300 winchester mag w/ 220 MK

[Mongo]

Hey Guys,

After sending 100 rounds down range, taking a beating and loosing barrel life, I figured I could use some help or a new direction.

Shooting 220 MK Sierra,or at least trying to) in the following:

- Remington short action,yep, short action) trued, etc.
- Hart 1:10" twist 29" barrel
- rifle basix trigger at approx 8 oz
- F class stock by Carl Bernosky/bedded/pillars etc

I have loaded 69 grs. H4831 up to 71.5 grs in .5 grain increments and shot multiple 3 shot groups with each.... only one or two which grouped less than 1/2",at 100 yards)... most are wildly grouping at 1.25" + . The 1/2" groups seem to be more of a fluke than the norm. Maybe one good group and three bad at a given load. No real consistancy sen.

Starting to see pressure in the primer at about 70 grs, and a little snap in the bolt lift.

Is this bullet too heavy for the twist and 300 Win ? Should I look at 190 MK, or maybe 210 Berger ? Or, go higher with the load ?

I realize I'm a slow learner, but I guess I couldn't believe that any of these loads weren't working so I just kept sending them down range... agh...

Any ideas would be welcome.

Thanks,

Mark

 

[tsiero]

Were the two 1/2" groups close in charge weight? I would shoot 5 each of the 1/2 charges out at 300 + yards. I don't think you are building a 100 yard gun.

 

[wnroscoe]

Try either the 210 Bergers or 200 SMK's. The 220 is at the limit of the 10 twist IMHO. Retumbo, RL22 & 25 are good powders also I7828 is good in a 300WM. Try two shot groups at 200 yards for your initial development, your just weeding out what doesn’t shoot. Either Dave Tooley or Bruce Baer uses this method on their heavy 1K rifles, less barrel wear and less components used, they say that if the first two arent in a hole, the third wont make the group any tighter. Start at +.010" n the L&G's, F215 or F215M primers.

 

[M700]

Didn't Kent Reeve use a Mauser in .300 Win mag & 220 SMK's to win the 1000 yard LR prone match at Camp Perry, summer 2006?

Guy

 

[mattdienes]

Get some 210 bergers and some H4831sc and 210m,if you have any) and start around 68gr to 69.5 and put bullets touching the lands go to 200-300 yards if your rifle doesn't shoot this load,well, you have some problems.
If it does,start tweaking the seating depth by going in .010 and out to .010 until you see the vertical go away,and 3-shots is plenty when tring to find a load,when you are close then go to 5-shot groups.

 

[Nucum]

Lapua brass! I had nothing but trouble with my .300 Winch. The one thing that made it work, was when I swithed to Lapua brass. Now it likes 190s & 210s with Reloader 22.

 

[Mongo]

I really appreciate the advice.

I've been at this only a year, learned alot and I realize sometimes I'm slow to see the forest thru the trees.

More details:

- Remington Brass, neck turned to clean up
- Federal 215M primers
- 220MK seated into the lands, probably 5 thou +/-

Here's a better report on the groups. After sorting thru them I think it looks a little better than my original despair. I am measuring the outside edge of the holes and subtracting .30" for group size, I assume this is a reasonable technique:

69.5 grs.
-,5) groups of three shots:,.8", .7",.6",.7", and 1.3") all have vertical... looks like triangles

70 grs.
-,2) groups of three: .55" and 1.1" triangle like with both groups

70.5 grs.
-,3) groups of three: .8", .6", 1"

71 grs.
-,3) groups of three: .3", .4" and 1.25",but this one is purely horizontal)

71.3 grs
-,3) groups of three: .25", 1",w/vertical), and .8",mostly horiz.)


After the first firing of the brass I only neck sized, and kept close eye on the headspace with a Redding headspace gage that uses the dial indicator. I'm working 30 pcs. of brass; Yesterday's loads were the 71 and 71.3 grs in which the brass was sized in a FL Redding bushing die. Near as I can tell I am keeping the headspace on the shoulder by using the Redding gage and comparing it when sized before/after..

Should I work the 71 gr load ? Maybe tweak jam length, or ?

Is the 215M primer the way to go, or.. ?

What do you think I'm doing to the barrel with these types loads ?

I plan to step up to Lapua brass shortly.

Thanks again,

Mark

 

[mattdienes]

Just remember,change only one thing at a time!otherwise you'll be chasing your tail.
Try changing primers 215m to 210m do your test, find what works and then tweak the seating depth.
note- maybe try slowing them down a bit.
Also, try to keep your brass sorted,meaning the number times each has been fired,this will make you pull your hair out.
The 220 is a good bullet!BUT there are others,if it is not working try a different bullet.

 

[tsiero]

Matt,

This is tsiero and back from the range today after taking your recommendation. I have a HG that was owned and competed and built by Bruce Baer. It is now a 300 Winchester. I loaded 66.0, 67.0 68.0 69.0 and 70.0 loads per you recommendation in Nosler cases. I had 5 sighters in 68.0gr of H4831 also. At 200 meters the 3 sighters went into .75". For the test the 66gr loads shot .4 and the 67gr loads shot .20" for three shots. I stopped testing. The best I shot with this gun was 5.5" with Sierra 200gr MKs at 1k yards for 5 shots. I am shooting that load at Tucson next weekend and will report.

Thanks

Ted Sierocinski