Rechambered Remington 600 from 222 to 223

Discussion in 'The Powder Keg' started by vrodhogrider, May 27, 2008.

  1. vrodhogrider

    vrodhogrider G&G Newbie

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    Hi Gang,
    I responded to a thread, reference Winchester Model 270, before; but this is my first thread. I bought a Rem. 600 "Mohawk" in 1987 at a US Army Rod and Gun Club here in Germany. The seller was a German gunsmith, who had rechambered the gun from 222 to 223 in accordance with the wishes of the previous owner (who was then unable to pay the bill).The mod was done very well. Largely because of increasingly difficult restrictions on American personnel who owned firearms, I was not able to shoot the rifle much. Recently, the situation became virtually impossible and I sent the Remington and my Winchester back to the US. After over 20 years with the DOD in Germany I'm now preparing to return to the states (and active shooting).

    Can someone advise me regarding a 223 bullet going through a 222 barrel? Would the rifle have performed better before it was rechambered? Do I expect reduced accuracy, range, stability or some other undesirable result (compared to before)? Or should there be little or no performance difference? What, if any, differences are there in rifling, for example, between a 222 and a 223 barrel, that are likely to make a performance difference? Would it be worthwhile to consider re-barreling, using a new 223 barrel? A lot can be accomplished with creative reloading. If the negative performance factors are minor, could they be overcome by tailoring the reloaded cartridge to the gun? What do you think? I welcome your advice.

    Before someone asks, I'm sure the safety recall mod has not been performed on the gun, yet.

    Just a short addendum. I have no way to compare current performance with pre-223 cal. performance. But, if it can be improved, I want to improve it.
    Last edited: May 27, 2008
  2. lefty o

    lefty o G&G Enthusiast

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    bore diameter, and bullet diameter are the same for both cartridges.
  3. samuel

    samuel G&G Newbie

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    You have a basic overall length on the .222 of 2.130" and the .223 is 2.260 meaning the magazine might be short for .223 cartridges,but I doubt that.The only other thing is how far the riflings are and whether you can chamber .223,s without hitting the riflings.I believe that would be ok as it sounds like a quality gunsmith,but I would have the chamber and freebore checked.You can have it done by any quality gunsmith or order the oal guage and do it yourself.You can also order the material and pour a chamber mold.I would use the mold but I dont think it is necessary.I would just be curious about the chamber.If you can chamber a cartridge and extract it and have no rifling marks you are safe to fire it.But for reloading get the riflings meisured. sam.
  4. Purdy

    Purdy G&G Enthusiast

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    The 223 reamer should have taken care of any concerns about "freebore"
  5. Mike Franklin

    Mike Franklin G&G Newbie

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    It took me a bit to look this up but the Remington .222 has a 1 in 14" twist. You'll likely find your best accuracy with lighter bullets.
  6. wunhunglo

    wunhunglo G&G Newbie

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    Does it carry a German Proof mark, it should have to by european law and if it does, then it has been thoroughly tested. I also have the greatest of faith in German craftmanship and would expect the job to have been properly carried out.
    As someone else has already pointed out it will probably work best with the lighter bullets.

    Good luck.
  7. samuel

    samuel G&G Newbie

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    I have little doubts that the workmanship is great but you have to know where the riflings are to load for the best accuracy and besides I didn't know how familiar he is with the gunsmith.What really would trouble me is whether the German gunsmith used C.I.P. standards or SAAMI and how much difference their might be.As to the chamber reamer,all reamers are not the same and we have the metric vs inch factor.To eleminate any questions I advise meisuring the oal and I would make a cast to check the chamber.There is a lot to it and as he mentioned whether he could expect good accuracy,You can have a very good barrel but if you are using mfg,d ammo and the bullet isn't right with the riflings,you cant expect the best accuracy.Besides,for no more than it costs,I believe meisuring the chamber and a chamber mold is a good investment.This is something I would do,even if the greatest gunsmith in the world had done the work right in front of me. sam.
  8. vrodhogrider

    vrodhogrider G&G Newbie

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    I appreciate the input.

