Cluster group causes

[bpost1958]

When developing a promising load with cast rifle boolits I use five shot groups. After that the load is checked over the chronograph for stable numbers.

After that, I shoot 10 and 20 shot groups to see what the load is really capable of.

What I am noticing is cluster groups, five or six shots in a very tight cluster then a flyer or two then another nice cluster.

Where would you start to try and get all of them in the same group?

I don't weigh bullets or make fancy alloys, just WW with some lino or mono tossed in for fun.

Can anyone explain cluster groups with cast boolits?

Thanks,
Bruce

[357maximum]

"I DONT WEIGH BOOLITS" - step 1 one right there..........it may prove enlightening.

Consistency is key at all levels. It starts with large batch smelting, alloy blending. Casting technique, temp, timing........it all plays a factor. Handloading techniques count here also.

Anywhere along the way you can make the Consistancy better...you make the groups better.

In any handloading venture/equation C=better groups.

[gray wolf]

What I am noticing is cluster groups, five or six shots in a very tight cluster then a flyer or two then another nice cluster.

I am sure you will get many thoughts on this. Mine is that if this happens with repeatability
IE. 5 shots and a good group, than a flier, 5 shots a group and then a flier, and so on.
Well that would eliminate many things IMHO. I would look at the barrel overheating, shooter fatigue.
However if it has no real pattern then it could be many things.

Seating depth,
neck tension,
powder drop,
Shooter gets sloppy or anything that breaks the consistency in reloading.
Wind I don't think so if it is a pattern. What are the odds?


five or six shots in a very tight cluster then a flier or two then another nice cluster


Again if it is repeatable.
What is happening after the 5 or 6 shots ? How hot is the barrel?
No expert on shootin cast but shooting is shooting and I know there will be more help for you from the big guns.

[swheeler]

five or six shots in a very tight cluster then a flier or two then another nice cluster

Take the brass that shoots the flier out of the equation, reload those that formed tight groups, try again. Remeber one thing at a time.

[Bullshop]

If in a rifle another possibility is lube purging. If so it can be even worse in colder weather. Something that could help is to use a minimum amount of lube. If your boolit has multiple lube grooves try lubing fewer grooves until you find the point where you have just enough lube to do the job.
I shoot a 38/55 roller with a 300gn tapered breach seated boolit. The boolit has several grooves like a Luverin design but is tapered for breach seating. With light loads it does its best with only one groove filled with lube, the bottom groove. One of its favorite loads with the boolit lubed this way is with 8gn red dot. The rifle is capable of incredible accuracy with that boolit with the one groove lubed and that load. It has accounted for first honors in at least one of our postal matches here at CB.
Looks like you have a few things to work with now.
BIC/BS

[lead Foot]

If in a rifle another possibility is lube purging. If so it can be even worse in colder weather. Something that could help is to use a minimum amount of lube. If your boolit has multiple lube grooves try lubing fewer grooves until you find the point where you have just enough lube to do the job.
I shoot a 38/55 roller with a 300gn tapered breach seated boolit. The boolit has several grooves like a Luverin design but is tapered for breach seating. With light loads it does its best with only one groove filled with lube, the bottom groove. One of its favorite loads with the boolit lubed this way is with 8gn red dot. The rifle is capable of incredible accuracy with that boolit with the one groove lubed and that load. It has accounted for first honors in at least one of our postal matches here at CB.
Looks like you have a few things to work with now.
BIC/BS
+ 1
It's refeshing to here lube can be the problem. I made some felex lube a while back and I noticed an improvement. I was shooting better groups when the barrel was getting hot. I noticed after 25 shots in a row then walking down to check the target and back (100meters)I cleaned the gun ~ the first patch I put through was rough and had a lot of resistance. The lube had cooled in the barrel. So I tried 10 in a row and run a patch through while hot ~ Ha no resistance. Just a theory but I don't have many flyers now except when I pull the trigger bad. You can try cleaning after every 5-6 shots. Every gun is differant and responds in differant ways. Cast boolits sucks you and brings you back time after time.
Lead foot;

[runfiverun]

i agree with the lube purge theory especially if it's regular.
if it's the first cold one it's the lube again.
if it's random i'd weigh,check brass,or technique in loading the cases.
could be as simple as the brass temper [neck tension,or seating issue]

[JSnover]

I don't weigh bullets or make fancy alloys, just WW with some lino or mono tossed in for fun.

Can anyone explain cluster groups with cast boolits?

Thanks,
Bruce

Well... WW, lino and mono are all different alloys. How much of each are you mixing and are you seperating each batch? Start keeping a note book. You might be surprised.

[bpost1958]

Well... WW, lino and mono are all different alloys. How much of each are you mixing and are you seperating each batch? Start keeping a note book. You might be surprised.


My method is WAG, I melt the WW and toss in some other good stuff to make it harder....... how much is tossed in is about two pounds, kind of.......

Maybe I better rethink my alloying technique :veryconfu:coffee:

I'll break out the big lead smelter and cast some ingots to get consistent alloy then sort some cases, then lube varying number of groves.....

I'll be busy for most of February now, thanks!!

Shootin' cast is a hoot! :castmine:

[Wayne Smith]

If you really want an education get a copy of Dr. (Franklin?) Mann, book "The Bullet's Flight" I think is the name of the book. I'm at work and the book is at home. This is exactly the question his research focused on, why fliers with some of the best shots in the world at that time.

As 357Maximum so clearly posted consistency is the first hurdle to clear. Until you achieve a degree of that isolating other causes is very difficult.

[Rocky Raab]

We've discussed everything except what might be the real cause: the jerk on the trigger, LOL!

In my own experience, I sometimes go rolling smoothly along shooting small groups - and then get complacent and change my hold or just let my mind wander. It doesn't take long with a process that only covers three milliseconds.

Then after a flyer or three, I buckle down again and concentrate. Small groups again. Gee, imagine that!

In short, all the load consistency in the world cannot fix the shooter.

[BABore]

One thing you didn't mention is if the clusters of shots are shooting to the same POI or are they in different places on the target. If the tightly clustered group is followed by a flyer or two, then it returns to the same original cluster, then I agree that it is likely lube, a boolit with a weight variance, reloading variable deviation, or you. If the subsequent cluster is in another area, then it is likely the bbl heating up and walking some. If this is the case, an easy test is to see if the same pattern repeats itself after the bbl is cooled.

When documenting load developements, I always make a detailed drawing of where each shot hits and the order. It's almost as good as a x-ray is to your doctor once you have a track record established and understand how things effect one another.