Meplats

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  • Last Post 07 June 2020
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Ross Smith posted this 02 June 2020

I've been told by CBA members that the meplat is probably the least important part of bullet anatomy. Here is  my concern. My original Don Eagan mold is wearing out a little where the steel sprue plate rubs on the top of the mold. Now it leaves some flashing around the meplat. Up till now I just mash it into place with the top punch during lub-size. Yesterday I tried the boring extra step of placing the bullet into my drill press chuck with the pointy end sticking out. While running at a slow speed I use some backed sand paper to re move the flashing. Today I shot 3 5 shot groups of pressed meplat and sanded meplat. I know that ain't statistical but the sanded groups were more consistent and a little smaller.

What say ya'all, are uniform meplats worth it for Target Ammo? And if so what's a good way to do it?

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Shopdog posted this 02 June 2020

Ross,one man's "target" ammo might be another's plinking fodder? Each person faces their own challenges in deciding whether it's worth any "extra" effort.

I say a resounding yes. Anything that makes my varmint rigs ammo more accurate,sign me up. The key is to develop processes that are streamlined by nature. Meaning,if you can cut out some variations without undo work then,why not?

I use torque wrenches with machined adapters as handles for Lyman 450's. Along with custom top punches it allows me complete control on reshaping ogive's and options on the any nose bump. Once the #'s are determined on the wrench,it's no more difficult than pulling a std handle.

Not saying that helps your situation,using it to illustrate how this process is just as easy as not. Sounds like you could use a "shaver",pencil sharpener style cutter/uniformer. I started to make one for sumthin and then changed the process after seeing a commercial offering somewhere. Heck,it might have been an Eagan product? Can't remember. BW

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Ross Smith posted this 02 June 2020

Shopdog: I actually tried a cheap pencil sharpener. Bullet didn't fit in far enough.

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John Alexander posted this 03 June 2020

Hi Ross,

If you are seriously considering sanding off the fin of all your serious bullets, why not do a batch and then use them to complete the experiment you started with the three group comparison.  Another 4 to 7 pairs of five shot groups with and without the treatment ought to give you an answer you can have confidence in. The results of your first three pairs don't sound too decisive.  Then let the rest of us know what you found and we will all know a bit more.

Besides, the extra testing would give you the excuse for an afternoon of cast bullet shooting -- what's not to like?

Unless the fin is quite thick, I would be open to a little side bet -- me betting that you will find that modifying the bullets is a waste of time. I suppose gazing at bullets for small defects is more productive than gazing at your navel -- but maybe only marginally.

John

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Ross Smith posted this 03 June 2020

John: You're probably right. The flashing is thin but very "un-uniform" from bullet to bullet. Also being cast of linotype, they're too hard to just use my thumb nail. I have some more cast up for another go. The ultimate is going to be finding a good replacement for the Eagan mold. The xcb is showing promise and I have a mold coming from accurate. Ardito and his long tapered throats..................

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Shopdog posted this 03 June 2020

Well Ross,owe you a thanks because;

Was sort of "on the fence" about a ring gage(of sorts) that could be of use determining out of roundness on the bore ride section of certain moulds. The body's runout has been delt with in a cpl different ways but the ogive presents some interesting challenges. Have made quite a few swaging nose punches and although they work great,it leaves a cpl areas "on the table".

Ordered a .220 NOS,reamer.... this one has a slight geometric "twist" (no pun intended) in it's design and can't say exactly what it measures till it gets here. It's tapered from 1/8" at the start end to a major straight section of .220,well at least that's how it was advertised? Yes,using it for a .22 mould. And specifically an RCBS 225-55 that "drops" @60g.

At the very least it's going to be a ring gage for a quick visual sorting,that's a given. The object however is to see if I can make it manipulative. Meaning make slight adjustments to the ogive and how these assist in not only seat pressure while loading but dynamics on chamber fitment.

Thanks again for the jog.BW

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billwnr posted this 04 June 2020

If it was me and I was in love with that mould I'd check with one of the better mould makers and see if they could refurb the mould.  It might just be the mould needs a new, or flattened, sprue plate.

 

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Ross Smith posted this 04 June 2020

Bill: 2 things, first these old Eagan molds are a "collector" item, and the wear is on the mold body and has opened up the sprue hole into an egg shape. I have what is going to be a replacement,I hope, coming. I wish it was an easy fix, but it isn't. This bench rifle is the fussiest rifle I own.

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billwnr posted this 04 June 2020

I have one of those "collector" moulds too.  That's why I said if you really, really want to shoot it you should get it refurbed.  What I find on my frequently used moulds is that the sprue plate is usually the issue.   I hear one of the new (relative term) mould makers makes an acceptable substitute for the Eagan mould.  The sub is a bottom pour though.  Heard it doesn't affect accuracy.

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Ken Campbell Iowa posted this 04 June 2020

speaking of Eagan molds, i recently found an old Eagan catalog from maybe 1985 ?? in my shop ....  ... kinda beat up and greasy, but nostalgic ... pm if you would like it for postage.   ken

 

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Ross Smith posted this 05 June 2020

Bill: Is that mold maker Accurate Molds, or NOE? They both make a couple copies of Eagan designs. The mold I ordered from accurate has a tapered base section and I hope that will fit the throat better. I have an NOE mold that is close to the mx4 30 ard#2 but it is too long for my 14 twist. Maybe a different powder would work better.

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billwnr posted this 05 June 2020

I've heard from other shooters that Accurate Molds makes a good copy.  Meplat is wider but other than that it's a good copy.

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Ross Smith posted this 06 June 2020

John A: I took your advice and shot 4 more five shot groups each for the sanded meplats vs the swaged(mashed) meplats. I was actually pleased with my consistency today, only one of eight groups exceeded 1". The sanded meplats averaged .848". The mashed during gc and sizing meplat group averaged .801. Best group for the sanded batch was .593 and best for the squished group was .607.

I think I'll skip the sanding. It was fun though.

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RicinYakima posted this 06 June 2020

Nothing Like Data, compared to opinion or the keyboard.

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John Alexander posted this 06 June 2020

Ross,

Excellent! Nice little experiment and it looks like it gave a pretty solid answer. 

Getting a better bullet fit over more of the bullet sometimes improves accuracy.  Throwing more bullets away to remove small defects (small wrinkles, rounded edges, fins) never seems to improve groups, no matter how logical it seems.

John

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Ross Smith posted this 06 June 2020

I've wondered about wrinkled bullets myself. Some one did a post on horribly mangled bullets and they shot just fine.

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John Alexander posted this 07 June 2020

There is an article in TF # 213 of a test of wrinkled vs. "perfect" bullets. I had an ornery mold that cast 30 bullets with some pretty gnarly wrinkles in a larger lot.  Six 5-shot groups of each fired alternately with six groups of perfect bullets from same lot.  Seventy five grain 22 bullets, BHN =15, 5 grains of 700X, Rem. small pistol primers, in 223 Tikka with 8" twist. 

Average of 6 groups of "perfect" bullets = 0.82 MOA

Average of 6 groups of wrinkled bullets = 0.78 MOA

 Be glad to send the text of the article but I don't have pictures of the wrinkles that are in issue #213.

John

 

 

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Ross Smith posted this 07 June 2020

John: I remember the article.

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