Case Capacity, Powder Position in the Case & Accuracy

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Last Post 15 October 2023

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Wm Cook posted this 07 October 2023

Since August I've been fighting a problem that has a powder, charge and bullet combination that'll agg in the .8's (my range, hand picked conditions, not implied in any manner that it could be replicated in match competition) some of the time but triple that other times with a production class .308 Savage.

When the load goes south it shoots as a pattern, not as an odd flier or two. And it can go from group to pattern quickly. And within the same range trip I've had it go South and come back North again before the end of the day. Its like every time I go to shoot a group I don't know if it'll be a group or a pattern. Best example I can give is its like the stem on your front rest isn't tight and the POI is wandering around. But bench equipment and bench practices are solid.

Below is an example which is typical of what I've seen many times these past three months. There were two other groups shot between the group on the left and the group on the right in the picture below. Ironically it just so happened that each group was shot with the 8th through 12th shot after barrel cleaning. The group on the left was the 7th group of the day and the group on the right was the 10th group of the day. Both are the same load shot in the same conditions. Side note: I load at the range in increments of 5 to 10 shots at a time as much to keep the barrel cool as it is to tweak the load.

Could it be the burn rate of the powder and the lay of the powder within the case?

All the powders I'm working with (fast to slow IMR4227, 5744, N130, 4198 and H4895) have a fill capacity in the 43% to 47% range with a 220 grain bullet running 1700 to 1780fps. All are extruded powders. I started using 5744 n the early spring after it showed some promise. I went back and bought a jug's worth of the same lot of powder. Far and away, the 5744 out shot all other powders that I've tried by a factor of 2. That said, powder is one of the few things left to tinker with.

If anyone has any thoughts on issues with the % of case capacity being used or the effect the powders position in the case many have on accuracy I would appreciate your thoughts. Thanks, Bill Cook.

A “Measured Response” is as effective as tongue lashing a stuck door.

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muley posted this 08 October 2023

with that bullet weight and the 1-10 twist try 30-33 of varget for a start. or 28-30 of vv135 in 1/2 grain increments

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MP1886 posted this 08 October 2023

Funny that it happens from the 8th to the 12th shot after a barrel cleaning. Makes me think cleaning the barrel has to do with it. You know many say you must season the bore after cleaning and the arguing begans with just how many shots do you have to shoot to season a bore? One friend says over 200...hmmmmmm

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pat i. posted this 08 October 2023

I'd lose the 5744 too. I thought it was going to be my savior with this 06 plain base thing I'm playing with but not the case, a lot of unburned powder left behind. I agree with Muley here and would probably start around 25 grains of Varget and work up, its probably cheaper than 135 or used to be and thats a good thing. You could also do yourself a favor and search the national match reports to see what the good PRO class shooters are using. Might require a new mold and change of powder but you'll be one step ahead of the crowd.

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OU812 posted this 08 October 2023

I had best accuracy using Reloader 7 in my 308...no vertical stringing from what i recall. Vertical stringing is usually caused by powder positioning inside case.

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Wm Cook posted this 08 October 2023

Has anyone had any experience with using Dacron filler with the slower "fast" burning powders? 4227, 4198, 4895, 5744?

The way the problem switches off and on confuses the heck out of me. For the life of me, when it shoots a pattern, it seems like I'm loading and shooting with each of the five cartridges with powder charges varying +/- a grain and a half. On an old thread I remember someone doing something like the NRA roll (?) or something like that where the cartridge is rotated before chambering. Can't remember exactly what thread that was.

Since I'm new I've been taking bullet to bore fit 101 for the past year. I have a Lyman 311299, three of Accurate's Egan design (230E / 219g) and a couple other of his conical tapered shape (220G & F / 206g). The bullet to bore fit on the mid sized 230E feels good but I have more to learn about fit than most of you forgot in the last two weeks.

Varget and N135 are on the shelf but I never gave them a fair chance. The initial velocities I worked up for each had a SD over 30. I'm not married to low SD but shied away from those two just because I had a half dozen powders that had SD's in the mid teens or lower. Next trip out I'll give IMR4227 a go.

Here are the numbers for the .308 Winchester cartridges that were shot in the last three Nationals. Sort is by powders used. There are repeat users in these numbers where come shooters used the same powder multiple years.

A “Measured Response” is as effective as tongue lashing a stuck door.

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OU812 posted this 08 October 2023

I taper bumped all my test bullets 1.5 degree included, so accuracy was pretty good with alot of powders and bullets (4759, 4198,4895,varget,rel 7,2400 etc).

