak primer with a decent amount of void in your casing.

[Redleg11B]

Lazy, would it then be better to to use a SRM for cold weather hunting loads? Or should I just hold it and try to trade it off for something else later?

This will be for a bolt gun, primarily range during decent weather (60*-80*) and deer (0*-40* temps). It will see limited use for groundhogs since I am only able to get out after them about 3x's a year due to work and family obligations. I do not forsee doing any predator hunting with it, and over 80* is where my tolerance for heat fades rapidly.

[Redleg11B]

Harpoon, I was under the impression that SRM also threw a little more flame. I know the military SRP (i.e. CCI 41) has a thicker cup.

[Harpoon1]

Harpoon, I was under the impression that SRM also threw a little more flame. I know the military SRP (i.e. CCI 41) has a thicker cup.

Yes, magnums are usually “hotter” but, “hotter” doesn’t necessarily mean better! The only way to tell, is to actually test the primer/powder/case combo you’re going to use.

My main point was don’t use 400’s in an AR! So by default, with an AR, you should be using Magnums exclusively anyway!

[Harpoon1]

Harpoon, I was under the impression that SRM also threw a little more flame. I know the military SRP (i.e. CCI 41) has a thicker cup.

Yes magnums are hotter! I see now from your previous post, you’re using a bolt gun. In general, hotter primers are recommended with ball powders.

[lazyengineer]

Lazy, would it then be better to to use a SRM for cold weather hunting loads? Or should I just hold it and try to trade it off for something else later?

This will be for a bolt gun, primarily range during decent weather (60*-80*) and deer (0*-40* temps). It will see limited use for groundhogs since I am only able to get out after them about 3x's a year due to work and family obligations. I do not forsee doing any predator hunting with it, and over 80* is where my tolerance for heat fades rapidly.

I don't have personal experience with it in Grendel, just .223. I would imagine it would be fine, especially with a CCI 450 or 41. If you have the chance to confirm your zero at below freezing, it wouldn't hurt.

[DIANEB]

Since I can't find 8208 XBR anywhere I bought a pound of 748 yesterday...

[LR1955]

All:

Giant circle I guess.

748, 2520, H-335 and BLC-2 used to be the big time powders for the Grendel. At the time, there wasn't any extruded powder as versatile in the Grendel. XBR changed that but we also found XBR to be touchy at its max charges.

So, re-inventing the wheel? Not really because 748 never got the velocities we expected so it fell out of favor. To me, 2520 is the most versatile powder for the Grendel and it also gives the highest velocities over a wide range of bullets and loads.

People talk about temp sensitivity. I never got high pressure signs from loads created in cold weather and shot in hot weather. And when it comes to elevation changes due to powder temps, yes, it exists. The problem is figuring out how much it exists because the distances you have to shoot to see a difference are pretty significant. The farther out you shoot, the more variables are involved.

I believe extruded powders are a lot better than ball powders but for the Grendel and its case capacity vs bullet diameter, it seems like ball powders are the way to go.

Primers? Doesn't matter if a bolt or gas operated rifle. You won't go wrong with the CCI 450. It is a very reliable and consistent primer and is almost a must for ball powders.

LR-55