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Old February 8, 2019, 08:07 AM   #1
JcBond
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Ruger M77 .220 Swift Bolt issue

I have a Ruger M77 .220 Swift. I bought it at a pawn shop about 5 years ago. It was made back in the 1970's It has always shot excellent, and I've had no problems with it. I usually always load 50 grain bullets for it. However, I tried some 35 grain Nosler bullets, and it did not like them. It was then I noticed pitting around the primers. I looked at the bolt face and there is pitting around the bolt face. There is a picture attached.

I've read different things about this. Some guys say just keep shooting it. Some guys say it's dangerous. I found a guy that said he can mill the bolt face down and reset the barrel. I'll probably have this done, but the guy is recovering from surgery so he's out for a while.

Anyone have any experience with this issue. I'd love to save this gun. It shoots really well.
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Old February 8, 2019, 11:55 AM   #2
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If it were me, i think i'd quit shooting it untill it was repaired.
I don't know if Rugerr could provide you with a new bolt?
You would have to check headspace before you used it, obviously. But may be least expensive option.
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Old February 8, 2019, 11:56 AM   #3
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That's gas cutting from shooting too many loads that were: A) Over-pressure. And/or B) Loaded with brittle primers that cracked or pierced when fired.

Seeing as it's a .220 Swift, I have to be a pessimist and assume over-pressure.

Normally, the answer is, "Just shoot it."

But this specific case looks pretty ugly. If those pits have much depth, the best option is to bush the bolt face.
You can't recut the face and 'set the barrel back' without also screwing with receiver geometry and modifying the extractor, ejector, and possibly the locking lugs.

Find a qualified, reputable gunsmith to bush the bolt face - as would be done for an oversized or eroded firing pin hole. (Mill out the damaged area, insert a bushing to repair it, and then mill back to spec and check/set headspace.)
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Old February 8, 2019, 02:49 PM   #4
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"...said he can mill the bolt face..." Probably be less expensive in the long run to have a new bolt fitted. Talk to Ruger's customer service. Have 'em look at the barrel wear too.
https://www.ruger.com/service/index.html
"...35 grain Nosler bullets..." Probably too light for the rifling twist. That's normally 1 in 14. The Swift usually likes 40 grains and up.
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Old February 8, 2019, 07:50 PM   #5
JcBond
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Actually today we scoped the barrel and it looks good. Not close to shot out. My gunsmith guy found a place that will cut that area out in the bolt and put in a new piece so you don't need to even set the barrel back. Just basically silver solder a new piece in there I think he said. They will also close up the firing pin area like it should be and not how it came from the factory. $180 was the quote and they said 14 weeks cause they are so busy. They said they are getting 30 bolts a day.

I think it might have been loose primers like FrankenMauser mentioned. When I first started reloading I really ground those primer pockets down when cleaning them on that automatic spinning machine, and I'm sure I ground those out too much and many of the primers were loose. .220 swift brass was hard to get when I started, and I had a hard time throwing any away. I've learned since then. Also, I do not shoot hot loads, and like I said above the riflings look good.

Anyway, I'll post the bolt when it gets back and see what this outfit can do.

Also T. O'Heir, it's my understanding these Ruger M77 bolts cannot be replaced. They are cast with the rest of the receiver or something like that. Anyway, that's what I heard. And yes, those 35 grains were too light. I usually shoot 50 grain bullets outta that thing. Had a box of 35 laying around, and I tried them. That is when I noticed that problem. I shot like -CENSORED--CENSORED--CENSORED--CENSORED- with those 35 grain bullets. I only shot about ten.
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Old February 8, 2019, 08:56 PM   #6
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"They are cast with the rest of the receiver or something like that. Anyway, that's what I heard."
You were mis-informed.

