7mm rem mag load help?

[Captainmorgan]

Gentlemen,

I made some rounds for my 7mm rem mag using 65 grains of reloder 23 and 154gr hornady SST bullets.
I shot 4 groups of 5 and overlaid the groups. I have 12 out of 20 within .800 and then 8 fliers/shots stretching the group out to almost 2". Take a look at attached target and overlay.

Where do I go from here to tighten up groups? Mess with jump or small changes to powder charge?

 

[imartin]

Do you have any idea how far you are from the lands? I would adjust seating depth if you are happy with the veolcity you are getting and see if things tighten up. I normally start by loading .020" off the lands and work up a powder ladder to find where you hit pressure. I usually do .3 gr increments. Look for a spot where velocity flattens out, and then load in that powder range and shoot some groups. Then I tweak my seating depth. I know some guys do it the other way finding their seating depth first. Just gotta find what works.

 

[TheBoctor]

What was your pace of fire? One good group of five followed by a bunch strung out makes me think your barrel was getting hot. If you're sure it wasn't running too hot, then what is your average FPS, ES, and SD's for that load? If those are good and tight then you need to mess with your seating depth.

 

[cajun]

You can play with the coal. I have had better luck with 140-150 gr bullets and powders a little faster. IMR 4350 and 150 Ballistic tip.

 

[Pa Grizz]

Have you checked the bullet weights I had flyers like that and check the weights and was surprised how much they where off.I found a dozen or more that were the same and my group improved

 

[Ace Quackhunter]

Have you checked the bullet weights I had flyers like that and check the weights and was surprised how much they where off.I found a dozen or more that were the same and my group improved

Great information on checking the weights. I was weighing some Berger 6.5 mm recently and discovered a couple of 6 mm in with the 6.5 mm. I would add weigh your Brass as well and check the overall length after you finish trimming.
Ace

 

[RT2506]

You did not state if this was NEW or previously fired cases. If previously fired how much are you sizing them? About 39 years ago with my first belted mag which was a Rem. 700 in 7 Rem. mag. I started out with new cases. I wanted to shoot the 139 Hornady interlock and use AA3100 powder. Best group I could get was right at 2" no matter what I did. All the time I was using the NEW cases which I would run through a full length sizer to make sure the neck was right. I thought I had a lemon of a rifle. I ran out of new cases so I started using once fired cases. A friend suggested to me to use a candle and smoke the neck and shoulder of a case and adjust the full length die so it just sized the neck and barely bumped the shoulder. The smoke area let me know how much was sized. I gave this a try and loaded up the best load I had found so far. First shot was on paper, second shot still only one bullet hole in target. I thought great now this rifle will not even put two in the target. Third shot still only one hole in the target. Forth shot still only one hole but it kind of looks a little bit larger. Shot five and still one hole but yes that hole does look a bit larger. Went to the target and BINGO. Five shots in about a 40 cal. size hole. Turned out that with a previously fired case size part way you could just about fill a case up to the starting of the neck with AA3100 and shoot any bullet from 139 to 160 gr and it would shoot bug holes. So you never know what little thing will turn a frog into a prince.

 

[twister]

when did you shoot the tight group? First?