Whats causing these groups?


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ole farmerbuck
January 24, 2010, 11:34 AM
I'm having trouble getting good groups from my AR. 20'' Bushy national match upper. Any suggestions? 40g v-max actually groups better than 52 or 55 grain. 1-9 twist.
http://i302.photobucket.com/albums/nn88/farmerbuck/shots.jpg
http://i302.photobucket.com/albums/nn88/farmerbuck/shot.jpg

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Walkalong
January 24, 2010, 12:44 PM
Could be anything. Need a lot more info.

ole farmerbuck
January 24, 2010, 12:59 PM
Ok It was about 50 degrees with some wind. Shooting off of a Zero Kick rest. I started out a little over 24g and up to i think 27.5 with these 2 being the best. The other groups dont show 2 or 3 touching like that, they're scattered some. These are 5 shot groups.

JimKirk
January 24, 2010, 01:07 PM
Look as if you have two distinct groups within the group. That is evident in both groups.

So my question are you double tapping or are these individual shots with a
concerted effort to get back on the target dot.

If you can manage to get the subgroups together, then the whole group would be good.

Have you played with the amount of powder to see if that helps? Are you crimping?
What dies are you using? Lots of question?

Jimmy K

You answered some of the questions while I was posting.

ole farmerbuck
January 24, 2010, 01:36 PM
I used Hornady fl sizing die and do not crimp and seat with a Lee dead length seater die. I tried to take about the same amount of time between shots. Maybe 15 secs pretty sure the cross hairs were in the middle of the red dot. Dot is 1/4" or so. Yes i played with the amounts of powder. If its cold out and the barrel isnt heating, do i still need to wait longer between shots?


3/8'' on dot size

sgte5
January 24, 2010, 01:48 PM
What trigger do you have in your AR? Every AR I have ever shot with factory triggers, were horrible to hold a 5 shot group. I've since went with JP triggers and have really improved. My latest AR 10 came with 6 3/4 lbs of trigger pull. At 3 lbs, it's the difference between night and day.

gearheadpyro
January 24, 2010, 02:03 PM
I don't shoot an AR, and have very little experience loading for semi-auto rifles. It's very possible that groups like those are related to your firearm.

In my bolt gun that group would lead to me messing with my to C.O.L. This may be a limited option for you though as a longer C.O.L. may not fit in your magazine or feed correctly.

One other thing you might try is crimping with a Lee Factory Crimp Die. That eliminated some of this type of group variation in my rifle.

Have you done a good load development (http://www.rifles-shooting-reloading.com/load-development.html) for this gun? Systematically tuning your reloads is the only way to get the most accurate ammunition.

ole farmerbuck
January 24, 2010, 02:15 PM
What trigger do you have in your AR? Every AR I have ever shot with factory triggers, were horrible to hold a 5 shot group. I've since went with JP triggers and have really improved. My latest AR 10 came with 6 3/4 lbs of trigger pull. At 3 lbs, it's the difference between night and day.
My trigger was done by Bill Springfield. About 3.5 lbs

ole farmerbuck
January 24, 2010, 02:17 PM
I've been loading them to 2.350. I guess i could try shorter. I did try some lightly crimping with the lee fcd. Really couldnt tell any difference.

Bart B.
January 24, 2010, 02:19 PM
If you're shooting the rifle with it resting atop a rest on a bench, those groups may well be normal. Horizontal stringing is common with most folks when they shoot holding their rifles atop a bench. Especially when they don't hold them very tight.

Try slinging up in a good prone position with the fore end resting on something firm and soft, then try it again. You may be surprised.

ole farmerbuck
January 24, 2010, 02:28 PM
I meant 2.250

ole farmerbuck
January 24, 2010, 02:30 PM
Ok Bart. if the wind ever stops i will. I'll get my target and post them so you can see all of them. :fire:

JimKirk
January 24, 2010, 02:35 PM
Farmer
I'm quite new to the AR rifle and I am working with my first AR, a DPMS Sweet 16 Bull barrel. That being said, I believe that it must be something to do with the ammo.

Are you getting consistent OAL, by that I mean not really tip to base, but some point on the ogive of the bullet to the base. I have found that the tip measurement will only give you what fits in the magazine. The bullet comparator in the photo below is what I use.

