250gr A Tip in a 308

[davidjoe]

This is what the combination looks like. If the high res picture works. Lapua Palma .308 and the Hornady 250 A-Tip. The launch pad will be a 32 inch 8 twist borerider barrel on a Stiller Diamondback single shot without a plunger.

 

[284winner]

You need 9 twist barrel. I did pressure test (4831SC, .5 grain increments) with 230 g in my 300 WSM, got it to 2895 with no signs of pressure at all. Good groups at 1000. But it is a 10 twist barrel and I had keyholes at 50 yards.
Checked 100 bullets and BTO was +/- .0005.

IMO...You'll need an 8 twist for the slow moving 308 with that 250 grain bullet

 

[davidjoe]

My particular rifle closes on a bullet seated this far out. I’m using a .338 Lapua Magnum die to seat the bullet for an initial pressure test. Factory Lapua load in left, 250 A-Tip on right.

 

[davidjoe]

None of this is a suggestion, kids. I use CCI 41 primers for experiments like this. 47.0 grains of RE 17 exhibited zero bolt lift resistance. The primer looked exactly how I anticipated it would, - fully utilized . (I’ve used 50 grains for 230’s). The shot was into sand solely to test pressure. Based on recoil, I don’t imagine this is a very fast load, but I’ll prep some at this level for target testing and follow up.

 

[Ned Ludd]

This is what the combination looks like. If the high res picture works. Lapua Palma .308 and the Hornady 250 A-Tip. The launch pad will be a 32 inch 8 twist borerider barrel on a Stiller Diamondback single shot without a plunger.

Isn't the case supposed to be bigger than the boolit?

 

[APGE]

None of this is a suggestion, kids. I use CCI 41 primers for experiments like this. 47.0 grains of RE 17 exhibited zero bolt lift resistance. The primer looked exactly how I anticipated it would, - fully utilized . (I’ve used 50 grains for 230’s). The shot was into sand solely to test pressure. Based on recoil, I don’t imagine this is a very fast load, but I’ll prep some at this level for target testing and follow up.

Are you using RL17 just for its velocity? I thought the general consensus was that it's terrible temperature instability was too big a trade off for the increased velocity. That was my findings, anyway.

I'm very interested to hear your results, regardless.

Any more pics of that rifle? It looks very clean.

 

[r bose]

This is what the combination looks like. If the high res picture works. Lapua Palma .308 and the Hornady 250 A-Tip. The launch pad will be a 32 inch 8 twist borerider barrel on a Stiller Diamondback single shot without a plunger.

A picture is worth a thousand words!! That projectile is a monster!!

 

[dcali]

This is not a good idea. You'll ultimately be frustrated by the vertical due to the lousy trajectory, not to mention the gun handling due to recoil. You'll just wind up with a barrel that you'll probably want to rechamber because of the crazy long throat.

 

[284winner]

It's really no different that the 300 blackout running the 200+ projectiles. Sierra has load data for the 230/240 smk bullets for the 300 Blackout.

 

[Longrange57]

This is not a good idea. You'll ultimately be frustrated by the vertical due to the lousy trajectory, not to mention the gun handling due to recoil. You'll just wind up with a barrel that you'll probably want to rechamber because of the crazy long throat.

Agree...F Open was mentioned in OP. I think a little more horsepower might be required! There are so many really good combinations that are already proven without super slow velocity and a mile long bullet!

 

[284winner]

308 vs 300 Blackout...Huge difference in powder capacity. Of course everything has it's limitations but I don't think the 300 blackout got that memo.

 

[davidjoe]

Guys, I’m impressed. This is at 200 yards and the labels explain my loads. The 250’s annihilated the factory Lapuas in accuracy. Now I’ll be the first to admit that a huge free bore does not favor the Lapua Sami spec round. Still, the 250’s hit as high at 155’s going presumably 2,930, at 200 yards.

1) there were no scope adjustments.

2) shot 1 was the high shot in both groups, which is common for me.

3) that’s 4 shots by the 250’s in the cluster.

4) there was wind, but the hold remained constant.

5) the group was Lapua first, a short break and then Hornady.

 

[davidjoe]

Of course the picture uploads don’t work at the range.

 

[284winner]

I would agree that the 308 is a bit small for the 250 grain bullet. I would also say anything is worth the effort if one were to set out to make it work. As in the mention of the blackout. Personally I run 185s max out of my 308. They seem to be the best of all worlds for me if I'm using them out to 1000+.

 

[davidjoe]

Now I figured it out.

 

[davidjoe]

The targets should be rotated as per hand writing.

The rifle is purely experimental. Way before A-Tips were conceived, Richard King finished it for himself with a straight 1.25” handpicked barrel with his chamber flutes. The rough stock work to give his barreled action that is longer than a 700 both a recoil lug well and a full tang stop was King, and finishing out full length bedding, filling, and complete cerakoting was Vance Durham, a detail master, of Harlingen.

 

[davidjoe]

Are you using RL17 just for its velocity? I thought the general consensus was that it's terrible temperature instability was too big a trade off for the increased velocity. That was my findings, anyway.

I'm very interested to hear your results, regardless.

Any more pics of that rifle? It looks very clean.

I didn’t use a chronograph today, but I didn’t expect the 250’s to impact as high as they did. The Alliant powders push the bullet more evenly over the length of the whole barrel than others I’ve used. I discern this from the middle and muzzle end of the barrel being hotter, almost always than the throat area, even accounting fully for my typical taper. Being able to load more powder by weight in the case than is used for even 200 grain bullets is only explainable if the pressure curve is in fact less peaky.

 

[284winner]

I didn’t use a chronograph today, but I didn’t expect the 250’s to impact as high as they did. The Alliant powders push the bullet more evenly over the length of the while barrel than others I’ve used. I discern this from the middle and muzzle end of the barrel being hotter, almost always than the throat area, even accounting fully for my typical taper. Being able to load more powder by weight in the case than is used for even 200 grain bullets is only explainable if the pressure curve is in fact less peaky.

Did you shoot those thru that 32" barrel ?

 

[284winner]

Not really surprising. I shot my 32" 284 barrel with the 195s vs the 183s. All shots impacted higher than the 183s. Also running the RE17 powder in that platform.

 

[davidjoe]

Turns out that barrel is more like 31 inches but yes, I did. I couldn’t stay long today but the interesting story will be how fast, or not, they are going. 50.0 grains into the dirt, as expected released the primer from the pocket, and further was hard on the bullet to seat. So, while 47 might not be the absolute max, it’s close enough to it for purposes of rough evaluations.

I’m certain these bullets would do a good job in a WSM. However, “Open” class improvements are pretty predictable as one can always adopt a bigger case/heavier bullet and then “improve” one of those, on up to their personal tolerance for buying new barrels. At some point, probably 195’s in a Saum, you just have to bear down on wind calling skills (that’s me now), because 1,000 yds is the competition max and not too much drift difference is attainable at the high end, inside that distance.

The .308 is a bit different though in that TR isn’t using anywhere near the whole case capacity. The Lapua Palma case head is no doubt the absolute toughest in Fclass, (short of their 338 LM) as well as the most reasonably priced. TR is blessed to be stuck with 30 cal, because 30’s BC’s really eat 7’s lunch. (It’s the turn of the .338 cal now to do the same).

A 250 bullet is huge. But the jump from 155 to 200 is virtually identical to 200 to 250. 200 isn’t even considered very heavy now.

Those bullets I shot aren’t seated very deeply. But in principle, if TR rules are so lax, what’s wrong with letting the bore force the bullet to align itself, instead of worrying whether they are perfectly straight in the neck, case/neck to the bore, etc.