Rel 7 was most accurate in my rifle. I we lived closer I would give you a pound to try.

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Wm Cook posted this 08 October 2023

Thanks for the offer Keith. I only shot three groups with the Rel 7 I have and that was just to get a quick impression of its accuracy and to sort out the grains/velocity for future use. To be honest I didn't give it a fair shake. Bill.

A “Measured Response” is as effective as tongue lashing a stuck door.

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muley posted this 08 October 2023

you say loading at the bench . years ago Dave Lee used one case and loaded at the bench. he usually had highest score or was near the top. when you shoot the cases sort them as close as possible. reload as a group. I think ,shoulder pressure can also cause verticle. just my thoughts

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CBA President

John Alexander posted this 08 October 2023

Bill,

You call them groups and patterns and say your "groups" will age in the 8s but the group you show is .36, if I am reading it correctly, an extreme example of your "groups". The ratio between an .8 and the "pattern" shown is 1.5, a ratio that is very frequent in any string of 4 or five 5-shot groups. For that matter, the ratio of 3.4 of the two groups shown also isn't a rarity in strings of groups. This leads me to suspect that you don't have a (powder, powder position, shooting, case or any other such) problem. But instead are just expecting strings of 5 shot groups to be way more consistent that mother nature allows. This is just a guess andI could be off base because it is based on only the two groups shown.

How about posting the size of consecutive groups in a string of groups using the same load. Then you can judge if you are really seeing groups and patterns or just seeing the usual variation of ALL strings of 5 shot groups -- which none of us like but have to live with because there is no cure.

I tried to debunk the idea that a string of groups should be about the same size with evidence in my second article doubting the "tuning" that jacketed BR shooters think they do in TFS #275.

I would appreciate your, or any other reader's, comment on that article since I received zero feedback of any kind.

John

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RicinYakima posted this 08 October 2023

John,

I think that you didn't get any feed back is because there are two opinionated groups; those that think small variations will make a big difference with consistent size and those of us who know that five shot groups vary greatly in size. You and JoeB did a lot to convince me of that.

Not meaning to break anyone's rice bowl, but there are a lot of products sold in shooting sports with little or no actual shooting data.

Four ten-shot groups would have less variation than four five-shot ones. And four 25-shot groups would be very close in overall size.

Ric

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Wm Cook posted this 08 October 2023

John, the small group on the left was an outlier and I never paid much attention to that particular group or its size. My groups are rarely that small. But it does show the "group" v "pattern" dichotomy that I've been frustrated with.

Attached you'll see every group I shot since May. All are with the same mold, same powder. The powder charge varied from 19.6 (~1700) to 20.4 (~1760) and the COAL was from 2.940 to 2.979.

From May 4th through August 8th I shot 17 groups and had an agg of .752. I want to stress that that agg can not be compared to what I would have shot Kansas City. These groups were all shot in readable conditions over flags and on a 60 bench range that I've been shooting for over 30 years. It doesn't get any more "home field advantage" than that.

You can draw a line from August 21st on and make a case that something happened because the next thirty days (August 21 through September 21st) I shot 34 groups and agg'd 1.219. I was doing a lot of shooting during that stretch because after I left the range on August 21 I knew something was broke and I started to scramble around trying to figure out what was wrong so I could get things together enough to make the Nationals. Switching scopes, re-torquing action screws, etc; nothing brought things back into line. I've been getting the group v pattern thing every trip out since then.

What I call a group is 5 shots with a POI all in the same neighborhood of each other. To me, shooting cast groups in the .8's to 1.2's in readable conditions is a good group. When you shoot a group with a flier you don't appreciate it but you can understand it. But when every trip to the range has the same load / conditions shoot a group one time and 10 minutes later it shoots a non discernible pattern, you start to look for what's broke.

When it patterns it acts as if conditions got significantly worse and someone took away my flags. Or to put it another way it was as if the intended 20.0 grain of powder was a random mix of loads that ran between 19 to 21 grains.

Sorry for all the crying about this. Its something technical and I'll eventually figure it out. I gotten a lot of help from the above responses and I'll get it sorted out. I just needed to vent. I was rather disappointed I wasn't able to meet some of you at the Nationals. Bill.

Here are the groups I shot from May though end of September. You can see where things went wrong after the first week in August.

A “Measured Response” is as effective as tongue lashing a stuck door.

