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What could be the cause of bad groups?

T

Tomekeuro85

Sergeant
Commercial Supporter
Full Member
Minuteman
Oct 11, 2007
592
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39
Chicago Suburbs, IL
#1
Long story short:

Gun is a Crusader in .308 with 150 rounds thru it.
Remington brass FL sized trimmed and sorted by wieght.
Primers are CCI
Varget powder


I made myself some 165gr GameKing hunting rounds, groups were average of .3-.4" at 100.

Decided that since 168SMKs are great they woudl do better at grouping.

Now I cant get better than .75" consistently at 100.

FL sized with redding dies .002" tension. Seated with redding seater, to 2.800 then 2.835.

Tried charges of varget ranging from 41.5 to 44.6 in .3gr increments.

I know me and the gun are not the problem... Im trying to figure out what else could make a difference, because I know the a Crusader has to shoot better than .75 at 100. Perhaps I just gotta find a good load? Any suggestions on improvements?

My only other ideas are to go thru the powder charges again and also try different seating depths. thats about all that is left to do at this point.

 
#3
Re: What could be the cause of bad groups?

I was thinking that also. Probably 175's first. I just bought 500 168's so i'll play around with those some more. If i dont drop below .4" consistently i'll try the 175's.

Also, the seating depth of 2.835 the bullet was jamming into the rifling about .02". That may be a cause...
 
#4
Re: What could be the cause of bad groups?

If your not getting any pressure signs then you might want to work up to the 46gr mark. A lot of people are running 45-46 grains of Varget powder with success. When I tried the 168's mine shot solid 1/2MOA at 45.5 grains......... Seating depth "shouldn't" be the problem with SMK's, they like to jump. I've jumped them anywhere from .015 to .070 with no noticeable effect on accuracy.

OR, it could be that it just doesn't like that bullet. FWIW, My GAP seemed to shoot the 175's better.
 
#6
Re: What could be the cause of bad groups?

Maybe this is a little coarse, but...

Why are you complaining that the GameKings, which are a hunting bullet not a match bullet, won't shoot inside of .3-.4 inches at 100y?

1) What are you shooting with a 308 that requires hunting bullets and even better than excellent sub MOA accuracy?

2) If there's valid reasons to question 1, then have you tried a good match bullet at all?
 
#8
Re: What could be the cause of bad groups?

I don't think he's asking about the Gamekings. He said those hold .3 to.4 groups. He switched to Matchkings and the groups are bigger. The only thing I could think of by reading this was the bullet seat depth may need to be kicked back so they aren't jammed into the lands. If that doesn't change anything see if the other rounds still hold the same group as they did before. If not check the crown.
 
#9
Re: What could be the cause of bad groups?

measure the gamekings to the ogive then seat the matchkings to match and see if that doesn't do the trick for you. Three grs in bullet weight should not through you that far off. If it will shoot 165gr gamekings 168gr matchkings should work well also. If not try some Amaxs, if they don't shoot move up to 175s or 178s.

Just my $.02
 
#12
Re: What could be the cause of bad groups?

What's the price difference for you between Game Kings and Match Kings?

I'm guessing the GKs are cheaper.

Just sell the 168s and stick with what works. Windage and elevation you can learn, but a less accurate load goes on forever downrange.
 
#13
Re: What could be the cause of bad groups?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body">What's the price difference for you between Game Kings and Match Kings?

I'm guessing the GKs are cheaper.

Just sell the 168s and stick with what works. Windage and elevation you can learn, but a less accurate load goes on forever downrange.</div></div>

Well my whole original idea was that if some hunting bullets can shoot this good, imagine what actual match bullets will do.

Anyhow, I went shooting again yesterday. Found somethin that might work well. 44.7 grains of Varget seated to 2.815. I shot two groups with this load.

First group- 4 shots went into .16" the fifth one went its own way and opened the group to .52"

Second group 4 shots were .24 fifth opened it to .48".

Now I can adjust this load accordingly and see what I can come up with. Theres seems to be a nice tight pattern minus the random flyers which im sure can be fixed somehow or other.

Which leads me to my next question: How can I fine tune this to tighten it a bit more?

