8 X 57 cast to bore, patch to groove?

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  • Last Post 28 July 2015
pondercat posted this 26 July 2015

I have an 8 x 57 Model 98 Mauser that I have had for many years.  I have been shooting cast bullets through it for a while now with consistent, but so-so accuracy.  Typically a good load for me will shoot a 2 1/2” group @ 100.    When I first got the rifle I shot jacketed only and accuracy was in the MOA range.  I slugged the barrel when I first got it just to be sure it was .323 which it was... er. . .is.  After reading about paper patching by sizing the bullet to bore size plus .0005 and patching to groove diameter I slugged the barrel today. I get a land diameter of .309 and groove diameter of .323 which means that I would have to apply a .014” or .015” (for .001 over) patch.  My question then is: Does that seem like too much?  or is it acceptable. And if that's OK for patching, then my 150 gr Lee .309 mold should produce the appropriate sized bullet if it drops @ .001” larger.  So if this is all well and good, then would I be better off finding a heavier paper that would patch the bullet with two wraps or lighter paper for three wraps? Should the final product then be sized to .324 or .323?  

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onondaga posted this 26 July 2015

http://castbulletassoc.org/forum/view_user.php?id=9145>pondercat

I do it  lot differently. Your method may work just fine but check my modern reasoning for doing it differently.

Stabilizing the bullet in the throat and engaging into the leade gives the bullet the best start for accuracy if the bullet is patched or not.

Pound cast or chamber cast to get a throat diameter and ignore bore and groove diameters. Chamber casting alloy that is inexpensive, has good instructions and is a cheap reusable lifetime supply for $15.99:

 http://www.rotometals.com/product-p/chambercastalloy.htm>http://www.rotometals.com/product-p/chambercastalloy.htm

I use Strathmore tracing paper from an office supply store.  It is 20# paper and measures .0018” thick when you check the thickness of 10 stacked sheets total and take an average.

--The rifle I shoot patched in has a .460” diameter throat. --A 2 turn patch totals .0072" --The .460 minus .0072 equals .4528” ideal bullet diameter for my patch material.

I size my bullets to that .4528” size and 2 turn patch them. I dampen the patches with Lee case lubricant, roll the excess moisture out on a glass slab and let dry completely. Graphite lube the patched bullets then size the patched bullet to my .460” throat fit. Rub powdered graphite into the  patch again with a  small scrap of Chamois.  Load your ammo and shoot. The barrel will do the rest of the sizing when shooting.

Try this method with your throat diameter measurement and seat your bullets to engage the leade.

I cast my bullets in Jacketed bullet scrap metal that is soft lead with ~2% Antimony. My bullet sizing dies are Lee and custom honed by me. The method I use is not original. It is from a book I trust that is available from Amazon:

http://www.amazon.com/Paper-Jacket-Paul-Matthews/dp/1879356023/ref=sr_1_1?s=books&ie=UTF8&qid=1437930595&sr=1-1&keywords=The+paper+jacket>http://www.amazon.com/Paper-Jacket-Paul-Matthews/dp/1879356023/ref=sr11?s=books&ie=UTF8&qid=1437930595&sr=1-1&keywords=The+paper+jacket

You have to diligently study the book to get this method extracted from the book or you can just follow the steps I outline from the book and copy me without all the studying. It works. I fire the patched bullets near factory ammo velocity. They shoot fine and group consistently under 1” at 50 yards from my .458 WM Colt Sauer Grand African sporting rifle.

The Lee Case Lube and graphite on the patches completely corrects the age old deficiency of patched bullets and makes them durable and weatherproof for carrying and hunting.

Gary

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onondaga posted this 26 July 2015

http://castbulletassoc.org/forum/view_user.php?id=9145>pondercat

What does your chamber throat measure from a chamber casting?

You will likely read my method and think if you follow it that your patches will be sliced by your rifling and fly out the muzzle shredded on firing. They probably will, that didn't matter over 100 years ago and it won't matter now. They might not be shredded anyway if you use the soft alloy I recommend, plus the Lee Case Lube and the graphite on your paper patches, but either way, the cutting and shredding of the patch on firing doesn't matter and does not effect accuracy.

A bonus in the book is that easy to understand methods to setup and follow for patch shape designing, and a bulk cutting method for patches that works well is fully described in the book.

I also suggest that if your rifle has a coarse throat from erosion wear and age, consider giving up with patched bullets for that rifle. It is not worth the fight with a coarse eroded throat and may never shoot well. If your throat and bore are in good polished shape, the rifle should shoot better with paper patched bullets fit and loaded as I described and shoot better than it ever did with jacketed bullets.

The book points out that, historically, copper jackets were only a production cost efficiency decision by ammunition manufacturers and that paper jacketed bullets, although laborious and time consuming to fit and fabricate, always shot more accurately than copper jacketed bullets. They still do. I only do it in one caliber occasionally because it is such a draining drudgery, but they shoot great. It literally takes me 3 weeks to get 100 rounds ready to shoot.

