Boat tail slugs - not used by more than a handful?

[Airgun-hobbyist]

I like the rebated boat tails with a long nose in my big bores shooting long range silhouette. They are a very stable slug. The length of the shank can be adjusted to be optimal for the rifling twist rate, the "football" shape and higher speeds all provide good accurate results as they transition over the apex to maintain good group size.

My next experiment with the rebated boat tail slugs is with a deep hollow point like the V-Knocker's, Hybrid's and SLAP slugs reaching down into the rebated tail section. The deep hollow point keeps weight balanced and centifigual rotational forces on the outside of the spinning slug.

I'm currently tuning in a Rattler 45 with them, adjusting length and shank to tighten things up. I'll be happy when it's stacking lead in a 1 moa group. Currently it's about 2 moa at 175 yards. Two groups, 17 & 11 shots in each:

 

[Ta-Ta Toothie]

When I get my rbt punch form Corbin, I'll be playing with these.

 

[Ballisticboy]

I like the rebated boat tails with a long nose in my big bores shooting long range silhouette. They are a very stable slug. The length of the shank can be adjusted to be optimal for the rifling twist rate, the "football" shape and higher speeds all provide good accurate results as they transition over the apex to maintain good group size.

My next experiment with the rebated boat tail slugs is with a deep hollow point like the V-Knocker's, Hybrid's and SLAP slugs reaching down into the rebated tail section. The deep hollow point keeps weight balanced and centifigual rotational forces on the outside of the spinning slug.

I'm currently tuning in a Rattler 45 with them, adjusting length and shank to tighten things up. I'll be happy when it's stacking lead in a 1 moa group. Currently it's about 2 moa at 175 yards. Two groups, 17 & 11 shots in each:

Be careful with the hollow point as it will move the centre of gravity back and reduce stability. You may get away with it, it will depend on how much stability you have in hand with the solid round.

 

[Airgun-hobbyist]

Be careful with the hollow point as it will move the centre of gravity back and reduce stability. You may get away with it, it will depend on how much stability you have in hand with the solid round.

The goal.is to put the cavity so deep that the center of gravity stays or even moves it forward some.

 

[Ballisticboy]

Even if you drilled it right through to come out of the base, the best you can hope for is that it will stay in the same place. The other problem you have is that the moments of inertia will be changed with very deep hollows, making the projectile more like some of the cylindrical projectiles which some like to invent every now and then. Cylindrical projectiles are really a disaster in a cross wind, as some companies have found out after spending a lot of money developing them.

 

[Airgun-hobbyist]

Even if you drilled it right through to come out of the base, the best you can hope for is that it will stay in the same place. The other problem you have is that the moments of inertia will be changed with very deep hollows, making the projectile more like some of the cylindrical projectiles which some like to invent every now and then. Cylindrical projectiles are really a disaster in a cross wind, as some companies have found out after spending a lot of money developing them.

Are the cylinder projectiles ypu refer to the FX Hybrids style? Seems like the Hybrids do well in every caliber, but no one has tried them in a RBT or the like. I can see where those would suck in the wind because they are so light. I wasn't going to remove much weight, going for a thin but deep hollow cavity, versus the big hollow cavity that the small calibers use. And yes, it was a goal to keep the balance point in the same place or slightly forward. What do you think?

 

[Engg.Ken]

Here is the thing, Boat tail slugs seat up to 2mm deeper into the barrel as compared to traditional elliptical ogive slugs. The depth where the base of the slug engages the barrel and seals the grooves is optimized by the barrel maker. If you go 2 mm deeper (in case of 22) than what the manufacturer has designed for, you introduce more variables. That's why at GMI engineering we have low confidence with Boat tail slugs and its widespread use.( unless barrel makers do something about it)

Unlike firearm cartridge, COAL. I think there cannot be any standardization in the Airguns industry. the only 2 brands who lead the way are @thomasair and @Skout-airguns . They frikin created slugs and matched them to their barrels and seating probes.

 

[Ballisticboy]

Are the cylinder projectiles ypu refer to the FX Hybrids style? Seems like the Hybrids do well in every caliber, but no one has tried them in a RBT or the like. I can see where those would suck in the wind because they are so light. I wasn't going to remove much weight, going for a thin but deep hollow cavity, versus the big hollow cavity that the small calibers use. And yes, it was a goal to keep the balance point in the same place or slightly forward. What do you think?

No, the ones I am thinking of were for military purposes, and they were true fully hollow projectiles (with obviously something to block the hole in the barrel). The problem in the wind was related to the stability, not the weight.

Yes you can use a small deep hollow point, but you will have to leave metal at the base and that will move your CG aft, though not by much. To move the CG forward, you will have to remove more metal from behind the CG than in front of it, which will be difficult when the CG is already towards the back of the projectile. I cannot see much advantage though, as the hollow point will not do much with the thick sides except reduce the mass a bit.

 

[Ta-Ta Toothie]

Here is the thing, Boat tail slugs seat up to 2mm deeper into the barrel as compared to traditional elliptical ogive slugs. The depth where the base of the slug engages the barrel and seals the grooves is optimized by the barrel maker. If you go 2 mm deeper (in case of 22) than what the manufacturer has designed for, you introduce more variables. That's why at GMI engineering we have low confidence with Boat tail slugs and its widespread use.( unless barrel makers do something about it)

Unlike firearm cartridge, COAL. I think there cannot be any standardization in the Airguns industry. the only 2 brands who lead the way are @thomasair and @Skout-airguns . They frikin created slugs and matched them to their barrels and seating probes.

Adjusting weight will change this. Guess I'll be finding out whenever I receive my punch...