Something I have never before tried is to blow out a case to a larger one of the same basic brass. This would be trying to make some .30 HART from 7mm STW's.

The 7 STW's are currently .030" longer than the .30 HART's so I want to see how much the neck will pull back when forming without a bullet. I would rather this than having to trim the .030" and then have the already lillipute necks of the HART that much shorter.

Thinking of trying some pistol powder and tissue paper method. Pros and cons please on that.

If you have done so yourself, approximately how much of a Bullseye like powder would you recommend?

Thank you in advance.

Heck just fire a 7stw round in the .30 hart. Your barrel won't know the difference.

I blow 280 caases out to .338 and larger. I would lose around .05" or my 280 case would be around the length of a 30-06.

Normally COW is around 15% of the case capacit of Bullseye or a fast pistol powder. With COW or some use old fibr wadding.

So in an stw start with around 15grs and work up until you form the case. I DON't take the pressure high enough to get a crisp shoulder if you are moving it. Slightly round it fine it will get crisp when you fire it for real. Not enought capacity difference to make an issue.

I don't know the Hart's dimensions but 8mag brass would work as well. Trim run in your die and fireform.

I will assume the 280 is the 280 Remington and the 338 is the 338/06, There has to be more to it than loading the case with powder, chamber then fire. The 280 Remington case is longer than the 338/06 from the head of the case to the shoulder by .041 thousands, meaning the 280 must be formed/sized first. Then there is the part about necking up, when the 30/06 is necked up to 338/06 or 35 Whelen the case shortens .030 thousands + or - very little,

The big change in case length is is attributed to the length of the neck, when the case neck is necked up it shortens, when the case neck is necked down it lengthens, some believe the neck gets thinner or thicker, when forming cases by necking up to create a shoulder the case body can compress if the effort is excessive when necking up.

When forming cases for the 30 Gibbs from start to finish the case shortens .040 thousands, the two factors, necking up for the 2nd shoulder and the case filling the filling the chamber when fired.

UNLESS: the shooter is suing the rifle that has the firing pin that drives the case forward to the shoulder before things get started, my firing pin crushes the primer before the other components know the primer was hit.

F, Guffey

Then there is that part where the neck sizer ball is pulled through the neck and the rumor the neck gets longer, when the neck sizer ball is pulled through the neck, the neck gets shorter, because necking up shortens, the neck.



Then without lube the sizer ball can be difficult to pull through the neck, in that situation the stretch could be on the part of the case the neck is attached to.

F. Guffey

Damn, Skippy. Is it really that hard??

Westbeeman, Difficult? I have never chambered a 280 Remington case in a 338/06 chamber, I have used 280 Remington case to check head space on 30/06, 338/06 and 35 Whelen chambers, when forming cases I form first then fire and techniques and methods require the shooter to be able to keep up with two thoughts at one time. 308Sako is talking about a .030 thousands between the 7mm STW before necking it up to .308, again I am a big fan of measuring before and after. as I said the neck will shorten before being fired. Ramrod says the 280 Remington shortens .003 + or minus, could be, I do not use the came cases he is using, I measure before and after and again after forming. I form 280 Remington cases for an Eddystone that has .016 thousands head space, from start to finish the 280 Remington cases come out to 2.505 without trimming and when keeping up with two thoughts at once? The chamber was/is the same as a 30/06 chamber with .016 thousands head space, I do not know how difficult is is for others to keep up with measurements, trimming the 280 Remington case for the Eddystone is not necessary, the added length is between the bolt face and shoulder of the chamber.

The 30 Gibbs can have two different length chambers, *I cut my 30 Gibbs chamber from an existing 30/06 chamber meaning the reamer did not remove all of the original chamber, I found this helpful when forming cases for the 30 Gibbs, the neck is .217 long, as 308 Sako indicated the neck on his 30 Hart was short enough, I formed cases using the 280 Remington with the shoulder forward of the 30/06 ..051 thousands and the case length .041 thousands longer, point being most of the chamber is covered with the additional length, the part I have little control on the neck pulling back when the case fills the chamber.

http://www.z-hat.com/Cylinder.htm

Cylinder brass: 2.650 case length for sizing and forming for chambers that use the 30/06 parent case, there are those that would load with powder and breakfast cereal, no advantage but for those that form first then fire use the extra length to off set the problem of the shortening case.

F. Guffey

The powder carbon left in the case neck is very abrasive so it can really grip the expander ball. If you don't use a lube you can at least give the neck a good brushing with a proper fitting brass bore brush. Some like using the brush with powdered graphite or mica.

quote:

I will assume the 280 is the 280 Remington and the 338 is the 338/06,

Nope they would be my PDK wildcats.
I was simply stating how much my necks shortened when I blew 280 cases out to a neck of .338. Since my shoulder is forward, taper reduced yes there is a lot more steps that weren't important to his question. If all he is doing is taking a 7mm neck to 30 cal then it won't shorten much. Will he need to trim. I have no idea.

Take a 270 blow it out to 338-06 and see what the neck will do. Shoulders are the same

Appreciate the suggestions and the help.

After measuring many times I have come to the conclusion that firing the rounds as foulers and simply developing a load for this purpose makes sense due to the amount of STW brass I have received.

I have annealed the cases before any necking up, and attendant trimming to square and come to .300 Weatherby length (parent case.) Only needed to take about .013" off the brass.

Ramrod340, "Take a 270 blow it out to 338-06 and see what the neck will do. Shoulders are the same"

The length of the 270 Winchester and the 280 Remington are the same length, 2.540, the 270 Winchester when chambered in a 30/06 will have about .040 thousands of the neck extended into the throat, that would go for the 8mm06, 338/06 and 35 Whelen, again, I form first and I am not a big fan of reduced loads.
The term "blow out" does not mean down the barrel, when forming blow out means against the chamber, when the case fills the chamber and the case expands, then we are back to the neck pulling back or when the neck is expanded (necked up) the neck shortens, and when the case expands in the chamber the case shortens.

I believe I am using the same brass used by all, I measure before and after.

As to the 280 Remington fired in a 338/06, no firing/blowing out required, neck the case up, size, measure, load, fire to get once fired cases.

F. Guffey

I've been blowing shoulders forward on 6 PPC cases 0.020 using 11 grains of BE, 1/4 sheet of toilet paper over the powder, filling the case with corn meal and plugging the neck with wax. I actually "worked up" this load from 8 grains to 13 and found that 11 worked as well as anything higher. You may require more powder for the bigger case or not.

I would bet that you will suck that 0.03 back without a problem but I would measure it for sure.

Greg

http://www.6mmbr.com/6ppc.html

F. Guffey

308Sako: If I were you I would run the cases into the 30 Hart die and then with a 8mm expander and then back into the 30 Hart to a point were the bolt will close with some resistance to form a small shoulder on neck to hold case on bolt face to give correct headspace for your chamber.

Seated the bullets into contact with the lands, fired with respectable 300 Weatherby load data, and came away with very nice cases, and a fire forming load that shot 1/2 MOA at 300 yards.

That load was 200 ft/secs slower than the finished cartridges potential and accuracy load, but no slouch either.