Home Forums Hunting & Shooting Gunsmithing Help with accuracy problem

I am at my wits end with a rifle I built about 2 years ago. It consists of Rem mdl 600 action, Pacnor bbl and High Tech stock. The caliber is 260 Rem. I started off with a PacNor prefit bbl, staineless supermatch, 1 in 8 twist 3 groove, #1 conture. After fitting it myself (not my first by any means :-), I glassed it into the stock and spent around 100 to 125 shots in load development. Best it would average was around 1 1/2" for 3 shots @ 100 yds. I tried pressure points and free floating but did not make much difference in accuracy.

Finally gave up and contacted Pacnor who graciously offered to inspect the bbl and action. After a short period of time I got the bbl'd action back from Pacnor with a letter stating that they had trued the action and replaced the bbl. I re-bedded the action to the stock and proceded to fire around another 100 rounds in testing only to still get the same dismal results of 1 1/4 to 1 1/2 inch groups. They were fairly consistent in that they always had 2 shots together and 1 flier that opened them up. Thinking I may have done something wrong on the bedding I took it to a "pro" who bed it again. This time the groups opened to a solid 2"! Took it back to him and he suggested that it must be in the metal work so we pulled the bbl off and the action runs true in his lathe and bbl threads look superb. Locking lugs look to be bearing evenly and around 85% contact. I left it with him as he suggests setting the bbl back and rechamber to eliminate the .015 of boltnose end clearance but I really don't think it is the problem.

BTW I started off with a NIB 2.5x8 Leupold and have tried 2 other known good scopes on this gun. Fired cases have less than .001" runout so the chamber is good. Using a borescope shows no flaws in the bbl and a well centered throat. At one point I thought maybe I had ignition problems so I replaced the firing pin spring to no avail. I hate to give up on this little gem as it carries and handles great but I cant live with it's lackluster accuracy. Anybody have any ideas on what could be the hang up with this gun?

Thanks,
Tim

Can you add something about your reloading technique/process. If there is nothing glaring in the way you reload, you might have to try full length neutral bedding. There might be too much vibration going on. Maybe I missed it, but how long is the barrel?

Chris

Your right, I forgot to mention bbl length is 23". Don't think there is a problem with my loading process as I load and shoot calibers from 17 CCM on up to 458 lott and have not had accuracy issues like this with anything else. That said, ammo was loaded on RCBS rochchucker with RCBS dies. Cases were FL sizedusing Redding competition shell holders to set the shoulder of fireformed case back .001" using the +.006 shell holder. Powder charges weighed to 1/10th grain. Loaded ammo runout .003" or less.

Have not tried the full length bedding as I have had issues with that method in the past. May give it a try though, you never know what will work!

Thanks,
Tim

What bullets and weights have you tried, powders and bullet seating depths?

Buy a box of factory ammo and see what it'll do. Hows the trigger? No magazine box binding? You sure the scope mounts and bases are good? Scope base screws bottoming out?

All good suggestions and all tried already. I have tried 100 gr. partitions and B-tips, 120 B-tips, 129 Lapua HP, 129 Hornadys and 140 Hornadys. Have mostly stayed with Hunter for powders but have also used Rl15, varget, H414 and AA 3100 with the various bullet weights. Seating depth has been 2.810 to fit mag box. I have also tried a box of Rem factory 140 gr. and they shot horrible! Trigger breaks at 2.5 lbs. Mag box is well relieved, was the first thing I checked. I have even tried shooting it without the box installed, no diff. Scope bases are weaver 2 piece with the individual screws fitted to not bottom out on bbl or bolt then locktighted in with blue locktight. Rings are PRW Leupolds.

Thanks,
Tim

Sometimes light rifles like this one are very sensitive to hold and/or technique. Often they have to be held and held consistently. Just laying the forarm on the bag lets the thing jump around too much. Remember, there is always a certain amount of rifle movement prior to the bullet exiting the barrel.
Another tip is to set your trigger with more overtravel. I was given this advice related to rapid fire shooting but it may be applicable here as well.
The only other thing I would do as regards the rifle would be to shorten the barrel by a couple inches. When it comes to accuracy, skinny isn't usually good; long and skinny is worse. GD

I have experienced similiar problems, especially the two shots close togather and always one flier.

I never did determine the cause, but a new barrel fixed it. It might be that your barrel is never going to do any better regardless of how it is bedded. If there is something wrong with the metal parts, no amount of bedding and/or rebedding is going to help.

One suggestion. Let the gunsmith set it back and rechamber, and re-crown at the same time. If this doesn't work, you might see if Pacnor will replace the barrel. Based on my experiences along the same lines, there is something, somewhere, wrong with the barrel.

Good suggestions...........I'd also support the comment about bench technique, very important on LW barrels.

I'd also suggest firing 2 shots, let the barrel fully cool, then fire 2 more shots and see if the group tightens.

With really light barrels (on hunting rifles), I'll rarely fire more than 2-3 shots w/o cooling.

I've also had best luck on light barrels, with neutral barrel point bedding. Almost NEVER have I had a really light barrel shoot its best floated.

