Groups of varying size at different distances...seating depth issue?

[Yagingaboy]

So I'm trying to work up a load for my 7X300wsm for my trip to Alaska in a few weeks. I started working up from 64 gr of RL25 all the way to 66.2 gr of RL25. With my 65.9gr load (and the loading .2 above and below that) I shot .375" 4 shot groups at 100 yards 2 weekends ago. I was ecstatic. I was getting 3075 fps average with an es of 30 fps. Good enough for me I thought. So this last weekend I loaded up 32 rounds with 180gr bergers seated .005" off and 59.5 gr RL25, cleaned my rifle really well, loaded up and went to the range. The exact load I did so well with the week before. Now the weirdness...

I had my rifle sighted in for 100 yards for load testing but I really want a 200 yrd sight in. I set up 3 targets at the 200 yrd mark, set up and prepared to start shooting. It was fairly early in the morning, 62 degrees with a 1.5 - 3 mph tailwind according to my kestrel. Having just cleaned my rifle I fired 2 rounds into someones old target they had left. The hits were fairly close to where I would have expected them, about 1.5 inches low but they were a couple inches apart left to right. I fired my next 5 shots into my first target with 3 minutes between shots. When I went down to see what my target looked like I almost fainted, it looked like I had shot it with a shotgun. I didn't measure it but I was around a 6 inch group. I went back and shot my next 5 shot groups into their targets using the same method. Same result. I was a bit PO'd. I set a target at 100 yards and fired 3 shots again. My group at 100 yards was .55 inches. I was really getting agitated now so I thought I would just shoot my last 7 at the steel at 500 to relieve a bit of stress. I pasted my target to the steel plate so I could see where I was hitting. I fired all 7 shots and all 7 hit. I drove down and looked at my target. I had a 2.5 inch group at 500. What is the deal? My groups start small get bigger and then get smaller again? Is that even possible? Could seating depth be causing this issue. Beings that I'm getting the velocity that I'm looking for I'm going to try some different seating depths this weekend depending on your ideas. Thanks in advance for any help or light you can shed on this problem.

 

[Johnboy]

well I think you just cleaned you rifel.some will come back sooner than others.and you said that you really cleaned the bore out.the load if the right load should never change that fast.heck I shoot one day with a great load and it was 180* turn from yours.the first few 5 shoot groups did OK.then cleand with a change in my still.shoot the last five and came home with a hudge smile.went from a inch or so to one ragged hole.

so with that said try your load again.but leave the bore alone.most will say just as I am about to.when testing just keep shooting the same powder loads for the testing.and while I am useing that load that ends up being the one load I go with I keep the bore just as it is.until the rifel shows something different I just keep shooting.cleaning is something we just need to find out for that rifel.it will speak to you.it just as anything else in the shooting world will do.shooting /trigger time tells us all kinds of things about our loads and rifel.even the style way we shoot.

the only other thing that comes to mind is the temp.R25 is is not like most of the Hodgden line of powders.you said you started in 62* temps.and with a 3 minutes between shoots added up to alot of time for the heat to change.but it may or should not have changed the POI that bad.so really want to blame it on the clean bore.

 

[Yagingaboy]

Thanks for the reply John. I have been wondering the same thing. As my last 7 shots were fairly good for me, I will go to the range without cleaning prior this time. The cleaning on this Lilja barrel has been extremely easy to do. I have very little copper fouling going on and it only takes a few passes with some Montana Extreme 50 BMG to get it squeky clean. The outside temp did change quite a bit while I was at the range. It went from 62 to 85 from start to finish. I chronied every shot though and they all stayed between 3045 and 3090 with the exception of 2 that were something like 2998.

Any other thoughts?

 

[maxpower]

Ive heard of a few shooters having problems with this cartridge, saying it can be hard to tune, who knows. I know the current world champion used one, maybe it can sometimes be finicky???

 

[treeman]

the way it groups at 100 and 500 I think i'd just take it hunting and not worry about it.
Darrell

 

[mikecr]

the way it groups at 100 and 500 I think i'd just take it hunting and not worry about it

Well for animals at 100 & 500 anyway...

Darrell, you should stick to shooting ranges & stay out of the fields.

 

[Yagingaboy]

Ok made it back to the range today. I tried playing with seating depth to see if that could help matters. I set up 8 targets. 4 at 100 yards and 4 at 200 yards. I had loaded 8 shots of each of the following seating depths (measured from the ogive, all with the same 65.9gr RL25 load), .005 off the lands, .020 off, .040 off, and .065 off (went past .060 and figured I would keep them all the same.) I didn't clean my gun this time purposely before I went to the range to test the idea of too clean of a gun.

I did the round robin shooting of 1 shot every 3-4 min firing 1 round from each load into the targets at 100 yards until I had shot 4 shot groups. All the groups were between .375 and .75 inches measured with a set of calipers. I let my gun cool while I did the good neighbor thing and spotted for a couple guys that were sighting in their gopher getters. I then shot at 200 yards doing the round robin shooting. My 4 shot groups were were anywhere from 3.5" to HUGE. What I found to be a bit funny was that the load that shot .75ish at 100 shot the best at 200.

Still don't know what is going on but at least I can live with the 3.5 inch group at 200, well as long as it still shoots good out to 500 and beyond. Kind of disappointed to spend this kind of money on this thing and have it shoot this way. I have 115 rounds down the barrel already and nothing to really show for it.

 

[2506]

I would try another bullet myself. It sounds like a stabilization problem to me. Maybe the bullet starts to wobble somewhere between 100 and 500 yards but settles down before it gets to 500 yards. No two barrels are the same. I have a 25-06 Shilen barrel that just does not like boat tail bullets but it will shoot lights out with flat base bullets. Go figure :

 

[Yagingaboy]

I love the 25-06. Been my favorite coyote/deer rifle since I was a little kid.

