Several years ago (maybe...7?) I bought a new Ruger MkII .243 SS/synthetic. I used this rifle for 3-4 years and it was pretty accurate. 100 gr. Hornady bullets at almost 3100 fps pushed by a full case of IMR-7828 would shoot into an inch. All the time.

3 years ago, I was using this rifle during hunting season and I noticed that I was not hitting the animals where I wanted to. I was shooting either prone or from shooting sticks, and there wasn't enough wind to make a difference. After the season was over, I checked the rifle on paper and now it was shooting 4"-5" "groups".

Of course I cleaned it thoroughly and tried it again. No change. I checked the scope and tried a different scope. No change. I checked the action screws - they were fine. I floated the barrel. No change. I tried a third scope. No change. I tried a different set of rings. No change. I had the crown re-done. No change.

So I got a Hogue stock - the one with the full-length aluminum block. No change. I bedded the action to that stock. No change. I even had the rifle re-barreled with an E.R. Shaw barrel. Now I can get factory ammo to group in the 2"-3" range usually, but sometimes in the 4" range still. My handloads (worked up for the new barrel) still group 3"-4" and I've tried other bullets and other powders.

Anybody got any ideas? I do also have a Timney trigger in it, and the trigger is excellent. I highly recommend this trigger.

Thanks to any and all for your time and suggestions.

Have you played with the bullet seating depth?

quote:

Originally posted by Snowwolfe:
Have you played with the bullet seating depth?

Yes, I have, but my understanding of varying bullet seating depth (within certain limits) is that it can make a good load great. It is not likely to make a bad load good.

Good idea, though.

I know you cleaned it but is there copper in the bore??? One of my Rugers had that problem after I took all the copper out it came right back to great accuracy

Dirt or roughness inside the bolt, or on the firing pin/spring assembly is causing the firing pin to do a shimmy shake when heading for the primer. This is resulting in erratic ignition and wierd barrel vibrations. Clean it out, and pray it was something this simple.

Second thought is that one of the bolt lugs got severely gauled and there is now a less than ideal bolt to barrel alignment.

Elkman2 - Yeppers - cleaned it all the way down. Got some CopperMelt back when it was still in production and that took it ALL out.

308Sako - I'm pretty sure, but not absolutely positive, that I've taken the bolt apart and cleaned it, but I will defnitely do that next. Also, I'll check the bolt lugs. I have closed it on a few tight rounds, but nothing I needed a hammer for. Would galling like that be plainly evident or something only the trained eye would see?

Thanks guys - I really needed some new ideas. All others are welcome.

More than half the times I see a rifle goes inaccurate, it is the mount to receiever screws are loose.

Take the scope and rings off and tighten the mounts. Put the scope and rings back on.

The reason it goes undetected is the rings are tight on the scope and tight on the mounts, and .002" movement cannot be felt.

I think the scope bases are built into the action.

quote:

3 years ago, I was using this rifle during hunting season and I noticed that I was not hitting the animals where I wanted to. I was shooting either prone or from shooting sticks, and there wasn't enough wind to make a difference. After the season was over, I checked the rifle on paper and now it was shooting 4"-5" "groups"

Is this about the same time you quit drinking?

I think the best thing to do is have the smith who rebarrelled it go over it with a fine toothed comb. At this point someone needs to look at it. How do the groups look- Like a shotgun, stringing horizontally or vertically?

Have you tried Sierra Matchkings in 107 grain by any chance?

Hello JLarsson,
Noted you changed most everything, not sure the Shaw barrel being one of the better changes, but think you said it did shrink the groups somewhat. Generally when you have such a magnitude of change in accuracy, first thing I would put under close scrutiny would be the bedding. Ruger Model 77's have a bit of a history not being easy to bed correctly even with the bedding block you mention. Do you have slotted screws for the action?? They work OK, but suggest you purchase allen head action screws, obtain inch/pound torque wrench and torque to some 55-60 in/lbs doing front screw first, rear screw last. It has been a while, but believe your rifle has a middle screw for the trigger guard and if so, snug just enough to make sure it does not work loose. If that middle screw/fastener is over tight, it will mess up the accuracy and can do that as well in a Win. Model 70. I am only suggesting the torque setting as a starting point and you may find improvement or lessening of accuracy with changes in torque. ( Take torque wrench to the range with you and experiment. )
Do you still have the original barrel?? If so, find someone with a Hawkeye Borescope and inspect closely. Not sure how many rounds you have through it, but if used for normal hunting number of rounds would not be that high. That caliber will eat barrels to a degree and if you have 1500 plus, would guess the throat has erroded. A set back would cure that for a while, but doubt you want to go back to the old barrel, just a thought. Are you getting a lot of copper (blue on patch) from your current barrel?? Check it with the Hawkeye and believe you will be somewhat shocked. A complete lapping job will help if it appears rough down the bore.
If loads are ones that has worked in past, trigger fine, new barrel, no change in bullet weight, sight system OK, no drastic change in loads, etc. etc. it does not leave much other than the bedding. I am sure all of us would be curious as to what you eventually find out. Only as a suggestion, should make one change at a time in order to sort out the problem(s) Good Luck

