250gr A Tip in a 308

[Nature Boy]

This is absolutely absurd!

And it's awesome!

Thanks for doing it @davidjoe

 

[davidjoe]

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!

There are definitely great combinations already, that permit TR champs to win F-Class matches. To do so they are making generally better wind calls than Open leaders.

But this may be the first bullet that permits TR to actually make smaller wind calls than Open, while holding the 10 ring.

.878 G1 and .442 G7. There’s nothing available Fclass legal, meaning .338 or below, that even approaches that.

 

[Ned Ludd]

There are definitely great combinations already, that permit TR champs to win F-Class matches. To do so they are making generally better wind calls than Open leaders.

But this may be the first bullet that permits TR to actually make smaller wind calls than Open, while holding the 10 ring.

.878 G1 and .442 G7. There’s nothing available Fclass legal, meaning .338 or below, that even approaches that.

Actually, there is:

https://www.warner-tool.com/product/30-caliber-198gr/

 

[dcali]

OK I take back my "this is a bad idea" from earlier in the thread. At least partially. This is just stupid enough to work. Against my better instincts I ran the numbers. It's not terribly interesting at 600 yards.

At 1000 though... that monster .440 BC is kicking in strongly and the retained velocity is just comfortably above transonic. The wind deflection is excellent, and *may* make up for the worse vertical, which isn't as bad as I expected it to be. A 10 fps variance in velocity adds about an inch or so of vertical over a 200 grain bullet at 1000. Not good, but not the end of the world. But can you really get 2400 fps out of a 250? A quick kinetic energy comparison says something closer to 2350 (given a 200 at 2625 as a baseline). Even at 2350, it's interesting enough to try.

Recoil energy is not as high as I'd have expected either - only about 10% higher than a 200. That drop in velocity helps even it out.

Bottom line is that there could still be some weird stuff going on that will wreck the party, but it's not totally batshit crazy to try. At least with someone else's money.

 

[Longrange57]

There are definitely great combinations already, that permit TR champs to win F-Class matches. To do so they are making generally better wind calls than Open leaders.

But this may be the first bullet that permits TR to actually make smaller wind calls than Open, while holding the 10 ring.

.878 G1 and .442 G7. There’s nothing available Fclass legal, meaning .338 or below, that even approaches that.

I love the experimental part of the deal. I've spent lots of time and money experimenting as well with various calibers. I've built and competed with a number of .308's. In all honesty with 28 inch Bartlein barrel I had best accuracy with 185 Jugg running at about 2740. It's actually still a competitive shooter at 5-600 yards. I tried 200's and worked fairly well but still had better groups with 185. My experience with the 230's was a train wreck. Groups were actually better with 230 SMK than 230 Berger. I only pushed them 2420 and the gun beat the hell out of me. A 250 in the .308 I think would be hard pressed to surpass 2350 and even at that would need a very fast twist barrel to achieve the max BC that Hornady lists for the bullet. I'm a fan of the ELDM bullets and think the 250 may be the hot ticket with some velocity. Hornady lists the BC for the 225...10tw .391 and 7tw .402
To achieve the .442, I would think at least 8tw at 2500. Just my 2 cents.
I hope it all works out! Looks like a great bullet/BC....keep up the good work!

 

[Acyr]

If my pictures actually post these are real world results of shooting 230 A-Tips verses 200.20X. Retained velocity is impressive. Over 1 moa wind deflection improvement at 10mph full value crosswind.

 

[davidjoe]

I’m thinking somewhat more than 2,400 is possible. While these bullets were on order, I did get SMK 230’s to 2,600 this summer without any brass drama, same gun. I don’t know how to factor into the calculations the bore rider throat, but that is the key. It’s how so much more powder fits in .308 comfortably.

 

[Acyr]

I had no problem getting 2550 out of the 230's with out any pressure issues. Accuracy was better at the lower node though. I do believe 250's out of a 308 is doable. Might just have to pick up a box or two to try out.

 

[Longrange57]

I’m thinking somewhat more than 2,400 is possible. While these bullets were on order, I did get SMK 230’s to 2,600 this summer without any brass drama, same gun. I don’t know how to factor into the calculations the bore rider throat, but that is the key. It’s how so much more powder fits in .308 comfortably.

32 inches and 8tw is definately helping and you may be right about 2400. Sounds like a fun project! Thinking outside the box....I like it!

 

[APGE]

OK I take back my "this is a bad idea" from earlier in the thread. At least partially. This is just stupid enough to work. Against my better instincts I ran the numbers. It's not terribly interesting at 600 yards.