"And yes, those 35 grains were too light."
Maybe for accuracy but had nothing to do with the bolt face damage.
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Old February 11, 2019, 07:23 PM   #7
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OK, you're blowing primers. That is an overpresure sign. The load is too hot. Now you've shot a bunch of them and pitted the bolt face. Yes, you can put a hat sleeve in to fix the bolt face, but that won't fix the over-pressure issue. Stop shooting those loads in your rifle.

And let's not be silly about twist/bullets weight. Winchester's first 220 Swift loads were under 40 gr and shot just fine. 1:14" twist will stabilize spitzer bullets from 35-55 grains just fine. I started out with a 22-250 I used to shoot 40 grainers in because I wanted top speed, and it shot fine. Is a 1:14" twist ideal for a 35 gr bullet? Maybe not. Will it fail catastrophically? Most likely not.
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Old February 12, 2019, 01:45 PM   #8
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Some say this and some say that?

And then? There are many reloaders that make this stuff up. the 220 Swift case does a lot of traveling, the case body has a lot of tapper. And then there is the sequence of events that happen between pulling the trigger and the bullet leaving the barrel.

There is an expert shooter that makes a lot of this stuff up, He claims it is the firing pin that causes all of the problems; he claims the firing pin drives the primer forward first and then seats the shoulder of the case against the shoulder of the chamber. Now, for those that can keep up if the firing pin drives the case forward with the primer the case head will have no choice but to have a gap between the bolt face and case head.

And then there is this thing about time and speed: When the primer is driven forward and then busted there is nothing there to prevent the primer from being driven back by the explosion. This is where it really gets complicated because there is nothing to support the primer like the bolt face, the primer drives the primer out of the primer pocket, when the primer backs out of the primer pocket gas escapes, it is about this time the case is driven back, the primer is reseated and then the worst of all things happens; the case body locks to the chamber and the case head is driven back to the bolt face without the case body because the case head starts to separate from the case body.

Again, I am the fan of eliminating all of that case body travel but it is not possible to have it both ways. And then there is that story about the case being shortened between the shoulder of the case and case head. they have that firing pin shortening the case as much as .005". I have killer firing pins, when my firing pins are let go they make that sound "KLICK", you would think my heavy hitting firing pins would shorten the length of the case with that loud 'CLICK!' , it just does not happen.

And then there was that day a friend wanted to know what was wrong with R-P ammo. I told him the phone number was on the box; call them!

He brought me 5 R-P 30/06 rounds that failed to fire; he had 5 shooters with 30/06 chambered rifles to attempt to fire them. The rounds had to have been hammered 7 times with 5 rifles, and the miracle? I measured the 5 tailed to fire rounds that been hit at least 7 times without shortening the case .001".

I pulled the bullets, saved the powder and then removed the primers and then seated the primers back into the same primer pockets (and then) chambered the 5 cases in one of my M1917 rifles, I pulled the trigger and busted the primers one at a time without shortening the case.

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Old February 12, 2019, 04:17 PM   #9
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I'd go along with rethinking your reloading process.Loading hot will expand your primer pockets. 220 Swift brass is hard to find. I bet your brass primes real easy. It might be time to scrap it. Its amazing how quick gas can cut a bolt face.

I'm not a professional smith. I'm an amateur tinkerer with some shop skills.


I'm thinking maybe Frank DeHass techniques of bushing a firing pin hole and getting the torch and silver solder out might be OK on a rolling block or a Martini but it might be questionable for the heat treat and general integrity of the locking lug end of a rifle bolt.

These guys with laser welders who do mold repair have saved my tail before.

I can't refer you to a shop,you may have to do some research.There is not a lot of heat involved . You may see bare fingers holding filler rod or riding the workpiece.

https://youtu.be/YNGuALnRQe0

https://youtu.be/ZG_1uYRb_lQ

Of course,if one was available I'd prefer a replacement bolt.

