breach seating

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Last Post 09 June 2017
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Ross Smith posted this 03 June 2017

I didn't know where to post this, hope this is the place. I have a Hoch mold that is tapered for breach seating .311 and 204 gr. If I load my 30-06 cases with the bullet seated out to where the gc and first driving band are in the case mouth, everything works just fine. If I breach seat the bullet to where it just engages, which is just infront of the case mouth, I get a dent in the case shoulder after firing. I'm using 30 gr. imr 4895, which is my standard load for cb's in my '06. Anybody have some ideas as to what is happening?

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frnkeore posted this 03 June 2017

The dents are because pressure is getting passed the case mouth. Your powder doesn't have enough initial pressure to expand the case mouth. A faster powder should cure it or, you can expand the case mouth with a tapered tool, until you feel a little drag on the neck when you chamber it.

Frank

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Ross Smith posted this 03 June 2017

Thank you, I'll give that a try. Ross

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argie1891 posted this 05 June 2017

I advise you to use a faster powder. sr4759 is one of the old standby powders.. and they just quit making it. but aa9 4227 and several other powders work well. I have been shooting a 32-40 cpa Stevens breach seated for 3 years not and it really helps shrink the groups. cant breach seat in any cba matches ( I think that is true ) I have ruined a few cases by not having enough pressure to expand the case against the chamber walls. another problem you can have if the case isn't expanded enough is gas can come back into your face through the bolt on some rifles. not something you want to have happen. for breach seating you need a fairly soft bullet like 20-1 25-1 velocity of 1200 to 1400 fps is pretty normal. I have used over powder wads made from everything I could think of but found no wad at all gives me the best accuracy. like all cast bullet shooting the name of the game is to experiment. try the American single shot rifle forum for a lot of information argie1891

if you think you have it figured out then you just dont understand

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rhbrink posted this 05 June 2017

Breech seating is allowed in the "Plain Base Class" rule 4.3

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R. Dupraz posted this 05 June 2017

Get ;yourself a copy of the Lyman Cast Bullet Handbook. In the 30-06 section it lists 10 powders for the 3ll299 at 200 grns, all faster than what you are using. 4895 is not one of them. However these are not breach seating loads but is a place to start.

I have been using IMR 4227 for cast loads in my "06" and others, to include breach seating, for many years. Not because it's the only choice but because that's what I had at the time, and it produced results for me so I just stayed with it. All I do is to start low and increase the charge a little at a time until I get the accuracy and pressure that works. Pretty standard load technique.

Not part of your question but when breach seating, I use a 1/4" disc of Floral Foam to keep the powder from spilling out of the case. This is the green foam that is used for flower arranging. It's totally consumed and leaves no residue in the bore after the round is fired. Other kinds of foam burn to a gooey mess.

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Ross Smith posted this 05 June 2017

Thanks all: I've used 4895 and 4759. Both work for accuracy for me. Breech seating is a new experience and I obviously needed some advice. I have the Lyman book and I even use it. Just got some unique and trailboss. Been reloading for 50 years and this is my first can of unique!

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R. Dupraz posted this 05 June 2017

Here are some five shot groups fired from a CPA 38-55 at 100 yds. from a few years ago. That one on the left was with 14 grns. of IMR 4227 and the Hoch tapered 310 grain bullet. It measured .796". All breach seated.

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Ross Smith posted this 05 June 2017

Mr. Dupraz: Very nice. I have high hopes for breech seating myself. Did I read that correctly? 311 bullet in a 38-55? I just checked my Hoch mold , it's a 309 180 but casts .3095 and 204 gr. with ww's. That might be part of my problem, and I will try casting with30-1 pb. Thanks, Ross

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R. Dupraz posted this 05 June 2017

Sharp eyes, I'm the one with the problem. I wasn't very clear. The bullet is a Hoch tapered 310 grain, 376" diameter.. Thanks

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Ross Smith posted this 06 June 2017

Mr. D: yah that sounds more gooder.

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4060may posted this 06 June 2017

just a note about floral foam...be sure to use the live flower, Floral Foam, the dry flower, Floral Foam will leave a lot of nasty in the barrel

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R. Dupraz posted this 07 June 2017

An easy foam test. Light a small piece with a match or lighter. If there is nothing left but fine dusty ash, you got the right stuff.

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Ross Smith posted this 08 June 2017

Well I tried some unique powder for the first time. The dimpling went away but there is still soot getting behind the case so I know I have to up the charge. I started with 13gr. which was the lowest listed for 200gr. cb. Still shot about 1.75" at 100yds.

While I'm on the subject, what gizmos do you use for breach seating in a bolt rifle? I made up a dummy cartridge filled with a dowel and epoxy and just used the bolt to cam the bullet into the throat and riflings. It must be about the right size as the effort is not too great and there is no leading. the bullet is a gc.

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frnkeore posted this 09 June 2017

oThis is the breech seater that I made for my 40X.

The extention to the right side of the BSer body, butts against the back of the action and keeps the BSer from going forward after the lever pushes the bullet home.

The depth is controled by the 2 nuts, on the brass rod.

The lever hindges on a bracket, that mounts on the iron site mounting holes on the left, rear of the action.

Frank