Need suggested Bullseye charge or red dot for COW fire form load

  • Last Post 17 May 2015
corerf posted this 13 May 2015

I have never used COW as the payload to fire form brass. I am forming 8x58RD from 45-90 and Id like to preserve both powder and bullets to get 90% fire forming.I am doing this to prepare for an in depth 8x58RD pressure/load data acquisition run using the RSI pressure trace and several of my 8x58's in very high condition.

Im kind of sick of wondering who or what is right about load data, thus preventing me from shooting them. Not sick of people, just sick of the VOID in data.

The Dutchman has made big strides but not complete enough. I need to be as efficient as possible to preserve funds (since Im dumping close to $1000 into the project). Brass needs to be up to snuff fast and at second firing w/o splits, etc. Ive never extruded brass with COW, using light pistol charges. Looking for the Ed Harris school of brass forming insight into how/why/what to do/use in various conditions. Thanks in advance for Anyone (not just Ed) who can speak into the task. Not just for 8x58 but in addition I have an excess of rifles that require funky chicken brass that need COW forming procedures. If there is a mathematical rhyme or reason to the charge vs payload calc, please enlighten me. Thanks in advance Mike

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onondaga posted this 13 May 2015


Reconsider COW filler. it is the heaviest per volume of commonly used fillers. Filler weight is added to bullet weight for total projectile weight in ballistic calculations and COW is heavy enough to throw seemingly safe loads into high pressure. COW also absorbs moisture from air.

BPI original filler weighs 4x less than COW per volume and BPI easily compresses up to 50% by volume. BPI is also non-organic, inert , high temp resistant and does not absorb water from air.

I can't recommend using any filler as a “Payload". That by definition is firing without a bullet. I hope you didn't mean that.


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corerf posted this 13 May 2015

You misunderstand Gary just a bit i nmy use. These will be COW only, extrusion loads. No bullet. Toilet paper over powder. TP to close case mouth.

Fired within 48 hours of loading simply to expand case mouth and shoulder area.

I DO need s compressible harder media, fluffy media will do nothing for me without a projectile.

Please advise.

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onondaga posted this 14 May 2015

Mike,  Either filler with no projectile presents an unknown hazard level to me and likely too little pressure to fire form a case. Personally, I would not do or recommend the no bullet route to fire forming brass.

My first recommendation would be to follow a Hodgdon recommendation from their 60% rule. If your cartridge case final dimensions are near 8X57 M, there are plenty of H4895 loads with many different bullet weights. Reduce to 60% or the minimum of 50% case volume of H4895 for a cast or jacketed bullet load for the weight bullets you have. There won't be an ignition problem following Hodgdon recommendations.

If your case volume is different than 8X57 M follow the Hodgdon 60% rule for the cartridge with the closest volume and caliber.


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corerf posted this 14 May 2015

Gary literally thousands of shooters are using this method to form brass. Thousands also use mouth to mouth load data for the operation. My hopes were to find a line of thinking involved in producing a load variable for fireforming with hard filler.

When I mean thousands, I mean thousands.

I appreciate the apprehension and cautions presented.


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Wineman posted this 14 May 2015

I have read that a case full of slow powder, compressed and the bullet into the lands holding the base into the bolt is a sure way of forming any case. I have not tried it myself. I did some COW loads and did not get the results in a 30-06 that I wanted. Your rimmed case may work just fine.


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delmarskid1 posted this 14 May 2015

I know that I have seen suggestions for COW fire forming on this forum. My mind is not nimble enough to locate things in our archives. 

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onondaga posted this 14 May 2015>corerf,

 "literally thousands of shooters are using this method to form brass."

I am not convinced by thousands of shooters, but I have no safety concerns following recommendations from Hodgdon and their 60% rule.

It is very typical that propellants act very differently at load densities and pressures out of the range recommended by the propellant makers. Hodgdon is very reliable and has good practical recommendations for trouble free reduced loads with H4895:


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Brodie posted this 15 May 2015

coref:  I have successfully fire formed 38-55 brass from 3030 cases with 10 to 12 gr of red dot under a case full of COW. I have also used the same load forming 6.5 Creedmore from 22-250 cases.  When you do it just point the barrel straight up and let her rip.  Brodie


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corerf posted this 15 May 2015

Thank you Brodie. Sounds very consistent, it's always 10 gr plus/minus it seems. The entire br world on 6.5mm class has adopted the practice and you have confirmed again as well all the other input I have sourced.

At a buck a bullet and the possibility of splits using just a bullet snd a 60 pct load, the cow loading is a gentler more mechanized method with excellent results, at least from my research.

Thanks for the confirmation. Ike

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TRKakaCatWhisperer posted this 17 May 2015

I've done a lot of .375 win from 30-30 and some 7mm Rem Mag to .458WinMag. In general, I always anneal first, and most need it again. Mild expansions are easy (.375Win from 30-30). Anneal, start with minimal charge, observe results, increase as needed.  Excessive charges tend to rip brass apart. Going from 7mm Rem mag to .458 is another story. anneal, expand to .357, anneal, expand to .40, anneal and fire form. (took a lot of experimenting to get it to work.) Probably used Unique.  10-12 grains.

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