Varget vs. XBR 8208 for 77 gr TMKs

[markm]

I did a head to head yesterday to come up with a 77 tmk load for the Tikka bolt gun with the 23.75" barrel.

"Sig" headstamped brass, Wolf SRMs and TMK 77 gr bullets.

The XBR load was 23.6 gr which is an old work up that's over published max. And the Varget load is 23.8 gr which is 1/10 gr over hodgdon's website max. Both loads run on the Chargemaster.


XBR shot: 2879 fps with an S.D. of 20

Varget shot: 2696 fps with and S.D. of 27

I thought the Varget would be a challenge because the TMK sits way back in the brass and eats up case capacity. The Varget is slower burning so I expected it to come closer to XBR due to the long barrel, but WOW!

183 fps slower. Both shot sub MOA 5 shot groups despite the mediocre SDs. The XBR load is way over published max, but I can't reasonably fit any more Varget into the brass to push it faster.

[sinister]

My load is 24.0 Varget (using a drop tube) or 23.4 8208.

Varget is a sentimental favorite (took me from nothing through Distinguished Rifleman and The President's Hundred) but 8208 flows better and has higher energy (I don't have to compress and crunch powder granules on bullet seating, which as you noted in your seating die thread, can crack the seating stem).

I'm perfectly happy with either, although if I had to buy today I'd go with 8208 -- it all depends on what's in-stock (Thales Australia produces both and they have to do the long ship ride from Down Under).

[markm]

I normally wouldn't mess with Varget in 223. Not because I don't love it, but I'd have to run the chargemaster to meter is well and it's bulky. I do use a drop funnel to try to get it settled as much as possible. But for these TMKs, I'll have to hit the easy button and run XBR.

Varget and the 69 gr killed it with velocity though. So far that's the biggest velocity gain in the long barrel, but we're always wanting to shoot the heavies.

When my seating die arrives next week, I'm back in Varget with some 88 gr test loads. The long loads still compress a little, but leave more internal capacity.

[MarshallDodge]

When I started using 8208XBR, it was because it had what looked to be a wider range of usage, and found that to be correct. For me, it has worked well in 223, 223AI, 6BR, and 308.

The only downside is that it seems to have a much wider variance from lot to lot. I was running 23.6 grains behind the 77 Nosler but started piercing primers when I went to the next bottle. Dropping down to 23.2 and all seems well.

In 223AI, I've sent the 75 Amax at 3010 FPS out of a 22" barrel. It gets to 1K with only 7.4 mils of elevation.

[markm]

I had the same experience with XBR years back. Same load on a different lot went primer pop city on me.

IMR 4064 was the worst lot variance shift with over 100 fps in 308 for the same powder charge by weight.

[HKGuns]

So I ran some of the numbers above through QL and y’all’s loads are pushing over 70k PSI.

Those are some pretty hot loads!

Be careful out there, especially that 24 gr Varget load @Sinister !

I know you all know what you are doing so not calling you out.

[markm]

With Varget?? I know XBR can get squirrely, but Varget is nearly goof proof.

I actually effed up the varget load and was way under max. Thus the anemic velocity. But with TMKs, they stab too deep into the case for running Varget with velocity as a goal.

Also... I don't recall either of these loads showing pressure signs.

[grizzman]

So I ran some of the numbers above through QL and y’all’s loads are pushing over 70k PSI.

Those are some pretty hot loads!

Be careful out there, especially that 24 gr Varget load @Sinister !

I don't see any mention of COAL and maximum case capacity (or even case brand) shown for these loads, so how are you able to determine pressure more accurate than a SWAG? Sinister's data paired with my default data gives the result of 59,336 psi.

[HKGuns]

I don't see any mention of COAL and maximum case capacity (or even case brand) shown for these loads, so how are you able to determine pressure more accurate than a SWAG? Sinister's data paired with my default data gives the result of 59,336 psi.

In the absence of real data I used the SAMI numbers and mag length. Yes a swag, but high enough to be worth noting for any newbs who may try to duplicate.

I just ran it again with LC11 fired case volume, as measured by me, and it brings it into the 55K range, which should be more than fine.

[Lefty223]

… XBR 8208 … have found that always has to be run HOT to have any credible performance, but like others mentioned, it can get squirrely, especially when switching lots and in extreme temperature differences, Summer vs Winter loads … says the guy living in the Northeast.