At 1000 though... that monster .440 BC is kicking in strongly and the retained velocity is just comfortably above transonic. The wind deflection is excellent, and *may* make up for the worse vertical, which isn't as bad as I expected it to be. A 10 fps variance in velocity adds about an inch or so of vertical over a 200 grain bullet at 1000. Not good, but not the end of the world. But can you really get 2400 fps out of a 250? A quick kinetic energy comparison says something closer to 2350 (given a 200 at 2625 as a baseline). Even at 2350, it's interesting enough to try.

Recoil energy is not as high as I'd have expected either - only about 10% higher than a 200. That drop in velocity helps even it out.

Bottom line is that there could still be some weird stuff going on that will wreck the party, but it's not totally batshit crazy to try. At least with someone else's money.

I had spent quite some time playing with the numbers using Quickload and Applied Ballistics before starting this thread. If the science is right, ballistically it is superb. That's entirely dependent on being able to get it to shoot from a bipod in an 8.25kg ftr rifle. Something I'm glad to see someone else's hip pocket trying

 

[Ned Ludd]

I would make the argument that in an experiment such this, there are two major [related] factors that must be overcome in order for it to be successful. The first of those two factors is achieving acceptable precision, the second is effectively managing the increased recoil. The two factors are not completely independent. Note that neither of those two factors are dependent on achieving the maximum possible velocity. For that reason, I would advocate letting the bullet's high BC do as much of the work for you as possible. Velocity would only really be a consideration in terms of some minimum acceptable value.

As an example, using the 0.442 G7 BC value referenced by davidjoe for the 250 A-tip and a 0.340 G7 BC for a pointed 200.20X bullet, JBM Ballistics outputs for the two bullets at 2350 fps and 2650 fps, respectively, suggest that in a 10 mph full value wind, the 250 A-tip would enjoy a 2.3" advantage over the 200.20X in wind deflection at 600 yd, and an 8.3" advantage at 1000 yd. That is equivalent to approximately 0.4 MOA and 0.8 MOA, respectively. IMO - that is not a small advantage, it's a HUGE advantage. How many points does the typical F-TR shooter lose just outside a given scoring ring, say within less than 1"? I can only speak for myself, but the answer is plenty. Even taking the accuracy of the typical F-TR shooter's wind calls into account, which are usually much better than a full value 10 mph wind, the predicted 0.4 MOA and 0.8 MOA differential at 600 and 1000 yd adds up to a significant amount of points over time.

My advice would be to let those 250s tune at whatever velocity they want. Juicing them up to 2400-2500 fps, even if you can actually achieve that at safe operating pressures, may not give the best results overall in terms of precision and gun handling. As I mentioned above, even at 2350 fps you're still talking about a big advantage over current 200 gr bullet loads commonly used in F-TR. I would hazard a guess that improved gun handling and precision would be easier without trying to wring the last possible bit of velocity out of the 250 A-tip loads. Further, it might make the reloading process a bit less difficult (i.e. not working with compressed loads), and I'd imagine brass life would also improve. At any rate, best of luck with the project. I hope it works out well for you.

 

[swc123]

Very interesting, thank you.

Hijack: This topic is a very good example of how absurd the F-TR rule is, that does not limit bullet weight.

Consider the following, the 2021 FCWC are to be held in South Africa. The real world practical supply logistics is that these bullets are currently only available in the USA, maybe North America at best. UK, Europe, Aus and NZ maybe in 2020, the rest of the world, definitely later. This is speaking from practical experience.

Not saying this is going to happen, but is entirely possible, the US 2021 F-TR team arrives with these marvels of absurdity, vs all other competing teams who will be at best, shooting something like the Berger 200.20x Assume the US F-TR team has found a way to shoot them with the required level of precision, then not much in it with this big an ballistic advantage?

If a limit on bullet weight is so unpopular, as it currently seems to be, a practical alternative could be to put a suitable time limit on new developments allowed for competition before a FCWC?

Hijack off.

 

[dcali]

If I had to guess, I'd say the big problem will be getting acceptable accuracy out of these. They're really long bullets that need to be spun fast. Throw in the recoil and vertical disadvantage, and they might just not be good enough. Only one way to find out.

Side note: I'm all for limiting TR to 155/80 grains. Not sure why it hasn't been that way since the start. It's too late now, but in hindsight, it would have made for a better game. On the other hand, we've seen a lot of refinement of 185-200 grain .30 bullets that probably would not have happened without TR. 155s were pretty well figured out.

 

[XTR]

Very interesting, thank you.

.... is entirely possible, the US 2021 F-TR team arrives with these marvels of absurdity, ...

