Others Slug Swaging - Testing - Tuning and Experimenting

[Billm]

I’ve been reading several threads where shooters mention their opinions or conclusions on slug and pellet theory. Some of it seems correct, some wrong and a lot are just assumptions or repeated myths. I’m not an expert on anything airgun related and make my own assumptions. This post isn’t meant to insult anyone, it’s meant to hopefully encourage some thoughtful discussion. I read a post in reference to slug velocity and I didn’t agree with it. My usual impulsive reaction was to start a response that argued against the posters statement. I felt their statement was backed up by faulty logic and I was going to post my counterpoint in a respectful way. Then I realized that my opinion was just that, an opinion based on my experience and that doesn’t make it fact. I shoot a lot now compared to how much I was shooting over the last 30 years. To stop from getting bored I make an effort to learn more about it. Personally, I learn something from most of these discussions.
Here’s one: lead hardness affects the velocity of two identically diminished slugs. My experiment leads me to the conclusion that it’s not necessarily true. I swaged about 80 52gr .30 slugs. I swaged half with Corbin lead and half from Nielsen lead. I don’t know, but supposedly Corbin lead is softer. I fired them all from the Sonoran, same day, same temp, same reg setting. They all shot at the exact same velocity with an SD of around 2. That would leave me to believe that the lead made no difference. Fact or fiction: softer lead equals higher velocity? I don’t know? My simple test leads me to believe fiction.

 

[Danman]

My simple test leads me to believe fiction.

Oouu good topic, as I hope to seriously wade into slugs and all that entails very soon....emails have been sent, phone calls have been made

I have .217 23gr slugs from ZAN, NSA, PATRIOT, & H&N. All different lead compositions...I should try this too!

I am hoping to slug tune a bit differently:
I plan to pick a slug (start with Jsb KO 25gr?) and do everything I can to get it to shoot well, adj reg, swap springs, adj tension, etc BEFORE moving on to a different slug manufacturer or weight.
Quite often folks will set the gun up roughly, and shoot various slugs through and see what's working. What shows promise will get retested, and so on....till they have some good results, I'd probably get lost halfway through.

I have purposely tried to mess up my S510s accuracy with 18.13jsbs by running multiple brands of lead/non lead, heavy/light, pellet/slug through it and then circle back to the 18.13 pellet. 95% of the time its last group will rival, or usually better the first group with those same pellets. Wishful thinking, but I hope i wont have to clean/polish my new slug barrel frequently!

 

[Solo1]

One thing I have noticed is zan slugs often shoot to higher velocity than others of the same weight. I have no reason for this at this time as I was shooting a lot of slugs end of last summer.

 

[Billm]

Oouu good topic, as I hope to seriously wade into slugs and all that entails very soon....emails have been sent, phone calls have been made

I have .217 23gr slugs from ZAN, NSA, PATRIOT, & H&N. All different lead compositions...I should try this too!

I am hoping to slug tune a bit differently:
I plan to pick a slug (start with Jsb KO 25gr?) and do everything I can to get it to shoot well, adj reg, swap springs, adj tension, etc BEFORE moving on to a different slug manufacturer or weight.
Quit often folks will set the gun up roughly, and shoot various slugs through and see what's working. What shows promise will get retested, and so on....till they have some good results, I'd probably get lost halfway through.

I have purposely tried to mess up my S510s accuracy with 18.13jsbs by running multiple brands of lead/non lead, heavy/light, pellet/slug through it and then circle back to the 18.13 pellet. 95% of the time its last group will rival, or usually better the first group with those same pellets. Wishful thinking, but I hope i wont have to clean/polish my new slug barrel frequently!

Add to the info. The more data and debate the better.

 

[Billm]

One thing I have noticed is zan slugs often shoot to higher velocity than others of the same weight. I have no reason for this at this time as I was shooting a lot of slugs end of last summer.

I just had that happen with pellets and the Alpha. One pellet is at least 10% heavier and shoots at a higher velocity over the chronograph. I suspect the diameter of either the head or skirt is the culprit with the pellets.

 

[pan60]

I would think ( no test just thinking ) that the hardens of the lead could effect validity in theory based on a few other detail one being a better seal but that being dependent on skirt design.
also the bearing surface is the lead galling or just moving through?
in any case I would think the biggest thing that would help with shooting slugs would be a standardized barrel bore dimensions.
this alone would allow for slug manufactures to get to a slug design faster.
the twist rate should not be a issue to figure out with some degree of reason but again being surface will make a difference as will skirt design.
we are dealing with pressures that are some much lower then that of a fire arm leading to small details make a larger diferance.
my personal view is that most slugs lack a adequate skirt design, have to large a bearing surface, and dont fit the bore adequately.
as for the lead hardness we have to get the other details corrected first.

