Extreme Spread of Group Sizes?

[21Bravo]

Okay, what kind of spread is conisidered acceptable from group to group?

I have a stock Remington LTR .308. With most loads the gun will shoot a .450 5 shot group or two, then throw a 1.110 or 1.200 group (all of these are at 100 yds). The barrel is floated with decent clearance and no evidence of touching. The groups almost without fail average out to .850 or so. I keep a log and the .850 average is very consistent but why the spread on the group size. The groups will open up and sometimes string and other times not. It consistly does this. I'm running a new Leupy Mark 4 4.5-14x50 FFP TMR reticle. The gun performed the same with the previous scope.


I've tried multiple different powders, bullets, bullet weights, brass, neck sized, non-neck sized,different seating depths, clean gun, not clean gun, 2 different optics. I'm using Lapua brass, CCI BR primers, and I've used Winchester brass. I've tried 168 Vmax, 168 sierra, Nosler 168 CC, 155 Sierra Palma, Lapua 155. Poweders are Varget and RL15. I'm measuring COAL with comparator, trickling my loads with a Pact digital scale that seems to be consistent when I check it which lately has been frequently. The only thing I have not changed is primers.


To put in prespective I have a PSS that has had some minor work on it and it will shoot an average of .500 with some in the .40 range and some in the .675 range. I've been shooting for nearly 30 years and loading for 20 years.

I have not lapped the rings on this gun. Could that be a factor? The gun is being shot off the bench and locked in solid. I'm doing my best to keep from torquing the rifle and I'm index the horizontal crosshair to minimize cant.


Any help appreciated.

Thanks,

21Bravo

 

[benjaminzero]

Re: Extreme Spread of Group Sizes?

Is the stringing and group size enlarging occurring consistently as the barrel heats up? That could be your issue. If you see your groups enlarging, perhaps wait 20min for the barrel to cool and try again.

Also are the stocks bedded? I know they have aluminum bedding blocks, but a solid skim bedding over it will almost always improve accuracy and consistency.

 

[McLarenross]

Re: Extreme Spread of Group Sizes?

My 700 VLS does the same thing. I get an average with my best load of about ~0.750 with some groups going under .400 and some as wide as 1.5! I just chock it up to a factory barrel. I keep telling myself I need to shoot more and burn this one out so I can justify a Bartlian(sp.)

 

[Topstrap]

Re: Extreme Spread of Group Sizes?

I just read a really really great post. Here is the link to it and also the text.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1815479&gonew=1#UNREAD

[[ I have, over the years, tried most of the reloading accuracy tips. Primer pocket truing and inside flash hole reaming, weighing and sorting cases, turning necks, polishing inside the necks, weighing all charges V/S dropping charges, ad nauseum. Adjustable front rests, heavy sand in the rear bag, lubricating the bags with talcum powder...whatever new tip might work to make the rifle and loads shoot more accurately. Now,I have, in the culmination of years of brilliant thought processes and experimental research, discovered the secret to accurate reloads. Since I have been practicing position techniques, trigger control and dry firing, consistent holding...actually the basics of long range shooting...ALL my reloads are more accurate! Anybody else discover this? ]]

Rifles are not my strong point but from helping a friend it amazed me how critical things like same pressure on that bipod, cheek and shoulder pressure, grip tension, having the same consistancy or pressure on your rear support device. It's amazing how many variables come into affect each time you fire that shot. Some days no matter what you do things just don't fall into alignment and group size or plate count suffers. Sounds like you have a good shooter and good loads to use. Unless you thrive on chasing that perfect group each time you shoot I'd say spend time shooting at plates or whatever it is you throw lead at and I bet your score and/or count will go up.

Topstrap

 

[21Bravo]

Re: Extreme Spread of Group Sizes?

Zeroed1983,

There isn't any conistency to wether it's the first group fired or the 3rd (or 6th for that matter). I've let the gun completely cool between groups and I've only let it cool a little. I've even cleaned the gun after a couple of groups to see if it changed anything. I could not identify a relationship to the variables I tested.

The stock is the factory HS LTR stock with the aluminum blocks. Maybe I'll skim bed it to see if that does anything. It's worth a try.

The intent for this gun is one that I can shoot off the bench or bipod for enjoyment as well as be lite enought to pack in the woods. Unfortunately, it's been primarily frustrating to shoot at the range since it's inconsistent.