Snowwolfe is right - Ruger MkII - mounts integral with receiver.

Mark - I'm not a drinker, but this rifle might change all that. lol Groups are roughly circular. I haven't tried the Sierra MK 107's. Might be good with the new barrel.

Driver - I DO have the allen head action screws, but no torque wrench in in-lb's. You are right about the middle screw, and I've always tried to make sure it's barely there. My sequence has been to tighten the front screw as tight as I can reasonably make it, then tighten the rear screw securely, but not as tight as the front screw, and finally to tighten the middle screw enough - as you say - so it won't fall out.

Not too much copper in the new barrel. One thought I had was that maybe the new barrel just needs "shot in" some more, and I suppose lapping would accelerate that.

I sure appreciate all the suggestions. I'm going to work through these some more. It was just such a shocker when the accuracy fell off so dramatically and all at once. I had a Mossberg .243 once that would shoot into 3/4" all the time. One late season deer hunt, I had it slung over my shoulder as a light snow was falling. You guessed it - next deer I saw, I leveled the rifle on her and....missed her clean. Threw another round in the chamber and nailed her. Got the gun home and examined it and about an inch in from the muzzle was this shadowy little ring. I was getting about 6" groups after that. I had the barrel cut off short of the ring and re-crowned and it went back to shooting under an inch. I'd like to think I've eliminated the barrel as the source of problems here, but with Driver's comment about the E.R. Shaw barrel, maybe not.

One more note - I did bed the action to the Hogue stock using Acra-glas, mostly to firm up the contact in the rear. With the front screw tight, there was about 1/16" gap between the rear of the action and the top of the pillar. When I bedded it, I tightened the front screw fairly tight, and just tightened the rear screw until I saw the rear of the action barely start to move.

Thanks guys!

If the tang is sticking up when the front screw is tightened, it will definitely be in a bind when you tighten the rear one-not a good deal. This would be a bedding problem.

quote:

Originally posted by jstevens:
If the tang is sticking up when the front screw is tightened, it will definitely be in a bind when you tighten the rear one-not a good deal. This would be a bedding problem.

Exactly. And this is what I was hoping to solve with the glass bedding by making sure the front was snugged down and then the rear has a good pad of acraglas atop the pillar to make it stress-free (hopefully).

I WILL say that the contact of the action on the front of the bedding block is almost perfect. Really an excellent fit. Now, with the bedding, the rear is good, too.

So....I keep trying. Some good suggestions so far.

Well, if everything was changed except the action, then it must be something like a bent firing pin, galled(or cracked) lug, or something really dumb, like a stock screw too far into the action and bottoming out. Put some magic marker blacking on the firing pin, and bolt lugs, to be sure both lugs are bearing. Look for rub marks on the firing pin, and the ends of the stock screws.

I'd revisit the ringmount idea. Just because they're the Ruger integrals doesn't make them immune to loosening - though changing your scope probably accomplished that.

My Rugers were/are sensitive enough to torque that I bought a $30 beam-type torque wrench made by Park for bicycles. I think I now have the main screw at 50 inch-pounds. Noted improvement over 30, and it loosens less than when set at 40. At 60 I worry about crushed wood.

Did I miss comments about the fore-end tip? If there's a hump there, I glass them in to stabilize. That has almost always shown improvement for me, and if that isn't enough improvement, it's easy enough to free-float. (I do it in that order since it's easier to remove glass than to build it up where it isn't.)

