Stirring The Pot

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OU812 posted this 28 September 2017

Larry's chart showing ideal fps for a given twist barrel. I think it has something to do with cast bullet falling asleep?

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OU812 posted this 28 September 2017

Chroni results using different powders. Trying to achieve 2000 -2100 fps and verygood accuracy.

223 Remington, NOE 80 grain SP (shortened 70 gr.), Linotype alloy, 1/12 twist Remington 20" barrel VS

4759 powder has less velocity spread, 748 and 1680 (old 680) has more velocity spread, but are very accurate.

Lapua cases, Winchester SR primer

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CBA President

John Alexander posted this 18 September 2017

Ric is absolutely right. Lots of CBA competitors do it.

Whether to allow it or not was a hot argument back in the late 1970s and early 1980s but has been long settled in favor of allowing swaging (aka bumping) as long as the unswaged raw material is a cast bullet.

John

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RicinYakima posted this 18 September 2017

Not anybody in power, but nothing in the rules about bumping. Plus guys have been doing it for years, sizing base bands and bumping noses.

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OU812 posted this 18 September 2017

If a cast bullet shooter wins a match and sets a record using a BUMPED BULLET, does bumping or swaging disqualify him? Some say bumping is not allowed.

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OU812 posted this 18 September 2017

Just discovered that linotype works very well along with more pressure. Have you ever noticed when you get the bullet fit correct, lots of different powders will work. I just need to find one powder that fouls barrel less (fire 10 shots then push wet patch down barrel and feel for hard fowling).

Annealing (making softer) linotype bullets before bumping. Bullets in picture are resting on copper plate then put in oven @350 degrees for 1 hour. They are allowed to cool slowly. Cooling bullets evenly while standing on bases "may" be a good trick. Lube groove will be filled with soft LBT lube before bumping. Bullets are then bumped larger and more round so that rifling engraves bullet more evenly when chambered. The bumped linotype alloy bullets will return to full hardness after a day or so.

Bullet is the NOE 80 SP bullet with shorted gas check shank (70 grains). This shorter bullet shoots best in the 1/12 twist barrel

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OU812 posted this 18 September 2017

Lee die was shortened and longer push rod was made in lathe. This prevents distorting pointed noses when sizing nose first.

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CBA Member

BigMan54 posted this 29 August 2017

After I flux I don't stir the pot until i add more alloy & have to flux again.

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

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CBA President

John Alexander posted this 28 August 2017

OU812 wrote: "Update for those who care."

Thank you. I was glad to get the dope on a variety of loads and powders. Such a pain to set up a chronograph.

John

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TRKakaCatWhisperer posted this 28 August 2017

NO! Cat hearding is done by subtle influence - building a relationship where the heard KNOWS you are loving AND the ALPHA cat.

Oh John, you are so tactful! All of this is art not science. Shoot it at paper, keep records and we will learn. There are so many variables, but we can herd cats if we have enough whips!

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CBA Member

RicinYakima posted this 28 August 2017

Oh John, you are so tactful! All of this is art not science. Shoot it at paper, keep records and we will learn. There are so many variables, but we can herd cats if we have enough whips!

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CBA President

John Alexander posted this 28 August 2017

"If you increased the powder charge (more pressure) would the groups decrease?"

You might think so according to the much loved principal that the bullet hardness should be matched to the pressure. However, things are a lot more complicated than that so the answer is maybe. Fortunately that give us the excuse to shoot groups and find out. Very little simple theory give us a reliable guide. The system is much more complicated than simple theory can deal completely with.

That is not to say that there aren't principals to guide us, but we still have to shoot to find out. Good thing from my viewpoint.

John

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OU812 posted this 28 August 2017

I have shot very good groups using "harder alloy" and 14 grains of 4198 (2000 fps?).

I wonder if the softer 20-1 alloy could handle that velocity. I am sure alloy would obturate very well, but would the shallow grooves in barrel grip the bullet without skidding or stripping?

I may try same test using more velocity...just to see how well the softer 20-1 alloy would work.

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CBA Member

shake posted this 27 August 2017

If you increased the powder charge (more pressure) would the groups decrease?

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CBA Member

John Boy posted this 27 August 2017

Notice groups got larger as bullet got harder.

... because harder bullets do not obturate in the grooves of the bore

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CBA President

John Alexander posted this 26 August 2017

I faithfully lubed the noses of bore riding bullets for years. It seemed so logical. Then my curiosity and laziness came to life and I shot some groups with no nose lube then some with – then repeated a couple of times. It didn’t seem possible that there was no difference. That particular load would shoot forever without bore cleaning and it made no difference at all whether the bullet noses were lubed or not.

I shouldn’t have been surprised, after all we have air rifle pellets that do fine and Lee push through sizing dies that require no lube.

John

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CBA Member

BigMan54 posted this 26 August 2017

I guess I missed 'OU812' comment about smearing the nose-riding section of the bullet with lube before firing, the 1st time I read this post. Now I remember my Dad dipping the bullets nose into a small container of soft lube just before carefully chambering some of his personal cast loads.

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

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Standard Member

OU812 posted this 26 August 2017

Update for those who care.

These loads above did not shoot well, the lower pressures and velocities would not stabilize longer 80 grain bullet in the slower twist 1-12 twist barrel. Sometimes I could see the bullets tilting before hitting paper. More velocity using 9.5-10 grains of 4759 or 10 gr 5744 shoots the soft bullet LOTS better.

Fast powders such as Tite Group (3 - 7 grains) shoots the soft 80 gr. bullet accurately without tilt in the 1/12 twist barrel .

5.7 grains of Tite Group chronied 1475 feat per second. (shoots accurately)

10 grains of 4759 chronied 1590 fps. (shoots accurately)

12 grains of 5744 chronied 1770 fps. (10 grains shoots more accurately)

11 grains of 680 chronied 1670 fps. (10.5 shoots more accurately)

11 grains of Reloader 7 chronied 1650 fps. (10.5 shoots more accurately)

BTW the older 680 powder (older Accurate 1680 pre 1996 year) works lots better than the modern Accurate 1680 (post 1996).

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OU812 posted this 25 August 2017

Softer 20-1 alloy loads ready for testing at lower velocities and pressures. Bullets have been squeezed in bump die. Loaded 223 Remington rounds have concentricity under .001 (round)

Today I will change lube-a-matic over to Alox and see how that works. A thin liquid film on bore ride section before firing may work good.

Attention to detail matters only when powder charge and bullet fit is correct.