Re-barreling a Ruger M77 MKII. What caliber?

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steveNChunter

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I have a M77 MKII stainless, varmint barrel, chambered .223. This gun was given to me by my father, who has taken it on many hunting trips to South Dakota and ended the lives of many, many prairie dogs. Its had I dont know how many thousand rounds shot through it, still shoots good, but could probably use a new barrel. (At least thats my excuse :D)

I want to re-barrel it with another bull or semi-bull barrel but in a caliber larger than .223. Ive gotta stay within the short action cartridge length of course. I want something good for deer sized game. No non-commercialized wildcats, but a factory round that you dont see every day would be cool. I kinda like the idea of something that everybody and their brother doesnt already have.

I already have a .243 win and a 6mm rem so those are out. Some calibers Im considering are: .260 rem, .257 roberts, .25 wssm, and .270 wsm. But Im wide open to suggestions. I realize I may have to get a new bolt for some of these calibers as the face diameter may differ, but thats ok.

The main purpose of this thread is caliber selection, but as a side note, give me some opinions of who makes the best aftermarket barrels without breaking the bank.
 
bolt head diameter and feed lips in the action dictate rebarreling choice. believe it or not new bolts can run a 100 plus and factories seldom sell them as a part. bobn
 
both of those are a little light IMO for deer. Anything compatible thats a little larger? I want to be able to shoot at least 95-100 grain bullets

A little research tells me that bolt face diameter has to be around .384

What are some more options? The .222 rem mag intrigues me, and I think it would work, but still lighter than I want to deer hunt with. This could end up being a varmint project instead...
 
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I'd look at 7mm TCU (7mm x .223 Improved for handgun metallic silhouette in Thompson Center Contender.)

Or .30 Apache (.30 x .223 used by at least one shooter for rifle metallic silhouette a good many years ago.) There is probably enough room in the magazine. You might have to take out some spacers and use a medium length follower, I am not real up to date on smallbore M77s, my only example is a .22-250 and it is at risk of getting rebarrelled to .308.
 
In order to get into deer hunting cartridges, and keeping the small bolt face in mind, you are looking at wildcat cartridges, which you said you didn't want. Any of the TCU cartridges (6.5, 7, or 30 TCU) will give you a rifle similar in power to a 30-30 or so. If you want to move up, trade the rifle or buy one in an appropriate chambering.
 
Ok, it is becoming more and more obvious that this is going to have to remain a varmint rifle. I have plenty of deer rifles already anyway so I guess its just as well. So switching gears, what commercial calibers can I use with that .223 bolt?

.204 Ruger is a necked down .222 rem mag, correct?
 
Yes the 204 is a necked down 222 Mag,
I think these all work 17 Rem, 204 Ruger, 223 rem, 222 Rem Mag, 222 Rem. there may be more but these come to mind.
 
If you are a reloader, how about going to a 223 AI. Offhand, I don't know what additional MV you'd get, but it's a thought. And maybe you want to think about the barrel twist rate, so you can shoot the larger bullets.
 
So switching gears, what commercial calibers can I use with that .223 bolt?
Click to expand...
.17 Fireball
.17 Remington
.204 Ruger
.221 Fireball
.222 Rem
.223 Rem / 5.56x45mm
.222 Rem Mag
5.6x50mm

Beyond that, even if it's commercial, it's pretty uncommon. (I admit, I may have missed a couple, though.)
 
.222 rem mag is too close to .223 to be worth doing IMO, I think .222 would be a step down ballistically, so that leaves .17 rem, .204 ruger and .223AI. I want to start reloading someday but currently dont so that pretty well kills the AI.

Im pretty solidly thinking .204 ruger will be the way to go if I keep the same bolt. But I believe Ill get the rest of the good out of the .223 barrel before doing that.

Maybe in the meantime Ill find a used M77 bolt with a larger face diameter and open up some more options.

Will an old M77 bolt work in a Mk II? If so I have an old M77 chambered in 6mm rem that could donate a bolt. That would open up some more options like .257 roberts or 7x57 mauser
 
The original M77 bolt will fit in the receiver, but will not work without modifications. I would say skip that idea.
 
You have several wildcat options as already and I went through what you're going through about 4 years ago. I finally settled on the 6X47 Rem as my cartridge of choice since my ultimate goal was a walking varmiter. Looking back I'd do some things differently, first is I wouldn't have used a slow twist barrel, I saved $100 and 14 weeks of waiting by using a 1:12 twist barrel that the maker had in stock which limited my bullets to sub 80 grains.

Next I would use either the .223 or .204 case instead of the .222 RM. Remington is the only one making the case and only in seasonal runs. Remington's brass is adequate there are much better brass choices for the .223 and .204 cases. Plus dies are readily available for either cartridges as well.

Now what I like about it is that every load I've tried in 60 to 70 grains usually goes around an inch and with a little bit of tweaking I can get most under ½". 80-85 grain bullets I haven't found a consistent 1" load yet. I haven't messed with 55 grain bullets as I run that weight in my .223's. So far the 70 grain Noslet BT has been my go.to bullet for prairie dogs to pronghorn. My longest kill to date on pronghorn buck is 305 yards. I have to be a little more discerning with my shots to avoid shooting through the shoulders but I just think of it as long range archery. If I could use a bullet like the 85 grain Nosler Partition Cornell Barnes 80 grain TSX I wouldn't hesitate to use it on deer.

If you feel that you need bullets heavier than 85 grains to kill deer you might want to considered the .300 Whisper or AAC Blackout. If you go with heavy for caliber bullets in a small capacity case you run out of powder room fast trying to get them to feed from the magazine. Plus another thing to remember with these cartridges are for sub 400 yard shots.on anything larger than a coyote.
 
I have 3 Rugar 77 VT rifles and I have put a lot of rounds through them so I speak from experience. My first was in .223 and it took about 10,000 rounds to "shoot out the barrel" and by that I mean groups > 1" @ 100 yds. My second is in .243 and it took 4000+ to do the same. My third is in .25-06 and I have not used this one as much, perhaps 1000+ rounds. The .223 and the .243 were rebarreled at the same time using quality after market barrels and to be perfectly honest the Rugar barrels are of equal quality and less expensive. The point of this is simple, if you want to rebarrel in the same caliber use a Rugar barrel (hammer forged quality is hard to beat) and if you want to change calibers find one that will work with the .223 bolt. If you need to change the bolt the total cost will be close to the cost of a new rifle. Just as a side note, Rugar does castings for receivers and other parts as well as suppling barrels to other gun companies. A new Rugar barrel is as smooth in the bore as a hand lapped $600 barrel from a custom maker.
 
how about some of the newer AR cartridges ( not sure how many are on the 223 case head, but 6.8 SPC, 300 Blackout, etc. ) not really an AR guy, but I know a slug of newer cartridge came out in the last couple years...

... but... you know I'm in the same boat, only with a Remington 700 heavy barrel in 223, that I know my FIL put over 2000 round through in one week, in SD P Dogging ... I haven't inspected the barrel yet, but am guessing the throat is likely at least slightly worn... I plan on rebarreling it back in 223 heavy barrel, because it's such an awesome gun as it's chambered...

BTW... he also had a 17 Remington that had 1000's of rounds through it, & had very noticeable throat errosion, that I rebarreled & chambered in 17 Fireball ( IMO, the most well balanced of the 17 centerfires ) ( thich also took a different follower, spring & spacer block for the mag, but the guns is awesome now, looking forward to wringing it out next summer
 
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