I have no idea about the Lee Dead length die, maybe someone with experience with it will come along.

Sounds like your shooting method is ok, may want to give yourself a little more time. I find that if I take a deep breath, exhale about 3/4 of it, hold then make my shot. I do this between each shot. If I'm shooting for a group, I give myself plenty of time. Whats the rush.

The trigger could very well be a big part of it. It took from 75 to 100 shots before I got the feel for my DPMS trigger. Yes I would like to replace it, but I don't have the funds right now.

http://www.sinclairintl.com/product/5581/Bullet-Comparators


Jimmy K

Sorry about the post lag ... phone calls...

ole farmerbuck
January 24, 2010, 02:40 PM
I've checked reloads with the Hornady tool that measures fom the ogive and was impressed with the consistancy the leed die seats. I didnt check these with it though.

rcmodel
January 24, 2010, 02:48 PM
What kind of scope?

Severe scope parallax could conceivably cause two groups in one group like that if you aren't getting your eye in the same exact place behind it every shot.

Suggest you get benched firmly on the target dot, and without moving the rifle, move your head from side to side & up & down and see if the cross-hairs move on the target.

rc

Walkalong
January 24, 2010, 02:58 PM
A 3/8" dot, in the wind, and you wonder what is wrong? Probably nothing.

Bart is right about shooting from a rest. It is different than shooting without one and takes some learning. It is very easy to push/pull/etc shots from a rest. Everything must be exactly the same each time.

It is very hard to teach shooting over the web. I stay out of most of these discussions for that very reason.

Get some books on shooting for accuracy from a rest. Go to a local match where they shoot matches.

Not trying to be a pain. It just is what it is. There are folks all over who can teach you. Find one at a range near you. :)

madd0c
January 24, 2010, 03:46 PM
1-9" twist? My 1-9 twist HATES anything lighter than 62gr bullets. If I shoot 55gr or lighter bullets, I get horrible groups. It is a 16" barrrel.

It looks like you have one shot that is keyholed. I would try some 62,69 and 75 gr bullets in your reloads and see if that won't tighten your groups.
madd0c

ole farmerbuck
January 24, 2010, 05:08 PM
A 3/8" dot, in the wind, and you wonder what is wrong? Probably nothing.

Bart is right about shooting from a rest. It is different than shooting without one and takes some learning. It is very easy to push/pull/etc shots from a rest. Everything must be exactly the same each time.

It is very hard to teach shooting over the web. I stay out of most of these discussions for that very reason.

Get some books on shooting for accuracy from a rest. Go to a local match where they shoot
matches.http://i302.photobucket.com/albums/nn88/farmerbuck/fortygrain.jpg

Not trying to be a pain. It just is what it is. There are folks all over who can teach you. Find one at a range near you. :)
But, here is forty gr v-max just a few minutes ago hiding behind a tree row with 40+ winds shooting out of the pickup window! 5 shots but only 85 or so yards. Pickup was rocking a little but managed to get shots off. I tried some 52gr now too but they didnt group well at all.
I have never seen a range let alone shoot at one. Nothing close here that i know of.

ole farmerbuck
January 24, 2010, 05:12 PM
What kind of scope?

Severe scope parallax could conceivably cause two groups in one group like that if you aren't getting your eye in the same exact place behind it every shot.

Suggest you get benched firmly on the target dot, and without moving the rifle, move your head from side to side & up & down and see if the cross-hairs move on the target.

rc
I was hoping you wouldnt ask about the scope but its a Simmons i took off of my Ruger varmit 22-250 and has always held zero. Its 1 year old. 6x20 Everything else i use are Nikons Monarch and Buckmaster. I will check it as you suggested RC. Thanks

ole farmerbuck
January 24, 2010, 05:14 PM
1-9" twist? My 1-9 twist HATES anything lighter than 62gr bullets. If I shoot 55gr or lighter bullets, I get horrible groups. It is a 16" barrrel.

It looks like you have one shot that is keyholed. I would try some 62,69 and 75 gr bullets in your reloads and see if that won't tighten your groups.
madd0c
I think the paper folded over is playing tricks on you. There are 5 shots there.

