Five shot or three shot groups, and barrel contour.

[longrangehunter]

So this subject is nothing new and has been written/talked about for decades but I'd like to share some observations over many years of shooting.

1)What is the intended purpose of the rifle, i.e.; Hunting 1-3 shots or a Target rifle w/ multiple shots.
2)How well it was put together. This can be a gray area since it would depend on the inherit accuracy of the gun.
3)The work that went into the load development and was the most accurate load found.

So today I decided to tweak the load I had started last fall on the 6.5x47 Lapua since I thought how could I have produced such fantastic results with the Kimber 308 Winchester and not with a gun built by one of the best rifle builder in the industry, George Gardner of GA Precision.

Admittedly I dropped the project since it was hunting season so today I decide to change seating depths around and see what happens? My starting point was .035" off the lands with the work done from last year. Since I already had 45 pieces already loaded I was only able to seat them Further from the lands.

The load consisted of 37.7 VarGet, BR4 primer, Lapua brass (nothing done other then ran them over a sizing button), @ 2.0850" CBTO with a 123 Lapua Scenar.

I retested the .035" load at 100 yards and the group was Ok- .620" 5 shot group, back on 10/27/14 this same load produced a .9765" group @ 273 yards.

These are all off a bench @100 yards.
.040" produced a .3600" 5 shot but a .1980" 1st 3 shot group.
.045" produced a .6155" 5 shot but a .2360" 1st 3 shot group.
.050" produced a .4350" 5 shot but a .1700" 1st 3 shot group.


As odd as it may seem I pick the worst of the three to test at 275 yards just as a starting point, but managed a .551" 3 shot group and corrected for the error and placed the remaining other two bullets closer the the center mass of the target with a dial change since I knew the heating of the barrel would through off the nice three shot group. (See last Photo).

Well it begun to rain after lunch so I was unable to shoot the other two loads at 275 yards, but even with a fairly heavy profile barrel, (GAP #6 contour) might be close to a medium Palma profile, the barrel would heat up enough to cause the bullets to walk!

I noticed this through out the testing today and have in the past as well. One reason I like super heavy barrels like a MTU is for this reason on a target gun, but for a hunting weapon not ever really needed.

In the past I used to use what is called a Master Target. It is nothing more then one target reused over and over again behind a fresh clean target. This will show the true potential of a given load in a given gun. Basically it will just have a big hole from all the bullets hitting the center target aiming point.

I think depending on the inherit accuracy of a given rifle, and the shooters ability, three shots are a good place to stop, let the barrel cool down, and either retest or move to the next different load to test.

In a hunting gun that might not be constant enough to move on to the other load, retest again with the same load over the same POI, maybe even for nine shots. The reason I say that is the gun just might not be capable of producing shot after shot constantly enough to show it's true potential because of slight errors. Either in the gun itself or the load or the shooter. And when doing load development I think sometimes people get caught up in the group itself vs. the overall mass of a given load and what it shows. Which is why the master target can show a more average true potential of a given load in a given rifle, and why when the barrel heats up can make the bullets walk.

 

[desertcj]

Nice shootin'. I agree. If a load won't shoot with 3 shots, then two more aren't going to help. If your' 3 shot groups are that good and you are looking for ultimate accuracy then by all means move up to 5 shot groups to prove the load. 3 gives a good indication of what's going on IMO.

 

[Elkman]

Very nice, the rifle will shoot :grin: :grin:

 

[pre6422hornet]

Very nice shooting for sure.

I shoot three shot groups but that is because I am a wierdo and I only load 3 rounds in any gun used for hunting ( barring a 6 shot revolver). I only take 3 arrows in a quiver. I only carry enough rounds to reload 3 times ( so I carry 3 in the gun and 6 on the belt)...

Yeah I'm weird...

 

[salmonchaser]

I like the master target idea, makes a lot of sense to me. Nice shooting.

 

[rodell]

Very nice shooting for sure.

I shoot three shot groups but that is because I am a wierdo and I only load 3 rounds in any gun used for hunting ( barring a 6 shot revolver). I only take 3 arrows in a quiver. I only carry enough rounds to reload 3 times ( so I carry 3 in the gun and 6 on the belt)...

