tight muzzle

J

j mckinnie

Guest
As it is believed that the best place to cut the barrel is the tight spot.i was wondering if anyone has tried shrinking a sleave on the muzzle to create a tight spot?
 
kreiger but I believe the lapping process make for a tight muzzle .what built in chok

?
 
If I recall correctly the late Shelly Davidson did a fair amount of testing with sleeves shrunk on the muzzle of a centerfire barrel. I don't recall any positive success and there was a negative when he went too far. It's been so long ago I don't think his information is searchable/available anymore.
 
I make it a point to slug every barrel I chamber before I ever chuck it up, If it has a tight spot anywhere in the portion I am keeping I send the barrel back to whoever made it.

Some rimfire gunsmiths swear by a tight spot near the muzzle. Shooting jacketed bullets I would think a tight spot might separate the lead core from the jacket since lead has no resilience at all and copper has some spring back. It for sure can cause excessive coppering.

A few years ago a friend had a new barrel that started coppering badly after the first 3-4 shots, never at 6 or 7. After the shoot I took the barrel home and borescoped it and then after a thorough cleaning I slugged it. Turns out it had a tight spot for about 4-5 inches about 3/4 the way to the muzzle. The vendor replaced it.
 
Other than Jerry, a friend of mine is the only one that I know of that "slugs" barrels before machining them. The reason for the quotes is that my friend casts his slug in the muzzle of the barrel, just like one would in preparation for lapping. He has done quite a bit of experimenting with lapping as well, having learned how to lap a finished barrel. Something that I am pretty sure that not many have accomplished. What I have heard from him is that for jacketed, exactly straight shoots very well, and that a very slight choke (almost at the threshold of detection, about a tenth of a thousandth) does too. Beyond that, he has run into problems getting barrels to break in. It takes more shots for barrels to stop coppering near the muzzle. For rimfire, choke has been desirable, and perhaps two tenths can be well tolerated. The key to being able to improve a barrel by lapping is that the last couple of inches at the muzzle be small enough. If that is the case, the bore behind it can be made more uniform, and very slightly larger, to good effect. Where you really have to pay attention to dimensions, is when you are building a barrel for solid bullets. The match has to be a good one, and you want it to be straight. IMO, if one does not do something like slugging or casting a lap, he is just hoping that an expensive barrel was done correctly. It is like not using a bore scope. I would say having, but in this case, I do not believe that cost is the issue.
 
Just something to think about - The barrel swells under pressure. With peak pressure near the chamber and dropping to 2000ish at the muzzle, it seems there might be some choke effect happening even with a perfect bore.
 
Dusty Stevens said:
A good set of deltronic pins tell the tale. Not the whole barrel but comparing each end
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That reminds me of a time I was having issues with a 3 groove barrel from a fairly well known manufacturer. The bore gaged pretty good on both ends. Then I ground some gage pins into a triangular shape and found the groove diameter to be .003 larger on the muzzle end!!! :eek:
 
Joe Woosman said:
Just something to think about - The barrel swells under pressure. With peak pressure near the chamber and dropping to 2000ish at the muzzle, it seems there might be some choke effect happening even with a perfect bore.
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A tapered barrel profile would have the opposite effect. I wonder which effect is strongest???
 
I know youve made an adapter for your federal air gage Joe. Tell us how much bigger at the muzzle a typical LV taper makes after they turn that much metal off of it and release the stresses that held it into shape before it was profiled
 
Dusty Stevens said:
I know youve made an adapter for your federal air gage Joe. Tell us how much bigger at the muzzle a typical LV taper makes after they turn that much metal off of it and release the stresses that held it into shape before it was profiled
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Dusty, use lead slugs and slug from each end of the blank. I've never found one that I could detect one that had a noticeably tapered bore. I've found a few that had a tight place somewhere inside and a couple that had bulges inside. I guess the bulges were caused trying to lap a fault or inclusion out since most of these were in a period barrel makers were getting bad steel. Right now Tracy is getting some really good steel.
 
Well i guess ill have to do it. I know a slug will find tight spots and such but an air gage will show how much.
 
Thru the years I have seen a few buttoned barrels with loose spots. These barrels had not been lapped. I am guessing that the button either slowed up or stopped. I have an old 722 .222 with a loose spot in about the middle that has no noticeable effect in it's performance. You can feel it with a snug patch.
 
martin zuck said:
Thru the years I have seen a few buttoned barrels with loose spots. These barrels had not been lapped. I am guessing that the button either slowed up or stopped. I have an old 722 .222 with a loose spot in about the middle that has no noticeable effect in it's performance. You can feel it with a snug patch.
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Many barrels with a loose spot copper just ahead of that spot because of gas blowby.
 
Choking Rimfire Barrels

mks said:
A tapered barrel profile would have the opposite effect. I wonder which effect is strongest???
Click to expand...

My old Anschutz 1411 M54 (rimfire) has a tapered choke towards the crown. I slugged it at about 0.0005 smaller than the bore. When somebody on a rimfire website asked why some newer Annies have a bulge at the forend of the barrel it was proposed that leaving the muzzle a bit thicker resulted in an automatic choke. Sorta like you are alluding to, but in reverse.

FWIW * Doghunter *
 
If someone adapt the bushing that has a close fit in the muzzle end to a cleaning rod and insert through the barrel, will this show any tight spot?

Or will this damage the rifling?


Just a beginner trying to learn something...
 
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