"Wasp Waist" bulge in cases

B

Ben_Snow

New member
Having some problems with what others on the forum have referred to as a "wasp waist" bulge after seating bullets .

The bulge is just barely noticeable and appears at the lowest end of the bullet inside the case, its usually more apparent on one side and appears PRIOR to crimping. While I'm stil a newbie, have loaded several thousand rounds of .357M on the same gear setup without a problem.

Lately I switched to loading 38SP using new Mag brass and with Hornaday "Cowboy Lead" .38 HBWC (148gr). The bullets drop into the the case flare nicely and the seating process is smooth with no problems. Last week I switched to Acme Coated BNWC-NRG (.38 148gr) and the bulging problem started, tried flaring the case mouth more, but it doesnt seem to help. I am seating the BNWC to the same depth as the HBWC's except for allowing the 'button' to protrude from the case. I also tried weighing the BNWC's, and there was deviation of as much as 3gr (148 -151gr); the Hornadays were almost all spot on within +/- .2gr.

I decided to shoot a batch of each (Hornady & Acme) from a rest (GP100 4") to see if the 'bulge' and/or the coated bullets affected accuracy. At 10yds with six rounds was able to punch a .75" grouping with the HBWC, immediately switched to the BNWC's and the next six rounds opened up to a 3" grouping with roughly the same circular pattern as the Hornady.


So cometh my questions:

1. Why are the coated bullet seating process so difficult? and why is the case bulging? Could the WC button cause the bullet to wobble during seating?

2. Could the wasp waist bulge or the improper seating cause the breakdown in accuracy? of perhaps the BNWC or the coating is an issue?

---Has anyone handloaded the Acme Coated BNWC and experienced any problems with seating and/or accuracy?
 
The only time I've ever seen that is when I've taken say a 308 case down to 243 of 270 case down to 25-06. I don't know any other way for that to happen.

Thing that really got me was the term "Wasp Waist". A lot of years ago, Herter made what they called a Wasp Waist Sonic bullet. I never tried them but a friend of mine swore by them. Also tried to tell me they were his idea and Herter stole it. They were a strange looking bullet. The shank was thinner at it's middle than either end, greatly reduced how much of the shank touched the rifling. Never seen anyone make one again. I've still got some old Herter bullet's and a few case's. Those bullet's worked, sort of but unless they were match bullet's they were a stranger to 1" group's for me back them. I did some loading for a guy some years back in a 22-250. Had a few of their 22 cal match bullet's and tried them, they surprised me! They actually shot very well! Wasp waist! Thanks for mentioning that!
 
The case is not properly expanded for your coated bullets. The bullet is expanding the top of the case as you are seating. Short of getting a new expander plug for your flaring die there really isn't much you can do about it.
 
If it's on one side, the bullets are not entering the case straight. Having a poor match between the seating ram shape and the bullet nose shape makes it worse. A ram for a round nose bullet can exaggerate tilt. The simplest cure is to use a Lyman M die type expander. The Lyman Multi-expander die is also available that is a powder-through die with adapters for most common handgun cartridge chamberings. Both make the flare form you see on the right. It allows you to set the bullet into the step it forms below the flare, so it is straight up when it meets the seating ram. This causes it to tend to seat straighter than it can if it starts out at all crooked. The less slippery a bullet is, the more easily this happens. Bullets seated straighter are more accurate than the same bullet seated crooked, but whether or not you can tell easily depends on the group size you start from.

Case%20Flare%20Style%20showing%20tilt_zpspxacapfz.gif


As long as the brass is sized smaller than the bullet diameter, which is normal for case grip on the bullet, you should see the bullet base position mirrored in the brass to some degree with a straight wall case. A soft swaged hollow base wadcutter deforms easily, so the case may bend the bottom in so that you have to sight down the side of the case to see it. With a harder bullet, it will show more, but should be reasonably even all around. You can find this in commercial loads as well. It's not a functional problem.
 