Walkalong
January 24, 2010, 05:35 PM
5 shots out of a rocking truck with 40+ winds that could almost be covered by a dime?

Wow. You should be giving us tips. :)

delta5
January 24, 2010, 06:13 PM
Have you tried any factory ammo to see if the groups improve?

243winxb
January 24, 2010, 06:49 PM
Normal groups from AR's. When the American Rifleman lists there tests for many different AR's in 223, 1 1/8" is about the average for 5 X five shot groups @ 100 yds. 25 shot total. But then internet groups are always much smaller.

ole farmerbuck
January 24, 2010, 08:28 PM
5 shots out of a rocking truck with 40+ winds that could almost be covered by a dime?

Wow. You should be giving us tips. :)
Maybe the wind helped me. Never know. lol Those were the 40 grainers now, its the 52's i'm having trouble with. Just checked the weather info and we had gusts up to 43mph. Most of my shooting is out the pickup window. Those little p-dogs usually have to be hiding most of their body or be quite a distance from me or they're gone!

ole farmerbuck
January 24, 2010, 08:29 PM
Have you tried any factory ammo to see if the groups improve?
No, all i have is some rp fmj's. Guess i could give it a try but i'd hope my reloads are better than them.

Grump
January 24, 2010, 11:44 PM
My son and I have seen that so often, we gave it a name: Two-grouping.

Maybe he got it from someone else.

Two different ARs (one the Grendel upper he sold) and a Remington 700 in .308 have all done it with differing loads. The Grendel would do round groups of 1-1/8 MOA with factory and some reloads, while other reloads would two-group a bit tighter with holes touching but diagonally apart 3/4-inch at 100 yards.

Kinda hard to zero when it does that.

It's not even predicable from which side of the magazine the rounds are fed from!

Both benched and bagged, and off a tripod for two of the three rifles. Two fully free-floated, the other a Colt HBAR as-is from the factory.

Voodoo and witchcraft, I suspect.

Bullet
January 25, 2010, 03:38 AM
Walkalong
5 shots out of a rocking truck with 40+ winds that could almost be covered by a dime?

Wow. You should be giving us tips.
+1

ole farmerbuck
January 25, 2010, 07:53 AM
5 shots out of a rocking truck with 40+ winds that could almost be covered by a dime?

Wow. You should be giving us tips. :)
I dont think i can give tips to people who reload more than me but i can usually work up pretty good loads. If the wind isnt too bad all i have to do is load a few and step out the door to the bench and try them. Nice to live on a farm! I just cant figure out why these 52gr BTHP's wont group like i thought they should.I have some 69gr Sierra's i can try but i like the lighter faster bullets for what i use them for. Using the mirror for stability out the window isnt too bad really. Thats how i hunt p-dogs. I drive through the pastures looking for them and lots of times all i get is a little head sticking up out of the hole some. Make quite a few long shots doing that so the loads have to be pretty accurate. I'm sure there a lot of people on here that can out shoot me but i do ok. P-dogs sure dont like seeing me. :)

Bart B.
January 25, 2010, 10:53 AM
Even the most accurate competition rifles will shoot sub 1/4th MOA at 100 yards in a constant 60 mph cross wind. If the wind changes speed by 2 mph and no windage correction is made, the groups will enlarge horizontally by 6 hundredths of an inch.

Walkalong
January 25, 2010, 11:25 AM
Good groups can be shot in the wind. As long as the wind is constant, it's not a big problem, but it usually isn't. Good groups can still be shot, it just gets a mite tougher.

Duce1
January 25, 2010, 11:57 AM
1-9" twist? My 1-9 twist HATES anything lighter than 62gr bullets. If I shoot 55gr or lighter bullets, I get horrible groups. It is a 16" barrrel.

It looks like you have one shot that is keyholed. I would try some 62,69 and 75 gr bullets in your reloads and see if that won't tighten your groups.
madd0c
As advised.

I was having the same problem and a buddy told me to go to a heavier bullet I was using 55 grain Hornady bullets.

He told me not to go below 60 grain bullets and I have not since loading up some and watching my groups come well within my expectations.

