FX Slug BC - Revised at Reply #49

[rsterne]

HAM published their first test of the new 22 gr. FX Hybrid Slugs today, in a comparison test to the 16 gr. FX Diabolo pellet.... See Reply #49 for revised data....

https://hardairmagazine.com/reviews/shooting-fx-slugs-and-pellets-in-an-impact/

You can read through that for the details of the comparison, but I gleaned one very important piece of information from it.... They had the muzzle velocity (860.5 fps) and that at 50 yards (772.5 fps), so using ChairGun I was able to calculate the BC.... I assumed the typical temperature (77*F) and humidity (70%) stated on the HAM website, and used the altitude they gave of 244 ft.... and further assumed standard barometric pressure, since those numbers were not given in this test.... I used the G1 drag model as being the most suited to this shape of slug, and calculated a BC of 0.062 0.071.... When HAM publish their BC for this slug, it may differ slightly because of the actual conditions during the test....

The SD of this slug is 0.067, so a BC of 0.062 0.071, works out to a Form Factor of 1.08 0.94.... not too surprising for a flat based slug of these proportions.... Anyways, for those of you who were wondering about the BC of these new slugs, we have our first independent piece of data for the 22 gr.... We can expect the heavier FX Hybrid slugs to have a better BC, roughly in proportion to their weight....

Bob

[JBinCO]

Bob do you recall what the marketing package gives as a BC?

[rsterne]

I haven't seen anything on the packaging.... However, I have seen claims of a BC of 0.080.... The Hybrid slugs are going to be available in different weights, perhaps that was for a heavier one?....

Bob 

[Dairyboy]

This is the rear of the packaging on the 22gr .22 Hybrids.

[JBinCO]

So how much of a variation is that?
Is that in the noise or a significant difference?
I have 500 rounds of NSA 30 Cal waiting for my raptor but that is as close as I have some to slugs yet
Lots to learn!

[UCChris]

They are claiming .08 for the hybrids. I'm no expert, but I'm pretty sure they're nowhere near that. When Nick's hollowpoints that are very similar state the same BC, but the hybrids have a way bigger hollowpoint and a super dished base...

[rsterne]

I didn't see that BC of 0.080 on the bottom of the package.... IMO, that is enough difference that it is outside normal variation.... However, since there is no standard way of testing BC, nor velocity, it is possible that in some guns, at some velocities, that could be correct.... The BC calculated from the HAM tests could vary a bit, depending on the atmospheric conditions of the day as well.... Nick claims the same BC = 0.080 for his 23 gr., which are a lot shorter (but a grain heavier)…. The 22 gr. FX slug is nearly as long as Nicks 27.5 gr. slug (which he states is BC 0.090)….

The only way to know what the BC is in YOUR gun at YOUR velocity is would be to test it yourself.... unless we get a LOT more data.... The cavities inside the slug, and the hollow base, should make no difference to the BC.... All that matters is the outside shape and the SD (weight)….

Bob

[UCChris]

The cavities inside the slug, and the hollow base, should make no difference to the BC.... All that matters is the outside shape and the SD (weight)….

Bob

Bob, thanks for this. Looks like I need to do some more reading on BC. I thought hollowpoints made BC lower.

[rsterne]

There is no difference in drag (FF) when comparing them to the same shape FN bullet (same Meplat diameter)…. the air in the HP travels with the slug, so they are effectively the same shape.... However, since they are lighter, the SD is lower, and hence the BC is as well.... but only because of the weight....

BC = SD / FF

Bob

[subscriber]

I might have missed accuracy testing with the hybrid slug?  Or at least, shooting them at paper at 50 yards?

The reason why I ask, is that the smooth twist barrel has a very slow effective twist rate, and is unlikely to stabilize anything other than diabolo pellets out to 50 yards.  If the slugs were yawing or tumbling, their BC would suffer badly.  That could explain the 0.08 VS 0.06 BC question.

Shots on paper, showing round or key holes with the slugs would be the clue...

[anti-squirrel]

Regardless of the actual BC, it will:
A: be greater than conventional diabolo-style pellet
B: further prove we are in the Golden Era of PCPs-  the fact we have manufacturers really exploring common-sales slugs and hybrid slugs makes this an exciting time

With my intention of getting a Korean cannon (Eagle Claw or the Sumatra) in .22, I'm following this thread closely for the grins- and hybrid slugs seem like a perfect projectile for what ails me

[skorec]

Personally I do not see any reason to use slugs under 50yd if it is just  not really windy weather. Exact ballistic I am obviously  adjusting  by iteration in chair gun . I am changing BC until it fit real ballistic line at 33m/66m/99m.


It is really nice to see all works whit relatively new idea – developing   slugs/bullets for  PCP AGs. 
I want to see testing of FX hybrid  slugs  at 100 yd.

[skorec]

There is no difference in drag (FF) when comparing them to the same shape FN bullet (same Meplat diameter)…. the air in the HP travels with the slug, so they are effectively the same shape.... However, since they are lighter, the SD is lower, and hence the BC is as well.... but only because of the weight....

BC = SD / FF

Bob

Next importent notice.

[subscriber]

Personally I do not see any reason to use slugs under 50yd if it is just  not really windy weather.

The reason could be because you have been shooting them at 100 yards, and a sub 50 yard target presented itself.

Dubber and his mates in SA shoot pest birds from 25 to 150 yards.  They appreciate the extreme expansion of hollow point slugs; and the hybrids in particular.  In the US, similar results could be achieved by shooting regular .30 pellets because there is no caliber restriction. SA is limited to .22; so those guys want the best performance they can get in .22.

Certainly, many people are going to ask themselves if their application justifies the cost of the FX hybrid slugs.  I am starting to ask that about regular pellets, over .177 caliber

[Babaganoush]

This is the rear of the packaging on the 22gr .22 Hybrids.

Dayuummmm!!!   I need to get me some of dem FX slugs.....they shoot flatter than my 220 Swift.

[Dairyboy]

This is the rear of the packaging on the 22gr .22 Hybrids.

Dayuummmm!!!   I need to get me some of dem FX slugs.....they shoot flatter than my 220 Swift.

Lol I just realized the "trajectory comparison" on the back. VERY exaggerated 

[Franklink]

This is the rear of the packaging on the 22gr .22 Hybrids.

Dayuummmm!!!   I need to get me some of dem FX slugs.....they shoot flatter than my 220 Swift.

Lol I just realized the "trajectory comparison" on the back. VERY exaggerated 

Dillon, didn't your hear that they're unaffected by gravity. At least that's what I heard on a YouTube video. Those Swedish engineers figured it out. Truly, FX is at the forefront of slug and Airgun development.

[rsterne]

Lol I just realized the "trajectory comparison" on the back. VERY exaggerated 

Especially when you consider that the MAIN component in trajectory is the VELOCITY.... The BC only plays a minor part, and if the slug is heavier than the pellet you used previously....

well you get the point.... 

Bob

[JBinCO]

Hey Bob what about wind?   What is the biggest component of that and how does BC play in?

[rsterne]

Wind drift is absolutely dominated by the effect of the BC.... roughly speaking it is inversely proportional.... double the BC, half the drift.... Velocity plays a relatively minor part, and in fact the drift increases above about 850-900 fps, even for slugs.... with a huge increase in wind drift in the Transonic range (Mach 0.8-1.2)…. Believe it or not, for a given slug, you would have to drive it between 2500-3000 fps to get the drift down to as low as it is at just 900.... That is one thing airguns really have going for them…. we operate right in the sweet spot for wind drift.... 

Bob