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I'll post what I've got. It's all available at the "CAST BULLET INFORMATION" Yahoo group.
BREECH SEATING BULLETS
Breech seating is the process of pushing the bullet into the rifling of the barrel. After breech seating, a primed and charged case is placed into the chamber and the gun is fired. Breech seating is done mostly with single shot target rifles.
The underlying original reason for breech seating was that some of the old cartridges such as 32/40, 32/35 and 38/55 have and had no neck. The chambers are straight tapers-there’s no neck. To hold a bullet in the cartridge case, a neck was formed on the case. The chamber didn’t have a neck and accuracy was less than stellar because in low velocity loads the case did not seal the chamber and gas blew back around the case. Breech seating allowed the case to seal the chamber, eliminating blowby.
The other advantages of breech seating are a reduction in labor required in reloading, and almost infinite case life.
Single shot rifle shooters will tell you that breech seating the bullet about 1/16” in front of the case gives better accuracy.
Here are the results for shooters who completed all group matches at the 2005/2006 CBA National Matches. PBB = plain based bullet, breech seated. PROduction rifle, HVY = heavy rifle, UNRestricted rifle. At least in these two years the breech seating more than held its own against the other, fixed ammunition classes.
2005 CBA Nationals
Summary PBB PRO HVY UNR
Average 5/100 0.631 1.290 0.782 0.769
Smallest 5/100 0.194 0.236 0.356 0.251
Average 5/200 1.750 2.585 1.952 1.960
Smallest 5/200 0.742 1.010 0.594 0.786
Average 10/100 1.009 1.629 1.162 1.014
Smallest 10/100 0.580 0.769 0.614 0.323
Average 10/200 2.951 3.214 2.486 2.589
Smallest 10/200 1.391 1.633 1.148 1.332
2006 CBA Nationals
Summary PBB PRO HVY UNR
Average 5/100 0.710 1.357 0.847 0.855
Smallest 5/100 0.186 0.495 0.151 0.259
Average 5/200 1.806 3.093 1.942 1.870
Smallest 5/200 0.862 1.075 0.742 0.482
Average 10/100 0.975 1.648 1.201 1.028
Smallest 10/100 0.662 0.688 0.558 0.420
Average 10/200 2.910 3.909 2.947 2.600
Smallest 10/200 1.356 1.284 1.474 1.141
Breech seating the old single shots slows me down (a good thing), I don’t have to do any reloading before the shooting session, and it draws interest from the other shooters.
It is often said that proper breech seating is with the bullet 1/32"-1/16" in front of the case mouth. I breech seat some bullets in some guns where the bullet base is not as far in the chamber as the case mouth; the cartridge case mouth goes AROUND the bullet when seated.
Here’s my way to measure the correct bullet seating depth for breech seating:
Put a bullet into the chamber of the rifle. Push the bullet into the rifling with a pencil, push with one finger on the end of the pencil until the bullet won’t go in any further.
Hold the muzzle of the rifle up to a light and look into the breech. If you see bits of light coming through the barrel grooves around the bullet, the bullet isn’t in the rifling far enough. Use a plugged case to push the bullet a little further into the rifling, check for light, and keep on until you can’t see any light coming around the bullet. You now have the bullet making a gas tight seal in the bore, which is what you want. (I have generally had better accuracy with breech seated smokeless loads when no light came around the bullet as breech seated, but not always. My Maynard shoots almost as well with light coming around the bullet as without.) Now take your cleaning rod with brass screw (see the Appendix) and put it in the muzzle of the rifle. Gently push the rod in until it touches the nose of the bullet. Put masking tape on the rod and mark it at the muzzle. Knock the bullet out of the barrel, close the breech, and push the cleaning rod in until it touches the breechblock. Put masking tape on the rod and mark it at the muzzle. Take the rod out, and measure the distance between the two marks. This is the distance from the nose of the bullet to the base of the case. Subtract the bullet length from this dimension, and the result is the length of plugged case that will breech seat the bullet to the no-light condition. Do this several times until you are confident that your answer is correct. Make a sketch of the chamber and the bullet with dimensions. WRITE IT DOWN!
There are several methods of breech seating explained below, in increasing order of the amount of work required. If a breech seating method leaves the base of the bullet below the end of the cartridge case, then see if a cartridge case will go into the chamber around the bullet. If the case goes in around the bullet, make a short-plugged case of the appropriate length and you’re in business. This method works well for me in my Maynard.
DROP IT IN
On rare occasions there is a happy coincidence of bullet, chamber and brass dimensions that allows breech seating with the charged cartridge case. I had a Peterson Ballard and a Remington Hepburn, and Bob Bross has a German Scheutzen rifle which work this way. My Werndl works this way. Drop a bullet in the chamber, push in the charged case with your thumb, and shoot. The case pushes the bullet into the rifling with little resistance. Try this first, you may be blessed.
PENCIL SEATING
If you’re not blessed, try pushing the bullet into the rifling with a pencil or a dowel. Sometimes, even with light coming around the bullet, you will get accuracy this way.
PLUGGED CASE/PUSHER
Use a plugged case and your thumb or a pusher to seat the bullet. A pusher for pushing the plugged case into the rifle is just a length of (1/2”-3/4” diameter) dowel with a round wooden furniture drawer handle on the end.