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Bud Hyett posted this 08 October 2023

Three thoughts:

Have you considered the barrel is losing its golden edge of accuracy? This can happen suddenly. This circumstance occurred at the Washington State Championship Match about a decade ago. Saturday the Savage .308 12BVSS shot well placing Alice in a position to win. Sunday morning the rifle would predictably group four or five shots, then throw a definite flyer out in the white, even outside the scoring rings. Watching the bullets go down the range, the flyers were creating a wake noticeably bigger. Visually checking the bore after cleaning, the rifling did not look as sharp. Checking the bore with a borescope that evening, the rifling was definitely worn in the throat. (Back to Savage for a new factory barrel.) To check this, shoot in the early morning with the Sun at your back and have a spotter watch the wake as the bullet goes downrange.

Many people report their best group their rifles shoot as the standard. The standard is what you expect the rifle to do every shot. A person should shoot ten-shot groups, at least five groups, establishing the expected group they will get in competition. If this group will give a clean score, then adopt it and practice under bad wind conditions. Judging wind and mirage effects are as important as the grouping capability of the rifle.

Does this rifle predictably throw the wide shots? This could be the barrel heating up in an uneven pattern. You can counter this. Either shoot the shots in the berm or hold off when shooting. I had a Trapdoor that reliably shot every eighth shot out at 2 o'clock in the eight ring with smokeless powder. (Lube purging?) In the informal practice matches at Windhill at the eighth shot, I'd hold at eight o'clock in the eight ring to usually get a nine or ten. Several old-time single-shot shooters at the turn of the last century tracked each shot in practice and held off in competition per their records.

Farm boy from Illinois, living in the magical Pacific Northwest

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Mal in au posted this 08 October 2023

I used 30 gns Varget no filler Lyman 311644 BV mold 20 bn Lino would consistently go Moa @ 100 mts, The rifle was a Schultz & Larsen mod.62 Qlympic 300 mt rifle. Tried 1/2 gn of Dacron filler to begin with was ok, decided to leave it out of the last 10 rnds. Bingo!! Have just parted with the S&L !! No matches being shot here these days for cast pills. Moving into PCP. Air rifles for a new challenge. Cheers Mal in au.

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MP1886 posted this 08 October 2023

I used 30 gns Varget no filler Lyman 311644 BV mold 20 bn Lino would consistently go Moa @ 100 mts, The rifle was a Schultz & Larsen mod.62 Qlympic 300 mt rifle. Tried 1/2 gn of Dacron filler to begin with was ok, decided to leave it out of the last 10 rnds. Bingo!! Have just parted with the S&L !! No matches being shot here these days for cast pills. Moving into PCP. Air rifles for a new challenge. Cheers Mal in au.

Hey Mal, glad to meet you. Hey Schultz & Larsen use to make a rifle chambered for one of their cartridges that I always thought was better then the 7mm Remingtoin Magnum and that is the 7mm Schultz & Larsen. Fine rifle and cartridge.

Sorry to hear there's not cast pills matches down your way. Have fun with that air rifle.....Cheers Tony in the Deep South U.S.A.

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CBA President

John Alexander posted this 09 October 2023

Bill,

Thanks for posting the list of groups. When 17 groups average X and the next 34 average 1.5X that certainly isn't group to group variation as I guessed. I have had the same thing happen sometimes with two weeks of shooting X followed by two weeks averaging 1.5X. Don't know the answer but my best guesses are 1, losing the groove for shooting a light rifle or 2, some sort of semi-permeant bore condition not remedied by routine bore cleaning aka magic. I think I have seen that blasting a dozen full charge JB loads has changed things back to X - but that may also be magical thinking on my part.

But when someone says small group followed two groups (or ten minutes) later by one three times larger we are likely seeing just typical group to group variation for 5-shot groups. Look at the individual group sizes in the 5 groups of an IBS aggregate and you will find that the ratio of largest group to smallest is often 3 or more -- sometimes by the winner. We seem to be able to quickly forget that happened or blame it on a bad shot, but it is just nature's way of telling us it is a probabilistic world whether we like it or not.

John

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Wm Cook posted this 09 October 2023

Ric

there are two opinionated groups; those that think small variations will make a big difference with consistent size and those of us who know that five shot groups vary greatly in size.

Fully agree. Its the agg that matters, nothing else. Winning a small group award and not finishing near the top is like kissing your sister. What bugs me is that I shot 17 five shot groups in a row that agg'd in the .7's and the next 17 agg'd in the 1.2's. Thats what led me to believe that something was broken.

Bud said

Have you considered the barrel is losing its golden edge of accuracy?

It doesn't look like thats the problem. I've got 1114 cast rounds plus foulers through the barrel now. Zero jacketed. Its bore scoped after every range trip to look for fouling and general barrel condition. It still looks sharp.

Many people report their best group their rifles shoot as the standard.

