RANGE UPDATE: Advice sought re 308 Win mid-range groups

[bobnob]

Gday Guys, I am working up a 308 Win mid to long range gong-ringer rig. The basis of it is a Sportco-Omark former range rifle. The rifle is probably 40 years old but has done l little to no work.

I have been working up loads close in and yesterday took the rifle out to 260y and shot the below 7 shot groups...

The bullet is the 168g Amax. The load on the left is 44g of H4895 and on the right is 46g of Varget (or AR2206 and AR2208 here). Both loads are doing about 2750fps.

Any analysis on the groups? The left group is tighter but the right has a good deal less vertical spread.


By the way the wind was consistent for both groups so discount that as a variable.


Interested in any advice as to which way I might take load development.

Thanks as always.

Bob

 

[bobnob]

I should perhaps clarify my question....

I've always felt that a smaller group is better, and a larger is worse/r.

But others (maybe more knowledgeable than me) sometimes say the shape of the group can tell you something.

Now bearing in mind the wind was the same for both groups, is there something the more vertical group vs the more horizontal group is trying to say to me?

 

[Dwh7271]

Others will probably have better input, but I like the left group. Right is a little horizontal.
Nice shooting.
I'd bet if you seat that left one a hair deeper it'll tighten further.
At the distance you're shooting either is good but my preference would be the left one.

 

[Guy Miner]

Horizontal stringing often indicates one of two things:

1. Wind - but you ruled that out. Still, I'd keep in the back of the mind as a possibility. A nearly undetectable amount of wind can cause the small amount of horizontal stringing you've shown in your photo.

2. Trigger - quite possible, by varying the position of your trigger finger, and how quickly you work the trigger, to produce that kind of horizontal stringing. Our trigger finger can have a large impact on group sizes, particularly horizontal spread.

I'd do more shooting with both loads, before writing off either. Too much chance of environmental factors, or human factors being the culprit, rather than the load itself.

A lot of mid-long range target shooters put huge faith in a group with a "tight vertical" spread, like the one on the right in your photo... I do.

You are working with two excellent powders for the .308 Win, and a very well respected target bullet. I've heard others from Australia talk about the rifle you mention, but have never shot one.

Regards, Guy

 

[Guy Miner]

BTW, the left group looks real tight, except for that one bullet dropped down lower than the rest of the group. And one shot a tad higher...

Often a low hit isn't caused by the ammo, but rather by shooting at a slightly different point in the breathing cycle. Having a little more air in the lungs can cause the shooter to put the shot slightly low, particularly if shooting from prone. Less air in the lungs when the shot breaks can lead to the higher hit.

Yup, I'd load and fire more of both, particularly out at say, 600 yards, and see what the groups tell you then. Maybe five, five shot groups at 600?

Regards, Guy

 

[SJB358]

I'd take them both out further and see what they do.

Seems like I really get to see what's going on the further I stretch them.

 

[bobnob]

Thanks gents. I'll be doing more of course. Today I'll push it out a little further, I've got a convenient 450y target that I can see still shoot from my bench which is a start. Beyond that I have to get prone for which I'll need to mow an area.

Couple of pics of the rifle Guy...

The scope I'm using at present is horrible too so there may be more improvement to come. I'll let you know how it goes.

 

[FOTIS]

Next time I would shoot 2---3 shot groups

 

[bobnob]

Shot the rifle at 450y this morning. Only shot the H4895 load, which makes about 2750fps with the 168g Amax.

The smallest group at the top was just under 5 inches. The largest at the bottom, was about 6 inches. If not for the blown shot on that last group it would have been just over 2 inches. I know I fluffed a shot on that group and I'll assume it was that high and left one.

That Chinese 4-16x Tasco is pretty poor getting out to that range. I can't see much point trying it further out until I upgrade the glass. Its not so much the magnification but the poor optical quality. At least it holds zero.

What magnification range does one really need to get out past 600 yards?

Any observations re the above? I'm a real novice at the long range game so any feedback will be interesting to me.

 

[Guy Miner]

I love that last/bottom group!

Yeah, okay, there's a flier out of the group, but you owned up to messing up a shot in the string of fire. Nicely done! Load and shooter are both doing well.

As to how much magnification you'll need - it depends at least in part on your target. If it's a big, bright NRA competition bullseye, not a lot of magnification is needed. I did most of my 600 yard prone competition with a fixed 12x Leupold. That scope had excellent, clear optics, which I appreciated. Over the years I also used a couple of more powerful variables, notably a 6.5-20x and a 4.5-14x. Never found the 20x necessary, though others on the firing line used those, and more powerful scopes.

If it's smallish varmints, coyotes and smaller, more magnification could be appropriate.

If it's big game, I'd feel perfectly content with something in the 10x - 15x for a top end.

