Finishing A New Barrel Blank ?

[Vetmx]

There is almost zero science when it comes to modern mass produced airguns shooting slugs. So there is not much science to show a book worm. Keep an open mind and that’s how we move forward. Know it all’s keep guys in the know from sharing important findings. If you’re shooting pellets, things are pretty simple. There is just more wiggle room with them.

I think there is science involved…but it can’t be used because guns aren’t being properly reproduced. 
not to much mention ppl are trying to shoot slugs out of choked barrels.

thomas air makes a slug gun….I would guess that gun it produced and reproduced down to a science. 

Thomas is in a league of their own. It’s a purpose built gun and I believe it shoots its own specific slugs. If we cut a LW or TJ, we still have a lot of work ahead of us. Thomas did all the homework on what they produce. I could be wrong because I never really looked into a Thomas deeply. 

 

[heavy-impact]

Nah your fine….you have your ideas 

I was mostly surprised to find argument against a squarely cut crown.

I'm not arguing against it I'm advocating for it. My point is that nothing is more accurate than having the exit cut square and being burr free. A bevel does not and can not make it more accurate, nor does it improve air flow. Square is a form of crown but it's the straight or concave bevel that I argue against for airguns with a protected muzzle.

 

[nomojo65]

Sub12 Airgunners has a very good YouTube channel showing and explaining barrel machining techniques. If you have this knowledge and skill I’m sure it’s all very basic. 
In Airgun or CF rifle barrels even the most precise machining can’t guarantee a hummer barrel.

 

[heavy-impact]

Sub12 Airgunners has a very good YouTube channel showing and explaining barrel machining techniques. If you have this knowledge and skill I’m sure it’s all very basic. 
In Airgun or CF rifle barrels even the most precise machining can’t guarantee a hummer barrel.

I've been watching a lot of his videos and I really like them. I was gunsmithing at 20 years old and have cut lots of rifle barrels and built custom 1911s. That's why I say I understand all aspects other than the chamber because PB chambers are cut with a reamer. I just wanted to have experienced guys talk about their methods and get tips and tricks on the lead in.

Thanks

James

 

[corny]

I’ve only done this once or twice. 
I have the advantage of using cnc.

Genswiss makes a solid carbide micro boring bar that can grove and turn. 
so I use a single tool to groove my oring and profile the whole breech tapering into the rifling after the loading port. 
I calculated the length of the ammo I planned to use, so the probe would just start to seat it into to rifling. 


for the crown, most tool holders have a slight angle to the insert, in my case I have a very sharp one that sat at -3 degree, I just kissed it. Finished it up with a brass cone and some polishing paste 

 

[thammer]

Here are my tapered reamers. They are helical flute to use in the lathe. Size 4 and 7. 4 can be used for both 22 and 25 and 7 for 357. 

Here's the chart as well. 

 

[heavy-impact]

Here are my tapered readers. They are helical flute to use in the lathe. Size 4 and 7. 4 can be used for both 22 and 25 and 7 for 357.

I ordered a 3 and a 6 since .22 and .30 are the only airgun calibers I use. Thanks

 

[thammer]

Here are my tapered readers. They are helical flute to use in the lathe. Size 4 and 7. 4 can be used for both 22 and 25 and 7 for 357.

I ordered a 3 and a 6 since .22 and .30 are the only airgun calibers I use. Thanks

That should be fine. Just measure and wrap it with tape at the max diameter you want so you don't take it too deep. Shouldn't give you any issues. I like the helical flute it is made for lathe use. I feel like it cuts smoother and removes chips better. 

 

[heavy-impact]

This is the pricelist I have been working with for TJ's...

CALIBER BORE GROOVE TWIST LANDS O/D PRICE PER INCH

.177 .172 .177 1 IN 22 4 .585"OD $5.20

.177 .172 .177 1 IN 18 4 .585" OD $5.20

.22 .208 .214 1 IN 18 4 9/16" & 1/2" $5.20

.250 .243 .250 1 IN 22 4 9/16" & 1/2" $5.20

.30 .294 .300 1 IN 26 6 15MM & 1/2" $5.20

.30 .300 .308 1 IN 20 6 15MM & 1/2" $5.20

.357 .350 .357 1 IN 26 6 15MM & 1/2" $5.20

.45 .450 .457 1 IN 24 6 5/8" $5.45

.58 .572 .580 1 in 20 6 .800 $5.50

Anyone know why the .22 barrels are only .214? All the others are standard size.