Walkalong
January 25, 2010, 12:57 PM
His 40 grain bullets shot well though. Unless of course the wind blew them in to the group, instead of out.

ole farmerbuck
January 25, 2010, 02:21 PM
His 40 grain bullets shot well though. Unless of course the wind blew them in to the group, instead of out.
The 40's shoot great, always have. It's only the 52's and 55's that are giving me fits. I have RL15 W760 and other powder i guess i can try. Not today, the wind is even worse than yesterday.

ole farmerbuck
January 25, 2010, 02:58 PM
Gusts up to 47mph today. I'd better get out there!:)

JimKirk
January 25, 2010, 04:03 PM
Its blowing 32 mph here in S. GA, time to get my AR out for a shoot!

My problem is... I have two trucks, a Toyota T100 and a Chevy 1500. Which would be the better truck to shoot out of? Both are long wheel base, the T100 has 300,000 miles the chevy 190,000.

Jimmy K

WNTFW
January 25, 2010, 06:44 PM
Ole Farmerbuck,
Is the target moving around on you? I shot Saturday. We had a workday at a range and the wind was dead calm in the morning. When it came time to shoot the wind had picked up. The targets could be seen moving.
I cut a group in half by altering the way the target was weighted down.

I have had it happen at indoor ranges also where the target carrier would just keep swinging.

TimRB
January 25, 2010, 07:09 PM
I couldn't find the range posted anywhere, but it looks to me like those groups are about 1 inch. If shooting at 100 yards, that's about 1MOA, which is pretty good.

It's nearly impossible to get an accurate picture of real group size with only five shots. Also, because invariably there are shots that touch combined with a few that don't, people usually (and often incorrectly) conclude that they have flyers or that there is something wrong. Shoot groups of ten or more. If you do the math, you'll convince yourself that it's almost impossible to shoot five shots that touch unless your rifle really is shooting less than 1/4 MOA.

Also, if you are shooting on a windy day you can still glean useful information by ignoring left-right spread in your groups and only watching the vertical.

Tim

ole farmerbuck
January 25, 2010, 07:54 PM
Ole Farmerbuck,
Is the target moving around on you? I shot Saturday. We had a workday at a range and the wind was dead calm in the morning. When it came time to shoot the wind had picked up. The targets could be seen moving.
I cut a group in half by altering the way the target was weighted down.

I have had it happen at indoor ranges also where the target carrier would just keep swinging.
No i dont think my targets are moving. The 40's were good and the heavier were bad. I staple typing paper to boxes filled with enough of BLOW dirt that they wont move. When i shot those in the 1st pic, it wasnt all that windy. Now the last pic is a different story. Windy hiding behind a small tree row.

ole farmerbuck
January 25, 2010, 07:58 PM
I couldn't find the range posted anywhere, but it looks to me like those groups are about 1 inch. If shooting at 100 yards, that's about 1MOA, which is pretty good.

It's nearly impossible to get an accurate picture of real group size with only five shots. Also, because invariably there are shots that touch combined with a few that don't, people usually (and often incorrectly) conclude that they have flyers or that there is something wrong. Shoot groups of ten or more. If you do the math, you'll convince yourself that it's almost impossible to shoot five shots that touch unless your rifle really is shooting less than 1/4 MOA.

Also, if you are shooting on a windy day you can still glean useful information by ignoring left-right spread in your groups and only watching the vertical.

Tim
The target was about 80 yards or so. I have a pile of dirt at that range, then 100, 125 and 150. Like to get them grouping at the closer 1st and then move on.

ole farmerbuck
January 25, 2010, 08:02 PM
Its blowing 32 mph here in S. GA, time to get my AR out for a shoot!

My problem is... I have two trucks, a Toyota T100 and a Chevy 1500. Which would be the better truck to shoot out of? Both are long wheel base, the T100 has 300,000 miles the chevy 190,000.

Jimmy K
If its only 32mph there then you'd better get after it.:) My old chev only has 170,000. Just gettin broke in! Surely some of you hunt shooting out the window so you know what i'm talking about. Oh yea, p-dogs are the only things i shoot that way.

JimKirk
January 25, 2010, 08:30 PM
Have you ever seen a 1000 acre plot of 100' pine trees with a 32mph wind blowing through it? Dorothy and Toto was in Kansas, right?

