lancetkenyon
Well-Known Member
L-25CM, R-.250AI (w. 250 Sav R-P brass)
Be cautious about using a case not originally used as the parent. There are differences in CM and .250AI cases that could cause issues.
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Should I AI it?
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Be cautious about using a case not originally used as the parent. There are differences in CM and .250AI cases that could cause issues.
I resized a couple of once fired 6.5 CM Lapua cases in my 250AI FL die this morning. I then expanded the neck with a .2545" mandrel. Key case measurements are attached. Biggest issue is the 3 thou difference at the base which is preventing the case from chambering. I read in my research that running the case through a 308 FL die solves this problem. I don't have a 308, but my 260 Rem FL die did nothing. I believe a small base body die would correct this issue, but I've no experience with them. Thoughts?
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Ckgworks
Well-Known Member
I have a SB 308 die.....I'll measure before and after and post tonight
Ckgworks
Well-Known Member
My sized down 6.5 creedmoor brass measures .466 at the base. The small base 308 dies didn't do much but brought it down to almost .465. I looks like it might work depending on your dies. I have some 250 savage brass on the way, but I would like to keep them for my Savage 99.......it'd be nice to find something to make brass out of that I don't shoot and I really doubt I'll have a Creedmoor.
.465 would be perfect. I think I'll give it a try.
MagnumManiac
Well-Known Member
To the OP, I have 22-250AI, 257AI & 260AI currently. Years ago I had 6.5x55AI, 25-06AI, 6.5-06AI & 338-06AI.
Today I have the 3 mentioned only, of all, these 3 appear to be the only one's worthwhile in their gains. I am sure the 250AI would also be in this bracket, but I'm not a fan. Great cartridge as a 22…
Sometimes the AI just isn't an efficient gain, this is true in almost all cases of 30 and larger in the 30-06 case. I built several 35 WhelenAI rifles, supplied die's etc and the results were lacklustre, the 338-06 was about the same, not even 100fps.
It's your choice whether you want to do it, it won't hurt anything doing so, it might drop the resale value, I know my Win Model 70 Stainless Classic would get more money if I hadn't chambered it from a 375H&H to 375 Weatherby, but that's what I wanted.
Cheers.
Today I have the 3 mentioned only, of all, these 3 appear to be the only one's worthwhile in their gains. I am sure the 250AI would also be in this bracket, but I'm not a fan. Great cartridge as a 22…
Sometimes the AI just isn't an efficient gain, this is true in almost all cases of 30 and larger in the 30-06 case. I built several 35 WhelenAI rifles, supplied die's etc and the results were lacklustre, the 338-06 was about the same, not even 100fps.
It's your choice whether you want to do it, it won't hurt anything doing so, it might drop the resale value, I know my Win Model 70 Stainless Classic would get more money if I hadn't chambered it from a 375H&H to 375 Weatherby, but that's what I wanted.
Cheers.
OP, would be much better to have a new barrel installed on the Ruger #1 instead of a re-chamber. As the throat dia wears, the gunsmith has to fit the reamer pilot to whatever the larger size has become. Some gunsmiths have a large inventory of reamer pilots Per caliber and some do not. If the reamer pilot is too small for the worn Throat dia, the reamer will just bounce around, creating a helter-skelter chamber. Also, there is no telling how crooked the existing chamber is about the bore axis.
AI chambers are shorter than the parent cartridge by at least .004. You could cheat, but you may have some case stretch. You can expand the necks up to 7mm, then neck down creating a false shoulder to headspace on.
Keep in mind your goal regarding the accuracy requirement of the new chamber.
AI chambers are shorter than the parent cartridge by at least .004. You could cheat, but you may have some case stretch. You can expand the necks up to 7mm, then neck down creating a false shoulder to headspace on.
Keep in mind your goal regarding the accuracy requirement of the new chamber.
Bret GRAVELINE Graveline
Well-Known Member
if you are wanting more velocity moving to another parent cartridge is another option, however comming up with all new componets in todays world can be a problem, i run two 257 AI with 21 & 22 inch barrels, both produce 3100 to 3200 fps with 110 to 120 gr slugs, the 21 inch produces the higher velocitie of the two, the 22 inch barrel is a rebore from 243 win, i also have to 6MM AI's both number 1's both rechambered from 243 win, When rechambering to a AI cartridge the improved reamer will start cutting before the pilot engages the bore, as long as the tail stock is indicated in properly and the barrel is running true the reamer will self center itself,
ntsqd
Well-Known Member
I am building a .243AI not for the increase in velocity, but for the reduced case stretch and supposed increase in throat life that a sharp(er) case shoulder appears to provide. If the OP is having similar case stretching then going AI seems like it will slow or stop that.
The .30-30 is supposed to be the case that most benefits from the AI modification. Comparing the before and after cases I can see why. I bought that rifle because it was what I wanted in a lever action (Win M64). That it had been rechambered into a .30-30AI was a bonus, not a problem. Collectors didn't want it (lower price) and I've been wanting to try that particular AI chamber and wasn't willing to rechamber anything else in current inventory.
The .30-30 is supposed to be the case that most benefits from the AI modification. Comparing the before and after cases I can see why. I bought that rifle because it was what I wanted in a lever action (Win M64). That it had been rechambered into a .30-30AI was a bonus, not a problem. Collectors didn't want it (lower price) and I've been wanting to try that particular AI chamber and wasn't willing to rechamber anything else in current inventory.
It boils down to your personal preference, and only you can determine if it is worth the cost, time, and effort for the percentage of gain. IMHO, there are other gains other than the velocity. I have a Ruger No. 1 in .243 Win, but I am going to leave it as-is. The re-chambering quote is fair/very good. My gunsmith charged me $250 to re-chamber my .30-06 to .30 Gibbs because he had to rent the reamer and gauges for $50.
Like others, I, too, like improved cartridges/chamberings, and all worth it to me.
- .270 AI
- .30 Gibbs
- .30 LARA
- .338 Thor
Good luck!
lesvoth
Well-Known Member
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Years ago John Barsness wrote an article about how he had Charlie Sisk build him a 6.5x55 Swede that purposely had the chamber cut so tight at the base that he had to run factory ammo through a 45 ACP(?) die so it would fit.
John explained in the article why he wanted it like that, but I don't remember.
It might be worth trying a carbide pistol die of a close diameter. I don't know which one that might be.
Redding 308 small base body die did the job. Ready to move on to fire forming.
Cutting rimless AI chambers isn't as easy as running a reamer until it cleans up. If that's what your smith wants to do take it somewhere else. The barrel needs to be set back at least a few thou before the chamber is cut, then the new chamber is cut using an Ackley go gauge and the parent cartridge's go gauge as a no go gauge. Ideally it's set back by exactly 1 thread so the markings stay in the same place after the chamber is cut.
Personally I'd just have it rebarreled if you want an AI chamber.
Personally I'd just have it rebarreled if you want an AI chamber.