My guesses right now are adjust seating depth a few thousandths in each direction, sort brass by weight, and neck size only to see how that works. Also try powder charges of 44.5 44.6 44.8 and 44.9 to get the neighboring charges, perhaps they'll shoot a bit better.
 
#14
Re: What could be the cause of bad groups?

Took my GAP Rock out today for the first time.

My loads:
168gr Sierra Matchkings
Varget
CCI 200's
Seated to COAL of 2.835
42.5 to 44.5gr in .5 increments

I found the same thing with one flyer ruining the groups. With the exception of 43.5gr, all groups would have been sub half MOA and all groups were under .75 MOA minus 43.5. I would like to find out as well how to minimize the flyers. I might switch to AMAX's and see if that helps eliminate the flyers tomorrow. Could it be a consistency issue with the Matchkings? BTW- Best group was with 44.5grs. I will start there and work around that number tomorrow.
 
#15
Re: What could be the cause of bad groups?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tomekeuro85</div><div class="ubbcode-body">

First group- 4 shots went into .16" the fifth one went its own way and opened the group to .52"

Second group 4 shots were .24 fifth opened it to .48".

Now I can adjust this load accordingly and see what I can come up with. Theres seems to be a nice tight pattern minus the random flyers which im sure can be fixed somehow or other.

Which leads me to my next question: How can I fine tune this to tighten it a bit more?
</div></div>

T, I don't want you to take this the wrong way, I'm sure you are a great shooter. That being said, If you have 4 going into sub 1/4 MOA and the 5th opening it up, its probably not your gun. Your getting nervous about putting that 5th shot in the same hole and subconsciously you are doing something different to throw that shot (tensing up, slightly flinching, holding the rifle differently b/c you are nervous ect, ect.)...... I've done and seen this very same thing MANY times. If the rifle will put 4 almost in the same hole its not the rifle, or the load. Think about it. What if you only shot a 3 shot group? You'd be thinking I have a repeatable sub 1/4 MOA load. A 3 shot group will tell you what the rifle can do, a 5 shot group will tell you what the rifle AND shooter are capable of.

Sounds to me like you and your rifle are capable of sub 1/2 MOA groups! Good shooting. I wouldn't touch that load, it shoots REALLY well.
 
#16
Re: What could be the cause of bad groups?

Well I know what you mean, However i didnt have any trouble holding .2"-.4" with my last load over a span of 100 rounds.. There were no flyers off course etc. Dead on single torn groups every time...

This is why im frustrated
 
#17
Re: What could be the cause of bad groups?

I too have a Crusader and it loves both the 168 and 175 SMK's. The 168's seem to be a standard at shorter ranges and should be shooting well. Using the 168's and 175's it's almost like I can't get them to shoot badly. Even on an off day they rarely shoot worse than .6" and your results should be similar. How consistent is your brass?? You may want to look for any other inconsistencies in your reloading such as neck run-out or maybe charge weight variances?? I think that everybody would agree that during the fifth round many people seem to pull it and ruin an otherwise fantastic group. This is probably why everyone tries to post their 3 rd. groups on here and why they're looked down upon as an indication of accuracy. To speak to the above guys point/comment, there is a lot to be said about how our mental state leads to variances in the group size. Maybe when you were shooting the GK's you weren't expecting much and weren't hyper critical about the group size, and therefore had different levels of expectation, stress, tension, time focusing on the shot, etc.. The following are the loads that I used and most all shot between 0.2-0.4 in. five rd groups. Please note that I use Lapua brass and the powder charge weight for your brass <span style="font-weight: bold">will</span> be different. Maybe someone else will chime in with a recipe using Remington brass or how much to change the powder due to internal volume differences. I would guess that not many here use Remington brass though. Good luck, I'm sure you'll find what it is that's holding you and a great gun from achieving small groups. I just noticed that you're also an IL resident. If you ever get out my way and want to compare notes/data or shoot let me know. Also, I could give you a copy of the chamber specs.

