Airforce barrel .256 barrel and .253 choke (choke removed)
Just cut off half inch of barrel at machine shop here at the shop. My barrel went from a .2555 or .256 breech down to a .253 choke originally. I’ve been chunking way too small of a slug out of it. With the lost half inch I got down to .2545 so I now have a .001 or .0015 choke. Probably less. I used pin gauge set. I pushed a slug through that was .251 and it was stiff all the way down. It had to be tapped through. Couldn’t feel a choke. Max diameter was .256. Barrel has .007 deep rifling all the way down barrel. A .247 pin slides all the way down the barrel now. Can’t feel a choke. A .248 is just a tiny bit tight to get more than a few inches down bore. I’m gonna shoot the .251 and then the .2505 hunter supply just to see what happens. If those don’t go good then I need to source some .2555 or .256 bullets to try. The machinist here wanted to build me a .25 bullet hybrid like a jerry six ring with small bands and the Ideal that tofazfou shoots. Of course if I’m shooting .256 good, a .257 mold sized down may work. Had no idea my barrel was so dang big. You could see the swage line on the outside of the barrel from factory. Was about 3/8 from end.
We have .001 reamers here. How much should the chamber be for easy loading? Is it better to lap? Is it good to jump to the lands like a firearm or is it better to be shaped like a craytex bulb where its a gradual taper? The .251 are a son of a gun to load…can’t imagine a .256.
Does the lead in the rifling get compressed or does is get displaced in the grooves or does it get smeared to the back of the bullet?
Sorry for all the questions, figured I’d get your thoughts on where I’m at at the moment. Will give you accuracy update tomorrow.
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I plan on getting a 257 barrel, but 1st things 1st, compressor is on my list for this year. I am pretty sure I am going with a Jim Sheldon one, or maybe a North Shore one
Jeremy,
What I said about steel fingers and 256 bullets was to illustrate how hard it is to chamber a bullet of 256 in that barrel without a lead.
You want to be just over like Doug says on your Groove diameter. A 256 would be just fine.
If you shoot undersized cast bullets in a air gun barrel you will have dismal accuracy.
My LW slugged out to be .2549 and I shot .256 bullets and did all right. But your better off with a TJ 257 barrel and a off the shelf mold in the long run.
RC
No need to try bullets.
You want to shoot a bullet that is .0005″ larger than your bore. With the LW barrel you can be closer to your bore size because they have 12 groves so more lead has to be dispersed.
For .257 I use a .25650″ ream to knock out most of the rifling. I then use a stone file to polish out the barrel until a bullet pushes in snug. I polish a little and keep checking with sized butlers never using one twice.
Same goes for .25. A .24950″ ream and then polish until slug pushes in snug. But this is for a real .25 that measures .25020″.
I originally used claipers in the barrel. Then I mic’ed the slug. I pushed a .251 through the barrel and got a .2545 on the front driving band and .2555 or .256 depending how the bullet was turned. Yall know of anyone who sells the different sizes? Do I need to find someone who could size a few for me? How far can I open up the lead in and still be ok? Kinda wish I could try 10 each of .253 up to .256 to see if any of those grouped. Would have to worry about polishing too much though if it was a smaller caliber bullet that ended up doing better. Ill shoot what I have tomorrow and see if I see any difference at all in accuracy.
Knifemaker…those are absolutely beautiful knives. I make knives as well, but yours are gorgeous. Fit to fitnish is perfect.
Ah- Um, look like good um throwing knife Ha-Ha !!
OK, that does it! I’m going out to my shop and dig out my one good Mic. If I can just remember how to read it! 😳 I’ve become a victim of the digital age. 😆 Taking a look at that guard to blade joint, and you can see that at one time I knew what the hell I was doing! LOL!!!
Mike
Are you sure it measures .25550″? Are you using a mic? By the numbers your giving sounds like a caliper.
If your barrel is .25550″ you can try to get a sizer to size to .25600″ at the largest. If it was mine I would make a sizer at .255750″
I would buy a lyman 257420 mold and size that bullet down.
So a .256 bullets isn’t a good idea? .251 seems to small. I’m preTty sure I got the choke out and its just my measuring skills since I slugged the barrel and the slug came out at .2555 or .256. What diameter bullet would you recommend for a .255 bore? I can take out a little with reamer and then polish out the rest.
Jeremy,
I cut a full inch off my two barrels when I dechoked them to remove it completely.
I would wait until I got bullets that I was going to shoot and then polish in a lead with several craytex bulbs, and it will take several unless you rough cut the lead part way. You see if you cut the lead for the individual bullet you have the tightest possible lead, I find that works better.
I did in fact size down the 257420 for my LW barrel, the other route is to get LBT make you a mold or your friend.
That extra lead will get pushed back past the bullet base if it is way over groove diameter.
And yes you would need fingers of steel to load a .256 bullet in there, as a matter of fact it would deform the bullet pushing it in and ruin accuracy.
Hope this answers your questions,
Roachcreek
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Ok, that all makes sense now. Looks liike I need to get some .256 and open up the lead for a .256. Thanks again for all the help yall.