First of all, I am not the best benchshooter around, but not the worst either. I have been trying to work up some loads for my 7mm stw. Shot some barnes 120 x's and got a vertically stringing group. 3 shots about 1.5 inches higher than the other, the top 3 are touching. Though I may have pulled, but other groups were similar. A couple shots high and a couple lower, nothing in between. Nosler partitions did the same thing.

So, is it my loads, my gun (barrel and action are glass bedded), scope problems (possibly bad parallax), or my bench technique.

I don't know what to try next, any help would be appreciated.

You may want to check your scope. The twin grouping you are experencing is often a scope that has gone bad.
I would start there.

muck

Are your loads hot enough to get uniform ignition? Sometimes we just need a little more pressure to even things out and burn right.

Most of my sporters do better from a clean barrel. I have a theory and it's only a theory that old fouling does not let that first shot go where it should.

Of course stringing can be many other things.

What is your load by the way?

There are a lot of possible causes unfortunately. Pressure from the stock is a good canadate.Sustained firing of say six large capacity cartridges could create a significant temperature differential from the top of the barrel to the bottom of the barrel touching the stock. If the barrel is a slim stainless the differential elongation ( exspandsion ) from top to bottom might be even more severe than if it were a heavey steel barrel. Serious free floating and or stock venting might help. Before you do that though, see what a little up front barrel pressure does. If it affects it either way you've got a start
What do your first 2 shots look like? Is a 1 1/2" difference a problem in your hunting rifle? Hang in there one of these guys will have the answer.

measure your OAL, tip to base.... since barnes are pretty nasty about being off the lands, it could be that they are slightly diff lengths

jeffe

The scope could be the problem, simmons aetec.

My loads are plenty hot, maybe a little too hot, and the barrel is a bull-barrel. I was waiting 4-5 minutes between shots to make sure that the barrel was cool. Outside temp was about 72 degrees. Barrel was cleaned the day before with shooters and butch's bore shine.

The barrel has been glass bedded, should it be free floated instead? I made sure that the sand bags were right below the swivel stud for every shot.

I do measure the col on every cartridge. I did find a small variance, about 6-8 thousandths. Because of my blind box magazine, I can't seat the bullets out to the lands. The problems have been the same with barnes and the partitions.

Anybody got the magic answer?

Anyone?

If you are truly putting the bags under the swivel stud and that stud is in place, it can cause vertical stringing.

As one other responder indicated, sometimes a little extra pressure will line out the group. Today I shot a .5 MOA group with 2460 powder in my 6 BR. The shots clustered in 2 distinct sub-groups. With another 0.5 gr of powder, the 5 shots grouped about .260 at 100 yds.
Ron

Justin,
Sorry I missed the content of your prior message when I suggested to add a little more powder. If you are already hot, you may want to try the Optimal Charge Weight method for determining how much powder to use.

http://home.earthlink.net/~dannewberry/dannewberrysoptimalchargeweightloaddevelopment/

I have used OCW before with success.

I have never been a big fan of glass bedded barrels. They shoot sometimes great but other times they walk around. My current gun had a tendency to move upward after a few shots. It seems the glass bedding under the barrel was forcing the action upward as the action became warm. Removing the glass immediately in front of the action and under the barrel solved the problem. Free floating barrels tend to wip around more but they do so in the same manner, I have found. Don't know if this helps or just adds to the problem.
Ron

Justin,

I have a 6.5-300 Wby that I shoot off a rest and it is the most "unforgiving" rifle I have ever shot. I believe this characteristic is due to recoil.

Recoil sensation itself is not really a problem, but the rifle's reaction to recoil is difficult to control properly. At 100 yards, I can create two vertically separated groups quite easily by varying shoulder pressure on the butt. Both groups would be "one hole". With firm shoulder pressure, it shoots well. Loosen the grip and bullets go high and a little left. A change in cheek pressure will cause a slightly different, but similar reaction for my rig. The problem is worse with my laminated BR stock, for some reason, while the HS precision varmint style stock isn't too bad. I think the pad is thicker on the BR stock and makes things worse. I had a diamond-plate aluminum buttplate on it at one time, and the problem wasn't as apparent, but it left marks and I had to get something to take the edge off.

Between having difficulty with an incompatable rest top and finally realizing the nature of the rifle's recoil sensitivity, I drove myself nuts trying to solve the problem.

As flat as the 7 STW shoots, it seems to me that velocity variation would have to be incredible to create such stringing as you describe. I would expect more like a shorter vertical tear, with much less bullet separation, if your problem was only velocity deviation.

As pointed out above, this really sounds like a bedding problem, but if you don't find anything there, you might experiment with your buttstock control some.

Good luck

Do you brace the butstock when you shoot? Sometimes you'll get verticle strings because the stock isn't supported.

It's happened to me before.

Thanks for the suggestions.

C210, where exactly should the sand bags be under the rifle? All the way to the front of the stock or closer to the action? I am going to work on some more loads next week, but 4 out of the 6 I have tried so far had vertical stringing.

Eshell and JLHeard, I will have to try griping the stock more consistently. I usually try not to grip the stock tight to avoid moving the rifle. If inconsistent firmness of grip can cause stringing, I will definitely pay more attention next time.

I appreciate everybodys input and right now, I'm not ruling anything out. I really want this rifle to shoot.

