Checking my (limited) understanding of bullet seating depth


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ric426
March 16, 2010, 10:37 AM
From what I've learned so far, I get the impression that , in loose terms and within a reasonable range, seating a bullet less deep is roughly analogous to using less powder in terms of net effect on velocity, recoil, etc. However, as with most things I'm learning about reloading, I'll bet there's a lot more to it, right? What are you fine tuning by varying bullet depth vs. powder charge?
This is for revolver use with wadcutters, so placing the bullet closer to the rifling doesn't seem to enter into the equation. However, if it helps with chambering with a speedloader, I wouldn't mind a little bullet protrusion.

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Walkalong
March 16, 2010, 10:46 AM
Assuming pistol since you mention revolvers.

Yes. A longer O.A.L. will decrease pressure while a shorter one will increase it.

For auto's and general shooting I generally want an O.A.L. that feeds great, and work up a charge from there.

With a target gun folks will generally find an O.A.L. that shoots the best, and go from there.

With a revolver you can load any O.A.L. that fits the cylinder. Finding one that shoots the best is a good idea, although sometimes they don't seem to care what O.A.L. you use. Work up the load from there.

rcmodel
March 16, 2010, 12:26 PM
so placing the bullet closer to the rifling doesn't seem to enter into the equation.Actually, it does.
I like to seat wadcutters out about 1/8" for revolver use.

That puts the front driving band in the .38 Spec chamber throat, and in theory at least, aligns it in the chamber better then when it is seated flush with the case mouth and rattling around loose.

When I shot with 5th. Army AMU about a thousand years ago, we had long seated factory WC for use in S&W K-38's, and short seated WC for use in S&W Model 52 auto's.

Testing K-38's in a Ransom Rest did show a slight improvement in 50 yard accuracy with the longer seating.

BTW: This is the same premise Elmer Keith followed when he designed all of his famous SWC revolver bullets. The front driving band is seated out of the case to enter the chamber throat and provide better alignment in the chamber on all of his designs that have proven so successful for about 80 years.

rc

918v
March 16, 2010, 12:40 PM
As has been explained earlier, seating the wadcutter out farther increases case capacity and decreases pressure, so you'll need to up the charge a bit to make up for the loss. The only issue in seating a wadcutter past the case mouth is bullet retention. Depending on which theory of wadcutter case tension you subscribe to (some people don't size the case and seat them with finger pressure, then taper crimp), seating the bullet past the case mouth may cause it to jump crimp under recoil and spoil your accuracy.

Walkalong
March 16, 2010, 01:02 PM
Actually, it does.
I like to seat wadcutters out about 1/8" for revolver use.

That puts the front driving band in the .38 Spec chamber throat, and in theory at least, aligns it in the chamber better then when it is seated flush with the case mouth and rattling around loose.


Something like this? It's lightly roll crimped into the cannelure. I don't know the brand. Bought em years ago. They shoot real well though.

http://www.thehighroad.org/attachment.php?attachmentid=115893&stc=1&d=1266450585

ric426
March 16, 2010, 01:03 PM
With a revolver you can load any O.A.L. that fits the cylinder. Finding one that shoots the best is a good idea, although sometimes they don't seem to care what O.A.L. you use. Work up the load from there.


So keep the charge constant while I experiment with O.A.L. even though the velocity will change with O.A.L.?

I guess it would get pretty complicated to try and keep velocity constant by adjusting charge while changing O.A.L. Too many variables at once. I can see that it takes a long time to come up with a single ideal load for a particular gun, especially for a rookie like me.

So to verify my approach for finding the ideal load for a given gun, if I choose bullet type & brand, primer, case and powder as defined starting points, the main variables that come to mind are:
Seating depth
Crimp
Powder charge

I get the impression that with light .38 loads and wadcutters the crimp should be just enough to remove the flare from expansion, so that leaves seating depth and powder charge to test in that order.

(Edit: I was righting this as the other replies went up. Sounds like the crimp may be more of a factor than I stated.)

Then, if any of the main starting points like bullet or powder change, I start the process over again. I can see why people try to stick with one brand of primer, case, etc. whenever possible.

Am I finally on the right track? Sorry, for all the questions and verifications, but I want to make sure I'm going about this safely and efficiently. I've got a lot of testing to do, but I can see that that is part of what makes this fun for some of us and drudgery for others.

rcmodel
March 16, 2010, 01:14 PM
You may be over-thinking this.
What are you reloading for?

There are so many tried and true revolver loads in use for almost a century, there is very little need to "work up" a load again for any of them.

For .38 Spl., a 148 HBWC and 2.7 grains Bullseye will shoot as good as anyone can stand on their hind legs and shoot it.
If it doesn't, there is something wrong with your gun.