Gary

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pondercat posted this 26 July 2015

Hi Gary, Thanks for the quick reply to my query.

I just went out and did a pound cast and the throat diameter is .324 and perfectly round. It is pretty, shiny and smooth. So if I read you right, I would decide on the thickness of the paper I intend to use and size the bullet to .324 minus the total thickness of two wraps of that paper?

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pondercat posted this 26 July 2015

That somehow makes a lot more sense to me than a thick wrapping. i just think I would be more comfortable with the bullet actually engaging some of the rifling rather than just riding the bore and counting on the paper do all the work. Thanks, Terry

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onondaga posted this 27 July 2015

Yes that is the math from your throat measurement. 2 wraps equals 4 times paper thickness. Tracing paper is good, but Air Post stationery is a little thinner and stronger if you can find it.  Some shooters use onionskin paper too but I have never tried that.

Note also that Accurate Molds has several designs in PPd bullet molds and you can specify diameter for their non lube grooved PP bullets, some have flat noses for hunting too. .3158” diam bullet would be good if you get the same paper I use.

http://www.accuratemolds.com/bullet_detail.php?bullet=30-172P-D.png>http://www.accuratemolds.com/bulletdetail.php?bullet=30-172P-D.png

You can specify .3158-.316” instead of .32 for this mold, this is a beautiful PP bullet for hunting or target.

Gary

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pondercat posted this 27 July 2015

OK Gary. Thanks for your help. I need to find maybe a .318 sizing di and work from there. I'll apply the same procedure to that 22-250 when the mould finally arrives. I just got word yesterday that it won't be here 'till Wednesday, but I have to work extra shifts this week anyway so won't have a lot of time to work with my bullets. I do appreciate your expertise and advice.

Terry

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pondercat posted this 27 July 2015

I just got your edited post. I'll go check that mould out and see what Lee has for push through sizers in that size range. Thanks, Terry

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onondaga posted this 27 July 2015

If you get an Accurate custom mold made to drop your alloy at the diameter you need. You won't have to size anything. Just roll on your Lee lubed patches, dry and graphite before loading.   That is fast, simple and precise, but not inexpensive for a custom mold. Some prefer to size the finished bullets anyway for the hard slick shine a polished bullet sizing die will give a Lee lubed, dried and graphite coated paper patched bullet

You will very likely have to custom hone a Lee bullet sizing die to get what fits. Don't feel bad about that. I custom hone those things for every caliber I shoot. It is not that hard.

You have more options now. I hope it goes well. Keep us posted with pictures too!!!

Gary

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pondercat posted this 27 July 2015

I just went over and configured a 30-172P mold at Accurate. The site does say 3-4 weeks for delivery. This is going to be a difficult wait. That is an amazing place. I did not see that he has any.22 molds, but does offer the option of submitting your own design. That might be fun! I'm happy you directed me there. I did not even know that place existed.

Terry

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pondercat posted this 27 July 2015

When you hone a sizing die, do you use the screw in a bullet method or is there a better way? I've re-sized molds that way and it works quite well, but the molds I've re-sized have all been aluminum.

Terry

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onondaga posted this 27 July 2015

http://www.castbulletassoc.org/forum/view_user.php?id=9145>pondercat

For honing an aluminum bullet mold I use the cast slug with a hex nut method and powdered pumice with dish washing liquid.

For honing a Lee bullet sizing die I use a slotted wood dowel with oiled emery cloth and an electric hand drill or drill press.

Gary

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pondercat posted this 28 July 2015

That is similar to my way of honing a bullet mold, but I've never honed a sizing die and was afraid of getting it out of round.  In your experience, what would be the maximum size increase you would attempt with your emery cloth method?   I would assume maybe 600 - 800 grit cloth?   Terry

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onondaga posted this 28 July 2015

Use 300 -350 grit  at drill slow/medium speed, those grits cut and polish finer than factory Lee finish. Finer is pretty useless. Use smooth up down, once per second strokes  and cutting oil bath. Fit of the wrapped emery should should be snug enough to almost take the die out of your hand. A loose fit will go out of round.

I find 3-5 minutes cuts off .001” metal --- you may be very different. Check by cleaning the die and running a bullet through to check how you are doing with a micrometer  frequently.

One of my simple honing tools for Lee dies :

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pondercat posted this 28 July 2015

Thanks for all the good information Gary! I think I have info enough now to get a good start at experimenting with paper patching for this rifle. My .22 mold will be here on Wednesday (hopefully), but I think I'll concentrate on learning to PP the 8MM before tackling that small bore. I'll shoot it lubed and gas checked for now. Thank you so much for sharing your expertise. The ideas behind paper patching are a lot less murky now!

Terry

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