Shooting out the truck window? What you mean like uh... deer, possums, aardvarks, stop signs, pole insulators ...stuff that that? You do know that Bubba was born just down the road a ways?

Us ain't got no p-dogs round hare, unlessen you bees talking bout dem hi class house dogs is ya?


Joking aside.
We don't get a lot of wind here, too many trees blocking it from blowing. March is usually our windy month. Not many windmills here.

Jimmy K

eitrheim31
January 25, 2010, 09:52 PM
It's only the 52's and 55's that are giving me fits.

Due to barrel harmonics your gun might just not "like" those bullet weights....

Bart B.
January 25, 2010, 10:34 PM
eitrheim31 suggests: Due to barrel harmonics your gun might just not "like" those bullet weights.... I don't think so. The barrel and its action whips at a very low frequency which has the muzzle axis changing the most. Most barreled actions whip at less than 100 Hz (cycles per second). And virtually all bullets exit in a narrow range of time of about 1 millisecond. So the barrelled action completes about 1/10th of a whip cycle before the bullet leaves. The difference over a 10% range of muzzle velocities doesn't change that very much.

This whip cycle is the fundamental frequency; harmonics are multiples of it and they have virtually no effect on muzzle axis pointing; maybe one tenth MOA at the most.

When you smack a barrelled action with a hammer and hear that high frequency, that's the sound wave going back and forth from one end to the other at about 18,000 fps. This creates only microscopic dimensional waves and are insignificant to accuracy.

Most barrels will shoot a very wide range of bullet weights quite accurate. Bullets have to be spun at their best right rpm rate by velocity and twist to do so.

Regarding number of shots per group, here's a chart showing the probability different numbers will represent what all bullets fired will produce for accuracy:

http://fuzzylimey.net/coachtalk/gsafig1.jpg

One 5-shot group has about a 57% confidence level of being the best accuracy for that load.

lopezni
January 25, 2010, 10:46 PM
just a thought, the 40 v-max is going to have a shorter OAL, maybe you need to seat the other bullets deeper? I know that 40gr definitely shoot better in a 1/12" bolt rifle, but in your rifle that seems odd.

ole farmerbuck
January 25, 2010, 10:56 PM
Yes it does. I'm going to try some 69's since i have them but really, 40's are just fine with me and what i use them for.


And thanks Bart

ole farmerbuck
January 25, 2010, 10:59 PM
Heck Bart, you arent very far from me. I might have to load this thing up and pay ya a visit. I'm 70 miles from our border.

ole farmerbuck
January 27, 2010, 08:53 AM
I got 5 Sierra 69gr BTHP loaded lastnight with Varget. Hopefully late this afternoon i will have a range report. Also loaded 5 more 40gr v-max. The wind is supose to be better today.

ole farmerbuck
February 7, 2010, 05:01 PM
Gee, what a difference a scope makes! I gave up and put on an old Leupold 3x9. It is the first scope i bought many years ago. I noticed the heavier the bullets were, the worse the groups were so i'm thinking the more kick, the worse it jars the scope? Anyway, this is 25.5gr H335 with 55 gr v-max. I know, its only 4 shots but i think i'm on the right path now. Come Monday, its time to order another Nikon Monarch 5x20x44.. I might try 26.0 gr this afternoon and see what happens http://i302.photobucket.com/albums/nn88/farmerbuck/newscope.jpgs should work on the p-dogs.

Walkalong
February 7, 2010, 06:00 PM
Excellent!

Doug b
February 7, 2010, 06:26 PM
26.0 grs. of H335 and a 55gr.bullet puts you over max. by .7grs. according to Hodgdon Data Center.

ole farmerbuck
February 7, 2010, 08:28 PM
26.0 grs. of H335 and a 55gr.bullet puts you over max. by .7grs. according to Hodgdon Data Center.
Yea but I believe it's way under according to Lyman, if i remember right. I'll check.

Walkalong
February 7, 2010, 09:07 PM
Speer #13 goes to 26.0 Grs H335 with 55 Gr bullets.

ole farmerbuck
February 7, 2010, 09:38 PM
I dont have my manual here at the house but i think Lyman shows 27gr for the 55.

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