 

[thammer]

He makes barrels off of other people's mandrels. The way he used to do it is he'll buy the mandrel you have to buy so many barrels up front then he can sell the blanks to anyone or you buy the mandrel and you decide who can buy the blanks. Guessing any good mandrel available is private use only. I'll be meeting with him tomorrow. Have to pick up four .357 barrels from him. He lives a few miles away so I get to pickup in person. I'll discuss it with him and if we could get a few orders together just have a custom mandrel made. 

 

[heavy-impact]

He makes barrels off of other people's mandrels. The way he used to do it is he'll buy the mandrel you have to buy so many barrels up front then he can sell the blanks to anyone or you buy the mandrel and you decide who can buy the blanks. Guessing any good mandrel available is private use only. I'll be meeting with him tomorrow. Have to pick up four .357 barrels from him. He lives a few miles away so I get to pickup in person. I'll discuss it with him and if we could get a few orders together just have a custom mandrel made.

Thank you.

 

[heavy-impact]

Can anyone shed some light on why Lothar Walther .22 airgun barrels are .215 bore .221 groove? All the .22 airgun barrels have the same spec no matter the riffling type or choke.

 

[nervoustrig]

I'm not sure if you're asking why they don't produce barrels with more dimensional variation or why these dimensions in particular. The former would invite speculation unless there's an insider who can speak to it. The latter is a little easier to answer. 22 cal being actually 0.217in (5.5mm), a barrel with 0.215 lands will support the pellet head quite nicely with some engraving...as well as pellets that are somewhat undersized. Meanwhile a .221 groove diameter is easily filled by the skirt. 

How closely they manage to hold the stated dimensions is another matter.

 

[heavy-impact]

I'm not sure if you're asking why they don't produce barrels with more dimensional variation or why these dimensions in particular. The former would invite speculation unless there's an insider who can speak to it. The latter is a little easier to answer. 22 cal being actually 0.217in (5.5mm), a barrel with 0.215 lands will support the pellet head quite nicely with some engraving...as well as pellets that are somewhat undersized. Meanwhile a .221 groove diameter is easily filled by the skirt. 

How closely they manage to hold the stated dimensions is another matter.

I'll be shooting slugs so I was thinking it should be more like .212/.217

 

[corny]

I'm not sure if you're asking why they don't produce barrels with more dimensional variation or why these dimensions in particular. The former would invite speculation unless there's an insider who can speak to it. The latter is a little easier to answer. 22 cal being actually 0.217in (5.5mm), a barrel with 0.215 lands will support the pellet head quite nicely with some engraving...as well as pellets that are somewhat undersized. Meanwhile a .221 groove diameter is easily filled by the skirt. 

How closely they manage to hold the stated dimensions is another matter.

I'll be shooting slugs so I was thinking it should be more like .212/.217

I can tell you from experience, I’ve been down this same road and had these same issues. 


I bought a rifled no choke blank and machined it for my gun. I couldn’t find a slug that grouped. I wrote it off as the bore being to large for most off the shelf slugs. I tried NSA .217 and .218. And several h&n

that being said it shot 22 redesigned quite well for the little testing is did. 


also, raw uses LW poly no choke poly barrels. And ppl seem to shoot slugs quite well with them. So mayb look into that. 

I ended up making a carbon fiber wrapped fX slug liner A, that worked like a champ. 


right now, if I was to make a barrel. I would start with an FX superior liner. Epoxy it into CF or steel 

 

[Vetmx]

I’m with corny on the TJ barrels. I’ve made several of them for several guns. They can pull double duty so there’s some things you have to figure out if you want to shoot slugs out of them. That barrel on my one gun shoots pellets so well that I pulled that gun off slugs forever. 

 

[heavy-impact]

I sent the question to LW so we should have an answer soon.

 

[nervoustrig]

I’m curious how you worded the question. For example it probably wasn’t, “Hey, why aren’t your pellet barrels made to suit slugs?”

 

[heavy-impact]

I’m curious how you worded the question. For example it probably wasn’t, “Hey, why aren’t your pellet barrels made to suit slugs?”

I consider chokeless barrels to be for slugs and choked barrels to be for pellets. Since .215/.221 is larger than other manufacturers specs I think it's a fair question.

Asking questions is how I learn when the answer isn't obvious. Doesn't make sense to have the grooves oversized for a pellet skirt to flair and fill the extra space. I've seen LW poly barrels shoot slugs through the same hole and I've seen a lot of people say they're good for high power slug guns. Are you saying it was a stupid question?

 

[heavy-impact]

LW just responded that customers have used their barrels for .217 slugs with no problems.