No, actually it's not. We shoot 200 grain bullets, considering that the team will be delivering our ammo to the freight company for shipment to SA in about 12 months the idea that the entire team would have time to test and develop loads for a new bullet at this late date is absurd.

This is not the first heavy bullet tested for F-TR, none previously have stuck, the only person to ever win the FCNC with anything heavier that I know of was Bryan Litz with 215s in 2015, and even then the US team used 200gr bullets for the '17 FCWC.

 

[284winner]

If I had to guess, I'd say the big problem will be getting acceptable accuracy out of these. They're really long bullets that need to be spun fast. Throw in the recoil and vertical disadvantage, and they might just not be good enough. Only one way to find out.

Side note: I'm all for limiting TR to 155/80 grains. Not sure why it hasn't been that way since the start. It's too late now, but in hindsight, it would have made for a better game. On the other hand, we've seen a lot of refinement of 185-200 grain .30 bullets that probably would not have happened without TR. 155s were pretty well figured out.

Too me, it compares similarly to the .223 w/95s. The 95 is a very long bullet for the .223 case also yet it is utilized. Time will tell on this new 250 paired to the 308 win.

 

[Ned Ludd]

It leaves it up to the shooter to decide what bullet weight to use. Ultimately, perseverance and the laws of physics will have the final say as to what bullet weights will and will not work in an F-TR rifle.

 

[284winner]

Can't wait till Hornady releases there new 338 ATip bullet.

 

[Longrange57]

Too me, it compares similarly to the .223 w/95s. The 95 is a very long bullet for the .223 case also yet it is utilized. Time will tell on this new 250 paired to the 308 win.

284 I agree with you. I like the idea of heavy bullet for caliber because I've seen the evidence in nasty winds. For whatever reason, often the heavies prevail even when what we have on paper says otherwise. My experience with 223, 7tw 30 inch barrel was an experiment as well. It shot both 90 SMK and Ber ok, but best groups came from 80 SMK. I never tried the 95's. In very few cases have I ever seen the absolute heaviest bullet give the best groups. For me, best groups are shot at 300, not 100 yds. Like what is being done here with 250 A-tip, I hope the project works out. Being able to shoot long, high BC bullets with accuracy is what we are all after. However, when comparing bore to length ratios, the longer bullets normally seem to have a tougher time with accuracy. Even by ELR standards, the 250 A-tip has about the longest bore/length ratio you will find, but I sure hope it all works out. I certainly understand others have had different results than what I have.

 

[284winner]

284 I agree with you. I like the idea of heavy bullet for caliber because I've seen the evidence in nasty winds. For whatever reason, often the heavies prevail even when what we have on paper says otherwise. My experience with 223, 7tw 30 inch barrel was an experiment as well. It shot both 90 SMK and Ber ok, but best groups came from 80 SMK. I never tried the 95's. In very few cases have I ever seen the absolute heaviest bullet give the best groups. For me, best groups are shot at 300, not 100 yds. Like what is being done here with 250 A-tip, I hope the project works out. Being able to shoot long, high BC bullets with accuracy is what we are all after. However, when comparing bore to length ratios, the longer bullets normally seem to have a tougher time with accuracy. Even by ELR standards, the 250 A-tip has about the longest bore/length ratio you will find, but I sure hope it all works out. I certainly understand others have had different results than what I have.

I read all the numbers on BCs with the heavy 7s and 30s. What I will say is the numbers look good...BUT it's really only theory. The reality is shoot them in wind and at ELRs. The biggest heavy 338 bullets will without a doubt, conquer all the 7s and 30s regardless what the numbers tell us. That of course is why you do not see the 7/30s at the ELR events. Sure you see the 300 Norma's now getting alot of attention. There's good reason for it. It's just not enough to compete with the 338,375 or 408/416s. Hell, I think eventually the 338 will be pushed out by the bigger cartridges in ELR. I think the new ATip in 33 caliber will keep it anchored in ELR for a bit longer.

 

[Longrange57]

I read all the numbers on BCs with the heavy 7s and 30s. What I will say is the numbers look good...BUT it's really only theory. The reality is shoot them in wind and at ELRs. The biggest heavy 338 bullets will without a doubt, conquer all the 7s and 30s regardless what the numbers tell us. That of course is why you do not see the 7/30s at the ELR events. Sure you see the 300 Norma's now getting alot of attention. There's good reason for it. It's just not enough to compete with the 338,375 or 408/416s. Hell, I think eventually the 338 will be pushed out by the bigger cartridges in ELR. I think the new ATip in 33 caliber will keep it anchored in ELR for a bit longer.

Yes sir...Fully agree!