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M77 Mk II accuracy issues

This is a discussion on M77 Mk II accuracy issues within the Ruger Bolt Action forums, part of the Rifle & Shotgun Forum category; I recently bought a new M77 Mk II in 7mm Rem. Mag., stuck a Leupold 3-9x scope on it and decided to do some plinking. ...

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Old August 9th, 2008, 06:31 PM   #1
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M77 Mk II accuracy issues

I recently bought a new M77 Mk II in 7mm Rem. Mag., stuck a Leupold 3-9x scope on it and decided to do some plinking. I was shooting Federal 150 grain Power Shok soft points. Okay, I know this isn't premium ammo, but it shoots quite well in my other rifles, regularly producing dime sized groups at 100 yards out of my .243 Vanguard and my Model 700 Remington in .270.

So I head out to a friend's farm and try to zero the scope. The results are terrible--all over the paper. The next day I take it to an indoor 50 yard rifle range and shoot from a sandbag rest. Results are better this time, but still not anything to write home about. 1.5 inch groups.

I've already ordered a Timney aftermarket trigger and am thinking on having the rifle bedded by a gunsmith.

Here's my concern: The 7mm Rem. Mag.'s selling point is that it's a very flat shooting long-range round, but with this kind of accuracy I'm beginning to wonder if I wasted my money on a Ruger and should have invested in some other rifle capable of making the 7mm Mag. do what it's supposed to do. An inaccurate 7mm is worthless and the web is full of people blasting M77 Mk IIs for their performance in this department.

Yes, I am aware that the accuracy of these rifles was poor in the 80s and 90s, but now Ruger is supposed to have fixed the problem with "hammer forged barrels" (whatever that is). Still, I'm not too pleased with the accuracy of my BRAND NEW model!

I'd be interested in hearing anyone's thoughts on this matter.

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Old August 9th, 2008, 07:40 PM   #2
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Give it a bit more work. Some rifles shoot better after breaking in. Also, try different ammo. A particular brand/weight might shoot stellar groups in one or more of your guns and poorly in another. Your 243 and 270 shoot great with it but the 7 mag might like something else. This is very common. You also have a huge difference in recoil between 243 and 7 mag. Don't give up on it yet. It's way too early for that.
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Old August 9th, 2008, 08:00 PM   #3
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LawyerGreg, 7mm Rem Mags never were the most accurate rifles in the world but you can normally get groups in the 1 to 1.5 MOA range with the right loads. 7mm mag rifles have a very fast twist in order to stabilize heavy bullets. Your gun will shoot much tighter groups with factory ammo loaded with 175 grain bullets ..... however the recoil is pretty intense. I have handloaded 150 gr bullets at a couple hundred fps slower than factory loads and got some decent accuracy. Remington sells a "managed recoil" load for the 7mm that uses a 140 gr bullet toned way down in velocity. It shoots about 1.5 MOA in my friends Rem 700 rifle, accuracy is decent, and recoil is modest.
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Old August 10th, 2008, 03:38 PM   #4
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Sometimes it is as easy as changing the bullet weight. My .308 loves 150 gr. bullets. But the heavier the bullets get, the wider the groups. Try lighter bullet.
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Old August 10th, 2008, 06:53 PM   #5
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Interesting. Of three responses, one fellow suggests a heavier bullet. The next guy tells me to go with a lighter one. So confusing.

Still, I get the point. Some guns have a preference for certain ammo and won't shoot well with others.

Interesting that the "retired gunsmith" says the 7mm Rem. Mag. isn't a particularly accurate round. I'd always been told that it was, but then I'm no firearm expert, just a guy who likes guns and hunting.

Perhaps this should be a question for a new thread, but in addition to my specific question, what do you folks think about the accuracy of M77 Mk IIs in general? I've always liked Rugers, but there's lots on internet chatter dissing the accuracy of this particular model. Are these Rugers generally less accurate than comparable Remingtons and Winchesters?