Jaywalker

Not to be a jerk, but when the problem is so elusive, why not rebarrel to 308 and call it a day?


Okie John

More great ideas. I really appreciate the time and help, guys. Life is crazy right now, so I'm able to talk about it more than I'm able to actually work on it, but you can bet I'm printing this whole thing out and I'm going to go over the whole thing again, start to finish.

The barrel is free-floated and I'm starting to wonder if it actually needs a little forend pressure. Not quite sure how to accomplish that on the Hogue stock, but I've got a couple ideas.

Okie John - Not being a jerk at all. If I do that, I'll probably pick 7mm-08, but I like it as a .243 and I've got a new barrel on there, though apparently not the best I could have chosen, lol.

JL, Lanny has a point I forgot to mention, the potential for an action screw to be doing more than it's original intended function... bearing on the lugs can happen. Look for this in the form of scratches on the outer face of a lug, not a bearing surface. If the lugs had gauled to any extent you can see it with your eye. Also there is a remote chance that only 1 lug is bearing at all. Put a marker on the bearing surfaces and fire a round, then inspect the lugs after the one shot. Now make a list of evrything which has been done to the rifle, and add up all the expense and time... This is called "tuition at the college of hard knocks!" Hope this helps.

308Sako - Yeah, I figure by the time it's all over, as long as I work it out, I'll have learned a lot. Actually, I'll have learned a lot either way, but watch for a bent barrel on the classifieds if I don't.

Hey Jon, You have done so many different things to the rifle without seeing any improvement that perhaps the problem isn't there.

For grins , let's believe there is nothing at all wrong with the rifle or the Trigger Yanker and focus on the cartridge.

Though IMR-7828 may have worked fine for you, it would not be my first choice for accuracy. The powder I'd like to recommend is no longer made - H450. But, there is nothing wrong with H4831 and H1000 for the heavier weight 0.243" bullets. I use a very long Drop Tube with the H1000 to get in what is a SAFE MAX Load in my rifle.

My recommendation would be to put the highest power scope you have on the rifle(14x-20x) and use enough ammo to get sighted in "close to center" at 300yds. Clean the barrel. Then run a Load Development series using the never improved upon Creighton Audette Method. Use the IMR-7828 as one Test if you desire. Try the H4831 in another Test.

Fully Prep the cases, weight sort and use BR Primers.

Use 100gr Sierra MatchKings or Nosler Ballistic Tips to Benchmark the rifle. The idea is to see what accuracy the rifle is actually capable of attaining. You can switch back to the Hornady bullets later on.

Seat the Bullets 0.005"-0.010" Into-the-Lands and watch for all the usual Pressure Indicators. If you are familiar with CHE/PRE, check that as you go along.

Don't worry about Velocity, because it is irrelevant anyhow. Focus on your shooting technique and shoot between heartbeats.

Shoot at the corner of a Black Square not a circle.

Those Tests should provide "Clusters" of 3-4 shots at a Powder Level where the Bullets are exiting at an Apogee or Perigee of the barrel Harmonic.

If you find the Harmonic Clusters, re-run the same "complete" Test(not just swapping in the Hornady) using the Hornady Bullets and see how they do.

Then re-shoot around the Harmonic Clusters and Fine Tune the Load by varying the Seating Depth

If you don't get good results with the 100gr Bullets, you might want to try a slightly different weight bullet. I've used a bunch of different brands and weights in 243Wins and had equivalent performance from all of them. My current Bullet of choice is the 90gr Speer Hot-Cor, but each rifle is different and yours might not like them at all.

Best of luck to you.

Hot Core -

Well, that certainly seems like a reasonable process in trying to establish if the problem is with my loaded rounds. The fact that factory rounds tended to group a little better would support the idea that perhaps it's the load.

"CHE/PRE" - Case Head Expansion/Pressure Ring Expansion? I do know a LITTLE about that, but not much more.

Thanks for the ideas about which powder(s) to use, also. IMR-7828 did work well before, but that was with the original factory barrel, so everything is different now. Hmm......Well, at least I can still use the 7828 in my .300 Weatherby.

I'll give it a go when I can. I appreciate the help.

Hey Jon, Check your PMs.

By the way, IMR-7828 may end up working better for you than anything else. Just because it didn't do as well in "my" 243Wins doesn't mean a thing when it comes to your rifle.