 

[Grunt64]

I’ve been reading several threads where shooters mention their opinions or conclusions on slug and pellet theory. Some of it seems correct, some wrong and a lot are just assumptions or repeated myths. I’m not an expert on anything airgun related and make my own assumptions. This post isn’t meant to insult anyone, it’s meant to hopefully encourage some thoughtful discussion. I read a post in reference to slug velocity and I didn’t agree with it. My usual impulsive reaction was to start a response that argued against the posters statement. I felt their statement was backed up by faulty logic and I was going to post my counterpoint in a respectful way. Then I realized that my opinion was just that, an opinion based on my experience and that doesn’t make it fact. I shoot a lot now compared to how much I was shooting over the last 30 years. To stop from getting bored I make an effort to learn more about it. Personally, I learn something from most of these discussions.
Here’s one: lead hardness affects the velocity of two identically diminished slugs. My experiment leads me to the conclusion that it’s not necessarily true. I swaged about 80 52gr .30 slugs. I swaged half with Corbin lead and half from Nielsen lead. I don’t know, but supposedly Corbin lead is softer. I fired them all from the Sonoran, same day, same temp, same reg setting. They all shot at the exact same velocity with an SD of around 2. That would leave me to believe that the lead made no difference. Fact or fiction: softer lead equals higher velocity? I don’t know? My simple test leads me to believe fiction.

Your test lines up with what I’ve seen. Lead hardness by itself doesn’t change velocity unless it affects how the slug fits the bore. If two slugs are the same weight, same diameter, and same bearing surface, they’ll usually run the same speed regardless of hardness. The friction difference just isn’t big enough to show up unless the sizing or fit changes.

 

[Billm]

I would think ( no test just thinking ) that the hardens of the lead could effect validity in theory based on a few other detail one being a better seal but that being dependent on skirt design.
also the bearing surface is the lead galling or just moving through?
in any case I would think the biggest thing that would help with shooting slugs would be a standardized barrel bore dimensions.
this alone would allow for slug manufactures to get to a slug design faster.
the twist rate should not be a issue to figure out with some degree of reason but again being surface will make a difference as will skirt design.
we are dealing with pressures that are some much lower then that of a fire arm leading to small details make a larger diferance.
my personal view is that most slugs lack a adequate skirt design, have to large a bearing surface, and dont fit the bore adequately.
as for the lead hardness we have to get the other details corrected first.

I agree with everything you are saying. The whole pressure difference invalidates applying several firearms ballistic theories to the pcp airgun world. A good example is the Berger twist rate calculator. I’ve recently seen several airgunners recommend it for figuring out if your twist rate will stabilize your chosen slugs. I’ve also seen respected airgun ballistics say that it dies not work for airgun slugs. I tend to agree with the latter. Every data I have entered into the calculator has stated my slugs will be extremely stable. The results don’t bear that out. I just ordered a cup base punch for my Corbin Press. I believe from the results that I have seen indicate that the cup base seals better than the dish base. I’ll find out hopefully.

 

[Billm]

Your test lines up with what I’ve seen. Lead hardness by itself doesn’t change velocity unless it affects how the slug fits the bore. If two slugs are the same weight, same diameter, and same bearing surface, they’ll usually run the same speed regardless of hardness. The friction difference just isn’t big enough to show up unless the sizing or fit changes.

Where I think it may make a difference us with the cup vase vs dish base on .30 or less slugs. Which correlates with your opinion. The AEA slugs are faster than the exact same weight and diameter (as best I can measure) slugs that I swaged. If you look at the Corbin image below the skirt of the cupped base (3rd from left) appear to be more likely to flare under pressure than the dish to its left. Softer lead might enhance that expansion.

 

[Billm]

I would think ( no test just thinking ) that the hardens of the lead could effect validity in theory based on a few other detail one being a better seal but that being dependent on skirt design.
also the bearing surface is the lead galling or just moving through?
in any case I would think the biggest thing that would help with shooting slugs would be a standardized barrel bore dimensions.
this alone would allow for slug manufactures to get to a slug design faster.
the twist rate should not be a issue to figure out with some degree of reason but again being surface will make a difference as will skirt design.
we are dealing with pressures that are some much lower then that of a fire arm leading to small details make a larger diferance.
my personal view is that most slugs lack a adequate skirt design, have to large a bearing surface, and dont fit the bore adequately.
as for the lead hardness we have to get the other details corrected first.