MM

Pac-Nor states that the 3 groove barrel raises pressures over the 5 groove configuration. Maybe not the problem but it is the one variation over "factory" rifles. That light contour and fast twist may not be happy with the 3 groove configuration. I have just tried a Pac-Nor polygonal barrel (more like a 5R than true polygonal) in .223 Remington, and found it very accurate, as is their standard 5 groove. Just a thought, guess, hunch - hell I don't have any idea. My Winchester M-70 Featherweight in 7mm Mauser never shot any better, even after all the bedding tricks, trigger adjustments, and incantations. It'll kill a deer, and that's about all I expect now.

The guys above have excellent advice.
I'll just throw some more ideas up against the wall, and maybe some with work for you. It's difficult to work a problem from afar.
I'm now weight sorting all of my brass, for every chambering.
I seat all my bullets for every chambering with Wilson seaters, or custom made seaters like Wilson's.
I work VERY had at the bench with my shooting technique, making sure every shot is made with the same hold, sight picture, and follow through. I use good bench equipment, a Bald Eagle front rest and rear cordura bag. I shoot with a scope level for load work. In testing with light weight sporters, I MAY have to reposition the stock forend on the front rest to find the sweet spot; some rifles shoot better with the front rest close to the receiver.
I use a 20x scope for load developing. It works.
I have good triggers on all of my rifles.
I start load developing with bullets seated .010 off the lands; that's the seating depth I used benchrest shooting, and it seems to work now as it did them. If the magazine won't allow for that seating, I go with the mag length LATER, after finding the best load. So far, accuracy is about the same after seating bullets deeper so rounds feed thru the mag.
With a good rifle, I start load checking with known good bullets, and powders with powder charges about 2/3 to 3/4 up from min to max charge. It seems to work, and when I find a load the shoots, I refine that load (powder charge) from there
I clean the barrel after 20 shots.

I'm out of ideas..LOL

Good luck,

Don

Thanks for all the ideas. It just may be bench technique. I have several other "fly" weight rifles (338 win, 6.5-284, 240 wby) that shoot fine for me but none of them have quite this light a bbl. When I get it back from my smith I will work on technique. I am also going to try the full length bedding idea, maybe what this gun needs!

If neither of those pan out I plan to shorten the bbl to 18" and see if that stiffens it up any. Unfortunately my gut tells me that WranglerJohn may be on the right track. I have several PacNor bbls two of which are 3 groove. Those 2 have been the most problematic accuracy wise of the bunch. I have noticed that they show higher preassures at lower velocities than a std 5 or 6 groove bbl does.

Don, I feel strongly that this is mainly a rifle problem and not so much an ammo problem. I have used the loading methods you talk about for some of my varmint and target guns but in this case all I want is MOA accuracy. Did not feel it would be needed for this level.

Thanks for all the ideas so far guys,

Tim

I feel your pain. I had a Remington Model 7 SS in .260 Remington with a 20" barrel. Brand new silver Leupold 2.5-8 scope. Never got that gun to shoot better than 1 1/2-3" groups. Like you, I tried a lot of different things (not as many as you though). After 2 years, I finally gave up. Took a killing and traded it off. Had a friend who had a .260 Remington;shot hundreds of different factory rounds that shot patterns, not groups. He dumped it too. I think the caliber is one of the most overrated I've ever seen. Good PR by the gun mag writers. They continually say how the Americans never warmed up to the 6.5's. Wonder why. If I ever tried a 6.5 again, it would be the 6.5 x 55 Swede.

That I gotta agree with that..........too many really good proven cartridges on both sides of it that will do as well or better to waste time, effort & money.

Not the 1st time 260 woes have come up.............

MM

What size bullets are you using? I just wonder if the 1-8" twist may not be the cause if the bullets are too heavy or too light.

I would have him cut a new crown first. Skip the chamber work for now and test it with a recut crown.

If that does not work bring something to the range to try a temporary shim(s) for the bedding.

I don't buy any of the talk that the 260 is a problem cartridge accuracy wise. Its just another piece of brass with dimensions that are similar to other accurate cartridges.

Lets see some pictures of those groups.

Talked to my smith yesterday and he has the action trued and bbl set back and chambered. Bedding is curing today. I will pick it up on Wed if everything goes right. I will try it the way he kicks it out then if it still is not fixed I will cut the bbl and recrown @ 20" (from the 23" it is now).

TheWarrior, I do not have any targets saved but I will save them from this next go around of testing.

Tim

trcuda, I have the same problem with a Brown Precision High Country Custom 7-08. Two shots and a flyer with numerous types of ammo and bullet weights. I am the second owner and the first could not get it to shoot either. The man that built the gun says he build his guns to shoot 3/4" but this gun has never done it with factory or reloads. the gun is now at HCR being bedded to see if that will make a difference.

The first thing I'd suggest is trying a new seating die. Perhaps your seating die is causing runout on loaded rounds, it's certainly worth a try.

If that isn't it, and with two barrels on the same action causing problems I'd figure there has to be something wrong with the action. It could be stress imposed by the magazine, something with the trigger housing, perhaps even a small crack somewhere. Perhaps the d/t for the scope bases is causing some stress when the scope is cranked down.