Handgun bullet seating depths

cdoc42 said:
I've already fired mine and the accuracy at 7 yards off hand is acceptable. I dismantled both guns and removed the barrels. A loaded cartridge with a COL of 0.950" plunked into the barrel and compared to just a bullet plunked resulted in a calculation that the bullet was 0.04" from the leade.

Repeating the procedure with my neighbor's Sig showed the same COL placed the bullet right at the leade. This suggests to me that we can expect battery failures to occur if the bullet is seated longer than 0.950".

At 0.950" the case mouth is at the very end of the top of the lube groove, so any further seating would appear to have the bullet seated too deeply, but that's what we'll have to do if he does not obtain the same level of accuracy as I did if we want to duplicate the 0.04" jump that I have. The other concern is deeper seating and reduced powder space but I'm not concerned that 0.04" will produce a significant problem. The other option, of course, is to opine his gun simply does not "like" this bullet from an accuracy standpoint and search for an alternative.
Click to expand...
So your question is about determining the optimum COAL, not about seating depth. Although, as you mention in this post, reducing the COAL also reduces the remaining case volume -- because it increases the seating depth.

That said, your concern about the lube groove is a non-sequitur. You are loading a revolver bullet for use in a semi-auto, and you are loading a coated bullet so (presumably) there is no lube. Even if the groove is lubed ... it's a lube groove, not a crimping groove, and the lube groove in a revolver bullet is intended to be completely within the case, not stop with the edge of the groove aligned with the case mouth.

If you need these loads to work in both guns, you can certainly load that bullet a few thousandths deeper. If you're at the maximum load already, back off the charge a couple of tenths, otherwise I wouldn't worry about it.
 
Thanks to the three experts for this marvelous discussion; it clearly points to the advantage of being a participant in the Firing Line. I've been reloading for rifles and revolvers for over 40 years and only in the last 4 years or so have I gotten into pistols. But for whatever reason, within the last week I happened upon this road to investigating seating bullets in the pistol as I do in the rifle. That's what sparked this conversation and I've now learned that getting that detailed in seating pistol bullets was more intellectual curiosity than useful procedure. The newbies here hopefully will get a take-away that there is always room for new knowledge.
 
That level of detail would likely be of interest to a bullseye competitor. I have a friend who is one of that breed. He weighs all his bullets and sorts them by weight, he separates brass by headstamp, then measures the wall thickness of the case with a tubing micrometer, and he does a number of other things that have no significance for most handgun shooters. That degree of fussiness could well make the difference between a score of 100 - 3X and a score of 100 - 8X, but for plinking or IDPA that level of detail isn't worth the time and effort.

Much depends on how you will use the ammo you load.
 
I be loading some .380 auto coated cast bullets tonight for both guns, using the info here, especially that re: best accuracy with flush headspace.

When I started in 1976 I read a book by John Wooters in two nights, which is where I learned the technique for determining the relationship between the rifle bullet and the lede. I dug it out of my library to review what he said about "ogive:"

"Benchrest shooters mostly prefer fairly firm contact between the bullet's ogive and the rifling,......."

and

"....but it isn't the tip of the bullet which contacts the rifling......it's some point on the ogive, well back from the tip and just in front of the full diameter section of the projectile."

44AMP, that was 44 years ago and your discussion above mirrors it. So - what would you like to call that point to settle the quandary for the next 44 years?
 
"....but it isn't the tip of the bullet which contacts the rifling......it's some point on the ogive, well back from the tip and just in front of the full diameter section of the projectile."

44AMP, that was 44 years ago and your discussion above mirrors it. So - what would you like to call that point to settle the quandary for the next 44 years?
Click to expand...
How about "the point on the ogive where it contacts the rifling"?
 
Last edited:
and in the past 44 years no one has come up with a unique term for that point on the ogive, which probably says something about how important it is...

I suppose Rifling Contact Point would do as a general term.

The thing about loading for handguns vs rifles is that while some things apply straight across the board, other things don't. Also even in rifles some things that are useful in some rifles for some purposes simply aren't for others.

As a friend of mine frequently says, when the subject of seating bullets 0.0xx" off the lands comes up, ..

"how does this help me shooting a .300 Savage Model 99 put down an elk??

The point is, while seating a certain distance off the lands may result in the most accurate load, it isn't a practical or sometimes even a possible thing in some guns, IF you plan to use them as repeaters.

Additionally, his rifle is already more than minute of elk accurate with both factory and regular handloads, so why bother??

When you shift over to handguns things get more complicated in some ways and simpler in others.

There are 3 types of handguns, revolvers, semi autos, and "others". There are physical limits as to how close to the lands you can get in a revolver. The closest you can possibly get is the bullet tip even with the front face of the cylinder (and be sure it won't move forward!!)

Semi autos are a mixed bag, running from pocket guns up through duty/service class guns, and all the way to magnums. Since the chamber and barrel are one, in theory you could "chase the lands' the way a target shooter can.

However, there are several factors that can get in the way. AND there are many factors that work against rifle level accuracy, no matter where the bullet is seated relative to the rifling.

The last class of handguns I called "other" and there are some of those that are essentially short barrel stockless rifles, single shots of bolt action or break action design where you can load bullets to 0.xxx off the lands if you wish.

An XP 100 or a T/C Contender are a couple examples of that.

But now, turn and take a look at semiautos again. From a pocket .380 to a GLock to a Desert Eagle, you find a huge amount of variations. many of them limiting the ability to load bullet long enough to reach the lands.

AND there is also the opposite where guns have "short" throats and some bullets cannot be loaded to max length and must be shorter to keep them out of the lands.

Its very much a gun & bullet specific thing.
 
This is a question for Uncle Nick concerning a comment you made in post #20 about replacing the Hornady bullet comparator with the Sinclair. Does this mean the Sinclair unit will fit in the Hornady body?
 
I'm not Unclenick, nor do I play him on TV ;), but yes the Sinclair comparator inserts do fit the Hornady body. And vice versa.
 
You must log in or register to reply here.
Back
Top