Author Topic: Win Mod 70 300 Mag WOES (Read 751 times)

BABore · « **on:** March 29, 2004, 08:33:17 AM »

I need some ideas or help on a Winchester Model 70 Super Grade in 300 Win Mag. I bought the gun about 5 years ago for $300. Figured it was a steal. Now I'm not so sure. I'll give a brief history of my struggle.

- Overall the gun was in good shape 95%
- Barrel had a lot of copper fouling. After days of hand cleaning gave up and bought a Foul Out system. Took 16 hours to get to bare metal. Lots of copper and powder fouling, just a touch of rust between layers. Cleaned bore was not pitted, good throat, factory rough.
- Worked up starting loads with new brass. Tried (3) different 180 gr bullets and (3) suitable powders for (9) different loads. All brass was sized, trimmed, deburred at both ends, then segregated by weight +/- 2 grs. Bullets seated 0.010 off lands with Stoney Point gauge. Throat seems pretty long.
- Shot (3) 3-shot groups with each load. Showed some bullet/powder preference, but groups were'nt consistent in size, shape or placement. Shrugged it off to small sample size. Necked sized fired brass and reloaded with most promising combinations. Loaded (9) rounds of each load, increased powder in 1 gr increments til book max.
- Again shot (3) 3-shot groups with each set. Found max charge with each set. Groups showed some charge weight preference, but again had small group followed by a large one followed by a small one. Hot barrel or cold barrel didn't show a pattern. Noted a tight group with the next stringing horizontal or vertical.
- Went home ticked. Looked at bedding/stock pressure. Found factory bedding at recoil lug was causing pressure on one side of barrel. Barreled action was twisted in the stock.
- Fitted the stock with brass pillars. fully bedded action and barrel channel. Free floated barrel.
- Best loads shot better, but still no consistent grouping.
- Added 6 lb pressure point in forend. Same thing.
- Fully bedded barrel. Same thing.
- My latest set of (3) shot groups were as follows
1.00" stringing vertical
2.25" stringing horizontally
3.50" nice large triangle
1.50" triangle with horizontal stringing.
Groups showed a tendency to walk around the bullseye. Some on the mark, some right, some left.
- In all of my shooting the barrel was cleaned every 12 shots, then a couple of foulers. Always watched the barrel temp.

- The muzzle crown looks fine, but hasn't been redone. The case neck runout, on a fired case is +/-0.0005.
- My limited experience says bedding problems or something else flexing. Have tried (3) scopes and (2) mount/ring setups.
- Would like to see if I can make this rifle shoot before I go to the expense of a new barrel and action blueprinting.

Please help, I'm running out of ideas. Might check the lug engagement tonite. Never done this before. If the contact is limited, How do you lap the lugs?

gunnut69 · « **Reply #1 on:** March 29, 2004, 11:00:12 AM »

You've done all the right things but haven't found the bug. Check to be certain the magazine isn't touching the action in it's recess. It's OK to touch on the sides but it must not bottom out in the relief cut in the receiver. Re-doing the crown may help, but I'm inclined to believe the action is flexing or is flexed and is causing the problem.. You may also check the fired brass, before sizing, to see if the case head is square to the centerline of the body. Spin the case on centers and check for casehead wobble. This would indicate the bolt is not bearing evenly or the chamber is not cut square. You must also face the fact that the bore may be so rough that as it fouls the accruracy rises and falls..

Coyote Hunter · « **Reply #2 on:** March 29, 2004, 01:14:02 PM »

BABore -

You didn't mention checking the screws that hold the bases on or ring screws either. Nor did you mention trying a different scope.

You might try firelapping the barrel, sounds like you have nothing to lose.

Also, how is the trigger?

sabotloader · « **Reply #3 on:** March 29, 2004, 05:14:32 PM »

In my limited experiance - I am leaning at the one thing you indicated you have not done - I know for a fact the crown can cause one heck of a problem and what you looking at really sounds like a crown problem... It isn't a HUGE problem but a big enough problem. You have done all the things that I would have done.

Another alternative if you have the proper equipment is to shoot the barreled action - minus the stock, but you know I think your problem would still exist - back to the crown....

Might give this guy a call he builds competition rifles from the ground up. He is a real personable guy and rates are great... He gives advise free.

http://twilightsystems.com/

BABore · « **Reply #4 on:** March 30, 2004, 08:12:35 AM »

Thanks for the advise guys.

Gunnut69: The magazine does touch the sides of the action cutout, but it does not bottom out (0.100 clearance). Checked the fired brass for the case head not being perpendicular to the long axis. It had +/-0.0005 runout.

I did blue up the lugs and closed the bolt on a fired case. One lug showed about 50-60% engagement. The other lug showed 30-40%. How do you go about lapping them, and do you think it's necessary. I also stopped at the local (Good) gunsmith. They were convinced that I should fully bed the barrel channel. I originally floated it. I then tried it with a couple thickness of electrical tape over the full floated area. (I was out of release agent) Is it true that you can use paste car wax for a release agent. If so, that's my next step. The gunsmith looked over the bedding of the action, lug area, channel, and the pillars that I installed. Said it all looked ok, just fully bed the barrel

Coyote Hunter: As per my original post (3 scopes & 2 mounts). Yeah, I always check the screw length. Been burnt only once. I adjusted the trigger a while back. Three pound, no creep or overtravel.

SabotLoader: I looked the crown over, and had the smith look it over today. It appears to be fine, but its on the list.

sabotloader · « **Reply #5 on:** March 30, 2004, 09:01:23 AM »

Just another thought that you have probably covered - Barrel throat erosion, the 300 can do that pretty easily also becase it is an overbore. If the throat is eroded it cause the bullets to get into the lands slightly off-center?

BABore · « **Reply #6 on:** March 30, 2004, 01:25:44 PM »

That could be a possibility. I guess I really don't know what a bad throat looks like. I do know that I have to seat the bullets a long way out to be 10 thou off the lands. This didn't overly concern me cause I have to do the same thing on a few other rifles too. My Bulberry Encore bbl in 338 has a really long throat and its new. Can the throat be properly checked without a bore scope?

sabotloader · « **Reply #7 on:** March 30, 2004, 04:35:43 PM »

yes, I believe it can be mic'ed... the only reason I bring that up is because of your description of the original condition of the barrel and the amount of copper fouling you described. If that barrel became somewhat restrictive it would accelerate the erosion of the throat also. I am really not a good enough source for this - I read your posts, see what you have done and think what I would do next...

These are just shots in the dark for me, the crown, the throat

rickt300 · « **Reply #8 on:** April 03, 2004, 02:44:30 AM »

I had similar problems with a Winchester Black Shadow in 500 Win mag. Wasted 60 dollars worth of Nosler partitions and it turned out to be the scope that came on the rifle as it was sold at walmart.