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Old June 14, 2018, 09:56 AM   #1
Ironworker
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Standard SAAMI chamber for 53gr V-max

Just received new 12"twist bbl. Gunsmith who is cutting the chamber said (22/250)"Standard SAAMI reamer will work,with room to seat bullets out farther if I want to touch the lands" . Others say they detest SAAMI reamers in custom bbls ,another says with zero free bore I can get an additional 1,000 rnds of bbl life . What say ye ?
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Old June 15, 2018, 01:05 AM   #2
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Use a standard reamer for a 22-250. If you go with a short leade, you will not be able to seat your bullets out very far at first, but you are looking at 53 gr bullets so I'm not sure that is an issue. If you go with AI reamer, you will have fewer case stretching issues, but dies for 22-250 AI will cost you $160-$200, rather than the standard dies for $40 for standard 22-250. Also, be aware that with a 1:12" barrel, you will have to watch your loads carefully so you don't spin the bullets apart. I had that problem with a 1:14" barrel (28" barrel, I was hitting 4,000 fps with 50 gr bullets).
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Old June 15, 2018, 12:13 PM   #3
T. O'Heir
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There's no such thing as a "standard" chamber for a specific bullet weight.
"...want to touch the lands..." That's about the OAL and is different for every chamber regardless of the bullet. SAAMI max OAL for the .22-250 is 2.350". Minimum is 2.290". Measured from the pointy bit to the flat bit with no ogives involved.
The SAAMI max chamber to the datum point at the middle of the shoulder is 1.5849" +.015".
"...say they detest SAAMI reamers..." Kind of daft considering all commercial reamers are made to SAAMI spec. Doing anything else means there's no guarantee commercial ammo or brass will fit the chamber. Kind of the point to there being an American National Standards Institute.
"...1,000 rnds of bbl life..." Barrel life has nothing whatever to do with the reamer or free bore. Barrel life is dependent on the load used.
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Old June 15, 2018, 04:59 PM   #4
Jim Watson
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The SAAMI .22-250 chamber has about .070" of cylindrical throat before the tapered leade into the rifling. If you did not have that, you would have to seat shorter, but could "chase the lands" longer as the throat eroded. A thousand rounds? I doubt it.
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Old June 16, 2018, 05:12 PM   #5
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If you want added barrel life, get the barrel cryo-treated after you've broken it in. Kevin Thomas found he got about 20% more barrel life out of stainless barrels so treated. After that, look at G. David Tubes throat reviving polishing bullet kit. He claims to double life that way.
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Old June 16, 2018, 08:36 PM   #6
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Very helpful

Thanks fellow firearms enthusiast
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Old June 16, 2018, 08:49 PM   #7
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Eroded throat ? Long ago there was a proper metallurgical examination of "erosion " . Of course it wasn't erosion . The hot steel would absorb carbon from the burning powder then subsequent heating and cooling of this higher carbon steel would cause cracking !
Solution ? Keep things cool ,slow fire is better that rapid fire . A cooler burning powder would also help.
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Old June 17, 2018, 03:11 PM   #8
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Also, I'm just thinking that I've not noticed non-standard 22-250 chambers particularly. There are half a dozen commonly made reamers for 7.62/.308 and for 5.56/.223, (match, Wylde, NATO, SAAMI chamber, etc.) but I've not noticed the 22-250 getting that kind of attention. Manson, Pacific, and JGS all list just one 22-250 reamer, presumably designed to cut the SAAMI Standard 22-250 Remington chamber. This means you'd have to go for a custom reamer to do anything differently other than the Ackley Improved version for which all the afore-named companies also make reamers.
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Old June 17, 2018, 05:13 PM   #9
Jim Watson
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Another option would be to get a barrel with a long cylindrical profile over the chamber so it could readily be set back, rethreaded, and rechambered to get to a clean throat.

Does anybody aftermarket nitride barrel bores?

Last edited by Jim Watson; June 17, 2018 at 05:31 PM.
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Old June 17, 2018, 07:35 PM   #10
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Ironworker, I don't shoot factory chamber rifles and I dealt with # of gunsmiths that chamber and throat for certain bullet. The made what's called throating reamer.

http://pacifictoolandgauge.com/311-t...d-neck-reamers

https://www.brownells.com/gunsmith-t...prod40868.aspx

Again gunsmiths I use have them. I don't have anything chamber till we talk about throating and I'll send them some dummy rds and most are pretty helpful.

Shilen does it http://www.shilen.com/faq.html#question3
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Old June 19, 2018, 01:48 PM   #11
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As long as the throating reamer cuts a more acute leade angle or a longer freebore (or both), that's certainly an option.
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Old June 21, 2018, 01:42 PM   #12
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T.O.
Not all commercial reamers are made to SAAMI spec. CIP uses a different spec. And if you change something like the the throat dimension then it has to be renamed. Hence 6.5-284 Win is SAAMI, where as a slightly longer throat is the 6.5-284 Norma(CIP spec).

Then there is the whole wildcat issue.

And don't forget proprietary.
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