The wasp waist exists because the case is being sized down too much or the bullets are too large.

Using a sizing of larger diameter might help or trying out the Lyman M die would also help to expand the case back before seating the bullet. My Lee die set the brass to .372 while a used RCBS die I bought off Ebay resizes to .375 and the RCBS expander has a deeper expander than the new Lee one I had. The Lyman M die is a good work around also. The Lee dies created wasp waisted rounds while the RCBS dies don't. I'm sure the Lee dies work fine for 125-158 grain jacketed bullets, but a lot of what I load is cast bullets sized to .358 and sometimes larger than 158 grains.

Can you pull the BNWC back out to see if the diameter is changing when your seating them that deep? The HBWC is probably being deformed by the internal taper of the case but the hollow base has the ability to expand back out.

I wouldn't worry much about the variation of the bullets weights but I would check to see if the diameters of the BNWC are all the same and verify they are around .358/.359.
 
Having some problems with what others on the forum have referred to as a "wasp waist" bulge after seating bullets.
Click to expand...

The old wasp waist case? I have had something like that; I have always called it a case that that has taken on the appearance of a snake that has swallowed something larger in diameter than the snake. The case that looks like it swallowed a bullet only happens to pistol cases and has never bother feed and fire except on 2 builds. I have a 1911 I built that likes new ammo, meaning the pistol likes new factory over the counter ammo.

I have wasp waist bullets but that is for another day.

F. Guffey
 
The insides of the case is tapered towards the bottom and the deeper the bullet is seated, the more of a chance of bulging the case. I'd pull a bullet from one of the "wasp waisted" cartridges measure it and make sure it wasn't being swaged down by the case. If not, just shoot 'em...
 
Read Unclenick's post. (I know, you already did :p)

I've experienced this problem with 38 Special (148 DEWC's & 158 LSWC's - 358") to the point were the ammunition would not drop into the revolver's charge holes. That's when I bought my first Lee FCD and remedied the problem. The collar at the base of the FCD "irons out" the ridge at the base of the bullet and solves the chambering problem. Otherwise, the ammunition was excellent (consistency, accuracy, etc). As time went on, I realized that the wasp waist phenomenon (to the point of chambering problems) was occurring only with my old "WCC 83 & WCC 85 stamped brass (which I bought tons of as loaded ammo back in - you guessed it - 1983 & 1985). For some reason, this brass was the issue. I guess it was just "old" - whatever that means. They had been loaded countless times, and then the issue started occurring. I have since shelved the WCC headstamped brass.

Why are the coated bullet seating process so difficult?
Click to expand...

I don't know. I get coating shaving when I load my coated 148 DEWC (S&S hardcast). It's a darn mess when I'm loading them. And I flair to the point where the case mouth diameter is so large, it can be difficult to get 'em started in the seat die. I bought 1000 of them and regret it. Still have about 700. I'm gonna load 'em and put 'em in the ammo pipeline. I shoot a lot of 148 DEWC's; so I should be through them all by mid-summer. Good riddance.

and why is the case bulging?
Click to expand...

I'm still asking myself that; as far as the WCC's go.

Could the WC button cause the bullet to wobble during seating?
Click to expand...

Possibly. I've tried and don't like button-nose wadcutters. I don't even understand why they're made. To top it off, they don't cut very sharp holes in paper either. I'm a big fan of DEWC's. Missouri Bullet Company makes some beauties: http://missouribullet.com/details.php?prodId=118&category=5&secondary=9&keywords= I shoot more of this projectile than any other. They are perfectly flat on the top. So I took one of my countless surplus round-nose seating dies and filled it in with epoxy to make a nice, flat, seater plug for them (I made several, actually). Flat against flat - can't get a more square seat than that.


Could the wasp waist bulge or the improper seating cause the breakdown in accuracy?
Click to expand...