Lapua brass
168 smk coal= 2.83"
Varget
Fed 210m
nodes @ 45.6 gn, avg. vel. = 2712 fps, ES=15, SD=8
@ 44.5 gn, avg. vel. = 2652 fps, ES=12, SD=6

 
#19
Re: What could be the cause of bad groups?

Just out of curiosity... I recently realized altho I clean the gun regularly with powder solvent, I have not cleaned with copper solvent in a good 250-300 rounds. Could this be causing poor groups?
 
#20
Re: What could be the cause of bad groups?

T,

The only other things I can think of is that maybe you have a really short throat and at your current seating you might be slightly into the lands (?). One other possibility is that with this new bullet, the rifle might require a slightly different hold than the Game Kings b/c it might recoil a bit differently (far fetch though).

I don't want you to take this the wrong way, I'm just trying to help you. If you were shooting .2 to .4 over 100 rounds consistently with no flyer's using gamekings, you might consider a career in benchrest. I've shot thousands of rounds of .308 and and even thousands of rounds through my GAP .308 and I don't think I've been able to pull off 100 rounds in a row with no flyer's, even shooting off a bench, with all groups being sub 1/2 MOA. If you can do it though, your a stud!

For me when first I received my GAP I too thought I was getting "Flyers" (I now call them F%#@ ups). The only reason I thought this is because this was the most accurate rifle I had ever owned. Let me explain: Before with my factory rifle and my duty M24 I was used to getting .4 to .7 groups consistently. These groups were usually nice round groups. When I got my GAP and first started shooting it, I would get a REALLY tiny group, then a group that would have 3-4 shots in 1/3MOA or less with one to two shots that opened it up to .4-.6. I would get pissed that those shots weren't in the 1/3 MOA shots. I "thought" I was getting flyers too. I wasn't really getting "flyers" I was now shooting a rifle that would expose my mistakes! My last rifles couldn't expose my mistakes that well because it wasn't accurate enough to do so. I now had a rifle to where if I was slightly off on my technique it would actually show up in my groups. And even though most the groups were still around 1/2" MOA I would still have those ones hanging out there that were apart from the 3-4 shots going into .33 MOA or less, making me believe they were flyers (even though I was shooting 1/2MOA). I then had a very accomplished shooter set the rifle up in his benchrest set up and shoot it. This guy has shot about 50X more rounds than I have. He proceeded to pound round after round down range with MY load and MY rifle. When I looked at the target there were 5 5-shot groups all less than .4 MOA, most were around 1/4". All but one looked like a slightly large hole. By the way, the reason I call the F' ups now and not "flyers" is because I realize its not the rifle, its me.

Some times you just have better days at the range than others than others. Even professional shooters recognize this. For example, in your first post in this thread, you stated that you couldn't get get the GAP to group any better than .75 MOA. On your second range trip you stated that you got two 1/2MOA 5 shot groups with 44.7gr of varget, with the 4 first shots on both groups going into sub 1/4MOA. The only difference between this load and one of the loads you used a trip prior was .1gr difference in weight. That's not going to make that big of a difference in group size. Your next range trip with, I'm assuming this same load, you stated:
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tomekeuro85</div><div class="ubbcode-body">Im using Varget and 168 SMK. Does anyone have successful sub half moa loads? I cant do it after trying every possible combination.</div></div>

The rifle is going to do exactly what it is told to do, you just have to be REALLY careful on what program you send it. At this point we are splitting hairs!

Sorry so long.....

 
#21
Re: What could be the cause of bad groups?

Just for kicks, tighten everything down again and re-try (scope rings at the base and the rings that hold the scope, actions screws, ect).............. You never know.......

I've had these work their way loose on me before.
 
#22
Re: What could be the cause of bad groups?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tomekeuro85</div><div class="ubbcode-body">Just out of curiosity... I recently realized altho I clean the gun regularly with powder solvent, I have not cleaned with copper solvent in a good 250-300 rounds. Could this be causing poor groups? </div></div>

Wouldn't hurt to run some ISSO bore paste with a ISSO nylon brush, follow up with ISSO eliminator oil and then clean as usual. I know some guys run alot rounds down the tube before doing something like this. I tend to stay on top of it, every 50 to 100 rounds depending on the gun.
 
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