I thought I saw on another forum I cant remember where, where a guy was indicating that soft seating your bullets increase throat erosion due to friction?? Does anyone have any evidence of this or seen anything personally in regards to this. I know soft seating increases pressure but if one was to reduce the load to allow for the increase in pressure how would this cause more throat erosion?? The only thing I can think of is the bullet is not getting a running start and this may somehow increase throat erosion but cant find anything anywhere to confirm this??
Does soft-seating increase throat erosion??
- Thread starter pitdog85
- Start date
I think its using very little neck tension, basically just enough for the bullet to not fall out (<.001) and then leaving them seated long so that the bullets will meet the lands and then be able to push back in on chambering with virtually no effort. That way you let the bullet dictate its natural seating depth into the lands which should provide consistency vs cramming it in there under lots of tension and which varies between shot to shot and would be a little bit different each time depending on each particular bullet. I can see both sides of the argument and I can see how both have their merits but who the hell knows which is really any better. If it works for you go for it.
With that being said it isnt a good practice for a field rifle where you might need to eject an unfired round without dumping powder in your gun.
I dont see it causing any more erosion than any other method provided pressures are equivalent as the OP said.
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Thanks for the refresher spife, I have heard of the technique, lol, I'm out, can't see myself ever trying it.
I could, because putting the bullet into the land causes a pressure spike. So, even if you "back it off" to slow it down. You are not running the same kind of pressure curve as a load of the same velocity with a proper jump.
Yup spife7980 is spot on with his description of soft seating and it is only for target situations not field like he says. It seems there is very little conclusive evidence as to whether it does cause more throat erosion or not I guess its one of those many things we don't really know how to measure properly. As corndogs suggests my gut feeling is the same I saw a graph somewhere where someone posted a pressure spike curve with same loads from same rilfe one seated into lands and one off, the one into the lands spiked sooner and the overall pressure was slightly higher than the load off the lands which spiked later. Anyway who really knows
That's the thing. You're saying same velocity which isn't the same thing as pressure. 60k psi just in the chamber is 60k psi just like 60k in the chamber and 6" of bore is. Sure the total volume in the second scenario would produce higher velocities in the real world but I suppose that would also be dependent on powder choice. I can see how one could argue that 60k just in the chamber with seating into the lands would be preferable in a throats erosion scenario to a longer jump and letting the bore get the 60k psi exposure too. I'm arguing each side in my head but I keep coming back to it being a wash and as pitdog said "who really knows?" There are so many variables one could shift the numbers just a little and easily get a result worlds apart from another. If it's a fast powder to get the pressure in the chamber only velocities suffer because that would mean it's rate of acceleration would lessen throughout its entire length of travel. If it's a slow powder that means that the bullet is already a good ways down the barrel and it's rate of acceleration wouldn't peak immediately and I see that leading to higher velocities but also fire cracking the throat. That's one argument people have for steeper case shoulders, keeps combustion contained in the chamber and helps not burn out the barrel. But none of that is the subject at hand. Throat erosion from 60k psi with the bullet already into the lands or 60k psi with it already past the beginning of the lands. Without regard to what would produce favorable results in the external ballistics. Or really 1" down the barrel if we get to the crux of the question. Who really know would be someone much more knowledgeable than I. Just FYI, personally in my practice I try to be off the lands as I find it produces lower pressures and higher velocities just like y'all point out so don't think I'm trying to bogart this or be oppositional or anything. Im just curious to know the science because much like statistics: I can get whatever answer I want depending on how I approach the problem in my head.
According to various handloading books I've read, you should go down at least a full grain from an optimized load if you decide to soft seat or seat right at the lands. Think of it this way - if you are 10 thou or 20 thou off, the initial detonation just has to free the bullet from neck tension, then part of the gasses vent into the unoccupied chamber volume and some gas gets past the bullet. Seated soft or into the lands, the bullet doesn't really move at the first pressure pulse and extra pressure has to form to get it over the friction of the lands.