I also agree with the caliber standardization. But, realistically speaking, that’s a fix for the next generation of airgunners. Unless everyone is going to rebarrel their guns.

 

[Solo1]

If what you’re saying is true then why do boat tails shoot so well?

 

[Billm]

If what you’re saying is true then why do boat tails shoot so well?

I’m mainly referring to the velocity difference between two dimensionally similar slugs and not the accuracy or BC. You notice there’s not a plethora of high BC slugs in other calibers yet.

Because the .22 slugs are swaged to the correct size of the bore. That’s the double edged sword with the .22 airgun caliber not being standardized. The caliber is so popular worldwide that they offer ammo in .216-.219, mostly .217 or .218 I believe. The .22 shooter can find the size that fits or works best with their barrel. In .30 there’s usually just one size and it either fits the bore or it doesn’t. That is where a malleable soft skirt on a .30 slug probably helps. I would guess and it is a guess that a consistent seal with no blow-by would be beneficial.

The other edge of the sword is the fact that manufacturers have to produce two or three variations of each .22 design if they want the maximum accuracy for everyone.

Speaking of the new high BC slugs, notice how they’re kind of out of the box compared to firearms. Heavy blunt round nose bullets with a boat tail vs streamlined spitzers with a boat tail. I don’t think they have a rebated boat tail either. My guess is that these slugs are a product of pure experimentation and trial and error. It’s basically a round nose pistol bullet with a boat tail- definitely unconventional.

 

[Grunt64]

Where I think it may make a difference us with the cup vase vs dish base on .30 or less slugs. Which correlates with your opinion. The AEA slugs are faster than the exact same weight and diameter (as best I can measure) slugs that I swaged. If you look at the Corbin image below the skirt of the cupped base (3rd from left) appear to be more likely to flare under pressure than the dish to its left. Softer lead might enhance that expansion. View attachment 19530

Cup‑bases can run faster in .22–.30 because the thin skirt flares easier and seals better at PCP pressures. A dish‑base is stiffer and sometimes doesn’t flare at all, so you get more blow‑by and lower velocity.

In high‑power PCPs the pressure spike is strong enough to deform a cup‑base skirt unevenly, which hurts accuracy. That’s why .308 and up usually shoot best with flat bases — they stay rigid, seal consistently, and don’t distort under acceleration.

 

[Pumacarl]

I’m mainly referring to the velocity difference between two dimensionally similar slugs and not the accuracy or BC. You notice there’s not a plethora of high BC slugs in other calibers yet.

Because the .22 slugs are swaged to the correct size of the bore. That’s the double edged sword with the .22 airgun caliber not being standardized. The caliber is so popular worldwide that they offer ammo in .216-.219, mostly .217 or .218 I believe. The .22 shooter can find the size that fits or works best with their barrel. In .30 there’s usually just one size and it either fits the bore or it doesn’t. That is where a malleable soft skirt on a .30 slug probably helps. I would guess and it is a guess that a consistent seal with no blow-by would be beneficial.

The other edge of the sword is the fact that manufacturers have to produce two or three variations of each .22 design if they want the maximum accuracy for everyone.

Speaking of the new high BC slugs, notice how they’re kind of out of the box compared to firearms. Heavy blunt round nose bullets with a boat tail vs streamlined spitzers with a boat tail. I don’t think they have a rebated boat tail either. My guess is that these slugs are a product of pure experimentation and trial and error. It’s basically a round nose pistol bullet with a boat tail- definitely unconventional.

Very good topic Bill, I love these threads!

In regards to the two different lead types, the velocity can match, or not in some cases, but what I really have noticed is that some lead, will require me to clean my barrels a whole lot faster than other lead types. Just from my own observations, in my own guns, JSB uses the lead that gives me the least grief, followed by Zan.

In regards to the spitzer shape of a firearm bullet that's just because it is designed to go supersonic. Ammunition that is designed to fly subsonic fly more effeciently with the blunt heads. None are, or will ever be, designed with a sharp VLD type tip. I'm sure Ballisticboy will be along to correct my poor description. lol

 

[Solo1]

I’m mainly referring to the velocity difference between two dimensionally similar slugs and not the accuracy or BC. You notice there’s not a plethora of high BC slugs in other calibers yet.

Because the .22 slugs are swaged to the correct size of the bore. That’s the double edged sword with the .22 airgun caliber not being standardized. The caliber is so popular worldwide that they offer ammo in .216-.219, mostly .217 or .218 I believe. The .22 shooter can find the size that fits or works best with their barrel. In .30 there’s usually just one size and it either fits the bore or it doesn’t. That is where a malleable soft skirt on a .30 slug probably helps. I would guess and it is a guess that a consistent seal with no blow-by would be beneficial.

