Partial vertical stringing

Bigeclipse

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Ok here goes. I’m working up some loads on a savage 7mm08. It is freefloated and bedded in a Boyd’s stock. I’m shooting off rear bag and front adjustable rest. I loaded 120 ballistic tips .040 off the lands. I am just shooting at 100 yards. I started my charge weights at 42 grains and then went up .3 grains every 5 rounds until I got to 43.2 grains. Purely shooting for groups, not doing ladder test or ocd test. I started with the lowest charge and went up. Here is where it gets weird. I shot 3 rounds of 42 grains and get a .6inch triangular group. I decide to not shoot the last two rounds and move on to 3 rounds of 42.3 grains. Again I get about a .6-.7 inch triangular group. I I then go to 42.6 grains. FYI I’m waiting 15 minutes per group of shooting and about 1-2 minutes between each shot. The 42.6 grain grouping was a vertical string 4 shot group with almost no left and right deviation but 2 inches vertical. Each shot was progressively lower than the next so I’m thinking maybe heat. So I let the barrel cool 20 minutes this time. I went and shot four of the 42.9 grain rounds and the same thing happened... it is pretty hot out so I’m wondering if the barrel is just getting hot and I should wait even longer? This is a savage magnum contour barrel so just a step up from a sporter in thickness. Thoughts?
 

rfurman24

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My thoughts are the entire reason for OCW and Ladder testing is to see nodes which eliminate the issue you are describing. In my opinion you are just wasting ammo. Most likely you are seeing a scatter node but without shooting the OCW and providing pics it is hard to say.
 

Bigeclipse

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My thoughts are the entire reason for OCW and Ladder testing is to see nodes which eliminate the issue you are describing. In my opinion you are just wasting ammo. Most likely you are seeing a scatter node but without shooting the OCW and providing pics it is hard to say.
I basically did an ocw but I was just doing a quick load workup as the furthest distance this rifle will see is 250 yards. I’ll post a picture when I can of the target. I did not do a round robin but I did shoot some fouling shots first. This gun does not love to be clean.
 

Bigeclipse

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Here you will see the target. I zoomed in on the two that had vertical stringing. I also labeled each shot in the group and you can see they progressively got lower. The one which has the 4th shot next to the third I actually let the gun cool 2.5 minutes instead of 1-2 minutes that I usually cool so I'm wondering if it truly is because of barrel heating up. The last grouping I waiting like 25 minutes before shooting but still did the typical 1-2 minutes between shots.
 

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bob4

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To rule out hot barrels I bought a Milwaukee battery operated fan. It's pretty hot in SWF during the summer and after 2 shots you'd rather not hold the barrel. And left in the Florida sun you'd be 30 minutes. 5 minutes stove piping with the fan I wouldn't call it ice cold but certainly ready. Really saves time.
Edit: I would have to think that only 1-2 minutes cool down time your barrel had to be getting warm.
 

Bigeclipse

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To rule out hot barrels I bought a Milwaukee battery operated fan. It's pretty hot in SWF during the summer and after 2 shots you'd rather not hold the barrel. And left in the Florida sun you'd be 30 minutes. 5 minutes stove piping with the fan I wouldn't call it ice cold but certainly ready. Really saves time.
Edit: I would have to think that only 1-2 minutes cool down time your barrel had to be getting warm.
Do you have a link to the type of fan you are talking about by chance? Thanks!
 

PowellSixO

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I've seen the exact same thing with many rifles when doing my load development. Here is a picture of my 243 when load developing. Some rifles just really hate some combinations.

20160604_151240_zps3jcakevz.jpg
20160606_071441_zps34evkm73.jpg
 

Bigeclipse

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I've seen the exact same thing with many rifles when doing my load development. Here is a picture of my 243 when load developing. Some rifles just really hate some combinations.
thanks. I have not really spent time load developing this rifle as it shoots factory loads very well(tried 3 different types of factory loads and all were sub MOA). so I figured this barrel must be decently accurate (sub MOA) with any load which was another reason I did not spend time with doing ladder tests or round robin style OCW testing. The problem is my wife scoped herself last year, not due to recoil but rather she was in a treestand and tried to shoot at a deer in a very awkward position and did not hold the rifle properly. She will never do that again. Anyways, now she is a bit timid because of the incident so I told her I would make her some nice light loads with some ballistic tip 120s which should cut the recoil down quite a bit which is why I'm also looking at the bottom of the load range instead of the top portion and still be able to take out a large whitetail at 250 yards and in. Maybe ill load up some of the 42 grain loads and try seating depth testing as that load was already good enough for 250 yard hunting.
 

rfurman24

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I personally would do at the lands, .010, .020, .030 off and see what you get. If it does not get better I would then try .050, and .060 off. I personally have always found .050 and in works. After that you could try +- .005 from the most accurate.
 

bob4

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Anyways, now she is a bit timid because of the incident so I told her I would make her some nice light loads
Maybe a clamp on Muzzle break is all the confidence she needs. For under 100 bucks I'll bet the 243 would shoot like a 22L. Honestly my 300WM now has less recoil than my 270win. Bought mine from Witt Machine.
https://www.wittmachine.net/
 

Gord0

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If you're going for a mild load I would try under that 42gr load and see if that group gets any tighter. If not, play with the seating depth a little at 42.
 

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