Last edited by HiBC; February 12, 2019 at 04:36 PM.
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Old February 13, 2019, 09:11 PM   #10
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Usually, the gas leaks around the sides of the primers that do that kind of boltface gas cutting is an overpressure sign. It can also be caused by excess headspace being too great (I know that sounds like a redundancy, but it is not, as "excess headspace" is a proper term for how much bigger the chamber headspace is than the cartridge is from base to seating surface). Too much excess headspace allows the primer to back out too far before the case head comes back to reseat it. Whether that is caused by the headspace being too long or the case being resized too far for the chamber is something the shooter should determine.

The gas leaks can also be caused by cases that have had their primer pockets expanded. That usually means the pressure was too high for the long-term. Folks who shoot such loads on purpose will generally figure the load is OK if the primer pockets don't over-expand in 5 loadings. If they expand too much sooner, that means the load is too hot, even for them. If they don't expand too much until the sixth shot, thats a maximum load (for that lot of brass), but they will be careful to retire the brass used for such warm loads after 5 loadings total to avoid having the boltface pitted.

So, don't over-resize the cases. -0.002 inches shorter than chamber size is enough. Get one of the Ballistic Tools primer pocket Go/No-Go gauges to check for expansion.
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Old February 15, 2019, 11:22 AM   #11
F. Guffey
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Quote:
Gunsmiths use "go" and "no-go" gages to measure chamber tolerances, and now you can bring this level of precision to your reloads with the Swage Gage primer pocket gage.
It sounds like they are trying to convince 'modern' reloaders they invented the concept recently. I am sure I have had a tool that measure the diameter of the flash hole for over 40+ years. I do not know what happened between then and now but I will swear back in the old days if the primer pocket hole expanded the flash hole also expanded with the diameter of the case head. And then there was the thickness of the case head between the cup above the web to the case head.

I have no ideal how they train high pressure to be focused on one area of the case head.

The 220 swift was not the perfect case, in my opinion the 220 Swift had too much tapper.

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Old February 15, 2019, 04:14 PM   #12
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You are correct. The copy of your tool that you kindly sent me works great. I am just not willing to give it away, so I'm not sure where the OP could put his hands on one. Next best, I suppose, would be to ream the flash holes to a consistent diameter and use pin gauges to check for a change in size.
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Old Today, 09:40 PM   #13
HiBC
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Some folks pay quite a bit of attention to detail. There is always another little gadget to use...or perhaps overuse. There are power primer pocket cleaning brushes,reamers,primer pocket uniformers,military crimp reamers,etc.

I'm sure all of these tools have their benefits and proponents.I'm not knocking them.With a little too much exuberance,some OCD,or routinely doing something that only needs to be done once,the size,form,roundness,etc of the pocket that fit the primer well enough to seal off high pressure gas can be compromised by the meticulous handloader..Brass is very easily worn,scraped,or cut away.A tool that enters the pocket out of square will alter the pocket.
And,of course,excessive pressure will expand the case head.

An old,well known technique is measuring case head expansion with a micrometer.The case head is like a donut with the flash hole and primer pocket reasonably concentric. If pressure expands the case head,it will also expand the primer pocket and the flash hole.

Intuitively,I'm guessing brass is made to tighter tolerance controls on the primer pocket than on the flash hole.

Some time back when I was doing more "outside the books"load development,it occurred to me the suppliers of plug and pin gauges will make them in tenth thousandth sizes. It crossed my mind to get a set of ten pins graduated every .0002 in small and large primer size from -.0002 to + maybe .0016. It seemed to me monitoring primer pockets with gauge pins could be useful.
Another one of those ideas a guy could do. I just used other methods and never bought the pins. But I believe its a workable idea.


On the "Dread Donut" in the case neck,it can be a common problem for those who neck turn the outside of the neck.The corner condition at the juncture of the neck and shoulder is critical.Any little step of original ,pre turned neck diameter that remains will be off set to the ID during sizing or fireforming.

And,true,as the shoulder is set back during sizing,larger diameter or thicker brass material migrates toward the neck. As the OD of the neck is sized,extra material will translate to a reduction of ID.Then,maybe the expander rearranges things again!
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