Not that I can tell. The talk of accuracy in 38 Special bores me, frankly. 90% of my shooting is at 10 yards. 99.9% falls between 5 and 15 yards. At those ranges, all my 38 Special ammo is tac-driver accurate - including wasp waist ammo.

or perhaps the BNWC or the coating is an issue?
Click to expand...

Well, they both have issues IMO; as aforementioned.
 
Pretty common question (pistol calibers) for those that use Dillon dies. Look up 'wasp waist' or 'coke bottle' and you'll see a lot of discussion.

At the end of the day, if they gauge OK, they'll shoot OK.
 
While I consider the "coke bottle" or "wasp waist" an asset in autopistol ammunition, you are obviously not getting the best out of .38 wadcutters.

The coated bullets are a lot harder than the HBWCs. Acme says "all bullets" are 92-6-2 alloy, labeled by Lawrence Lead Co. as "Magnum Alloy." They are hard enough and large enough at .358" to expand the case beyond what the expander die did. Also, hard bullets seldom do as well as soft in light loads. Also, you will not find target shooters using coated bullets in 50 yard slow fire, they are just not as accurate.


If you just must shoot those, you could get a larger expander plug, preferably of the Lyman M type*. It won't cure the wasp waist, but will ensure that it is formed evenly by a steel die instead of a lead bullet.

*Buffalo Arms will make you a M expander of any diameter you specify.
Standard sizes at
https://www.buffaloarms.com/reloading-supplies/custom-bullet-expander-balls/330-384
 
It won't cure the wasp waist,
Click to expand...

Again, I have 2 45 ACPs that like new over the counter factory ammo. Store bought ammo just flies through them, on the other hand it is not easy to look cool at the range when shooting reloads. SO! I measured factory over the counter new ammo and compared the measurements with my reloads. If my reload cases did not have the appearance of having swallowed a bullet my reloads flew through the two pistols.

(Another: So) I sized my reloades in a carbide full length 45 ACP die. I only sized enough of the case to remove the 'swallowed a bullet appearance'; when finished my reloades looked like factory over the counter new ammo and the sized cases flew through my 45s like new ammo. All of this was before the 'wasp waist'.

A friend suggested I did not know how to load for the 45 ACP so he offered to load a few thousand cases and meet me at the range. His ammo worked in every 45 ACP at the range but mine. I took his ammo home and returned after sizing and his ammo flew through my 45 ACPs.

Anyhow, if the case looks like it swallowed a bullet there is a very big chance it will not feed in my 45 ACPs.

F. Guffey
 
You said you were over flaring the case's to get a bullet started. You will greatly lower case life doing that. Case's will start splitting from the mouth down.
 
Wow, lots of good info...

First -- Thanks to all those that replied, appreciate your time and input. Thanks Unclenick for the graphic, as a visual person that really helped. Jim's mettalurgy on Acme also raised eyebrows.


Second --- A root cause analysis

Knowns:

1. The Acme Coated BNWC were considerably less accurate than the Hornaday Lead HBWC's with both using same powder load and brass source. Shot @ 10yds (indoor range) using a Caldwell Pistol Rest; .75" group for (6) HBWC, 3" group for (6) BNWC.

2. All controllable factors (within my ability) remained the same.

3. The leaded 6 rounds were shot first, then 6 BNWC's. Only six shots of each is a small amount of data, but the results were too glaring to ignore.

General Assumptions (on my part):

1. Acme Coated bullets causing problem (or)
2. Poor seating of bullet causing wasp waist resulting in poor accuracy (or)
3. Button Nose and/or coated bullets causing problem

Specific Forum Input Assumptions (on your part)

1. Button Nose are a poor design
2. Acme Coated Bullets are harder/Less accurate (92-6-2 alloy)

Solution(s)

1. Toss all the coated Acme BNWC in the trash (all 400 of them)
2. Purchase an "M" expander die to smooth out the wasp waist possibly resulting in greater accuracy.
3. Just Shoot 'em

Course of Action

--- Probably number #3 (thanks Mik). The accuracy is poor, but these will not be used for competition. Unless I can find another solution I dont have much of a choice. I could purchase the Lyman M expander, but if that doesnt fix the problem will have dug myself another $50 deeper into the problem. My intent of purchasing the BNWC was to reduce lead exposure, thats it. My GP100 loves WC's @148gr, so was hoping to move to a coated WC without a change in accuracy. Time to try another brand (and buy a smaller quantity).