By the way, I did shoot two different loads for OCW testing. Both of the loads I settled on do the same thing as far as opening up and tightening back down. It does not seemed more pronounced whether it's 25 degrees out or 80. It just has me baffled.

Maybe that's just the way it is but I can't recall having a rifle that would group like this. They've either shot 2" groups and stayed close to that (factory, non-beded run of the mill hunting rifles) or .750 or close to that for a worked up load in a decently built rifle.

I shoot more consistent groups with my 1903A3 set up for across the course match (open sights) than I do with this rifle.

Thanks for your input.

Craig
aka 21Bravo

 

[ArcticLight]

Re: Extreme Spread of Group Sizes?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 21Bravo</div><div class="ubbcode-body">I've tried multiple different powders, bullets, bullet weights, brass, neck sized, non-neck sized,different seating depths, clean gun, not clean gun, 2 different optics. </div></div>


But did you try a different shooter?

That's not a huge spread, it's possible either you are getting confident, excited to have a tighter group?

Taking too much time breathing and sighting etc?


For me, my best groups are where I quickly aim, breath, squeeze, all of that in 1-2 seconds, anything more and I start bouncing.

My damn near perfect 5 shots in one hole target back in 2005 was shot in about 6-8 seconds, bam bam bam....
(It was 34 and snowing and I was comfy)

 

[Lumpy Grits]

Re: Extreme Spread of Group Sizes?

What do you have the stock screws torqued to?
If it's an HS stock set them to 65 in. lbs.
Had same issue you have now. The stock would flex in recoil and "kiss" the bbl. depending on how much I would "load" the stock when firing. Just opened up the bbl. channel a bit and all was good.
One other thing to do would be to recut your crown.
Respectfully,
LG

 

[MitchAlsup]

Re: Extreme Spread of Group Sizes?

Start keeping two different sets of books (columns in one book)
Place the good groups in one column, and the bad ones in another.

After a couple dozen groups, if the standard deviation of both sets is about the same, it is likely a mental issue with the shooter.

That is the gun+ammo shoots to its standard deviation (long term), while the shooter can "go all fuzzy" and do random things.

 

[KHOOKS]

Re: Extreme Spread of Group Sizes?

I've been shooting a stock LTR for about two and a half years. Do not do a lot of group shooting at 100y but my load is shooting a moa out to 500y when I do my part. Things I have learned about my rifle is it shoots better dirty!! When I first got it I done the barrel break in thing and cleaned it every few shots for the first 50 or so then every 20 for the next hundred or so. After the fisrt 300 or so rounds the rifle just never would hold a five shot string together 3-4 shots where in there with 1-2 shots falling out just a little. After a match one day I stayed around and shot some just for fun. The match started with a clean cold bore. The gun didn't hold a tight group on the 4 targets we place 5 rounds on in the match. I thought I was causing this so I thought to myself I need to practice a bit more. I shot a few more groups that day and after about 50 rounds the groups just tightened right up. I don't think alot about why the groups got better at the time. I got home and cleaned the bore and the next time out the rifle shot like shit few rounds tight then a few fliers. I keep shooting and then it happened again all of a sudden the groups where back shooting like I ended the last time before I cleaned the bore. Well I didn't clean it for over 800+ rounds and it was still holding a moa no problem from 100 to 500. I didn't clean the bore until the spring this year and the first match after cleaning I shot like shit. Now after I clean the bore I go and run 30-40 rounds down the tube before I go to a match.

 

[21Bravo]

Re: Extreme Spread of Group Sizes?

ArticLight,

I hear ya. I was thinking that too, as far as getting confident and doing bad things without noticing. So, the last couple of times out I took the PSS with me. I was alternating guns to let them cool and relaxing in between groups. The PSS shot as it usually does with no group larger than .750 and the LTR performed as it ususally does, .500 to 1.2 or so. As I mentioned in an earlier reply, I can keep more consistent groups with a Lyman sighted 1903A3 that has been tweaked out than I can with the LTR. I don't and will never rule out shooter error but generally I can call my shots. But again, I will never be too cocky to say it wasn't me. But this is about 300 rounds and not just a couple of groups and throw in another varible I don't get near the spread with my PSS. But as another varible, the LTR throws lead all over the place with my PSS load, but the PSS shoots the LTR load fine.

Craig
aka 21Bravo

 

[1lnbrdg]

Re: Extreme Spread of Group Sizes?

More barrels are probably worn out by cleaning than shooting.

On my AR-platform, I clean the bolt group about 150~200 rounds, the barrel about every 500 rounds.