Vertical stringing, how much does powder charge matter

[rickyw]

Here’s a group I recently shot with my 375 H&H. I’m wondering how much of this, if any, may be due to the load? I’m shooting a Speer 270 grain boat tail loaded to 3.6”. Unfortunately I cannot load longer because the magazine is 3.6”, but it’s quite a ways off the lands.
I’ve tried multiple powders and they all shot terrible with this bullet (no vertical string, just all over 3.5-4 MOA). CFE 223 shot the best, but produced the stringing. I wanted to use this Speer because it’s about the softest bullet you can get for expansion at a bit longer range. So below, is the group from 76 grains CFE 223. I essentially duplicated this group again 2 days ago. Would working through a few different charges have a chance at a reducing this amount of stringing? Or, I’m on to another bullet. Thanks

PS, rifle is a classic stainless model 70. Bought it on consignment earlier this year. Appears very lightly used. I put it in a stockys carbon fiber stock, torqued to 50 inch pounds. It is not yet bedded.

 

[Q_Sertorius]

Assuming this is a 100-yard group, I think it’s something in the way you are controlling the rifle. At least that’s what other people have told me about groups with vertical stringing like that.

 

[rickyw]

Assuming this is a 100-yard group, I think it’s something in the way you are controlling the rifle. At least that’s what other people have told me about groups with vertical stringing like that.

I’ve wondered that as well but I’ve had that looked at by an instructor while i shot this rifle with this load. So, I’m setting that variable aside for the moment while asking this question…

And it may be nothing to do with the load, but I wanted to explore that possibility a bit

 

[UPThunderbolt]

Here’s a group I recently shot with my 375 H&H. I’m wondering how much of this, if any, may be due to the load? I’m shooting a Speer 270 grain boat tail loaded to 3.6”. Unfortunately I cannot load longer because the magazine is 3.6”, but it’s quite a ways off the lands.
I’ve tried multiple powders and they all shot terrible with this bullet (no vertical string, just all over 3.5-4 MOA). CFE 223 shot the best, but produced the stringing. I wanted to use this Speer because it’s about the softest bullet you can get for expansion at a bit longer range. So below, is the group from 76 grains CFE 223. I essentially duplicated this group again 2 days ago. Would working through a few different charges have a chance at a reducing this amount of stringing? Or, I’m on to another bullet. Thanks

PS, rifle is a classic stainless model 70. Bought it on consignment earlier this year. Appears very lightly used. I put it in a stockys carbon fiber stock, torqued to 50 inch pounds. It is not yet bedded.
View attachment 952152

A friend bought a new .300 wm Tikka and had the scope mounted at Cabelas. While developing a load for it, we ran into a similar group pattern. Scope mounts and action bolts were all loose. After torquing them down, the vertical string grouping went away.

 

[rickyw]

A friend bought a new .300 wm Tikka and had the scope mounted at Cabelas. While developing a load for it, we ran into a similar group pattern. Scope mounts and action bolts were all loose. After torquing them down, the vertical string grouping went away.

I could always recheck but I used a torque wrench on everything, torque to spec, except the Warne mountain tech ring screws are torqued to 25 inch pounds. Loctite on the base screws. SWFA scope

 

[UPThunderbolt]

I’m a long way from being an expert, but if your rifle has a free floating recoil lug, I would also check to make sure it is properly seated. I’ve run into that issue a couple times.

 

[Odd1out]

I would check everything stated above again and also look for a cracked ring. Generally they crack near the weakest part which is the screws. U could run the torque wrench a few times on the screws. A hair line crack will show up as you check a few times and start having to re torque.

Sent from my SM-G986W using Tapatalk

 

[rickyw]

Will recheck. Thank you

 

[35WhelenAI]

Action is not bedded/seated in the stock with even pressure IME with vertical stringing. Take a business card and slide it between the fore end tip and the barrel to put some up pressure on the barrel. Or cut a piece from a plastic bottle and fold it over so it fits snug.

That group is too tight left to right to be anything with you, IMO/IME.

 

[NWBLKTAIL]

Action is not bedded/seated in the stock with even pressure IME with vertical stringing. Take a business card and slide it between the fore end tip and the barrel to put some up pressure on the barrel. Or cut a piece from a plastic bottle and fold it over so it fits snug.

That group is too tight left to right to be anything with you, IMO/IME.

I agree with this


Bed that thing

My M70 in my Stockys VG would throw occasional stringing until I bedded it.

Now I get tighter more concentric groups. I’ll post a group from after bedding and before same load

 

[WVELK]

Will throw my hat in as well. There are a lot of good articles on “causation” for vertical stringing. There are LOTS of potential causes. It would nearly be impossible for us to know what you may or may not be experiencing. All I can do is offer a few more things to consider. Each of these have caused me to experience stringing similar to yours:

1. Bullet not leaving at the top or bottom of the barrel harmonics. For me, just a tenth of a grain of powder here or there changed everything.
2. I have changed primers and kept all other load variables the same and taken it out. Did this recently with a 7 SAUM and a bullet I don’t normally shoot.
3. Your cadence of shots can impact it. For example, when really trying to work on a load, I shot a shot set a timer, shot my next shot 3 minutes later, then the third 3 minutes later. Then let the gun cool before the next 3 and do the same (3 minutes between shots). My 338 RUM will string vertically if I get into rushing shots.
4. Not having enough rear pressure on my rear bag causes stringing.
5. When you are on the bench what is your setup?

Hope one of these helps. I know it can be frustrating been there.

 

[Vern400]

I have a rifle that will shoot high if the front rest is hard. Put it on a soft bag, or roll up a towel under the fire end and it's fine. I think it happens more on kickers too. Just a thought.

If I were shooting a 375 it would be due to flinch.

 

[TaperPin]

What a great rifle - I didn’t know if I’d rather have a Remington or the Winchester to take to Alaska so I bought them both a year before the move and had fun shooting the heck out of them. Heavy recoiling rifles really benefit from good bedding, but that Winchester push feed 375 from the late 1990’s was consistently a 1-1/2 MOA gun, as much as I hoped it would eventually find a load it liked. The first box of ammo was never better than 1-1/2 MOA as was the last box before it was sold to a friend.

From how you describe it, it sounds like you are getting used to the recoil. It really helps if you have another heavy recoiling rifle to judge if you’re having problems or if it’s the rifle. Having someone either load it or not and hand you the rifle will also show right away if you have a flinch.

One quirk with heavy recoiling rifles is the rifle moves rearward more, maybe twice as much, before the bullet leaves the barrel than with small cartridges, so inconsistent front or rear bag pressure, or pressure into the shoulder, grip pressure, grip on the forend, will change point of impact noticeably more. Watch the front swivel stud and keep it from touching the bags or it can push shots vertically. If that last shot had firmer rear bag contact it would push shots lower on target.

 

[35WhelenAI]

I have a rifle that will shoot high if the front rest is hard. Put it on a soft bag, or roll up a towel under the fire end and it's fine. I think it happens more on kickers too. Just a thought.

If I were shooting a 375 it would be due to flinch.

That's a good point. I've always felt a softer cushion would give more inconsistency. I typically shoot off a harder/firmer leather bag with "ears" the forend settles down into. I put the foreend about halfway between the sling swivel stud and the recoil lug, has worked well. Going to try something a little softer next time at the range and see how it works, although I don't have problems with stringing.