The unchoked barrel and effects on slugs?

[rangur1]

I have read many posts regarding unchoked barrels being the way to go if shooting slugs is your desire. On the other side I have heard that a choke is beneficial in shooting slugs as it gives the slug the necessary rotation to fly accurately. The key part being the slug needed to be sized properly and the barrel needed to be cleaned fairly frequently to remove the lead build up. So , how does an unchoked barrel work on a slugs flight ? If the diameter is too small , the slug would seem to bounce off each side of the barrel as it is shot. If it is too big , the barrel would cut into the slug for the entire length of the barrel , causing too much drag and crippling the flight of said projectile, no? 

Secondly , I see 4 current barrels FX , CZ , LW , polygonal , also heard of TJ's barrels - not sure what their design is. FX barrels seem specifically designed for the hybrid FX slugs. The others , more universal. Now too me it appears barrels with deeper grooves would cut deeper into the slug , affecting it's flight for the worse , so are shallower grooves the way to go? Lastly , the polygonal barrel confuses me with the shape , are the lans and grooves straight? If not , how on earth does it work ? 

 

[biohazardman]

Choked a un-chocked barrels both shoot some slugs well for the most part. Each needing to be fed a specific size and shape of slug for best accuracy of course. There are a few barrels out there that just don't seem to like slugs well though.

FX barrels seem specifically designed for the hybrid FX slugs.

I started checking slugs for my FX 700mm slug A barrel and found it to shoot 33.5, 36, 36.2 ,38.5 and VK 340gr slugs very well these were the first I tried and with many .5 inch groups at 100 yards I did not pursue this any further. It also shot the JSB 33.95 Heavies lights out on the same tune. The Superior shoots several/many slugs well also.

Now too me it appears barrels with deeper grooves would cut deeper into the slug , affecting it's flight for the worse , so are shallower grooves the way to go?

It may seem as you say and although it can be somewhat detrimental it is, for the most part, a mute point as it usually does not have that much of an affect.

Lastly , the polygonal barrel confuses me with the shape , are the lans and grooves straight? If not , how on earth does it work ?

In polygonal barrels the rifling is still there it is just more gradual like hills and valleys instead of the sharp cliffs and crevasses of the cut rifling.

It still werqs the same it is just harder to see.

 

[Brent]

Choked a un-chocked barrels both shoot some slugs well for the most part. Each needing to be fed a specific size and shape of slug for best accuracy of course. There are a few barrels out there that just don't seem to like slugs well though.

FX barrels seem specifically designed for the hybrid FX slugs.

I started checking slugs for my FX 700mm slug A barrel and found it to shoot 33.5, 36, 36.2 ,38.5 and VK 340gr slugs very well these were the first I tried and with many .5 inch groups at 100 yards I did not pursue this any further. It also shot the JSB 33.95 Heavies lights out on the same tune. The Superior shoots several/many slugs well also.

Now too me it appears barrels with deeper grooves would cut deeper into the slug , affecting it's flight for the worse , so are shallower grooves the way to go?

It may seem as you say and although it can be somewhat detrimental it is, for the most part, a mute point as it usually does not have that much of an affect.

Lastly , the polygonal barrel confuses me with the shape , are the lans and grooves straight? If not , how on earth does it work ?

In polygonal barrels the rifling is still there it is just more gradual like hills and valleys instead of the sharp cliffs and crevasses of the cut rifling.

It still werqs the same it is just harder to see.

And I believe the softer transition of the lands is a little more forgiving as far as lead fouling goes in a polygonal barrel. Your best bet is to slug the barrel and take measurements to find the best fit before you do much else. 

 

[john79]

if anyone has some pics of a pellet or slug that has been through a polygonal barrel and a traditional rifled barrel for comparison that would be great thanks.

 

[stoti]

Here are a couple pictures of pellets pushed through a Poly barrel and a standard barrel along with pictures of a Poly and standard barrel. Sorry, no slug pictures, I’m sure there is something on You Tube though. 

There are so many variables that contribute to the accuracy of a slug, beside the diameter, that it is imperative that you test them. It’s not as simple as slugging a barrel to find the right diameter, especially with a choked barrel. I’ve had slugs from .2485” to .2503” all shoot great out of the same barrel if the gun is tuned properly. Some slugs just won’t shoot out of a particular barrel but most will if you take the time to tune it properly and find the right velocity.

I lube all of my slugs and almost never have to clean either of my LW Poly barrels or our FX barrels, they are a lot more forgiving than traditional lands and grooves. Barrels and slug design has come a long way in just the last 3-4 years and it’s easier than ever to get them shooting out of your air gun.

Non choked barrels have always been touted as better for slugs and that may have been the case in the past. It still may be for the larger calibers and heavier slugs, shot at extremely long ranges. There are plenty of choked guns that shoot slugs and pellets sub moa. I have a LW Poly barreled gun with a 1:30” twist that shoots 33, 35 and 37 grain slugs as good as anything out there. Who would have thought? The point is, these are not centerfire rifles, shooting a projectile at 3500fps. There are many different variables that contribute to their accuracy besides the diameter. I would advise getting a recommendation of a couple of proven slugs out of your caliber and platform and start with those. If you start with too many, it can get overwhelming and very confusing quickly. 

The original FX Superior liner was designed for the Hybrid slugs and it shoots them well. However, the Slug A, and Heavy liners will shoot a variety of slugs from say 29gr up to 43.5 grain without a problem. There are plenty of great shooters on AGN that can attest to that. 

CZ, LW Poly, FX and TJ’s are all great barrels. If you’re not building a dedicated slug gun, the LW, CZ and FX are all superb, choked or not. I’ve shot pellets and slugs extremely accurate out of all of them.

Good luck and Happy New Year!

Stoti

Standard-left

LW poly-right

Just a very tiny sample of different slugs in .25. Different diameters, base designs, bearing surfaces, density, meplats, ogives and weights contribute to differences in accuracy out of the same barrel.

 

[MartMan]

bio hazard man, or any body else, Please!
I'm thinking to cast 357 hp from a MP mold NLG 147 gr. for my modded Bulldog
NLG or LG
Any thoughts on this for me.
Thanks

 

[Loff]

if anyone has some pics of a pellet or slug that has been through a polygonal barrel and a traditional rifled barrel for comparison that would be great thanks.

I don't have Poly barrel but FX Superiour and superiour heavy compared to traditional rifled barrel (Snowpeak P35)

FX

Traditional