Here's a breech seater or pusher made from a piece of quarter inch steel rod and a furniture handle. The business end of the rod is filed round to fit the primer pocket in a plugged case. The furniture handle is drilled a quarter inch about half way through. The bend was made by sticking the rod between the planks on the bench rest and bending to fit the gun-a Martini. About $3 and a half hour's work.
Sometimes the bullet will breech seat easily. If the bullet goes all the way in and the breech will close on the plugged case, you’re in business. If the bullet goes part way in and the gun shoots accurately, you’re still in business.
BREECH BLOCK SEATING
If your rifle has an action which will push your plugged case into the rifle, such as a Ballard, Stevens 44 or 44 1/2, Maynard, Aydt or New England Firearms Handi-Rifle, then put a bullet in the chamber, push in a plugged case, and close the action. If you can do this without undue strain on the rifle then you may be in business.
OLD TIME BREECH SEATER
The traditional breech-seating tool is a rod with a handle on one end and a cartridge case on the other. The end of the rod is threaded, the cartridge case is a loose fit on the rod, and there is a flat-ended nut on the rod inside the cartridge case. A bullet is put into the cartridge case, the breech seater is put into the chamber, and the rod is pushed to seat the bullet.
MECHANICAL BREECH SEATERS
The most powerful bullet breech seater is a lever apparatus hinged to a rear sight base or to the action mortice, which pushes a plugged case and the bullet into the rifling.
Accuracy can result with a properly designed bullet; breech seated using one of the simpler techniques. I have often wondered if the more powerful breech seating techniques don’t deform the bullet.
Bill McGraw:
Some years ago, I wanted to breech seat CBs in my bolt action rifles. I knew that a plugged case worked in SS rifles and decided that this was the way to go. I used wood dowels, some with an inverted gas check crimped on the dowels. Others were lead filled cases. Each was adjusted for OAL for the different bullets in 30 caliber rifles, my 03 Sporter in 30/06 and 30/30s in a Rem 788 and a lever action Marlin 336. The 03 was the main target rifle I used in BR matches.
After using the fixed OAL breech seaters, a friend, Phil May, made adjustable breech seaters from cartridge cases using a discarded exhaust valve stem as the plug. The base of the cartridge was drilled and tapped for the threaded stem, the stem being drilled and tapped internally for two Allen screws, one to act as a lock screw and the other used to disassemble the seater. The top of the stem was fitted to the base of the neck of the case and had a flat head screw fitted to the stem as the adjustable part of the seater in the case neck. There was also a lock Allen screw below the seater screw. To adjust the seater, the seater screw was adjusted up or down and once the seating OAL was settled, the stop Allen screw was adjusted to stop the seater screw from going out of adjustment. Both the 03 and 788 would not seat my bullets fully into the throat and the base of all CBs would extend into the charged case necks the same as for the fixed breech seater cases. Once the OALs were found for each bullet so that there was a good gas seal, (no light could be seen around the seated bullet), the load data could be easily adjusted for an accurate load.
The 03 became a 1 MOA rifle in a short time. Even with a good gas seal I used a variety of wads in the charged case to improve accuracy and reduce bore fouling.
Many years ago, these seaters were featured in TFS with an article and photos. Phil May and I had decided we needed to make another design so that we could have indents and adjustment from the rear of the seater rather than from the front as the Allen stop screw was difficult to set properly. We found that rather difficult and used the ones we made.
These seaters allowed a bolt action rifle to find its most accurate loads by loading one case, (only deprime, prime, load the powder charge and add a wad in the neck), at the bench with a variety of factors of bullet alloy, diameter, OAL and the usual powders, charges and primers. It reduced the time involved in loading fixed ammo in the shop and subsequently finding a load that was not accurate. It was readily apparent within 3 shots if a load was promising or not. Once a target load was found, we could either breech seat at the bench for a match or load fixed ammo for the same load data, although the OAL might be somewhat shorter. The plastic vinyl, (PVC), wad was still used with the fixed ammo and I believed it solved much of the small amount of gas cutting that occurs with even the best of match ammo."
HOW TO MAKE A PLUGGED CASE
A plugged case is a cartridge case that is filled with some material and that is used for breech seating. The length of the plugged case determines how far the bullet is seated into the rifling. It is often recommended that the bullet be breech-seated ~1/16" in front of the case mouth. In some rifle/bullet situations it may not be possible to seat the bullet this far forward, and the case may fit around the breech seated bullet.
One way to make a plugged case is to fill an empty cartridge case with lead alloy, and file to length.
Another way is to put masking tape around the mouth of a cartridge case and then fill the case with epoxy. The masking tape makes the process neater and allows the epoxy to extend beyond the mouth of the case a little bit, 1/16th of an inch or so. After curing the epoxy is trimmed to length.
A third way is to cut a wood dowel to length and put it in the case. If the dowel is too loose, melt some bullet lube in the case to hold the dowel.
Here are three plugged cases. Left is a case with a piece of twig in it, cut to fit. Center is a case filled with lead and filed to length. Right is a case filled with epoxy and filed to length.
Here are the cases from the side, showing the different lengths.
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Need a beginner's guide to breech seating a 32/40 (Read 3626 times)
