Altaros 0.25 Cal Slug Grain / FPS / Drop / Drift

[CanMike]

Okay so I've been reading and reading and pondering, etc.. LOL Im pretty sure I am getting the 700 Panthera 0.25 next month, and been going over slugs, tunes, etc. Seems like the Alteros Slugs are the top ones currently.

I've also ready and been advised that statying at 900 FPS is the sweet spot for these. So I was playing around with the ballistic calculators and was comparing the 49 and 66 grain Alteros slugs. When Iplug in these values nothing really changes in terms of drop and drift. I'm not changing their respective BC but just wright.

So does slug wait change anything with everything else the same (Other then the FPE at impact)

Trying to learn as much as possible before finalizing my decision. Initially was thinking 0.30 CAL, but thats just the need the biggest version of something in me Im sure you guys can relate to that.. LOL

Thanks
Mike

 

[Sicumj]

In my 25 I use a 27 gr slug. Are you talking about .30 cal slugs at 49 and 66 gr?

 

[CanMike]

No they have 60grain for 0.25.. I don't think they make slugs for the 0.30

ATP QUEEN .25 -6.36mm for FX barrel​

Parameters of SLUGS:​

• Ballistic coefficient BC 0.245 (function G1), BC 0.128 (function G7-recommended use this G7 function)
• Diameter - 6.36 mm .2504"
• Weight - 3.92 g - 60 grain
• Length - 12.9mm 0.51"
• Quantity 100 pcs

 

[steve123]

Try the three different weights of Altaros slugs for precision and use the one that shoots the best. I haven't tried the 66 grain but have the 49.5 and the 60 and the 60gr groups slightly better in my Vulcan3. Though that means for me it's single shot only vs the 49.5 which are short enough to fit in the mag.

It'd be long way out in distance before the heavier slugs show less drift. IIRC it's only a few inches at 300Y.

 

[LDP]

When Iplug in these values nothing really changes in terms of drop and drift. I'm not changing their respective BC but just wright.

You have to put the correct BC for each slug not just the weight.

 

[CanMike]

60 grain, BC 0.24
49 grain BC 0.21

So I guess the weight makes diffrence in BC

There then the I don't see weight doing anything else in the ballistics chart other then more FPE. So seems like FPS drives a flatter ballistics curve, but I guess at the expense of accuracy once you push past a certain FPS.

Mike

 

[Coinwa]

Weight makes no difference in BC… length and profile determine BC.

Two projectiles of the same weight and caliber can have vastly different BCs, and two projectiles of vastly different weight can have equal BCs.

 

[CanMike]

So I plotted these two graphs with the BC and weights and one set at 900 FPS and one at 1025. No accuracy data here, just ballistics. So until you are out beyond 300 yards doesn't look like grain / BC have any real impact. But when raising the FPS to 1025 do you see a change in the curve.. Interesting..


Mike

 

[Coinwa]

Drop is typically easy to compensate for…. It’s science.

Compensating for Wind Drift, on the other hand, is some combination of Art, Science, VooDoo, and Prayer.

 

[Airgunmann]

Weight makes no difference in BC… length and profile determine BC.

Two projectiles of the same weight and caliber can have vastly different BCs, and two projectiles of vastly different weight can have equal BCs.

Weight kind of does have to do with bc using to 2 different calibers at the same weight because the smaller cal is going to be longer and sleeker to be the same weight thus making it a higher bc is it kinda does in a round about way

 

[Coinwa]

Not if the smaller caliber of equal weight is a flat based round nose, and the one of larger caliber is a spitzer….

When the mass is used to create a sleeker form, then it is reflected with a higher BC.

Here’s another example, that belies your assertion: Nosler makes 55 grain ballistic tips in both 5.56mm and 6mm… the 6mm has a higher BC, even though it has lower sectional density (mass:frontal area ratio).