The other edge of the sword is the fact that manufacturers have to produce two or three variations of each .22 design if they want the maximum accuracy for everyone.

Speaking of the new high BC slugs, notice how they’re kind of out of the box compared to firearms. Heavy blunt round nose bullets with a boat tail vs streamlined spitzers with a boat tail. I don’t think they have a rebated boat tail either. My guess is that these slugs are a product of pure experimentation and trial and error. It’s basically a round nose pistol bullet with a boat tail- definitely unconventional.

I remember you saying that you’re slugs contacted the groove when you pushed a slug through when you first started swaging. I know its the same with my sub moa

 

[Billm]

Very good topic Bill, I love these threads!

In regards to the two different lead types, the velocity can match, or not in some cases, but what I really have noticed is that some lead, will require me to clean my barrels a whole lot faster than other lead types. Just from my own observations, in my own guns, JSB uses the lead that gives me the least grief, followed by Zan.

In regards to the spitzer shape of a firearm bullet that's just because it is designed to go supersonic. Ammunition that is designed to fly subsonic fly more effeciently with the blunt heads. None are, or will ever be, designed with a sharp VLD type tip. I'm sure Ballisticboy will be along to correct my poor description. lol

I’m glad you’re joining in. I really like these discussions too. I’ve already learnt a lot from your shared experiences.
To everyone reading: I don’t care if anyone tells me I’m wrong , just tell me why I’m wrong, don’t insult me or anyone else. I really hope to learn from All of you. If you have an opinion, share it, it could be that one angle no one is considering. Quality discussions and debates really help to grow a community like this.

 

[Billm]

I remember you saying that you’re slugs contacted the groove when you pushed a slug through when you first started swaging. I know its the same with my sub moa

They did. If the fit/seal is not the issue, then why what aren’t they as fast? I doubt very much the BC has much effect inside the barrel - internal ballistics. Or does it? I don’t know.
But I also seem to remember that their velocity increased when I powder coated them. If the velocity increased, why? Supposedly powder coating increases the diameter, but it also supposedly creates less friction.

 

[Solo1]

They did. If the fit/seal is not the issue, then why what aren’t they as fast? I doubt very much the BC has much effect inside the barrel - internal ballistics. Or does it? I don’t know.
But I also seem to remember that their velocity increased when I powder coated them. If the velocity increased, why? Supposedly powder coating increases the diameter, but it also supposedly creates less friction.

Well that’s why zan started coating their slugs right to create less friction and help stop barrel fouling

 

[Danman]

Because the .22 slugs are swaged to the correct size of the bore. That’s the double edged sword with the .22 airgun caliber not being standardized. The caliber is so popular worldwide that they offer ammo in .216-.219, mostly .217 or .218 I believe. The .22 shooter can find the size that fits or works best with their barrel. In .30 there’s usually just one size and it either fits the bore or it doesn’t. That is where a malleable soft skirt on a .30 slug probably helps. I would guess and it is a guess that a consistent seal with no blow-by would be beneficial.

Typical American, skip right over .177 Jk....4.50, 4.51, 4.52, 4.53(pellet only) all exist for your testing & shooting pleasure. (And i believe Soren Drost did/does make his own slugs!)
I tried jamming a Jsb 10.03KO 4.51 once in my TX just to see what would happen....I would have had to hammer it into the breech, never happened lol. My brother shoots them in his magnum springer of all things.
Certain ammo companies don't bother with .177 cal, but most still do. Heck JSB is out with the MK3 already, they get more love than .22! Im still surprised JSB hasn't made some heavier .22 slugs yet.

 

[Billm]

Typical American, skip right over .177 Jk....4.50, 4.51, 4.52, 4.53(pellet only) all exist for your testing & shooting pleasure. (And i believe Soren Drost did/does make his own slugs!)
I tried jamming a Jsb 10.03KO 4.51 once in my TX just to see what would happen....I would have had to hammer it into the breech, never happened lol. My brother shoots them in his magnum springer of all things.
Certain ammo companies don't bother with .177 cal, but most still do. Heck JSB is out with the MK3 already, they get more love than .22! Im still surprised JSB hasn't made some heavier .22 slugs yet.

I told you I shot .177 exclusively until 16 months ago. That’s 50 years of .177. The Barra 250z in .22 was my first venture outside of .177. The .177 is still the international king when it comes to choices in ammo. But they’re not making the super high BC slugs in .177 yet.