Vertical groups

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Last winter I bought a rifle from a friend, it is a m38 Cooper in 218 Bee. I have tried working up a load but haven't found one I liked. It would give groups of about 3/4 to 1 inch. The groups didn't really have any particular shape. Not very impressive and not what I believe the rifle is capable of.
Yesterday I tried a load using 45 gr hornet bullets and 4227 powder. I started at 11 grains and then went to 12 gr and 13 as well. All of the groups were vertical and the 13 grain group had about 3/4 inch of vertical and about 1/10 inch of horizontal.I have used 4227 with other bullets and not gotten groups that were anything to write home about.
Now I understand that inconsistent ignition can give verticle, but I have used this powder and primer combination before and not seen this problem.
Could it be an action torque/bedding problem?
Could it be I finally found a good load and now other problems are starting to show up?
Any ideas?
 
Oal will change the vertical stringing play around with .005" changes and it will settle down unless something is loose but it sounds like an oal issue
 
I'd try 50gr's just to see if the weight makes a difference. I had a barrel on a 308 (1-10 twist) that was very mediocre with 155's but shot groups 1/2 as large or less with 185's. Also perhaps it doesn't care for 4227 and you should try 4198. Personally, I've found vert strings are the result of a poor load, groups that are open all over are could be a rifle scope problem. Just my findings. Best of luck.
 
Your vertical may be a result of how accurately you can measure powder. One or two kernels of powder can make a big difference in your 11 to 13 grain load. This will translate onto the target.
 
stringing could also be breathing. Make sure you're releasing all your shots at the same time in your breathing cycle. Accurately measuring powder is also a good thing to rule out as Terry suggested above.

Let us know if this improves!
 
When I reload for any of my cartridges that I seek accuracy from, I throw from my powder measure into the pan, on to the scale and trickle to final. I am pretty sure that part is good.
What I am not so sure of is my shooting technique. When I shot the groups with the verticle stringing, the winds were light and I presumed the problem was with the load or the rifle. It was previously suggested that I change the oal. So I started with the best load and worked from there, I lengthened the oal by about .010 for each load. The load that gave verticle the day before, shot rather well.
Apparently what I did was use sloppy technique and then jump to the conclusion the fault wasn't mine.

My apologies for wasting your time.
 
Could be a velocity issue. If you we're using a temp sensitive powder or some such thing that could cause a fps issue. Neck tension could cause a fps issue. Just a couple things you could look at that I didn't see mentioned. Have you ran your load through a chrono?
Oh and i really like ramshot tac powder it's extremely fine almost like dust. It measures really nice. Designed for smaller call like 223
 
Barrel heat and ammo temperature is also a factor. You wont get much for temperature difference between ambient and ammo in the summer/fall but in the winter it can be huge. Even with temp stable powder. Noticed a 4 inch difference in shot placement at 400 yards when taking ammo out of the truck in -20C.
How long are you waiting between shots? I used to just shoot at the range while doing development. But a buddy reminded my to have consistent wait times. When I would miss a shot, would quickly jam another round in and pull the trigger. Usually for worse results causing more frustration and quicker shots. After 3 or 4 shots would be pissed off and stepped away from the rifle for 5 minutes and next couple bullets would fly straight. Now I use the stop watch function on my phone, set it for 3 minutes and wait till it goes off before loading again.
The other one that I didn't think about until going to Rob Furlongs course was how long a round stays in the chamber before firing. Amazing the heat transfer into the round from a warm barrel...now if I don't pull the trigger within 10seconds of closing the bolt, rack it out and load a fresh, cold round.

Just my 2cents worth
 
Range report... Thanks all for the advice, some didn't quite fit, some I tried, some I may have to try in the future.

I tried a load of H4198 and 50 gr Hornady sx, tried a few loads and the starting load of 13 grains showed potential. The load at C.O.A.L. of 1.995 should be just about touching the lands gave me a group with 2/10" of horizontal and 1/2" of verticle. Right after that I shot a group with a C.O.A.L. of 1.980 and it gave me a 3/4" group. Hmmm...

So I loaded up some more rounds at both lengths and a few days later I tried for some groups. I started with the 1.980 load and experimented with different ways of rifle hold and rest combinations. I got three groups of 3/4 to 1". Then I went to the 1.995 for three groups, still trying different hold/rest combinations. I got two groups that were interesting, one had four into 4/10 and a low flyer. The second group had three into 3/10" and two low flyers. The third group wasn't that great but the wind was getting up and I credit that.

So I have a load with a certain coal. gives interesting groups. I have a starting point. I may try to borrow a chronograph and get a spotting scope and see if there is a pattern. I will try to get my hands on a micrometer seating die to see if I can dial in a more consistant load.
 
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