Name another caliber, and there is probably already a "standard" load for it to.

Working up loads is SOP and necessary for very accurate rifles.
But you can pretty much pick any of the old time "standard" loads for handguns, and go for it.

rc

918v
March 16, 2010, 01:15 PM
Are you shooting solid wadcutters with a crimp groove or hollow base wadcutters?

rcmodel
March 16, 2010, 01:25 PM
Either one.

For instance:
Missouri Bullet 148 DEWC like most all of them, has crimp grooves on both ends.
http://www.missouribullet.com/cw3/assets/product_full/ppc1.jpg

I'm fooling with Berry plated HBWC recently.

rc

ric426
March 16, 2010, 01:32 PM
You may be over-thinking this.
What are you reloading for?

There are so many tried and true revolver loads in use for almost a century, there is very little need to "work up" a load again for any of them.

For .38 Spl., a 148 HBWC and 2.7 grains Bullseye will shoot as good as anyone can stand on their hind legs and shoot it.
If it doesn't, there is something wrong with your gun.

I'm sure I *am* over-thinking this, but I'm learning a lot in the process. Plus, I enjoy the experimentation. I could just go with the standard load, but I like to understand why it works and what the variables do. Until I started reading threads and asking questions here I wasn't even aware of things like the effect of powder position or seating depth. If I listened to some reloaders at the league I'm joining I'd be experimenting with 1.8 gr. of Bullseye behind a 148 gr. HBWC and *really* getting into trouble!

Here are the two bullets I'm working with:
Speer 148gr. HBWC and Berry's 148gr. plated HBWC
http://home.comcast.net/~ric227/Speer148HBWC.jpghttp://home.comcast.net/~ric227/Berrys148HBWC.jpg

Neither has a defined cannelure. If I'm not seating them flush and crimping over the end, can I treat the upper band on the Speer as a cannelure? Just crimp the plated bullet lightly into the side wherever I end up seating it?

Walkalong
March 16, 2010, 01:32 PM
I'm fooling with Berry plated HBWC recently.
I just ordered some of them. I have had good success with their solid WC, and wanted to see if the HBWC shot any better.

Just crimp the plated bullet lightly into the side wherever I end up seating it?
Yes. I use a taper crimp on plated bullets.

ric426
March 16, 2010, 01:56 PM
Yes. I use a taper crimp on plated bullets.

Will a Lee seating/crimping die do a good enough crimp or do you recommend something better? I'd like to be able to seat and crimp in the same operation if possible.

rcmodel
March 16, 2010, 02:01 PM
Any seating die will do the job perfectly.
You just have to adjust it to where it does it they way you want it.

Your revolver seating die is a roll-crimp, so case length will be more critical then with a taper crimp die, but it will still work.

rc

918v
March 16, 2010, 02:22 PM
Neither has a defined cannelure. If I'm not seating them flush and crimping over the end, can I treat the upper band on the Speer as a cannelure? Just crimp the plated bullet lightly into the side wherever I end up seating it?
No. That is not a cannelure, but you can tapercrimp in that area. Just don't try to rollcrimp against it. If you size the brass, you can seat them to whatever OAL you want and tapercrimp. If you don't size the brass, then you are pretty much limited to flush seating.

Walkalong
March 16, 2010, 02:40 PM
I prefer to taper crimp for plated bullets because it is easier to set up and much less dependent on consistent case length, making it easier not to damage the plating, although I do trim revolver brass.

Any brand taper crimp die will do.

Lee (http://www.midwayusa.com/viewProduct/?productNumber=469800), RCBS (http://www.midwayusa.com/viewProduct/?productNumber=471839), Redding (http://www.midwayusa.com/viewProduct/?productNumber=719395), Lyman (http://www.midwayusa.com/viewProduct/?productNumber=802434)

It doesn't matter which.

ric426
March 17, 2010, 10:31 AM
Well, I tried loading up a few Speer HBWC crimped at the top of the first band. I think the OAL came to 1.275". Also bumped up the powder charge by .3 grains to compensate for the extra space. After I'd done about 10 it dawned on me that I'd better make sure they chamber ok in my Model 14 PPC gun. Sure enough, it turned out that they didn't drop down reliably enough for speedy reloading, so I wound up shortening the seating to 1.260". Now they drop in fine and still come right up to the chamber neck. I won't have a chance for any bench testing until next week, but I'll shoot a couple of PPC lines tonight to compare them with the regular flush seated loads I've been using. Even if they don't shoot any different, maybe they'll load a little quicker. I need to get the cylinder chamfered...

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