Worked up a pet load for my 300 WSM but with limited powder also shot Hornady CX, Federal TA and Norma Bondstrikes out of my Browning Mountain Pro X Bolt. Here is my question: My handloads and the 3 factories all had the same POI at 100 yards but here is the catch: In all 4 loads: 2 of the shots (3 shot groups) would be 1/2 inch but all of them had a slight flier about 1 inch from the 2 that were together. I let the barrel cool between each 3 shot groups. Opinions on why this happened? TIA
Opinions on groups
- Thread starter Pineman
- Start date
- Nov 4, 2004
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The seating depth needs to be tuned to your rifle. Maybe try seating your bullet .010" deeper. Repeat if necessary.
It should tighten up your groups.
JD338
It should tighten up your groups.
JD338
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- #3
xphunter
Handloader
- Sep 15, 2005
- 1,092
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Even with factory ammo you can play with seating depth (Deeper at least)
If you have a inertia bullet puller, yes you can tune a factory cartridge. All you need to do is move the bullet forward first, then seat to your desired length from there. Done it before. All you're doing at that point is seating a bullet in a powder charged and primed case, same as in reloading. You want to go forward first to relieve any excessive grip such as a factory crimp that might of been utilized in the factory loading.
Not sure I'd trust them in any and all circumstances without putting a crimp back on them with something like a Lee factory crimp die, to ensure there is enough, and equal neck tension since the bullet was forced to be freed up by moving it forward first, but it will let you know if seating depth can pull in that flier.
If it's seating depth, more times than not 2 together and 1 out can be tightened up by going shorter. Not a guarantee, but if it was me I'd try shorter first whether trying it on the reloads or the factories. JMO.
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- #6
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So I went and measured the 4 different brands of ammo that I was having the issues with. Of course they are all slightly different in length. If I understand correctly from the above comments: try to seat the bullets .01 shorter for each brand and go and try groups again. Am I correct in this assumption? TIA
This is somewhat a matter of opinion so if others would disagree it's not like they'd be concretely wrong, but to me .010 is leaning towards the side of fine tuning. To me if I had a consistent flier and that flier was making an otherwise say 5/8" group a 1.25-1.5" inch group I'd take a bigger swing at it to try and instantly see a noticeable improvement or detriment. .020-.025 is what I'd do minimum. Depends how much ammo you are willing to test. I tend to try and move big enough that I can see I made a substantial difference then try .005-.010 on either side once I'm getting close.
To me if .020 is way too far the other way on a rifle/load that isn't behaving, then I need to figure something else out with the rifle. I don't want to deal with a combination that .010 past takes me from where I needed to be, to junk.
Also, I re-read your original post. Not familiar with the rifle in question, but the words "mountain pro" in the model suggests to me it's lightweight with likely a lightweight thinner contoured barrel.
Before you go to the work of what's been discussed so far I'd check some things. Strange things happen, so nothing is impossible, but it's not every day that 3 different factory loadings and a handload would all display wanting to shoot but having a flier mixed in, and the reason would be the seating depth is off on all 4 types.
Make sure the barrel is free floated as it should be all the way back. It probably is, but check. If it's a light barrel, make sure the rifle is being supported on the front bag well to the rear. Preferably back at the recoil lug or close to the magazine. You want to eliminate getting some barrel slap mixed in on some of the shots.
Just a suggestion. Seems very odd you're getting the same results (a flier mixed in on an otherwise good group) on 4 different types of ammo.
Before you go to the work of what's been discussed so far I'd check some things. Strange things happen, so nothing is impossible, but it's not every day that 3 different factory loadings and a handload would all display wanting to shoot but having a flier mixed in, and the reason would be the seating depth is off on all 4 types.
Make sure the barrel is free floated as it should be all the way back. It probably is, but check. If it's a light barrel, make sure the rifle is being supported on the front bag well to the rear. Preferably back at the recoil lug or close to the magazine. You want to eliminate getting some barrel slap mixed in on some of the shots.
Just a suggestion. Seems very odd you're getting the same results (a flier mixed in on an otherwise good group) on 4 different types of ammo.
George Foster
Beginner
- Dec 4, 2005
- 225
- 85
I have found my bullet touching the lands oal first and then started 0.10 off the lands and worked deeper. I have as a general rule 0.50 to 0.60 off the land lots of times to give the best accuracy.
George Foster
Beginner
- Dec 4, 2005
- 225
- 85
There are those who suggest trying, 0.10,0.50,0.90, and 0.130 off the lands, they say one of those will likely be the best.
