Magic Groups

M

murphy

Guest
Recently I did a series of tests on my private rifle range using AR2206H powder. My rifle is a REM700 BDL with 8x scope in cal. 223Rem, and my load was 26g of AR2206H 55g sierra varminter projectiles Rem 71/2 primers and Federal brass. This was a completely untried load in my rifle so I decided to move the seating depth around a bit to see what happned. There were no surprises at first when I seated the projectile slightly into the lands and got a three shot group at 100yds of about .8" Next I seated them just touching lands and got agroup of .4", still about what I expected, so I kept moving them away from the lands and rifle was holding steady at between .7" to .8". I continued in this manner untill I was .197" off the lands then suddenly my group plummeted to .159" Now for a factory rifle with an 8x scope this seems to be too good to be true but the wind won't stop blowing long enough for me to find out. What are the odds against a good but not spectacular rifle suddenly starting to put them all through the one hole? I will attempt to post a photo of the group in the next box as I am out of room. Reguards Murphy.:eek:
 
Magic Groups Continued

I am not a computer whiz so if my photo does not come out, forgive but here goes.
 

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First of all, thank you for reporting some interesting data. Most would not have had the curiosity to keep backing the bullet away from the lands. I believe that distance from lands acts very much like varying charge weight.

Secondly, you need to remeasure that group. No way is it a one. I think others will agree. This is not to discourage you, just to propose a probable correction to your facts. What is the spacing of your grid lines?
 
To Boyd Allen

My grid lines are 1/2 " apart and I just remeasured the group center to center and edge to edge and I still get .159." I really don't mind if my group is a bit bigger than .159" as the forces in play are still the same and thats the important thing. :D
 
good group

i once heard the comment that a record string is one where all the fliers went inside. ;) Fred
 
Murphy did you measure the COL or just with a stoney point ? If so, how close was it to the factory COL for the cartridge and bullet weight ?

DR
 
To DNR4

The point where my rifle started to shoot is .078.5" shorter than the overall length specifyed in the Sierra manual. My rifle has a history of wanting to shoot well back from the lands so although this load was a new one, it was not entirely a lucky guess that made me test them over such a wide range of seating depths. Even so I very nearly missed this one, as it was the last seating depth I tested. I don't own a Stoney point but sorely need one especially when working with my Hornet, which is much more unforgiving than the 223. The Sierra Varminter Projectile is especially difficult because of the variation in the soft lead tips. The jackets seem pretty even so lately I have taken to measureing to the end of the jacket and leaving the tips alone. I have an idea that groups such as the one I poted on the net, may not be abberations but can prove unrepeatable because of sloppy reloading practices especially with reguard to seating depth.:eek:
 
To Butch

If I can some how get your address I am happy to post you the target so that you can measure it. If you wish send me an Email send it to wirraleigh@bigpond.com:D
 
I just scaled the attached image using the 1/2" grid line reference and got approx. .33 by .19?

Still a very nice group.
 
Murphy, its interesting mainly due to the fact that all my factory rifles have ended up liking anywhere from .005 to .02 below factory C.O.L for a given bullet. examples

Ruger .243, 75 gr Hornady, factory 2.640, my actual seating is 2.635
Remington 700 .243 100 gr Sierra SPT 2.650, actual 2.630
Ruger 1V 22.250 52 gr HPBT match 2.350, actual 2.335
Remmy 700 25.06 117 Sierra Gameking 3.165. actual 3.160
Win 70 25.06 117 gr sierra gameking 3.165, actual 3.155
Cooper 220 Swift 52 gr sierra HPBT Match 2.680, actual 2.668

I had the cooper rebarrelled, due to way to many hot loads , but the old barrel was pretty much the same. It just like to be seated at 2.675.

So maybe this is just a good way to start on a factory rifle, back off the seating depth .02 and work up towards the lands.

DR
 
To DR4NRA

Thats the best bit of information I have had in a long time. If I had known that 20 years ago it would have saved me a lot of heart break and thousands of bullets as I have always been told that close to the lands was the best place for a bullet to be. As to the group size, if I hold my mouth differently an poke my togue out a bit I can stretch it to.161" but no more. I don't particularly want the target and will send it to anywhere in the world if any one wants to measure it.:eek:
 
Group size

By eyeballing the group in your picture my estimation would be around .300 Still very nice group for a factory rifle.
 
Murphy

You want a realistic answer to your Question. The odds of your Rifle repeating that one time performance, (darned, good, I might add), are pretty slim.