I wouldn't be concerned a wit if all of 51 recorded groups agg'd in the 1.2's. It was the sudden breakdown after the first week in August when I went from decent group that agg'd in the .7's to the 1.2's.

Does this rifle predictably throw the wide shots? This could be the barrel heating up in an uneven pattern. You can counter this. Either shoot the shots in the berm or hold off when shooting. I had a Trapdoor that reliably shot every eighth shot out at 2 o'clock in the eight ring with smokeless powder.

I thought barrel heat or dirty barrel was my ticket out of jail for a period. I went to tracking the number of shots fired group by group since the last cleaning. Current practice is load and shoot one or two group at a time. So I can rule out barrel overheating and/or a dirty barrel. I had enough data that showed that cleaning every 17 to 23 rounds didn't trash the group size. In other words, groups shot after cleaning did not need a break in period. As is I can go to record after two fouling shots. When shooting groups I can call fliers when they happen. Once a group patterns there could be three or more shots that fling out of the group.

Next trip out I want to try a series of powder charges (still 5744; 19.6, 20.0, 20.4) with one group having the powder shifted toward the bullet and then repeat with the powder pretty much centered and level in the case by rolling them on my bench mat before chambering/loading.

If that doesn't work it back to playing musical chairs with powders and mold selection.

This year Bob Haufschild and Robert Olson both shot sub MOA with a .308 in Producion class. I don't have the experience they have and probably not the bench skills but I have an A+ personality, I'm stubborn and I have a touch of OCD going on. If I live long enough I'll get it sorted out. The one sure thing is that you learn a lot sorting out problems like this. Thanks to all, Bill.

A “Measured Response” is as effective as tongue lashing a stuck door.

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RicinYakima posted this 09 October 2023

You show 50 groups in in 5 months. That is not enough practice, you need to shoot the same load and bullet and settings more.

Last time I shot with Bob Haufschild, he told me he shot 25,000 rounds in less than ten years practicing. When I was getting ready for scoped Military Rifle Nationals, I would shoot 400 - 500 rounds between the middle of April and the first of June when I had to start driving. I tried to make every shot like make or break match winner.

FWIW

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John Alexander posted this 09 October 2023

"but I have an A+ personality, I'm stubborn and I have a touch of OCD going on. If I live long enough I'll get it sorted out. The one sure thing is that you learn a lot sorting out problems like this. Thanks to all, Bill."

Sounds like you have the right personality and attitude.

Some additional thoughts, although I suspect you have already tried them.

I have never had any luck when things went south with diddling with small powder charges or powder changes. I have had real trouble when changing lots of 5744. If I understand correctly it has been made by several plants over the years.

You don't even mention alloy in your table so I assume, like many top shooters it is linotype. I would try something somewhat softer for a few groups. If you do it may be wise to guard against the case sizing or damaging the softer alloy

Cases change as they work harden and more if annealed. I would check a few dummy round to make sure it comes out of the chamber the same length as it went in.

I would seat and pull a few bullets to make sure they weren't being "sized" or otherwise damaged during seating.

I don't think it is likely that a linotype nose would upset to a larger diameter while being seated but you might check to be sure.

Are the land marks or absence of such on the nose the same on an extracted round as they were when shooting the small groups?

Good luck.

John

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lotech posted this 09 October 2023

As for bullet hardness, as John Alexander touched on, I remember advice from Glenn Latham in THE FOULING SHOT years ago... I don't recall his exact words. but the basic message regarding bullet hardness was to use the softest bullet that would handle the load/ velocity without leading the bore. This would usually provide best accuracy. Generally, I've found this to be excellent advice.

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Lucky1 posted this 10 October 2023

I'll take the proverbial 'bullet' on this one. I'm very human and prone to error, some larger than others. So there are days I'm really on and days that won't give me a break. Last Nationals case in point. Got a third in the Little Bore with the 233 on Fri. Since it's both group and score, I was really pumped for the rest of the weekend. Saturday and Sunday was the plague of constant flyers etc that just made this match an endurance test. Same rifles, same loads, same shooter. I know better than to blame the rifle or load. The only way I'd be willing to go there would be shooting with a machine rest in a tunnel to reduce operator error. So John talking a 1.5 rule makes a lot more sense to me now and I'd be happy with some days to get it that close. I'm not the only one to go to the range and have a load and rifle do way worse than the week before and then work great the next time. Summary time- this game has so many variables it is hard to pin it down to one particular thing; especially with the human factor. One variable not mentioned so far is temperature changes over a season. With no chronograph readings I wonder about some changes going on there as well.

Scott Ingle

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