Transonic performance of 185 Hybrids in 308

[calgarycanada]

I understand not every bullet performs good through transonic/subsonic zones. I remember reading on this site somewhere that 175 OTMs and 185 juggs perform good through transonic speeds but I'm wondering about 185 Hybrids. Do they perform as good?


I have some mild loads already loaded that I wanted to try at longer range through short barrelled 308. They'll be shot through 1-10" twist. Gun shoots 1/2 moa at short ranges(upto 400 meters). It'll be used for steel so 1.5 to 2 moa at 1000-1200 yards will get the job done.

 

[calgarycanada]

Anyone ?
Bryan?
Eric?

 

[Turbulent Turtle]

Here's why I hesitated so long to answer your question. You start off by making pretty far-out performance claims and then you want to see if your chosen bullet will perform well far outside the parameters the vast majority of members of this board respect. Mild .308 loads, short barreled rifle and expecting 1.5 to 2 MOA at up to 1200 yards. You forgot to mention that you do this offhand, in high winds.

 

[SheepDog]

The best way to find out if your bullets will do well through the transition is to try them. Knowing the parameters that affect a bullet during this transition might help. It has to do with the center of pressure and the center of gravity as one moves relative to the other. I wish you the best of luck in your endeavor.

 

[XTR]

Sure, it will get there, but...

Most people run the 185 in F-TR in the mid to high 2700s out of 30 inch barrels, the bullet is still well into the super sonic range at 1000. You can't get there (with reasonable loads) with a short barreled 308. If you are looking at transonic at 1000 you are probably going to be running close to 2550 or so MV. The "come up to 1000" will be in the range of 36MOA and you'll be right on the edge of super sonic, definitely in the transonic range.

You mention 1200 yards... that is another challenge.
Have you ever looked at the elevation needed from 1000 to 1040 with a 308? That 40 yards will be in the range of 4 MOA ! The total elevation needed to get to 1200 from a 100 yard zero will be over 50MOA, and your windage will be over an MOA per MPH of full value wind. Good luck, you'll need it.

 

[calgarycanada]

Here's why I hesitated so long to answer your question. You start off by making pretty far-out performance claims and then you want to see if your chosen bullet will perform well far outside the parameters the vast majority of members of this board respect. Mild .308 loads, short barreled rifle and expecting 1.5 to 2 MOA at up to 1200 yards. You forgot to mention that you do this offhand, in high winds.

Oh BTW I forgot to mention I'll be shooting from back of the pickup truck while doing 70 MPH, on a moving target

On the serious note, all I asked was performance of a bullet through transonic range.
The question was for people who have tried this bullet through transonic zone. Not for those who just want to discourage others or those who think you need 30+" barrels and hot loads to hit target at 1100m with 308. Don't get me wrong I have that type of rifle as well for FTR but here I don't need to stay in 10 ring. It's not a competition so it doesn't matter how small of a group it'll produce. I can bring bigger targets of upto 48" gongs.

And yes I will try them myself and find out but there is nothing wrong with doing some homework, is there?

Question was basically comparative, does 185 hybrid performs more like Juggs or 175 OTMs, meaning somewhat predictable or does it perform like 168 sierra match king and not predictable at all.

BTW I'm on high elevation so at 1200 yards (1097 meters) Elevation required should be around 51 MOA
Wind deflection of 10.5 MOA
I have lot more than that available in Nightforce (70 moa from 100 m zero) coz it's sitting on 25 MOA Near base.
So yes I have rough idea of what I'm doing, my wife claims otherwise but that's a different story

 

[Turbulent Turtle]

In the late 70s and early 80s, I used to shoot fullbore at Connaught ranges and the ammunition that we used was issued ammo, army surplus stuff from C-I-L. The bullets were nowhere near what we have today for the long trip to 900m and I would say that a fair percentage of the hits on target were keyholes. So the best thing to do would be to get a LARGE cardboard or butcher paper and place that at the target line and aim for that. The shape of the hole, if you get one, will tell the story.

Now, the pickup you mention shooting from, what kind of cab does it have? And is it 4X4? That will make a difference.

 

[SheepDog]

Calgarycanada,
I wasn't trying to be dismissive at all. It's just that most people don't run rifle bullets to ranges where they have to contend with the transonic effects. Generally faster twist rates help but the problem is that the center of pressure changes in relation to the center og gravity and the longer the bullet is, with the same amount of twist, the more it can deviate from its path. Even with more spin long none sharp bullets are more prone to upset than shorter bullets. The one bullet that I know that is nearly unaffected is a round ball because its center of gravity is in the middle from any perspective. That keeps it balanced during the transition. It also has the BC of a brick. The closer to the nose that your center of gravity is the more stable the bullet is.
I don't know if that helps at all but now you can at least understand why the bullet gets unstable.

 

[calgarycanada]

Calgarycanada,
I wasn't trying to be dismissive at all. It's just that most people don't run rifle bullets to ranges where they have to contend with the transonic effects. Generally faster twist rates help but the problem is that the center of pressure changes in relation to the center og gravity and the longer the bullet is, with the same amount of twist, the more it can deviate from its path. Even with more spin long none sharp bullets are more prone to upset than shorter bullets. The one bullet that I know that is nearly unaffected is a round ball because its center of gravity is in the middle from any perspective. That keeps it balanced during the transition. It also has the BC of a brick. The closer to the nose that your center of gravity is the more stable the bullet is.
I don't know if that helps at all but now you can at least understand why the bullet gets unstable.

As you said, some designs are better at dealing with challenges that bullet faces during subsonic flight. Bryan has mentioned it a few times that bullets with shorter boat tail with shallower boat tail angles fly better through transonic zone.
175 OTMs being one of those designs that fly ok at those transitional speeds. I'm just wondering about performance of 185 Hybrids.

 

[paulT]

I prefer the 185g Hybrid over the Juggs for 1000y-1200y shooting with its higher BC however the juggs do seem more uniform when sorting say 1k bullets by ogive along with bullet overall length Verses the 185g Hybrids just wish they were as Consistant as the Juggs when Batching.

 

[Mr.Knowit all]

From what I have seen- All of Litz's hybrids have a 7 degree boat tail. I have read that that 7-8 degree is the best for the least problems when entering trans. (1339). I like my SG to be in the high 1s low 2s for the best results.

 

[Canadian bushman]

Since you are shooting a 1:10,
I would expect you to get more consistent results with the 175 or the juggernaut simply because their higher lever of stability.

Bullets that are "overspun" tend to handle the challenges of coming back through the sound barrier a little better.

My 308 wears a 1:9 for this reason.

 

[DocUSMCRetired]

You should be ok, I don't anticipate any issues.

 

[calgarycanada]

You should be ok, I don't anticipate any issues.

Thank you sir !