250 Hornady A Tip, or what happens when the bullet is longer than min COL?

[dellet]

Was at a local shop today and this bullet came up. I was given a few to come up with a load.

First issue is the nose is down inside the neck at 2.26".
Second issue is at that length, it only leaves room for about 6 grains of powder.

Hope it's jump tolerant, it hits the lands at 2.580".

Looks hopeful as a single shot load, I think about 1500 fps. as a super.

Always something new to try, and new things to learn.

[rebel]

dellet, at 1500 fps about how far (yards) till it hits transonic do you figure?

[gds]

I had no idea this bullet was available.

I have a feeling it would be limited to single shot type guns.

[dellet]

The Ballistics are interesting, I will probably work on these two project simultaneously. They have similar issues. Long and heavy for cartridge, similar velocity window and will both have a limited range.



The 250 A Tip and a cast .377, 393 grain bullet in a 38-55

250 A Tip, 950 fps, 100 yard zero.

4.0” @ 50 yards
-38.5” @ 200 yards 920 fps
-118” @ 300 yards 900 fps.

393 cast 950 fps. 100 yard zreo

4.1” @ 50 yards
-40.1” @ 200 yards
-124.8” @ 300 yards

250 A Tip 1500 fps. 100 yard zero.

1.2 @ 50 yards
-15-3” @ 200 yards, 1380 fps
-29.7 @ 250 yards 1350 fps entering trans-sonic turbulence.

393 cast 1500 fps. 100 yard zero

1.3” @ 50 yards
Enters trans-sonic @ 110 yards 1350 fps.
-17” @ 200 yards 1260 fps
-33.5” @ 250 yards 1210 fps.

So much for numbers and calculators.

I think in time there will be a 200-300 yard sub-sonic bench rest class. It will be interesting to see what bullet development that brings. The cast bullet is sub MOA capable as a super at 200 yards.

[dellet]

When you take a bullet that 1.870” long and set it in an empty case, it basically measures the same COL as a loaded Nosler Varmageddon, 2.050”. That only leaves .210” room for powder if you load to magazine length, 2.260”



When you load to 2.260”, the nose of the bullet is below the neck line.



Based on previous loads, I decided to try CFE BLK. Sooner or later I will find a use for that powder. True to form velocity was about 10% less than similar powders, but no sign of pressure. Pretty sure I can pick up at least 100 fps. Changing powders.



For the sub load it was more difficult powder to choose a powder. Only being able to get 6 grains in the case was in issue. Shooters World Blackout has always given me 100 fps per grain. With a heavy bullet, some compression i hoped for around 650-700 fps. A place to start. Quickload predicted 890 fps,

The photo below shows why the rule for subs is to start high, and work down. It’s very important working off the grid with subs to make sure you can confirm the bullet leaves the barrel. This is the lowest velocity I have ever recorded, I have had some never leave the barrel.

The other issue is stability, this bullet is not stable at 350 fps, even in a 1/7 twist



The bright spot was the initial load for the 38-55 super. This was just a bit faster than I wanted but a start.



Some work to do to get this into a function load for an AR, but I think it might be possible still.

[bangbangping]

The other issue is stability, this bullet is not stable at 350 fps, even in a 1/7 twist

Luckily, the shot was captured on video:
https://www.youtube.com/watch?v=yZOeHoyNd6c

[dellet]

The other issue is stability, this bullet is not stable at 350 fps, even in a 1/7 twist

Luckily, the shot was captured on video:
https://www.youtube.com/watch?v=yZOeHoyNd6c

I think that telephone pole had less arc.
I was able to see part of the flight.

[dellet]

Hitting a wall on this working in a standard magazine. I can only get about 9-925 fps at 2.260" with 7.2 grains of Accurate #9. This is max charge by capacity and Is not cycling the action.

I need a powder that is more dense than #9, with less bulk. #5 is a possibility but I don't have any to compare. Anybody have insights on that?

Going super and loading longer is no problem, 1350 fps with 12.5 grains of 296 and no pressure signs. Max case capacity is about 14 grains, so 1500 fps is realistic.

[rlandry6]

Looks like it may be a single shot load.
It maybe little help in this scenario, but cavity back bullets sell a Precision-Reflex 5.56/300 magazine that is modified to all loading out to 2.360. Every little bit helps.

[dellet]

Looks like it may be a single shot load.
It maybe little help in this scenario, but cavity back bullets sell a Precision-Reflex 5.56/300 magazine that is modified to all loading out to 2.360. Every little bit helps.

First choice is to get it working without any real modifications.

If it shoots good then it might be worth exploring other things, being able to get another 1-1.5 grains powder in the case would probably work.