Finding if defect enlarges group ain't as easy as it seems

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John Alexander posted this 3 weeks ago

After applying gas checks and lubing a recently lot of cast bullets, I checked and found 7 of them had bases not perpendicular to the long axis of the bullet. They weren't off much but they definitly leaned when stood on their bases. Shooters "know" that this will ruin accuracy. I like to confirm that a defect has an effect on group size by shooting some. Even good "logical" assumptions are often wrong.

I loaded twenty rounds. I planned to shoot four 5 shot groups, two with bullets that looked good, one with four defective and one good bullet, and the final group with three defective and two good bullets.

The two groups with good bullets averated 1.22" at 100 yards

The two groups with a mix of bullets averaged 1.62"

This isn't enough groups to be confident, but it sure looks likte the defects did what defects are supposed to do. For additional information when I shoot groups to find what defects do I paint the noses red with a sharpie, which leaves a red rim around the bullet hole. Thus you can see where the indivigual bullets landed.

In the first defective group I found the four red rimmed holes made a 0.96" group. The "good" bullet hole was about an inch from the center of the four shot group -- what we call a flier. The three defective bullets in the second group made a 0.5" cluster, one of the good bullets landed an inch high and the other landed an inch low making the group slightly over 2".

I don't believe that bullets with bases other than 90 degrees to the long axis shoot better but this sample sure doesn't prove they shoot worse. I have been shooting comparison groups with bullets that lean for several years Sometimes the good bullets average better and sometimes the defects. I'm still not sure how much they enlarge groups -- if any. I've got to pull all these shooting results together and see if I can draw a conclusion. I don't have the guts to shoot them in matches yet, but I'm not sure they enlarge groups -- counter to superficial theory.

If you pay attention, cast bullet shooting will make you humble.

Has anybody checked into the effect of leaning bullets?

John

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MP1886 posted this 3 weeks ago

John wouldn't one think that the pressure firing them would seat them 90 degrees level?

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John Alexander posted this 3 weeks ago

Maybe -- but the gas checks had already been mashed twice with prependicular faced rams, once in sizeing in a Lee push thru, and once while being lubed in a RCBS lubisizer.. But who knows. Maybe the mighty blase from five and a half grains of powdeer does the trick. OR -- it may be that the obsessing we do over a perfect bases is based on the false assumption that the base has to be perpendicular and perfect. Until we do more experimenting we won't know, although most of us think we know.

130 years ago riflemen had their knickers in a twist worrying about what the muzzle blast did to the bullet's flight and imperfect bullet bases. (N0, I wasn't there as some might claim.) Dr. Mann, being the curious type, cut down one of his good barrels from something like 30" to 12" in steps and firing groups at each length. He found that the barrel when 12" inch and producing maximum muzzle blast shot just as well as at 30" barrel and much less severe muzzle blast. Riflemen went right on believing what they liked to believe.

We are indeed too early old and too late smart.

John

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Urny posted this 3 weeks ago

MP1886 is sharing a thought I have often wondered about. Perhaps the effect would be greater with checks that do not crimp to the bullet?

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John Alexander posted this 3 weeks ago

But is there an "effect"? Or, is it a non-problem. Has anybody measured one? I have been trying find out for years and I still can't prove that leaning bullets affect groups. To answer the question that 1886 poses somebody with a good shooting breech seating (plain base) rifle could answer with an experiment.

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TRKakaCatWhisperer posted this 3 weeks ago

.... I checked and found 7 of them had bases not perpendicular to the long axis of the bullet. They weren't off much but they definitly leaned when stood on their bases.
....
Has anybody checked into the effect of leaning bullets?

John

Were the defects oriented in the same direction? I think Dr Mann did an experiment like that.

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delmarskid posted this 3 weeks ago

Joe Brennan did experiments with filing bullet bases to extreme angles. I don’t remember if they were plain based or checked. His results were similar to yours. He cut notches and a bunch of other things too. He also filed rifle muzzles at angles. Evidently when we spin things at these rpm’s it makes them go straight.

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MP1886 posted this 3 weeks ago

I'm sure many of you, as have I, examined fairly undamaged fired gas checked bullets. Here's what I've noticed. I've observed that the center of the gascheck is pushed in much. Some say this is the "peak" of the gas pressure. I don't think that it is. I think the base pushes in because the edges which are supported or braced by sides of the gascheck which are pressed firmly against the bore/groove of the barrel so not letting the bottom edges of the gascheck to be pushed in. You know that even minute amounts of Unique used in cast rifle bullets exerts a lot of gas pressure. Upon firing the gas pressure expands the neck so to release the bullet and from there to the end of the chamber then on to the throats is where the base of a cast bullet can be bumped up leveling that gascheck. This is my opinion.

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Urny posted this 3 weeks ago

Hello, John. My limited experience testing improperly seated checks suggested that a more experienced shooter and tester would be needed to draw any meaningful conclusion. In short, I do not know. There are suspicions that permit me to keep trying, but that is it.

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John Alexander posted this 3 weeks ago

Hi Urny, That's the right attitude, keep on trying.

If you shoot groups of "defective"bullets and groups with good bullets alternately and the defective, on average, make bigger groups you have evidence that the defect should be fixed or those bullets should be culled out no matter what size groups you, your rifle, and bullets are able to shoot.

If there no significant differencee in the average size of the groups of the defects and the good bullets. Maybe the defect isn't worth worrying about.

in the groups of the defects shoot smaller groups than the apparently good bullets you have just seen how the randomness of nature can throw you a screwball.

Keep on trying and post your results. Maybe we can all learn something.

