Just how bad is 1/8" freebore in a 20tac barrel?

[Centerfire]

This is my first custom rifle, and I'm pretty annoyed to find that my 20Tac barrel has 2.5x more freebore in it (100,000) instead of the 40,0000 that the reamer was supposed to produce.

That is; when I use a 39 grain Sierra bullet, the minimal amount of case neck I need to hold the bullet firmly in place produces about 100,000 th's of freebore. On my ruler, that equals a little over 3/32" or slightly under 1/8" . (I'll sure not use any 32 grain bullets!)

I don't know enough about this stuff to conclude if it was the reamer manufacturer that screwed up, or it's the smiths fault. ???? I kind of think it wouldn't be the smith's fault, as to produce an overly long chamber would cause excess space with case bulging or head seperation. (?)

I haven't fired this rifle at the range yet. The bore is otherwise supposed to fit Lapua brass in a "tight chamber" without case turning.

What went wrong? ...And might accuracy be effected with 1/8" freebore?

[trotterlg]

As long as it is the reamer that cuts the throat, (some do and some don't) then the Smith had nothing to do with it. If the reamer does not cut the throat and the smith used a throating reamer I would talk to him. Larry

[sicero]

centerfire, Exactly what are you calling freebore? You are talking about three times the thickness of your thumbnail. This stuff is hard to measure with a ruler. Kenny

[Centerfire]

Kenny,

What I mean is that the ogive of the bullet is situated so that it is aprox 1/8" of an inch from touching the rifling. The bullet must jump this 1/8" gap, where as I thought the reamer was going to produce a gap that was only going to be 40thousands of an inch. (or less then a 1/16") This is as far out as I can move the bullet close to the lands before I run out of firm neck grip.

It seems I read a lot about you guys saying how you like your bullets to be touching the rifling for best accuracy.

[GreatWaputi]

Every rifle is different; some like to kiss the lands, while others like a bit of jump. There's no way I can reach the lands in my CZ 527 American Tac. .20 and still feed from the magazine, but it's plenty accurate.

[sicero]

Centerfire, When you do set the bullet out far enough to touch the riflings, how much bullet is left in the case? I also would not be happy if there was no way to load up against the rifling. There doesn't have to be a lot of the bullet in the case. Kenny

[scootertrash]

While it is true some rifles may benefit by touching or jammed into the lands, it ain't gospel. In fact, I'm finding more and more .20 calibers like .030 jump.

I also don't like jamming bullets in a hunting rifle. I've seen too many times, guys load up, then for whatever reason, the shot is not taken. Then upon extraction, bullet sticks in the lands, and they end up with an action full of powder.

And I'll also agree, it doesn't take much bullet in the case to hold it. But if you shoot pdog quantities of ammo all summer long like I do, it sure makes it easier to chase the lands if you've got something in the case to begin with.

Mike

[JoeZ]

How long is your brass?

How are you coming up with these measurements?

Do you have a reamer print? That might clear up alot.

Did you send a dummy with a bullet seated to your specs?


Who accepted reciept of the reamer? If you did and did not go over the print I would say your smith is out of it. At best the reamer company will do is regrind it for you. Do not be surprised if you get charged. You used it (see above when I asked did you get the print)

If your smith recieved the reamer then it is on him. I would get the written contract/purchase order/instructions you had with the smith that spells out you wanted no free bore.



or If the reamer is yours have it reground and get the smith to sit the barrel back two threads. Call the smith let him know the reamer cut too deep shoot it in the mean time. I do not get with in .005 on a hunting rifle and more like .015.

Welcome to the wonderful world of custom rifles. I got one here with a $400 dollar barrel and a another $100 to get it coated is f-ed up. I can not even get it set back and done by a good smith becuase I got no chamber area left on the barrel to move to. Need a $500 dollar tomato stake?

[A17Shooter]

Centerfire,

Have you done a chamber cast? A casting will allow you to look at and measure all the dimensions of your chamber. My experience has been that the neck area of the chamber is sometimes longer than necessary. If that is the case you could trim the cases to a longer length, if this is possible, and regain some of the seating depth. If the neck dimension is exceptionally long the TAC 20 brass could be made from 222 Mag trimmed to a safe length and neck reamed if necessary. Of course, you could just go ahead and shoot it, you might be pleasantly surprised. After all, Weatherby does this long freebore thing as standard practice.

Good Luck,

[Coyotejunki]

That sounds like total BS. If I buy a reamer and the reamer manufacturer goofs up then they will charge to fix the reamer? Plus your barrel isn't going to be right either. So I'm guessing you'll have to pay the gunsmith to do all this again because it's not his fault.

I got $crewed a while back. Sent a deer rifle in for a simple rebarrel job in a standard cartridge. The smith took 18 months and screwed it up, I wanted about 1.5" of shank infront of the receiver and he contoured it like a Rem sporter, and cut the barrel 2" shorter than I wanted. I can't set it back now either. The same guy cut my brothers chamber .125" too long. Luckily we were able to set back and rechamber his rifle. This so called smith never fixed this either, but he died so I don't feel the need to mention his name.