What you probably have is a nice Rifle with about a .500 to .600 agging capability. For a Factory Rifle,that is pretty darned good......jackie
 
That's a nice group...no doubt about it. Repeating it...consistantly....slim. Believe me...I know how that goes. Anyway, one thing to purge your mind of is COL , don't think about it...don't worry about it...it's probably the most non-precise measurement you'll ever read. I could go into great detail as to why but my fingers are tired. Anyway, looks like you have a real good shooter to be proud of. Shoot five-five shot groups over the course of a day and pick the load that does best throughout the temp change, etc. That will kill a lot more varmits than the occasional great group...Heck, tape that group to your stock...it may only happen once but at least it did and is a FACTUAL story.

Hovis
 
To jackie schmidt

Your assesment of this rifle fits in with what I have come to expect fom it over many years, though I don't think I could judge conditions well enough to shoot an agg, which I believe is 25 shots. At no stage did I ever imply that my rifle could shoot tiny groups consistently, but they are becoming more common as I refine my seating depth techniques. The whole purpose of this spread was to show the importance of getting seating depth right. I believe that too many people ignore it or don't understand it, even experienced gun writers, or maybe it is just too dry a topic for them.:eek:
 
Magic group - accuracy potential -some thoughts

I was last evening thumbing through a foot high pile of targets from my 6PPC.
I came to a few interesting conclutions. Fist of all had I all the money that went through those targets I could buy myself a brand new car or better still if I had all those components they would probably last my for the rest of my life :) Secondly it would be wise to hide those targets to prevent that my wife saw them and made calculations such as how many new pair of shoes could have been bought for the price of the components :) And thirdly it would be wise to hide them period :eek:. It is my estimation that if I took aggregate from all the aggregates it would not be very much below .3000 at 100 meters wich would equal about .2700 at 100 yards. It is a full blown benchrest rifle with custom action and best of barrels shooting custom bullets like Bruno 9S and such. Aggregates under .2000 are not all that common and single groups under .100 at 100 meters and under .200 at 200 meters are rare occurrance. I also saw a few groups that I would wish that my worst enemy had shot.

So when somebady stands up and claims he is shooting quarter inch groups day in day out with his factory rifle I tend to close my ears and just say yeah right. First of all no factory rifle is accurate enough to aggregate under .250 Secondly shooting aggregates that small are next to impossible with out 2oz trigger and 3 inch forend of stock and at last it takes a good shooter to shoot day in day out aggregates of that size.

Now I am by no means belittling you your rifle or your shooting. I am just pointing out facts. I agree with Jackie enjoy your very good rifle which has as he said probably .500-.600 aggregating capabilities but dont get disappointed if you cant repeat this group on a consistent basis. And my advise is not to spend all its barrel life trying to find the magic load, statistically chanses are if selection is based on 2 or 3 three shot groups that you end up rejecting better loads in favour of worse. Just find load that works for you.

I talk from experience as in my younger days I did all the tricks in the book to make factory rifles competitive in Benchrest. Needless to say I didnt succeed. For an example one Sako .222 went through free floating bedding trigger change fiber glass stock I even shot 52 gr Remington bullets from it but it never was more than an average varmint rifle .750-1" aggregates.

On the other hand just by replacing the factory barrel by Hart barrel or something else this rifle became sub .500 rifle. The single most productive change to improve accuracy in a factory rifle is to change the barrel in my opinion.

It is my firm belive that nothing but full blown Benchrest rifle can and will aggregate in the long run under .2500
 
To .25shooter

Thanks 25shooter for your very sincere comments, The fact of the matter is that I have reached a level of refinement where I have outgrown my rifle. I need to take a reality check and go out and do some serious varmint hunting or move on to the next level which is competition benchrest. Sadly like a lot of people the credit crunch has got me and I may have to abandon my retirement.:eek:
 
Gee, I thought this WAS the factory rifle room. Nice of you guys to come in and tell us what miserable POSes we've got. Just buy that box gun, spend enough money to buy a gunsmith a new house and you too can agg .250 less than when it came from the box. :D
 
I went back and reread all the posts. No one remotely said that his rifle was a POS. As far as putting a pile of money into a factory rifle goes, a better move would be to sell it and buy a used Benchrest rifle, if shooting that sort of equipment is what you want to do. I am sure that we all have had a lot of fun shooting tuned up factory rifles. The thing that I notice most often at the range about non-competition shooters is that they may say that they want better groups, but are highly resistant to changing anything that they are doing, regardless of how little it might cost, or even if there is no cost. This doesn't particularly bother me, but it is a little strange.
 
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