Last edited by LawyerGreg; August 10th, 2008 at 06:55 PM.
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Old August 11th, 2008, 05:48 AM   #6
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LawyerGreg, Let's start with the cartridge. The 7mm Mag is a "belted" cartridge that is famous for long range hunting. The magnum velocity coupled with the very aerodynamic 7mm bullet provides excellent retained energy at very long distances. In the overall scheme of things, a 7mm Mag is not one of the cartridges known for inherent accuracy. A 308 Win, 300 Win Mag, 7mm-08, and 243 Win are some of the cartridges that seem to be very accurate in just about any decent gun. Not to say there aren't some 7mm Mags that are tack drivers but the norm is "hunting grade" accuracy. That means 2 to 2.5 MOA, (up to 2.5" per hundred yards). The 7mm Mag's max reliable killing range can extend to 300 yards ... that still a 7.5" group ... good enough for a typical deer sized animal with a 8" kill zone.

Now for the rifle. The best out-of-the-box factory produced rifles are Sakos. Next come Tikas ... both are Beretta products with a 1 MOA out-of-the-box guarantee. Ruger M77s are not even close and are not notoriously accurate ... but are plenty accurate for hunting. Again, there are exceptions but in general, Ruger Mod 77s are not match grade accurate and don't need to be for hunting.

Matching bullet weight to twist rate and velocity makes for the optimum accuracy, even more so at long ranges. Your 7mm Mag rifle has a 1:9.5 twist rate and favors the 175 grain bullets. It would be a freak thing if accuracy were better with a light bullet unless the velocity were reduced to non-magnum levels. I just posted a twist rate chart in the library. It shows 168 to 175 grains for 284/7mm bullets. 168 Gr for lower velocity rifles such as a 280 Rem and 175 gr for high velocity rifles such as a 7mm Mag.

For some reason, many people seem to think rifles must shoot sub MOA groups to be used for hunting. For bench rest or target shooting maybe, but for hunting, this is simply not true. M-77 are great rifles ... maybe not the most accurate but they are a solid performer at half the price of a Sako.

Bozack, Here's how twist rates work. Each bullet length has an optimum spin rate for down range stabilization. The industry doesn't use "bullet length" as a standard but they do used bullet weight. Because weight and length are pretty much proportional within the same caliber, you can use weight as a reference. You can match the bullet to the spin rate in three ways ... change the twist rate, change the velocity, or change the bullet weight. Because the twist in a barrel is "fixed", it's much easier to adjust the bullet weight and/or powder charge to match the twist rate. Comparing a .308 cal to a 7mm is apples and oranges. A 7mm bullet and a 308 bullet will be considerably different in length for the same weight and will stabilize at different spin rates. Yes, you could find a velocity where a 150 gr bullet would stabilize but it sure wouldn't be at magnum velocities.

Last edited by Iowegan; August 11th, 2008 at 06:18 AM.
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Old August 13th, 2008, 06:39 AM   #7
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The 7mag is a very accurate round. I have a Win M70 in 7 mag and can consistantly place three shot groups under an inch at 100 yards. I think you are jumping the gun by replacing the trigger and bedding the rifle. Try some different ammo. Make sure the rings are tight on the scope. Good luck.
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Old November 11th, 2008, 08:07 PM   #8
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My M77 Stainless/Synthetic will shoot 3 rounds at or under 1 inch at 100 yards with the right load. Some loads will down to approaching 1/2 inch group. I am firing off the sad bags when doing this, but the 2004 (I think), vintage Ruger Rifle I own is more than capable of good accruacy. I am also admittedly at best only a medoicre rifle shooter, and probably that is being too kind.

First thing I have to ask is recoil: The 7mm mag in my opinion produces enough recoild that I developed a flinch after only a few rounds when shooing a friends A-Bolt. Some shooters can fire a magnum rifle round repeatedly from the bench or off the sandags and not develop a flinch. I know I am not one of those types of shooters, even 20 .270 rounds of the bench will start to give me a slight flinch unless I have a shoulder fitted recoild pad on. If your other rifle is a .243 perhaps the 7mm mag recoil is jarring you during your range sessions and opening up your groups.

Or maybe that is not the issue in your case.