Yeah I'm weird...

No, no, no. The correct number to carry is 11!

 

[Guy Miner]

Longrangehunter - OUTSTANDING!

Now we're getting into marksmanship, and practical riflery.

I've had people pooh-pooh me, because I test my hunting rifles with three shot groups. Well... I've NEVER had to fire more than three shots at a game animal. So I don't care what the hunting rifle does with 5 or 10 or 20 shots...

And those slender barrels heat up fast.

So... three shots for my hunting rifles. Now, I may do SEVERAL three shot groups, but frankly the most important accuracy standard for a hunting rifle is the cold bore shot... Will it hit where you want it to, at 200, 300 or whatever yardage you select, time after time.

For a match rifle? I fired 20-shot strings of fire at 600 yards in competition. So I guess I was using a 20 shot "group" to test my loads, the rifle and the accuracy... Take that you 5-shot advocates! :twisted:

Regards, Guy

 

[longrangehunter]

Ok, pre6422hornet...... I'm still laughing but not at you, but the way in which you phrased your post.

Honestly, I mostly got used to loading three rounds for testing myself, simply because the barrel gets hot and like others stated if you can't get it done in three shots more wont make it any better. But, and here's the reason why sometimes things don't always work as planed. A flyer, wind, a bad something<like that, but unless you are working with a very accurate rifle, the load might need to be tweaked or abandoned altogether? And that's were the individual will need to make an informed decision whether or not to work using the same load or something different altogether.

But yes, even this gun, which has a fairly good size barrel still heated up enough to make the bullets walk. For those times when the three shot group seems to produce good results, stop, allow the barrel to fully cool down and retest. That could be for 2 or 3 three shot groups, this will give you a better idea of what to expect for the given load and rifle.

The idea behind the Master Target is the net results will show the cumulation of the load and what you'll notice is those shots out of sink or flyers will disappear into the mass of the hole in the master target. This is the gun's average potential and is more accurate of its true accuracy.

Thanks Guy. Like you said, if I see or notice a series of instances were the group is great for a given number of shots, quit there, and test again. But if you're forced into a long string, well you gotta do what's necessary. Oh, and us old guys can't see as well as when we were much younger. I can read the lettering on the target, but then the center seems to go blurry in and out often now..... but Hey, the groups still look good!

This gun was built as a Tactical Match rifle, but I'm not loving the idea of it as of yet, my other one is still better.

The 275 yard target was shot prone, in the snow using a harris bipod. The CBTO should read 2.0750" not 2.2750".... man, am I getting old or what?

 

[Guy Miner]

Prone in the snow? :shock: What are you? Some kind of hard core rifleman or something?

 

[nvbroncrider]

The one thing you can never account for on a given day is the wing nut on the trigger some days 1/2" is the best I can shoot others I can hold under .1".

If I could tell you what I was gonna be like on a given day I'd pick my LD days for sure.

Boy that's some good shooting there I bet that the differences in that load is more to do with the shooter than the ammo.

 

[Guy Miner]

No kidding. I've taken my match winning rifle & ammo and done poorly with it on a bad day. :evil:

On the other hand, I've taken a factory built rifle and won a match too... :mrgreen: Never know... We do the best we can. With good marksmanship, anything is possible!

Guy

 

[257 Ackley]

Nice shooting and great topic! Laying in the snow in Idaho makes it even more impressive . I'll stick to the heated shacks we have at our club for any load work right now.

3 shot groups work for me with any of my hunting rifles. For target/match rifles, I work up loads using 5 shot groups at 100 yards. Once the best powder charge, primer and seating depth with the bullet of choice is found, it is time to go to 300 yards to verify the "vertical". Here is a great article to explain in more detail how this can be done:http://www.6mmbr.com/laddertest.html

 

[PJGunner]

I remember as a kid reading it what was purported to be gun rags of the day where you had to shoot ten shot groups to prove the worth/accuracy of the rifle. Later on it dropped to five shot groups and now three. :roll: I knew this one old guy who has passed on to that great shooting range in the sky who was fond of the one shot group. He had a target that he'd put one shot into it then went home. Next time he came to the range He's tack the target up, shoot one shot, pull the target and go home. I have no idea how many shots went into that target but there' s one small ragged hole dead center. My guess about .80". I always meant to ask him how many times he's shot at that target but just never did. I got to be friends with him as he live quite close to me and we traded guns, bought and sold back and forth and I have a few nice pieces that I got from him. I just always thought it was kind of dumb to do a 52 mile round trip to shoot one shot. :?
I go back and forth between three and five shot groups but with the shortages of late, it's been strictly three shot groups. 8)
Paul B.

