VII. Reloading Information

B. Bullet & Shot Information

4. Some Bullet Seating Tips

by Norm Johnson (njohnson@nosc.mil)

A rec.guns poster wrote:

I've been meaning to ask... I've had a little trouble with loading short bullets in both .38 and .45 ACP. I can't seem to get them seat perfectly straight. In both cases I'm using a flat seater with a flat point bullet. I usually try to flare the case mouths as little as possible to extend their life, but I *think* that I flare them enough. In both cases the expander plug is somewhat tight, .4493 and .3547, which also seems to be giving me a *very* hard time in seating soft point bullets in he .357. Have any suggestions?
Get a Lyman "M" die to solve the seating problem. I gave up on belling cases years ago because of the same difficulty. I use "M" dies in all calibers (rifle included) and have not ever been dissatisfied with them. A few years ago I purchased a couple dozen "M" die expander plugs from Lyman to use when I need an over-size or special diameter plag. These I have a machinist friend turn down for special experiments.

They do, however, come in a great varity of sizes from Lyman if you do not have access to a lathe or machinist's services.

How much expansion or bell does the M plug put on the case mouth?

The following should let you determine the steps for associated calibers:

M" Die dimensions from Lyman 


             Diameters +.0000          
                       -.0005          

             First  Second             
Rifle Plugs  Step   Step    Bullet sizes
                                     
     22R     .222 / .225    .222-.226  
     24R     .242 / .246    .243-.244  
     25R     .255 / .259    .256-.257  
     26R     .262 / .266    .263-.265  
     27R     .276 / .280    .277-.279  
     28R     .282 / .286    .283-.285  
     30R     .307 / .311    .308-.310 
     31R     .310 / .314    .311-.313 
     31AR    .318 / .322    .319-.321
     32R     .320 / .324    .321-.323  
     33R     .337 / .341    .338-.340  
     35R     .357 / .361    .358-.360  
     37R     .374 / .378    .375-.377  
     45R     .455 / .459    .456-.458  
                                     
Pistol Plugs                         
                                     
     25AP    .249 / .253    .251       
     30P     .307 / .311    .308-.310  
     32AP    .310 / .314    .311-.313  
     32P     .313 / .317    .314-.316  
     38AP    .353 / .357    .354-.356  
     38P     .356 / .360    .357-.359  
     10mm    .398 / .402    .399-.401  
     41MP    .408 / .412    .409-.411  
     44MP    .427 / .431    .428-.430  
     45AP    .450 / .454    .451-.453  
     45P     .453 / .457    .454-.456
The main shaft of the expander portion is the "First Step". It is typically a few thousanths smaller than bullet diameter, as are conventional expander buttons.

The "Second Step" puts a small step of increased radius in the case mouth about 1/16th inch deep (adjustable). This step is a couple thousanths over bullet diameter to aid effortless start- ing.

Ideally, the first step would be about .002" under bullet diameter while the second step will be 2, 3, or 4 thousandths over bullet diameter.

Usually the best cast bullet diameter is about .0005" less than the chamber's measured throat. Most of my .30 caliber rifles shoot .310" or .311" cast bullets best. For ease of seating these oversize bullets without distortion, I keep several plugs on hand and have a machinist friend turn them to my specs if I think it will help.

It is also highly desirable for the nose of the bullet to be of bore riding diameter. To check this for a given bullet, push the bullet nose first into the rifle's muzzle. If it goes in without resistance, the bullet nose is too small and good accuracy is not as likely.

Does the seating die crimp out the bell or do you just leave the cases expanded?
Your choice. For my lever actions I sometimes crimp. For bolt actions, I do not.

As for damaging hollow points or other softnose bullets during seating, I use seating stems that fit the bullet of concern. If you have no way to have these made up, I have two other suggestions.

  1. If your seater die is an RCBS, send the seater plug along with a sample bullet and they will provide you with one that fits the bullet. This is a free service that RCBS offers.
  2. Barring the above, a route that I have often taken is to use a semi-wadcutter seater plug, clean it up VERY WELL and turn it so the cup of the seater is facing up. Next apply some form of mould release (silicon spray or whatever) to the bullet. Pour some epoxy into the cup of the seater and fit the bullet so that it forms a proper shaped cavity in the seater cup -- viola, you have your own custom seater. I have done these a number of times over the years and each has loaded thousands of rounds. Removal of the epoxy can be accomplished with a quick pass of a propane torch. If the bullet is a hollow point, place a dab of epoxy into the hollow point cavity immediately before placing the bullet into the epoxy filled seater cup.
I pulled a bullet and reseated it just over 0.150" longer before I got any engraving marks. Yet with that Federal ammo, the rifle shoots .5 to .7 inch five-shot groups at 100 yards all day long. Never varies. How could this wuz??? I thought jumps like this were supposed to push a rifle into the 1 to 1 1/4 inch range at a minimum.
Not always. Nearly half my rifles shoot their best loads with cartridges that are loaded with the bullets at distances somewhat off the lands.

Years ago I believed what the gun writers said but circumstances opened my eyes. I was single loading for a Winchester 88, be- lieving that only on-the-lands cartridges would perform well. However, I wanted to use the gun for a hunt so backed off enough to be able to get the cartridges into the magazine. Lo and behold, it did somewhat better. I found the same to be true with other guns. For my single shots, I still start with the longer OAL approach because it seems to win out in some small majority of instances but for magazine rifles, I do not bother anymore. Each gun has its likes and dislikes. We can begin with the approach that works best most of the time but do not be surprised when someone finds that an anomoly to conventional wisdom works better, sometimes much better.