My rifle has ammo preferences I suspect yours does too. Firing 1 type of ammo and not getting good accuracy does not mean your rifle is inaccurate. If you are getting poor accruacy with 4 or 5 loadings with differing bullet weights loaded by more than 1 factory ammo maker then you would be reasonable to suspect your rifle has accuracy issues.

Some examples

Remington 130 gr. Accutip- The best I could do is 3 inches at 100yards. Very Dissappointing.

Remington 150 gr. CLSP- Groups hover in the 1-2 inch range with the best being a little under 1.25 inches.

Federal 150 Hi-Shok SP - Groups between 1.5 and 1 inches if I do my part with boring regularity.

Winchester 130 gr. Silvertip - Groups were between 1 and 2.5 inches with stringing from what I considered to be hefty recoild (for a .270 anyway) until I had got two brilliant .75 inch groups.

Hornady 150gr. SP - Groups at or slightly under 1 inch if I do my part very consistently.

Sierra 140 BTHP Handload- Groups under 1 inch consistently, 2 standout groups that are in the .5 inch range.

Sellier & Bellot 150 gr. SP - Groups from 1.5 to .5 inches, most spoiled groups have one shot away from the other 2 due to shooter error.

Nosler 150gr. Ballsitic Tip - Groups from 1 to .5 inches again depending one weather or not the shooter (me) gets excited and rushes the third shot.

My advice is to try a few diffrent loadings and possibly let another shooter try his/her marksmanship with your rifle before making any conclusions.

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Old November 16th, 2008, 11:42 AM   #9
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My M77 in 270 Win shoots 2-3" (or worse) at a hundred with factory ammo. The rifle just does not like a lot of powder that many of the factory rounds juice their loads up to. I worked up a load (with less powder) for it that shoots to 3/4" so I'm guessing your rifle will shoot you just have to figure out what it likes for ammo.

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Old November 17th, 2008, 06:51 PM   #10
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Ditto on everything said about bullet weight and powder. Both my M77 and #1 are real fussy about ammo. WW 150 powerpoints shoot about 3", my handloaded 150 Hornandy SST will shoot 3/4". Same rifle, same day, same shooter. Ahhhh patience, keep trying differnt ammo, clean the barrell properly, and maybe try a Timney trigger.

You want to talk about accuracy problems. I have an M1A that I spent a great deal of time (4 years) working out the issues on it. Now It will shoot 1" with many tyoes of ammo. Before it shot about 4". I was ready to through it in a lake (just kidding).

Just my opinion, but I did see a noticable improvement after I replaced the forward and aft action screws with hex head screws and then torqued the action screws to Ruger's specified torque values. Brand new, all the action screws were kind of loose (less than 20 in-lbs).

I bought a nifty torque screw driver from Midway. The hex head screws were used because you cannot torque the Ruger supplied screws very well. The hex head screws work great and look better.
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Old November 17th, 2008, 07:59 PM   #11
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A quick primer on spin stabilzation is this: The bullet needs to travel in a certain velocity range to benefit the most from the spin. Too fast, and it's zipping past the rifling so quickly that it doesn't get any traction. And no traction on the rifling = insufficient spin. Too light of a charge and the bullet is grabbing the rifling too much.
Something other than bullet weight, twist rate, and velocity, although certainly directly related is the barrel harmonic. My father has a BAR II with a BOSS on it and with a given load and bullet weight the grouping can go from nice and tight to all over the page....literally with the twist of a little weight on the end of the barrel. It's something else to consider about if you're having trouble dialing in your groups.
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Old June 8th, 2013, 06:57 AM   #12
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Reuer 77 Markll 7mm Mag.