John

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John Alexander posted this 3 weeks ago

Cat Whisperer,

The leaning bullets were loaded randomly, not all in the same direction.

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John Alexander posted this 3 weeks ago

Delmarskid,

I have forgotten those experiments. I wonder if they are reported in his last edition of his book.

Joe did a lot of great experimenting including such counterintuitive things as finding that baffles in powder measures don't do anything useful. I miss his interesting and sometimed abrasive posts.

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fc60 posted this 3 weeks ago

Greetings,

Most of my ammo testing is pistol at 50 yards. Ammo may group well at 25 yards but the same ammo might not group at 50 yards.

Perhaps testing rifle ammo at 100 yards is too forgiving?

How do the straight bullets compare with tilted bullets at 200 yards?

Cheers,

Dave

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MP1886 posted this 3 weeks ago

Delmarskid,

I have forgotten those experiments. I wonder if they are reported in his last edition of his book.

Joe did a lot of great experimenting including such counterintuitive things as finding that baffles in powder measures don't do anything useful. I miss his interesting and sometimed abrasive posts.

I can say this. The Belding & Mull is one of the most accurate powder measures ever made. The reason I believe is it drops it's powder so accurately is it takes the powder from a sliding block which has the chamber in it. In resting position it draws powder from the reservoir. When you slide the lever it slides the block towards the discharge hole isolating the resevoir, then it moves back to the resting position to be filled again and waiting till you slide it.

I've heard that baffles in the Redding's powder measures DON'T do any good.

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John Alexander posted this 3 weeks ago

MP 1886,

I have heard that about the Belding and Mull measure but have never seen a test to verify, On the basis of hersay I bought one complete with original instruction book. I was on to something else at the time and carefully put if away -- never to be seen again, but still have hopes of finding it, If it is indeed the best, I wonder why those super anal folks shooting jacketd benchrest or some of the long renge shooters who fuss over the last kernal of powder don't seem to use them.

I don't think Joe's results showing baffles don't make the charges more uniform was limited to only Redding. I will have to look that up.

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John Alexander posted this 3 weeks ago

fc60,

You are absolutely right, some loads that shoot fine at short range may not shoot so well at a longer range. My local range has only a 100 yard range. So many interesting things to look into, so little time.

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MP1886 posted this 3 weeks ago

MP 1886,

I have heard that about the Belding and Mull measure but have never seen a test to verify, On the basis of hersay I bought one complete with original instruction book. I was on to something else at the time and carefully put if away -- never to be seen again, but still have hopes of finding it, If it is indeed the best, I wonder why those super anal folks shooting jacketd benchrest or some of the long renge shooters who fuss over the last kernal of powder don't seem to use them.

I don't think Joe's results showing baffles don't make the charges more uniform was limited to only Redding. I will have to look that up.

With ball powders and round flat powders like Unique, and the fine tuberlar powders like 4227 the B&M will slice all zeros on your scale all of the time. With most large grain tubular powders it will slice zero all most all the time. This are dependent if you operate it correctly.

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JimF posted this 3 weeks ago

Just to add to this discussion on grouping/accuracy . . . .

i’ve seen many shooters at the range shoot with the muzzle NOT out over the edge of the bench.

Does this make any difference in accuracy, due to the muzzle blast bouncing up against the underside of the bullet BEFORE it gets out beyond the edge of the bench?

Likewise, I’ve wondered if my Garand suffers from a similar woe, cuz I sometimes use a gas cylinder lock screw that I’ve modified to convert the rifle to a “8-shot, straight-pull, bolt action repeater”.

Dunno, but interesting!

Does the escaping gas “upset” the bullet as it exits the muzzle?

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lotech posted this 3 weeks ago

I have four Redding measures, different versions. The newest is more than thirty years old. These are the only measures I've used for a long time for all my handloading. With or without baffles, I've yet to see a difference in actual use, though baffle use sounds good in theory.

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Ken Campbell Iowa posted this 3 weeks ago

on the B&M *VISIBLE* measure .. a great feature is that after you fill the hollow measuring tube you get to inspect that the tube is full .... nice especially with large stick powders ...

also ... maybe giving the same grins we get by even shooting cast bullets ... they are just plain nostalgic ... I bot mine about 1955 ... and yes, I have 2 or 4 other Redding/RCBS somewhere that I loaded a box or so with ... real smooth, fast ... boring ...

oh, yes I do find the RCBS Mighty Mite handy for turning out a big batch of handgun fodder.

Also, as in Belt and Suspenders ... I still also additionally dip stick every charged brass before I seat the bullet.

ken

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MP1886 posted this 3 weeks ago

Just to add to this discussion on grouping/accuracy . . . .

i’ve seen many shooters at the range shoot with the muzzle NOT out over the edge of the bench.

Does this make any difference in accuracy, due to the muzzle blast bouncing up against the underside of the bullet BEFORE it gets out beyond the edge of the bench?

Likewise, I’ve wondered if my Garand suffers from a similar woe, cuz I sometimes use a gas cylinder lock screw that I’ve modified to convert the rifle to a “8-shot, straight-pull, bolt action repeater”.

Dunno, but interesting!

Does the escaping gas “upset” the bullet as it exits the muzzle?

I was doing some testing for a company that was making muzzlebrake barrel tuners and can tell you that muzzlebrake affected the bullet accuracy of cast rifle bullets only. The company making them told me I could cut the muzzlebrake part off on the lathe which I did and the cast started shooting better. I don't know what it was doing, the gases escaping from the brake weren't melting the bullet any.

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