New Style Seating Ram

[quicksylver]

Ok guys, here it is.

Last nite I was loading some 30-06.

I used two different bullets but did not bother to change the seating ram in my Lyman seater.

Then I got to thinking, with all the talk about seating depth etc, wonder if a seating ram could be made to duplicate the lead in my rifle.

That way I would ( theoretically) only have to set the die once as every bullet type would be seated to either touch the rifling or be slightly off depending on how I set the die.

Maybe that is what happens now!

What say ye of greater minds and Millers of Metal ?

 

[Brad]

You would need a hunk of the barrel with a chamber cut with the same reamer.
As the throats wears the seating stem would be of limited use as it won't be worn the same.

Easier system is to use the Stoney Point tool with the bullets being used to set jam OAL. Then adjust dies accordingly. This tool also gives an indication of throat wear as the throat moves forward.

 

[quicksylver]

Brad...thanks for the reply.

I agree with what you said, but what I was trying to figure out was a tool that would allow you to seat a bullet to the correct OAL length regardless of the nose profile without adjustment after you have determined what the OAL should be.

So I guess the process would go something like this;
1. Determine required OAL for one bullet style
2. Adjust seating tool for that bullet.
3. Seat any other bullet for that firearm without further adjustment.

It seems to me that requardless of the nose profile or diameter it is going to contact the rifling at some point, where ever that is would determine that particular bullets OAL.

SOOOO..even if the diameter inside the seating stem was smaller than the lead it could be adjusted for the proper OAL.

I just don't understand why I keep adjusting mine for the different bullets I use.

 

[Brad]

Not sure I follow.
Bullets with vastly different nose shapes will contact the rifling at different points. Each bullet needs to be seated to an OAL based on that bullets nose profile.
Good example. I was learning to shoot HP with my AR. I was using a 69 Sierra loaded for magazine use. Worked well. I had a bunch of 52 HPBT from Hornady I wanted to use up. Fed from the magazine fine but wouldn't chamber. What the hell? Nose profile was such that the ogive contacted the lands before the round was fully chambered. Seated them deeper and they worked well. Those bullets already had a far shorter OAL than the 69 Sierra loaded rounds.

I don't see a way to use a single seating depth for various bullets.

Am I missing something?

 

[quicksylver]

Brad....thank you for taking your time with this.

I ran into the same situation 20 yrs ago when I switched from the 03 to ar in the HP shoots.

I skipped the m1 and m1a.

Actually I think we are saying the same thing.
I am just not as good as you are in explaining myself.

As you say there are numerous bullet styles and their noses vary.

But at some point each will engage the rifling, obviously that results in various OALs.

Now if we had a seating stem that mimicked The lead area where the bullet contacts the rifling we could throw any bullet in there and it would be seated at the correct OAL for that bullet.

Another way of looking at it would be to take a washer with let's say a .30 center and drop various 30 cal bullets through the center.
Each would go through to various degrees
But unless I am way off each would stop where the nose dia. Matched the hole in the washer.

So put that washer inside the seating stem ,adjust seating die for a known bullets OAL and would you not be ready to go for all other bullets (provided they fit the mag)?

 

[Brad]

Ok, so you want a seating stem that is easily adjusted for a single rifle. Know the shape of the throat and leade and mimic it in the seater. Eliminate the trial and error method.

 

[quicksylver]

Exactly. ..

One other question ,if you loaded various style bullets for the ar should you not be able to take a washer with let's say a .221 hole, drop it over the bullets and have it end up the same distance from the case neck each time?

 

[Brad]

No. Each bullet has a different nose shape.
Look at a secant vs tangent ogive. One is "fatter" than the other. In a 224 diameter bullet the point at which the nose hits .221 is quite difference in the two ogive shapes.
Even in cast a different exists. I can use an SWC in my Marlin or a RD style bullet. The RD hits the lands with the nose before engraving the full diameter body. The SWC doesn't engrave at all, or very little, until the full body portion hits the rifling.

 

[fiver]

he want's a seater that seats on the ogive not the tip.

for cast 30 cal's he would have one made to seat off a point on the nose that was .300 or .301.
that would set his nose the same depth away from the rifling and every round would chamber with the same amount of jump to touching the lands.
[except for the full body diameter due to design differences]

now if you had a die cut to mimic the throat in the rifle [new] and a mold made from that throats drawing.
you could set the die up to seat with and adjust it downwards by the amount of jump you decided was best.
it would in effect become a one trick pony [but probably dang accurate and at good speed too]

his question is super valid and I use a cheap=O hornady comparator to do just that.
if I find that my 120gr h-point zippers shoot best .0015 off the lands and have a base of case to ogive measurement of 2.222 and I buy some 84gr varmint blasters I can set the ogive distance again to the 2.222 measurement and have a pretty good shooting load right out of the gate.
this lets me actually use the powder and primer combination to tune the second load.

 

[Brad]

I understand the ogive searing but can we assume the ogive of various bullets will all touch the leade at the same point? Pretty close most likely but is close good enough?
Think on it. Do all 30 cal bullets measure .305 at the same point from the front full diameter band? What about .306 or .307?

 

[fiver]

well I think close is good enough.
once you establish whether a rifle likes a long or short jump it seems to do fine with the long or short jump another .002-3ish one side or the other isn't that big of a deal.
it's somewhat like finding that window in a ladder test, once you have that half grain window where the holes overlap
as long as your keeping the powder in that window a little variation doesn't affect where the bullets land all that much.

 

[Brad]

Ok, close enough.
I dont think trying to get .005 off with that method would work well. Neither would touching. Well, not without verification and measuring with the specific bullet in question.
The absolute worse case scenario is having some just touching and some .002-003 off. Never gonna have consistency that way. Lesson I had to learn the hard way.

 

[fiver]

if your going with just touching then yes this probably wouldn't work well. [except for the one bullet style]
if you are going for that, a technique I use often is to control the neck tension close to .001 and seat about .005+ long.
let the chambering of the round do the final seating of the boolit for you.
this doesn't work in a semi-auto BTW.

 

[Brad]

I often do the same. Works well with a bolt gun. Bad idea in a Ruger #1 too. Or a Marlin lever action. Or a Contender.
Ruger #1 is worst as there is no way to shove the round forward with enough pressure to move the bullet back a little. Guess how I know that?

 

[fiver]

same way I found out my Dodge's antenna is perfect for poking rounds back out of the 300 BO upper in an AR rifle I'm guessing.
or that if you cut the ball off the top it'll fit down a 22 cal barrel.

 

[KHornet]

I learned long ago to always have a rod at the range. And if I forget to take a one piece with me, I always have a back up in my accessories box in the form of a GI screw together rod (with and extra section for my long milsurp bls.