In response to all the hoopla about the inaccuracy of the Mark ll 7mag, I have one myself and would not trade it for any other. Most guns, as it was stated earlier in this forum, are sensitive to bullet types, but are also sensitive to types of powder, brass, and even primers. I have been an avid reloader since the early 70s and have a lot of experience in this field. I have my 77 Mark ll. 7mm mag shooting 3/4 inch groops at 100 yards using Winchester cases, Nosler 140gr. Ballistic tip bullets, Federal 215 primers, and Reloader 22 powder. I also have it shooting 1/2 inch groups using all the same components except going with the Nosler 175gr. Spitzer partition bullet. I have had several Ruger rifles over the years and through hand loading have always had very good results. If a person really wants to enjoy their firearm and get the most out of it then you should load your own ammunition and custom load fot the gun it is going to be used in.
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Old June 8th, 2013, 08:59 AM   #13
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Make sure it's not your optics or it's mounts. My M77 MK2 which was built in 2006 will shoot MOA with factory ammo, and a $80 3-9x scope. Chambered in .270 win. The rest of the rifle is stock.

I'd say its the optics or the ammo. I think Ruger makes some of the best mass produced rifles on the market right now. And from what I've seen they all have at least acceptable accuracy. Ruger's past accuracy issues were because they had different manufactures making barrels for them and they were poor quality and inconsistent. That problem has been long solved, and doesn't really have to do with the barrel being "Hammer forged."
I have seen pictures of sub MOA groups with Ruger's new American rifle.
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Old June 8th, 2013, 09:30 AM   #14
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Iowegan is 100% correct with what he's saying. the 7MM Remington magnum ISN'T a very accurate round, but it is sufficiently accurate. Regardless of how accurate or innacurate a cartridge is, their will ALWAYS be people claiming a cartridge is super accurate or super innacurate! This is because they have a very limited experience, and they could easily have a rifle or two that either over-performs or under-performs when compared to the cartridges average capabilities. In order to form a balanced opinion and truly understand a cartridges capabilities, one must have shot over a dozen rifles in that cartridge and have averaged out the results; this will give you a much better idea than what your 1 Savage or your 1 Ruger did chambered in any given cartridge. For example, my dad has fired literally HUNDREDS of rifles, and well over a hundred individual hunting rifles; and he says while the 7MM is sufficiantly accurate in the rifles he's fired, he doesn't believe it is an exceptionally accurate cartridge. Has he fired incredibly accurate 7MM Rem mags? Yes. Has he fired innacurate ones? Yes.

Now, on to the Ruger M77 itself. Is it an innacurate gun? In my experience, NO! It is, however, a fussy gun which is why ity has the bad reputation for being innacurate. Many M77's just need their barrels lapped or some ammo experimentation and suddenly they're exceptable or even exceptional. I had nearly given my M77 up for dead until I adjusted the 3 stock screws and switched to using Nosler bullets, now it shoots MOA.

Last edited by trigger creep; June 8th, 2013 at 09:32 AM.
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Old June 8th, 2013, 09:51 AM   #15
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1.5 @ 50 translates to 3 @ 100 --- not good enough.

I have over 10 M77 MKII's and all of them have been epoxy bedded. I like them and they all shoot well - both accuracy and dependablility.

It appears that you use factory ammo and do not wish to get involved with loading your own or extensive stock work like epoxy bedding.

I would do:

Check to see if all action/stock screws are tight - the front screw should be as tight as you can get it using the right size driver with a thick grip. The smaller back screws should be slightly less. This will avoid bending the receiver - screws can exert lots of tension.

Check to see if the magazine box is not jammed so tight against the front screw/floor plate and rear trigger guard making the magazine box some sort of bedding feature for the action. Get a small mill file and remove small amounts of magazine box at the back and front of the box where it contacts the bottom metal so when the piece is reassembled and screws tightened up the box moves slightly when pushed around. The action receiver screws must be the primary bedding features between stock and receiver.

Check out the crown at the end of the barrel with a magnifier. Look for dings that might impact the bullet as it exits the barrel.

Try out another type of ammo. The 7 mag (I had one at one time) is no more or less accurate than most similar size belted magnums. The twist rate of the Ruger will handle bullets weighing 120 to 162 grains and some 175 grain depending on bullet length.

And -- good previous point -- swap out the scope for one that you know works.

Before you terminate ownership get a good gunsmith the epoxy bed the rifle, check out the crown, and do a trigger job.
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