    Thanks Guys. Operation of the rifle with the 223 cartridge is smooth and problem-free. There is no problem chambering, firing or extracting. The spent shell shows no deformation of any kind. I bought a re-chambered Argentine Mauser once when I was young and Totally ignorant. I learned what a butchered rechambering job can mean. The rechambering was well done. I do think the suggestions about the usefulness of a chamber mould and the associated measurements are worth following.

    My primary concern is whether there is any significant effective difference between the rifling (twist) for a 222 and that for a 223 and whether it is significant enough to make it worthwhile to re-barrel. Mike Franklin wrote that the twist for 222 is 1 in 14". Is it the same or close to the same for 223? If the twist configuration is not a significant factor, then what I need to know is what bullet types and weights would give maximized performance.:feedback:
  9. samuel

    samuel G&G Newbie

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    The way it works is it takes so many rpm,s to stabilise a bullet.Given equal twist(1in14")since the muzzle velocity is slower in the .223 than say a .22-250 the twist must be faster to get the same rpm,s.A .22=250 at 3610fps will stabilise up to 55gr bullets with a 1in14" twist but the .223 would be limited to 50gr and under because of the lower muzzle velocity.That is why the mfg,s use a 1in12"twist with .223,s but stick with the 1in14"twist in the .22-250,and .220swift.You had no option in twist but it should be no problem with 50gr and under bullets.You might get a 55gr spfb bullet to work,the same as the higher velocity rifles like the .22-250 may stabilise flat base bullets in 60gr.The longer the bullet,the more spin it takes to stabilise. sam.
    Last edited: Jun 1, 2008
  10. Ron AKA

    Ron AKA Suspended

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    I agree with what Sam says with regard to twist and bullet weight. In your case you have a .222 Rem converted to a .223. The .223 has a larger case and will give higher velocity. So with respect to stabilizing a larger bullet the converted rifle will be better than the old .222. It would seem a bit strange that Remington would have put a 1 in 14 twist in the gun, and you may want to do a bit more research to see if that is really what it is. You could also try marking a cleaning rod and to check how many inches it takes to get one revolution.

    The velocity effect on spin is not really all that much. Berger for example rate the spin required based on the bullet weight and design and don't give a velocity required. Check this link out. It says 50 and 55 are ok with 1 in 14.

    Berger Bullets

    If you want to figure it out and have access to Excel here is a formula developed by a Don Miller to determine what twist you need for the various bullets and velocities. I think it is a bit conservative however, and I have been unable to match the twists recommended by Berger.

    Sg=(30*C5)/((C7/C4)^2*C4^3*C6/C4*(1+(C6/C4)^2))*(C8/2800)^(1/3)*((C9+460)/(59+460)*29.92/C10)

    Where:
    Sg - is the stability coeficient and should not be less than 1.4, but more is ok
    C4 - Caliber in inches (.223 for both .222 and .223)
    C5 - Bullet Weight in grains
    C6 - Bullet Length in inches
    C7 - Barrel Twist in inches per turn
    C8 - Muzzle Velocity in fps
    C9 - Temperature in degrees F (59F normally used)
    C10 - Pressure in inches of mercury (29.92 normally used)

    For interest I ran a 55 grain through the formula assuming 0.7" length and a .222 velocity of 3100 fps. It came out at Sg equal to 1.15, or not enough. However when I increased velocity to 3300 or .223 speed, it only increased to 1.17 or an insignificant difference. And at either speed it needs about a 1 in 12.5" twist to reach the 1.4 for Sg.

    So I think your short answer is that the barrel was made slightly better if anything by rechambering. A 1 in 14 twist if that is what it is, should give you the best possible accuracy in the 50 grain bullet weights, better than the faster twist barrels. However it will be limited to 55 grains or so. You will want to stick to the flat base, shorter bullets.

    Here is a good link where they discuss the twist rates required for a .223.

    223 Rem + 223 AI Cartridge Guide

    Ron
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