I've been comfortable on coyotes & mule deer at 400 - 440 yards, with my 6x, but for me, that was pushing the envelope a bit.

But that's me. Also - I learned to greatly value precise, repeatable elevation & windage adjustments. Not all scopes are consistent with this.

Regards, Guy

 

[Elkman]

What does the rifle do at 100 yards. What I am seeing is consistent with MOA grouping, which is not really bad for a 40 year old rifle. You didn't mention glass bedding or any other stability tricks. We're you shooting from a bench? What kind of forearm support are you using. The there are lots of variables that will effect the grouping. For most game it's good to go! I have a variable to 10, on my 308, and up to 14 on my 7 mm Mag and 300 WM.

 

[bobnob]

Ok, I floated the barrel and bedded the recoil lug area. Used good old JB Weld for the bedding. That seems to have been successful.

I am using a plain (and possibly less than satisfactory) MTM plastic rifle rest, over a rough bench (an old office desk placed under a tree) to shoot from.

As of today, I have fitted up a good bipod and will brave the poor optics and shoot the rifle prone from 600y later in the week.

As to what it does at 100y, at my 120y range it was doing around 1moa give or take. It did shoot a few near 0.5moa groups but also a few more like 1.3moa.

I appreciate the help guys. I will report back soon!

 

[257 Ackley]

At this point you may want to do a ladder test with powder charges in .2 increments on either side of this load to see what happens. The vertical is pretty good minus the flyer for the rifle you are shooting. Once you see where the harmonics really fall in, you can play with seating depths to fine tune the load.

As Guy said in another post, minor changes in wind can do crazy things to horizontal stringing once you stretch a bullet out past the 300 meter mark. Focus on the vertical first and once that is determined, pay attention to mirage and subtle wind changes.

 

[bobnob]

Today I went out with the intention of shooting the rifle at 600y prone. As I was setting up the targets there was about a 15kph breeze right at 90 degrees to the bullet path which worried me a little.

Anyway after a couple of sighters which were high but only 1.5 inches apart, while I was adjusting the scope for elevation, you guessed it the wind gusted right up and stayed any where between 25 and 35kph!

Anyway I thought "I'm here I might as well have a go" so I blazed away with two five shot groups, in between the groups I adjusted for windage which was problematic given the strength and variation of the winds.

Anyway here are the two groups at a GPSed 595 yards...

]

]

Being a total newb at prone shooting especially beyond 400y I was quite happy with the vertical dispersion which is right about 4 to 4.5 inches. The horizontal is of course abysmal really but its the best I could do in the wind.

I am still using the crappy Chinese Tasco and alloy Leupy Rifleman mounts, both of which can count their future in days. I also need to do something about the length of pull. It is too short given these rifles are generally shot with those heavy shooting coats and with the use of wraparound slings.

So with some improvement to the gear, some more work on technique and a calm day the rifle is definitely showing promise, even if today's outing was a little frustrating.

]

 

[DrMike]

I'd say you are coming along quite nicely. The absence of a vertical string is positive. The horizontal stringing sounds as if it could be attributed in some measure to wind. Learning to dope the wind is a skill that demands practise. Still, your shots would serve to bring down a moose or an elk. Hence, I should think red stag and even large hogs could be in some peril.

 

[Oldtrader3]

Vertical dispersion at 600 is excellent. If you can just find a calm day or dope the wind?

 

[Guy Miner]

Good deal!

Vertical isn't bad, and horizontal? That's just what happens out there at 600 yards and beyond...

I think I finally threw away the target, but I had a 600 yard target that I kept for some years. Had a really tight vertical, and the horizontal spread was about 18" as I recall.

What I'd done was to take my match .308 to the range and blazed away shot after shot, aiming directly at the bull, and deliberately not trying to make any adjustment for windage throughout my string of fire. The breeze was almost undetectable at times, and very mild at other times. It was more than enough to blow the bullets considerably off line...

Good education for me, and a great reason to appreciate high BC 7mm & 6.5mm bullets! :mrgreen:

You're doing good stuff, getting out there at 600 yards and shooting that .308 Win. Good work!

Guy

 

[SJB358]

Not too shabby! That's great shooting really for that sorta wind. Way to go. Looks like that rifle will shoot just fine.

 

[bobnob]

I feel more satisfied now than I was yesterday after reading your comments and reflecting on the conditions and my lack of experience.

I'll get something with a little clearer optics, fix up that length of pull, work on getting my technique a little tighter, wait for a calmer day (!) and put up a couple of wind flags.

Truth is other than the scope which isn't too bad in good light there's not much wrong with the rifle or load.

Thanks for the tips and encouragement. It's great fun.

 

[Elkman]

Making progress is always great fun. Keep it up, practice does help. :grin: