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Author Topic: New MKII won't handle pressure of Old M77  (Read 944 times)

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Offline Sourdough

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New MKII won't handle pressure of Old M77
« on: July 06, 2004, 08:21:46 PM »
I have been shooting a M77 that I bought in 1983, when the wife and I got orders to go to Alaska.  It is a blued M77 in .338 Win Mag.  I have worked up a load of 76.5gr of H-4350, with a Nosler 225gr bullet.  This load shoots well in this gun, and I have been shooting it for 20 years with great results.  A few years ago my wife and son gave me a new M77MK-II, Stainless in .338 Win Mag.  I figured I'd try my old faithful loads in the new gun, (wrong).  I got real high pressure signs.  So I started dropping powder, I had to drop 4.5 grains before I stopped getting high pressure signs.  Point of impact also dropped drastically also.  I've tried other powders and loads in this new gun.  It just does not have the trajectory and range that the old one does.  In other words I'm very dissastified with my new Ruger M77 MK-II.  When I got into the Brooks Range this fall I'll be taking Old Faithful, the Blued one.
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Offline scruffy

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New MKII won't handle pressure of Old M77
« Reply #1 on: July 07, 2004, 08:26:19 AM »
Any idea why the new one won't take the pressure?  Are they throated differently, different chamber specs, etc?  Just curious...

later,
scruffy
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Offline Coyote Hunter

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New MKII won't handle pressure of Old M77
« Reply #2 on: July 07, 2004, 10:27:56 AM »
What high pressure signs were you getting, and

Did you chrono the loads from both rifles?
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Offline Lawdog

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New MKII won't handle pressure of Old M77
« Reply #3 on: July 07, 2004, 10:28:46 AM »
Sourdough,

Quote
I have worked up a load of 76.5gr of H-4350, with a Nosler 225gr bullet.


I don't wonder that you are getting high pressure signs with that load.  It is only about 6 plus grains over MAX recommendations of Hodgdon.  Hodgdon recommends a 75.0 gr. starting point for H-4350 using the 225 gr. bullet and a max. of 78.0 gr. in the .340 Weatherby Magnum.  Word to the wise, I would cut back if I were you.  Lawdog
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Offline Sourdough

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New MKII won't handle pressure of Old M77
« Reply #4 on: July 13, 2004, 07:11:29 PM »
Lawdog:  I've been using that load for 20 years with my old Ruger.  I don't get any high pressure signs at all, other than short brass life.  After three trimmings I discard cases.  

With the new Ruger I had shinny rings around the case just above the base.  The primers were flattened, and had a hole blown in the center, where the firing pin struck.  Also the lettering was flattened and the face of the bolt was impressed on the case head.  Brass had even flowed into the extractor opening.
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Where is old Joe when we really need him?  Alaska Independence    Calling Illegal Immigrants "Undocumented Aliens" is like calling Drug Dealers "Unlicensed Pharmacists"
What Is A Veteran?
A 'Veteran' -- whether active duty, discharged, retired, or reserve -- is someone who, at one point in his life, wrote a blank check made payable to 'The United States of America,' for an amount of 'up to, and including his life.' That is honor, and there are way too many people in this country today who no longer understand that fact.

Offline Lawdog

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New MKII won't handle pressure of Old M77
« Reply #5 on: July 14, 2004, 07:44:18 AM »
Sourdough,

Why you are not getting high pressure signs in your old Ruger escapes me.  But every manual I own says you are way over maximum.  As I stated before the load you are using(76.5gr of H-4350, with a Nosler 225gr bullet) borders on what is used in the .340 Weatherby Magnum.  Personally, for safety reasons even in your older Ruger, I would cut back on the charge level.  This is just a friendly warning but do what you want.  I believe you are treading in unsafe waters.  Lawdog
 :D
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Offline Darrell Davis

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New MKII won't handle pressure of Old M77
« Reply #6 on: July 19, 2004, 12:01:41 PM »
:D Hey there shooters,

Guess I would come down with Lawdog at first glance.

However, as indicated in one of the other posts, just what does the cronograph say about the vel. in your "old" rifle, and what does the vel. show on the "new" rifle with the decreased loads?

There are just to many possible -unknown to us, - factors which could be entering into the picture to do anything other the go with Lawdog's warnings.

But, bearing in mind that many rifles will in real life shoot slower then the books indicate, just what are your rifles doing?

Sending a dozen loads over the screens with the "old" rifle may show that it really doesn't shoot as fast as thought, while the "new" rifle and "lighter" loads may just be right in there. Just to many blind spots and corners from where I sit to say anything other then back off until the proper tests can be made.

Be safe and keep em coming! :wink:
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Offline oso45-70

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« Reply #7 on: July 20, 2004, 10:40:56 AM »
Genleman,
It don't take much difference in bore size to make a lot of difference in
chamber pressure. I have had two rifles of the some cal. brand and have a world of fifference in pressure, Thats why the Books always tells us to use a starting load and work up. I would bet that if you checked your bores you would find a difference in them. and anothr thing there can be a little variation in your chambers which can cause a pressure increase.
There is a lot of things to look at, But the thing that sticks out is the load its self, It may be just my way of thinking but it seems a little warm.
I hope you can figger it out. Good luck and stay safe........Joe........
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Offline Sourdough

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New MKII won't handle pressure of Old M77
« Reply #8 on: July 24, 2004, 09:10:06 AM »
The way I got to this load 20 years ago was to take all my loading stuff out to the range one day and start shooting, and reloading five shells at a time.  I started out at the low recommended load in the Lyman Manual.  I then worked up half a grain at a time, looking for pressure signs.  I kept going till I started getting the first indication of high pressure, flattened primers.  I stopped there and dropped half a grain in powder.  That's the load I have been using for 20 years in that Ruger .338.  I feel very comfortable with that load, in that gun.  Too bad it won't work in other guns.  Over the years I've killed many Moose and Caribou with this load.  It is capable of dropping a Moose of Caribou out to 500 yards, one shot, with no problem.   Guess I should have started the other guns the same way, just figured since it was the same caliber, and the same manufactor, they should be able to shoot the same load.  Found out the error of my thinking.  Won't make that mistake again.
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Where is old Joe when we really need him?  Alaska Independence    Calling Illegal Immigrants "Undocumented Aliens" is like calling Drug Dealers "Unlicensed Pharmacists"
What Is A Veteran?
A 'Veteran' -- whether active duty, discharged, retired, or reserve -- is someone who, at one point in his life, wrote a blank check made payable to 'The United States of America,' for an amount of 'up to, and including his life.' That is honor, and there are way too many people in this country today who no longer understand that fact.

Offline oso45-70

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« Reply #9 on: July 24, 2004, 11:36:48 AM »
Sourdough,
Don't go beating your self up, You are not the only one to do this,, I did the very same thing. I had worked up a load like i was supposed to and used the load for about four years, Then found a deal on another gun just like the one i had been using, In fact thr ser.#s were real close so i never gave it a second thought. Well let me tell ya the outcome was sure different. I almost blowed the thing up. Lesson well learned. On top of that when i went to reload, I had to reset my dies. This little incident was in
1952 and i've not forgot how stupid i felt.  Have a good day Sir and stay safe.............Joe..........
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