Fire-forming (in general)

[spclark]

What I'm wondering is: is the CoW method easier on barrels than fire-forming with normal load practices?

It sure seems so in terms of time any money! Compare 16 grains of Bullseye without a wasted bullet to 40+ grains of Benchmark and a $0.45 Berger, times quantity of cases needed to get thru a weekend's match schedule.

I'm working up a wildcat 7mm for an any/any rifle this year. Cartridge is an 'improved' 7-08. By that I mean it's shoulder is 3.5mm farther out while shoulder angle stays the same. Neck's are short in the manner of Stan Ware's 30 Wolfpup.

Last weekend I'd loaded up some necked down Lapua Palma cases with a reasonable load of Benchmark under some Sierra 100 grain Varminter HP's. Accuracy at 100 was pretty decent off a bench while cases showed rounded angles.

Until today I'd never tried the CoW fireforming procedure but with the weather where I am and the economics of 'wasting' bullets over firing blanks I though I'd give it a try.

Today I fired similarly necked down cases but loaded with 16 grains of Bullseye under a 1/2" square cotton patch then ~ 18 grains of corn meal (what was handy; haven't eaten CoW for 60 years!) topped off by another patch then wadded up blue paper towel.

I also reloaded & re-fired the cases formed up last weekend.

This time even the first-time fired cases are much closer (by my eye) to the chamber contours compared to those fired last weekend. A couple will be sacrificed for making seating depth cases to fit my Stoney Pointe gauges so I can get on with developing specs for the bullets I want to use eventually: Berger's 168 VLD, 180 VLD Hunter or 180 Hybrid.

In view of what Jason Baney reported out of his 7x47 early last year I'm hopeful the extra case capacity of this cartridge (dubbed 284 INCH by its creator, forum member RGC (Robert Chombart); there's a 260 version also) will boost velocities upwards of 100 fps depending on propellant choice.

 

[Nvreloader]

Sp Clark

I also use that same method of FF cases, only I adjust the amount of powder/CM,
use 1/4 square of toilet paper, for large cases, 1/8 square for my small wildcat cases.

I am using just enough powder (Bullseye) to get good 90% formed corners on the shoulders/brass
and filling the case full of CM, tamping down the CM tight, keep adding CM and tamping it down,
until there is about 1/8" of the neck not filled.
Then I slide/push the case neck into a large/big candle to fill the neck with wax
keeps the CM in place.

Less powder + and the extra CM forms the case shoulders perfectly,
and I also use just BE powder ONLY, with TP, keep increasing the powder amount until you get the results wanted, use no more than 2.0gr steps, a little goes a LONG way with BE powder.
The difference of amount of powder used between annealed brass and non-annealed brass can make a difference.

DON'T use that/YOUR amount of BE with a tamped full case of CM,
as you can blow primer pockets, don't ask how I know.

I also made a FF jig that uses short pieces of stress proof 1-1/2" dia rods,
cut just long enough to fit whatever cases I am FF, these FF jigs thread into a 3" center piece of SP rod
that is threaded on one end for a firing pin device.

The FF case is fitted with a "C" shaped washer that fits the extractor groove,
the FF jig is chambered using the reamer just about .003" deeper than the chamber,
I can adjust the case using the dies to get the proper fit.

When making the FF jigs, I use the largest vent hole at the top of the jig possible,
minimum is the caliber size of the case, up to 3/8" sized hole.

I have a 4" x 3' long size of PVC pipe with a rubber cover on one end,
then makes a 90* bend into the garbage can, stuff the FF jig thru the rubber cover,
and "fire in the hole", less mess, when I cannot get outside to FF etc.

Wear hearing device if inside!!!!!!!!!!!!!! IT'S LOUD...............
Tia,
Don

 

[Robert]

Sp Clark

I also use that same method of FF cases, only I adjust the amount of powder/CM,
use 1/4 square of toilet paper, for large cases, 1/8 square for my small wildcat cases.

I am using just enough powder (Bullseye) to get good 90% formed corners on the shoulders/brass
and filling the case full of CM, tamping down the CM tight, keep adding CM and tamping it down,
until there is about 1/8" of the neck not filled.
Then I slide/push the case neck into a large/big candle to fill the neck with wax
keeps the CM in place.

Less powder + and the extra CM forms the case shoulders perfectly,
and I also use just BE powder ONLY, with TP, keep increasing the powder amount until you get the results wanted, use no more than 2.0gr steps, a little goes a LONG way with BE powder.
The difference of amount of powder used between annealed brass and non-annealed brass can make a difference.

DON'T use that/YOUR amount of BE with a tamped full case of CM,
as you can blow primer pockets, don't ask how I know.

I also made a FF jig that uses short pieces of stress proof 1-1/2" dia rods,
cut just long enough to fit whatever cases I am FF, these FF jigs thread into a 3" center piece of SP rod
that is threaded on one end for a firing pin device.

The FF case is fitted with a "C" shaped washer that fits the extractor groove,
the FF jig is chambered using the reamer just about .003" deeper than the chamber,
I can adjust the case using the dies to get the proper fit.

When making the FF jigs, I use the largest vent hole at the top of the jig possible,
minimum is the caliber size of the case, up to 3/8" sized hole.

I have a 4" x 3' long size of PVC pipe with a rubber cover on one end,
then makes a 90* bend into the garbage can, stuff the FF jig thru the rubber cover,
and "fire in the hole", less mess, when I cannot get outside to FF etc.

Wear hearing device if inside!!!!!!!!!!!!!! IT'S LOUD...............
Tia,
Don

Don,
Some good advice there.

R.G.C
c-g-designs.blog4ever.com