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22-250 re-barrel chamber questions

 
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  #8  
Old 10-26-2012, 10:50 PM
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Re: 22-250 re-barrel chamber questions

Thank you, shortgrass, for the link to the saami chamber prints. Interesting stuff. If I am reading the prints correctly, it appears that there are two common chamber leade angles for .224 cartridges:

1*, 30'
  • .218 Bee
  • .220 Swift
  • .225 Winchester
3*, 10', 36"
  • .222 Remington
  • .222 Remington Magnum
  • .223 Remington
The oddballs are the .22 Hornet @ 3* of chamber leade and the 22-250 @ 2* of chamber leade.

While I don't know how to compute the exact amount of freebore that these chambers would yield, I can at least generalize by comparison.

The 22-250 would have more freebore than the Hornet or any of the .222/.223 family, but less freebore than the Bee, Swift, or .225 Winchester. The amount of freebore would be much closer to the latter group of cartridges than to the former.

Judging by what I know about my rifle's length to the rifling, I would say that the freebore in my rifle's barrel is likely longer than a SAAMI chamber would be.

If I accept the idea that a "normal" SAAMI chamber would have between .025 and .050 of freebore, that would mean that my chamber has been cut with between .075 and .140 of excessive freebore.

Since my rifle has shown no symptoms of excessive headspace, I am inclined to believe that the leade angle on the chambering reamer was out of spec. I know my gunsmith rents his reamers (like many smiths do), so I wonder if the problem with leade angle would have something to do with an earlier repair/resharpening of the reamer.

To anyone who actually knows something about machining, am I in the ballpark on this?
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  #9  
Old 10-27-2012, 07:40 AM
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Re: 22-250 re-barrel chamber questions

Hmmmmm,,,,,, rental reamers... Only the company that made the reamer or re-shapened it will know for sure. The company that is renting it out,,,, well maybe,,, maybe not. That is why I buy/own every reamer I have (I now have 50+). I can specify what I want, and I know what I'm getting. If you want precision, that's how you get it! I might be stepping on some toes here, but, of the other "precision gunsmiths/builders" I know, none 'rent' reamers. That's one of the things that contributes to the 'overhead' in this business, tooling. There's no free lunch! When judging throat/lead length in a used barrel round count needs to be taken into consideration, especially with rounds like your .22/250
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  #10  
Old 10-27-2012, 08:22 AM
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Re: 22-250 re-barrel chamber questions

I agree. Never have, never will rent or even borrow a reamer. I run a high pressure flush system and it keeps them in tip top shape.
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  #11  
Old 10-27-2012, 08:48 AM
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Re: 22-250 re-barrel chamber questions

Thank you, shortgrass, for your insight.

The throat length on my rifle was established when I began load development for it after break-in. The round count at the time was well below 100.

Your stance regarding not renting chamber reamers makes good sense for someone whose interests emphasize precision.

Given the fact that I am after a higher accuracy standard this time around and plan to use a better quality barrel than I started out with, paying attention to the reamer that will be used looks like kind of a no-brainer and worthy of honest discussion with my smith.
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  #12  
Old 10-27-2012, 12:28 PM
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Re: 22-250 re-barrel chamber questions

I have a couple barrels that are 1:12 twist, and one in 1:14 twist for 22-250's. I would never consider a 1:14 twist barrel again! 60 grain an lighter bullets in most cases work well with a 1:12 twist rate, but if I were to order in another barrel it's be either a 1:11 or a 1:8. Here's my thoughts on this:

* the 1:12 twist will just barely stabalize the new Hornaday 53 grain Vmax bullets with a .29 B/C. Easilly handles B/C's of .27. But sooner or later we want to try the 60 grain + bullets with the higer B/C's. That's where the 1:11 will help you out to about .32 B/C (most guess at the exact numbers), but moving to a 1:8 (or even a 1:9) barrel will be a huge jump. Then you can shoot the higher B/C bullets at will (maybe even a 75 grain bullet)

Being as we are going to get a new barrel in 22-250, I'd simply send the action to PacNor, and let them do all the work. They're cheap when you look at the complete package. I'd also order it in in 22-250AI with a fast twist barrel. Throat it for 75 grain bullets. Dies are easy to come by, and brass life is much longer. Make your case from firing factory loaded 22-250 ammo, or better yet use necked down .243 brass cut back to the max length of your chamber minus .020". I shoot a similar round chambered in 6mm (6mm/250AI). Will push a 105 grain AMAX to almost 3100fps with groups in the mid twos.
gary
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  #13  
Old 03-16-2014, 06:50 PM
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Re: 22-250 re-barrel chamber questions

Quote:
Originally Posted by Trickymissfit View Post
* the 1:12 twist will just barely stabalize the new Hornaday 53 grain Vmax bullets with a .29 B/C. Easilly handles B/C's of .27. But sooner or later we want to try the 60 grain + bullets with the higer B/C's. That's where the 1:11 will help you out to about .32 B/C (most guess at the exact numbers), but moving to a 1:8 (or even a 1:9) barrel will be a huge jump. Then you can shoot the higher B/C bullets at will (maybe even a 75 grain bullet)
gary
Neither Berger, Nosler, Sierra or Hornady makes a 60 grain bullet with a B.C. higher than the Hornady 53 grain V-Max. Some come close, but the 53 grain V-Max appears to be higher than all of them. Actually this shocks me.
Maybe my research wasn't extensive enough.

Spence
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