 

[Johnboy]

well I say its sad that its not the clean or not bore.can you say just how many rounds been down the bore.may just be coppering up on ya.hasn't broke in yet.if so lapping it can help alot.or the Tubb bullets.but .75 at 100 should be just as good at 200 but not always but should.can you take it to 500 if so try it.just might be the case of the bullet needing to stretch her legs.some cals/bullets are just as one said before.hard to dial in.just thought of the simplest thing ter first time I posted with what you posted.

keep us posted want to help out the best I can.even want to really see just whats the reason for this.learning is the best in this game.

 

[mikecr]

I 'think' I would use whatever bullet & seating combo that provided .375" groups, and shoot a ladder with a different powder.
It won't do you any good to have a hunting gun shooting bad between 100 and 500, and then who knows what beyond.

 

[Erik Cortina]

Ok guys, let's stop and think about this one for a while. All I can figure is the gun took a few shots to settle in, which is the shots he took at 200 yards, and therefore the shots at 100 yards and 500 yards were good.

The second time around, well, I don't really know what happened, but as far as I know, bullets that shoot 5" groups at 200 yards will never shoot 2.5" groups at 500 yards, even if they were unstable at 200 and they stabilized between there and 500. Once the bullet deviates from a given path it will continue on that path, stable or not. So there is no way a 5" group will then become a 2.5" group further out.

I guess plan B would be to move 300 yards back if a 200 yard shot presents itself while hunting! ;D

 

[Long Trang]

Yagingaboy,
I'm probably way off base here, but I have to throw in my .02. I ran into a similar problem with my stick not long ago. The rifle had proven sub MOA countless times, then I took a trip to the northeast and went to the range. At 100 yards my groups were lucky to be 6"!!! Funny thing was, occasional shots were nearly dead on. It was so radical and unpredictable that I couldn't find a common frame of reference to adjust my scope to compensate. I'm not the best shot in the world, but I'm certainly not the worst and I was firing factory ammo, but 100 yard 6 MOA with a custom competition qualified rifle...from a bench with pod and bags? I was pulling my hair out.
Then that night I went to clean it and discovered something very intriguing, I could literally move my barrel back and forth over a millimeter. The action screws had worked so loose I could easily turn them with a fingernail.
I'm not saying this is the cause of your problem, but when it happened to me, I had the exact same bizarre and inconsistant shot placements.

 

[Yagingaboy]

Long, I checked all my screws when I got the gun back from the smith but I haven't checked them since. Currently I have 117 rounds down the tube. I was cleaning every 20 shots and will go back to that. I guess that other than this hunt I am going on in Alaska having problems between 200-300 yards really isn't a big deal. In NW Montana you are either shooting less than 100 yards or 6-700+. I'm going to go test this thing out at 835 and 940 this next weekend. On part of our property in N Idaho I can shoot out to those ranges. If I can put 10/10 on my steel plate at 940 I will be more than happy. The plate is 10 X 10 so it is about 1 MOA at 1k yrds.

 

[Yagingaboy]

So for the heck of it I stopped by the local sports center here and paid way too much for a box of 175 SGK's. I loaded them up starting at 62gr and went up to 65gr in .5gr increments. What a difference. The hotter loads shot really well. Well, not "well" by BR standards but well by my standards. I had 2 3 shot groups that were under and just about an inchish. I didn't have my calipers with me, left them sitting on my loading bench but eyeballing it using the 1 inch lines it looked close enough for me. I had a couple of rounds left and guestimated my drop at 500. 1st was high and the second rung the gong. I'm feeling a little better now. I'm going to try to work these loads up to where I can get 3050 fps and hopefully my groups are just as good as with the lower loads. Reverse engineering, using number of clicks to put me in center of target I'm right about 2900 now as it is. Probably another grain should put me where I want to be for speed. I will load in .2 gr increments from 65 to 66 and see where that puts me on paper and through the chrony. Got my fingers crossed because this weekend is my last chance to get this dude humming. After that, it's north to Alaska. ;D

 

[AusFclass]

do you have your paralax adjustment set correctly? not so the target is clear like a lot of guys do but so the cross hairs dont moove when you bob your head looking throught the scope. thatll easily explain varing groups at different ranges.

 

[Yagingaboy]

Aus, I think I do have my paralax set correctly. I had to fiddle with my focus a few times when I first had the scope mounted but once I got that right I was able to get the paralax knob set to where I don't have movement on the target when I move my head up and down or left to right. Oddly I had to set the paralax nearly to infinite to get it to work at 200 yards. At 100 yards it is actually at the 100 yard mark on the paralax knob. At 500 there still isn't any paralax with it set to infinite. So at 100 yards I'm set at the 100 mark, at 200-500 I'm at infinite. Does that sound messed up? The scope I'm using is a Zeiss Conuqest 6.5 - 20.

 

[AusFclass]

interesting!!! would it be worth swapping scopes to find out if thats the issue?

 

[Yagingaboy]

Well, just got back from the north slope. Everything went well. I was able to take a medium sized bull caribuo at 474 yards with a double lung/heart shot. The 175 gr SGK's turned his chest cavity into jelly and I lost almost no meat whatsoever. He only ran 20 yards from where I hit him and tipped over dead very quickly. I guess the 7X300 wsm is a really good medium game round after all. I packed 20 rounds with me in about 8 miles off the haul road but I really only needed 1 in the long run. It was a good time.

Aus: I'm going to explore sending my scope to Zeiss and having them check the parralax adjustment to make sure it is working properly.