 

[preacher]

The last few years I tend to load 4 rds for load trials. If 2 are outside my accuracy goal, I pull the other 2 later and pour the powder back, reuse the bullets. I normally wait about 3 minutes between shots in the winter time, more in the summer. If 3 really excite me, I'll wait for the barrel to get completely cold and then shoot it. If it groups nice I'll later zero with it and try it at 300. Seems to work for my purposes. I've had some eye opening disappointments and some eye bugging successes...point is, any flaw will show up at 300. (You guys know this, I'm preaching to the choir! ha) I've used the 5 shot groups for dedicated smallbore varmint rifles ( .221, .223, .204, 22-250, etc)

 

[longrangehunter]

It's raining again around here and hasn't snowed in a month, but I had over 2 feet of snow at one time. Now there's about a foot on the valley floor.

There are a few things to like about shooting in the snow.

1) It's clean!
2) It forms to your body like a waterbed only doesn't move under you, even the gun with enough snow that's setup (old snow or anything packable).
3) Even when seated a lot of your body can be supported, even your back if on a up hill side and enough snow is around. Snow drifts work really well if in the right position.

Part of my reasoning for witting this was because even with a fairly stiff barrel, those groups can still walk and the 6.5x47 isn't burning a lot of powder, 38.0 grains. The other reason was sometimes we get caught up in the single group, and that if you had a single target as a backer you'd notice that they form a single raged hole. Whether it's an inch or three, that's still three inches or about the size of a tennis ball. More then enough to never worry about shot placement while hunting as long as that's the distance you're shooting at.

Doesn't look like I'll get back to testing anytime soon since it's suppose to rain all week. I'm glad I went back to tweak the load or I may have never cut the group almost in half. 0.20" MOA is nothing to sneeze at but during a match more then three rounds are very typical, and why those last few shots can bring nothing to the table.

 

[longrangehunter]

I got a chance to get out between the bad weather at lunch time today. Since I had only a short break in the weather I decided to just shoot the same load I shot at 275 yards, only this time at the steel up on the hill behind my house from 600 yards. The fog rolled in by the time I got out there, but I still made all five round connect with the steel.

So here's the setup:
First off notice I wasn't laying directly behind the gun and in line with where I was shooting, Bad form. But I didn't care to be laying directly over the hump of snow at the edge of the road which would have put me into the wet snow covered roadway, so this is what I went with.

You can't tell in the photo, but on uphill shots it's best to have really long legs on the bipod, especially in snow. This one adjusts from 13 1/2"-27", I had it at 19" and I should have extended them even further but it was beginning to rain and I got lazy, so I just pickup the front a few times to put more snow under the legs, but it still wasn't enough and here's why.

If the sight picture is uncomfortable, and you're too low in the rear, move the legs higher. Much higher then you would think is usually needed. This way your head will be more in a upward position and not facing down while trying to look up. Hope that makes sense? If it's wrong you'll notice your neck is aching and the sight picture is hard to stay in focus and the scope likes to go black. This was only a 10 degree uphill angle, which is not much at all, but enough that long legs are required in these conditions for a proper sight picture.

If it's too high in the front just the opposite is true and you'll notice you're raising your chest off the ground and needing a lot of rest under the rear stock to stay on target. In this case lower the legs, bottom line you should be completely comfortable and feel a ease with no odd muscle movements to stay behind the gun, and directly in line with your shooting position and the target.

Bottom line is if you're fighting to stay on target the shot wont be easy. Once you can master getting stable in the field, the shots become easier. The more you practice in the dirt, or in this case the snow, the easier it gets. Actually snow is the best substance for supporting your entire body, including the gun. Plus if your short on fill, the snow can be worked into whatever is needed or removed away. Snow has dirt beat hands down, and keeps them clean!