Hmmmm, ACME.... That brand didn't work out to well for Wil-E-Coyote either ...Maybe I should have taken the hint from the Saturday morning cartoons.

acme.jpg
 
Last edited:
His ammo worked in every 45 ACP at the range but mine.
Click to expand...

Lot of that going around, Guff.
The high priced barrels/guns call it a "minimum match chamber" which means undersize because the diameter spec for .45 ACP NM is the same as for the service barrel.
I suspect the cheap guns/barrels sharpen their reamers too many times. Same result, undersize chambers.
 
Ben,

One other factor is the die makers fact resizing dies have to be made to size the thinnest brass spec enough to grip the bullet. Most brass isn't that thin, and is actually over-resized by a standard die. This exaggerates the bulge.

In pistol brass there is often a taper, but the carbide sizing dies size them straight, and that exaggerates the bulge in them, too.
 
UncleNick Wrote:
One other factor is the die makers fact resizing dies have to be made to size the thinnest brass spec enough to grip the bullet. Most brass isn't that thin, and is actually over-resized by a standard die. This exaggerates the bulge.

In pistol brass there is often a taper, but the carbide sizing dies size them straight, and that exaggerates the bulge in them, too.
Click to expand...


UncleNick --- But why do the Hornaday LHBWC fit like a glove during hand seating? The lead HBWC's fit down easily to approx. 30% inside the shell prior to crimp, and the crimp area over the entire interior surface (post-crimping) is smooth with no vestiges of anything. The same brass and die were used for both, yet the coated cause problems. Jim discussed the hardness of the bullet, that would make sense if the problem occured during the FCD crimp process, but the hard seating occurs prior to that step. Could a sloppy coating process (too thick) increase the diameter of the bullet and cause a problem?
 
The soft and hollow base of the Hornadys swage down in size easier than the cast plain based bullet. You can probably deform the hollow base with your fingers.
 
Agree, but why would the LHBWC press into the case (30% inside) with only slight finger pressure, yet the coated are a bear to get started using the same mouth flare? I tried flaring the mouth even more, it allows the coated bullet to enter slightly more (maybe 2%-3%), but then its stuck again. Its alomost like the coating is increasing the diameter of the base.

Some of those replying in this thread requested I pull one of the bullets and measure to see if swagging has occured, and I still owe them that measurement. I also need to measure the base of the leaded vs coated to determine any variance in base diameter prior to seating. Let me get back to everyone with those measurements. Thanks
 
Ben Snow said:
But why do the Hornaday LHBWC fit like a glove during hand seating? The lead HBWC's fit down easily to approx. 30% inside the shell prior to crimp, and the crimp area over the entire interior surface (post-crimping) is smooth with no vestiges of anything.
Click to expand...

It's going to be two things, I expect. One is the harder bullet doesn't squeeze to a smaller diameter like the hollow base can. The other is a guess (since I don't have any) that the lubricity of the coating against brass is lower than the lubricity of the wax and motor mica Hornady puts on their swaged bullets.

Have you ever seated a jacketed bullet in cases sized in the same die? How does the feel compare? I've run into soft plastics before that actually produced a lot of friction with brass, so I am curious about that.

The accuracy will be partly the centering issue. Being seated off axis may actually be deforming the base of the coated bullets a little, and it takes very little base distortion to get very poor precision (group size).

What does the weight distribution of the coated bullets look like?
 
You must log in or register to reply here.
Back
Top