If you're gripping the stock AT ALL, there's a high likelihood that inconsistent grip from shot to shot is causing your vertical stringing. The 7mmSTW burns a lot of powder, but doesn't recoil so hard that using a Past recoil pad on the shoulder or using a sissy bag between your shoulder and the stock wouldn't tame the recoil enough to completely avoid gripping the stock anywhere. At the bench, I keep the rifle firmly against my shoulder, but bearly have any touch of my cheek to the stock, and nothing else touching the rifle anywhere. I try to squeeze the trigger by "pinching" the trigger finger and thumb together, touching the trigger pad with the part of the fingertip directly opposite the cuticle. Try this. Your groups should tighten up.

I would suggest shooting over a chrony. If you get a wide variance between shots, I would suggest finding a more consistant load.

This is a great thread with a ton of good advice. Sounds like you are pretty knowledgeable and have some experience. However, there are so many variables you have to play with it gets difficult to determine exactly what you need to do. I like to start with the easiest changes that have the most impact on the way a rifle shoots. I'm definitely no expert, but it would be very frustrating (at least to me) if I had a ton of work done to a gun to fix a problem that resided in the scope. That rifle packs a bit of a wollop and puts a lot of stress on the scope. You may want to swap the scope with one you have on another rifle that you know for certain works properly. All scopes have their problems, but Simmons seems more prone that others. What do you really have to lose except the 30 minutes it takes to swap the scope and bore sight it, and the additional range visit?

Thanks for all of the advice. There is more real world knowledge on this board than I can find in any book.
I am going to start by changing my bench technique. Move the sandbags forward a little and have little or no contact with the stock except for my shoulder. We'll see if that helps.

If not, then I will have to buy another scope to use to swap out because my only other rifle is a 22-250 that wears a cheaper Swift scope. That gun shoots in the .3s, so I might try that scope.

As for load consistency, I have had this problem with all 5 loads I've tried for partitions and 2 loads with Barnes. Everything I shoot through it moves vertically. Usually 3 shots in .75 but the other one or two open the group up to 1.5 to 2 inches. Not a real big deal for hunting rifle, just want to do everything I can do to fix the problem.

Still open for my suggestions, can never learn too much...

I am having the same problem with my Rem 700VLS .223. I have shot this off the sand bags and bipod. The groups are less than 1/4 inch apart but I keep hitting the same to holes. My scope is a VXII 3-12 AO. Scope works great on other guns. This is somthing to do with the rifle. I have tried different ammo, even factory ammo. I have tried different grips on the stock. I keep getting the same results. A budy of mine even shot it and had the same results. If anyone can figure out this problem I would be greatful to them.

Thanks

Ray

Justin you have received some excellent advice on this thread. But, it is very easy to start chasing your tail and never figure out what the problem is or if there even is a problem.

Generally, I would say that vertical stringing was either bedding (#1) or possibly a scope or scope mounting problem. I doubt it is your shooting technique. Sounds like you do alright with your other rifle. Whatever you are doing in this regard, just make sure it is consistant.

I think it is more probable that it is your loads.
You have only fired 5 loads with 2 different bullets. I would try at least 3 different powders. Work up at least three loads with each powder. Same primer, same bullet, same cases and same overall length. When you find a load with some promise you can fine tune the load. Only change one variable at a time.

Another consideration would be your bullet weight. A 120 grain pill is pretty light in this caliber. It is a bit over-spun by rifling more appropriate for heavier bullets. I would think 160 grainers would be your best bet or at least move up to 140 grain bullets.

Just my opinion

I have managed to shoot an entire box of 140 gr partitions and nothing under 1.7 inches. 80 % of the loads were strung vertically. I tried everything from mild loads to near max loads. I did some digging for my old targets (just moved) and found some from last year. The 120 gr X's were shooting about .75 inches last year. Makes me suspect my scope. I am at my wits end.

I have tried almost everything except different powder and scope.

If your group is climbing, THE BARREL IS GETTING HOT.

I won't rule out anything, but I wait 3-4 minutes between shots and 15 minutes between groups. The stringing also occurs on the very first group through the last.

i agree with c210 i would free float the barrel back to the recoil lug. just my opinion,but i think as the barrel heats it moves differently against the glass bed. i presume it is a wood stock. i think if it was the scope the point of impact would continue to change. another point is that as the wood stock swells and shrinks with the atmosphere it would cause different pressure on the barrel, even with the glass bed. this is just my humble opinion
don

Hmmm, just a thought, but if it shot well last year, and not this year, did you, perhaps, take it out of the stock and reassemble with different screw torque? FWIW, Dutch.

I have had the exact same problem when my action screws came loose.

One group a about 1 1/2" higher than the other.

When I tighted up the action screws the group came together.

Have you checked all your screws to make sure they are tight.

Free float the barrel! A friend of mine has a Ruger 77 .308 that had a VERY tight fit between the barrel and stock from the factory and would string shots vertically no matter what kind of loads were worked up, after he free floated the barrel it became a whole new animal, the vertical stringing problem is now history. As mentioned in earlier posts the problem is barrel heat and without a free floated barrel the problem is magnified greatly. If that doesn't eliminate or greatly reduce the problem, try a new scope.

I'll check those action screws tonight. I haven't removed it from the stock since last year. If those are fine, then I will have to remove the glass and free float the barrel. It's a laminated stock, so stock-swelling shouldn't be a problem. I will keep you guys posted...

The rear action screw was a little loose, I tightened it about 1 1/8 turns. Hope that is the problem.

Justin
That is exactly the problem I had. I believe you will find you are back in business now.
Really weird how the group shifts back and forth like that when the action screws get loose.

I really want to thank everyone for their advice on this one. I haven't had the chance to shoot after tightening the action screws, but I am confident that everything will go back to normal.