Breech Seating?

[ajc44mag]

Hello,Gentlemen.
Does anyone know any details about breech seating?
My situation to try a comparison is this.
I have a BPCR in 40/65,set up with a good Bench Rest scope(Leupold 24X BR),and I'm looking for the best accuracy I can find off the benchrest...and then I'll go back to my Vernier tang site.Of course,I'm trying different cast bullet styles,but what of breech seating?I can open my action and look down the bore,(unlike muzzleloading)and know that seating a bullet "into the lands"can increase accuracy.I can further picture someone pushing a bullet into the breech until it's "snug".....but then what?You have to ensure the powder charge is right there at the bullet base,without a "gap"...how can a case "slip" around our bullet and not disturb it?Wouldn't we be better optimizing the OAL of our fully assembled benchrest cartridge?Is there a difference ?
AJC

[felix]

First off you'll need what is called a tight neck chamber for the best results from breech seating. Why? So you can cut around the neck of the case until the boolit will actually slip fit, leaving only 0.001 total neck clearance, 0.002 at the very most. If you desire, and this is not required, some seating friction, use something like shotgun polygrits over the powder and under the boolit. The poly amount should offer just enough friction to do the job and no more. You do NOT want a boolit to grab the lands and hold on. ... felix

[45 2.1]

a quick and dirty breechseater can be had thusly: take a fireformed case from your rifle, make sure a bullet you intend to shoot (soft I hope) will slide into the neck, if so cut a hard wood dowel that just fits into the case long enough to have about 1/8" clearence left when in the case. Put your lubed bullet in the recess and gently put it into the chamber. Seat the case fully and remove case and plug. load a fireformed case with primer and powder behind it and shoot.

[Buckshot]

.............True breech seating, as practiced form the beginning and to this day normally sees a leade and boolit with a meticulas fit. The bullet is forced into the lands either by a lever arrangement hinged to the action top by various means, or by a 'pusher' type breech seater. In the later you have a tube which has the dimensions of the chamber so as to be an extremely close fit.

Into this false cartridge goes the boolit. It's set into the chamber and a rod with a handle is pushed which forces the boolit forward until the pushrod comes up to a stop. The charged cartridge case (usually with a wad right at it's mouth) is slid into the chamber, and the breech is closed. Normally the boolit's base is right 'at' the casemouth.

The other type has a suitably curved lever with a pivot device that fits into a mating claw arrangement, usually on top of the action. A pushrod hinged to the lever is used to seat the boolit into the lead. The pushrod bears against the base of the boolit, and by pulling the lever down it forces the boolit home. A charged case (as above) is placed in the chamber.

Ususally in scheutzen breech seating, the slug is tapered to match the leade or multi-banded like a Loverin, and both types are fully engraved to their length (but usually not to the full groove depth), except at their bases to effectively seal the barrel. The boolits did not enter the case.

Offhand I know 3 favorite powders used by breechseaters are 4227, SR4759, and AA#9. I'm sure there are others. Normally one case was used for every shot. It was deprimed, reprimed, charged (pre-measured, or volumetricly thrown at the time), then a wad was pressed into the casemouth. The case was index marked so it was placed in the same exact position for each shot. Usually a 'W' or similar type hand tool was used for de and re-priming, while the case was not sized at all.

..............Buckshot

[MOA Shooter]

Hello,Gentlemen.
Does anyone know any details about breech seating?
My situation to try a comparison is this.
I have a BPCR in 40/65,set up with a good Bench Rest scope(Leupold 24X BR),and I'm looking for the best accuracy I can find off the benchrest...and then I'll go back to my Vernier tang site.Of course,I'm trying different cast bullet styles,but what of breech seating?I can open my action and look down the bore,(unlike muzzleloading)and know that seating a bullet "into the lands"can increase accuracy.I can further picture someone pushing a bullet into the breech until it's "snug".....but then what?You have to ensure the powder charge is right there at the bullet base,without a "gap"...how can a case "slip" around our bullet and not disturb it?Wouldn't we be better optimizing the OAL of our fully assembled benchrest cartridge?Is there a difference ?
AJC

The two things gained breech seating are bore alignment and uniformity of combustion. If the gun isn't throated for breech seating an improvement in alignment is questionable, especially if the tooling used to breech the bullet isn't precise. Well loaded fixed ammo is easily as accurate.

Uniformity of combustion is a matter of meticulous brass prep when seating the slug. Partial sizing of the brass to get just the right bullet grip along with the degree of compression the powder works best at, usually that grip is very light backed by the pwoder charge to set the slug into the leade firmly. Getting the best consistent groups from a BPCR normally is a rewarding challenge.

MOA.

[Bad Ass Wallace]

As you have a 40/65, you might like to try the Lyman tapered bullet. This can be loaded fixed but with the last driving band set into the case.

Took me a lot of experimenting to get excellent accuracy but essentially a very soft alloy is used as the bollit has to 'upset' into the rifling when swatted by the powder charge. Loaded as shown, you can get a full 70gns of powder in the 40/65 case but you will need to clean after every shot.

If you rifle is a 1874 Sharps or Highwall, then there is just that little bit of camming power in closing the breech to seat these into the rifling just like a seating tool would achieve.

[MOA Shooter]

Wallace what kind of lube are you showing in those pics?

MOA.

[Bad Ass Wallace]

Lube is my own mix; 4 parts beeswax, 3 parts coconut oil, 1 part olive oil.

I store cast boolits in sealed containers and only fingerlube and load 2-3 days prior to a shoot. This mix softens as you work it then after filling the grooves and in contact with air it 'firms up' again.

This group shot with a 45/70 Sharps, black powder and the home made lube

[ajc44mag]

Thanks,guys.
I appreciate your responses and insights.
******,you're a hoot!Sounds like a great lube,that was GOOD SHOOTING,and that helmet is a time tested design,I guess.
How was your winter?Spring must be right around the corner for you.
Ajc

[Bad Ass Wallace]

Thanks,guys.
I appreciate your responses and insights.
******,you're a hoot!Sounds like a great lube,that was GOOD SHOOTING,and that helmet is a time tested design,I guess.
How was your winter?Spring must be right around the corner for you.
Ajc

Ah the helmet; well I tried to give the photo to the police to put on my shooters licence but they don't accept photo's with hats on the head!!!!

Winter is just finished, I had to put on a sweater only 2 mornings when it got down to zero deg C. Our biggest problem at the present is water as we haven't had good rain for about 4 years. Should have had 26" by now this year and we have had just 7". Won't be long before the dog raises his leg and ten trees will mug him