OAL tolerance for classic .38 wadcutter load


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ric426
May 25, 2010, 01:01 PM
I'm loading a bunch of the classic .38 special target load, 148gr dual bevel base wadcutter over 2.7 gr of Bullseye. After all my experimenting, it's still the best load in my S&W revolver. Imagine that. All those shooters over the past 50 or so years were right...
My question is, just how bad would the variation in OAL have to be before you'd notice a difference in performance for that kind of load? I'm seating the bullets with a light roll crimp in the crimp groove for an average OAL of 1.240" and generally don't see more than a +/-.005 range. I would think that, given my mediocre shooting skills, they will be fine in that range. I have a lot of other factors affecting my accuracy a lot more, but I'm curious about what OAL tolerances to strive for in my reloading.

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ReloaderFred
May 25, 2010, 01:14 PM
When I was shooting PPC matches back in the late 1970's and early 80's, I didn't worry as much about the OAL of my reloads as I did watching that front sight! I worked my way up to Grand Master before I stopped shooting the matches.

My guess is you'll be fine with what you're loading, though I used bevel based wadcutters for the 7 yard, 15 yard and 25 yard lines, and used only hollowbase wadcutters for the 50 yard line. My powder charge was what you're using now, and it's a proven load.

Just make sure you only put one charge in a case, since I was shooting next to a guy who double charged (or maybe triple charged) one and blew his Model 19 with Bomar rib to smithereens. The rib, when if finally hit the ground, looked like a horseshoe and the top three chambers of the cylinder were blown open in the classic revolver blow up. Just be aware of this possibility and enjoy shooting this most accurate load.

Hope this helps.

Fred

moxie
May 25, 2010, 01:28 PM
Typically, most don't use that "crimp groove" at all when loading wadcutters. Rather they push the bullet in a bit deeper until only about the thickness of a fingernail is peeking out of the case. OAL on mine works out to 1.172." Use either no crimp whatsoever, or only a very light taper crimp. Be sure you don't overexpand the case during the expansion step.

ric426
May 25, 2010, 01:57 PM
Just make sure you only put one charge in a case, since I was shooting next to a guy who double charged (or maybe triple charged) one and blew his Model 19 with Bomar rib to smithereens.

I've got a Powder Cop die set up with optical sensors that are sensitive enough to alert me of even a slight over charge as well as an undercharge, so the chances of a squib or blow up are greatly reduced. I don't take anything for granted though and still spot check with a scale.

Typically, most don't use that "crimp groove" at all when loading wadcutters. Rather they push the bullet in a bit deeper until only about the thickness of a fingernail is peeking out of the case.

I've been told both to seat almost flush and to use the crimp groove so I loaded batches of identical components at both seating depths. I found no difference in accuracy and the rounds with more of the bullet protruding were easier to load (at least until I can get the chambers chamfered) so I'll go with the crimp groove for now. If I'm loading HBWC I seat them almost flush, but so far the DEWC's have been cheaper and easier to get.

243winxb
May 25, 2010, 02:05 PM
what OAL tolerances to strive for in my reloading. .005 or less for a single stage press. For a progressive a maximum of .010" Since your roll crimping, case length is maybe more inportant, so you crimp is uniform. Here is what Lee has to say about COL in general. Seating depth variations

There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step and/or trim cases to a uniform length.

The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.
http://www.leeprecision.com/cgi/faq/index.cgi

243winxb
May 25, 2010, 02:07 PM
S&W M52 autos get seated flush. Revolvers in the crimp groove. Or what ever works for you.

Walkalong
May 25, 2010, 02:40 PM
For a progressive a maximum of .010"By tweaking seater plug or two, I have been able to keep all my O.A.L.s to .005 or under varience on my LNL. Some are almost dead on everytime, while some vary the whole .005. (Maybe .006 here or there ;))

ric426
May 25, 2010, 03:31 PM
I'm using the flat Hornady seating plug on flat nosed bullets, so that probably makes any bullet size variations almost negligible in my case. At least I don't have to deal with the bullet shape variable. I probably see more variation from lube and/or lead buildup on the plug than anything else and seating the bullets at the crimp groove significantly reduces any buildup in the die.

Iron Sight
May 26, 2010, 11:27 AM
38 specials. I am using Missouri bullet 148G DEWC roll crimped at the crimp groove. They shoot good. OAL ends up around 1.250.

Watch out for PMC 38 special brass & the MO bullet .358 DEWC. Upon bullet insertion the inside taper of the case will produce a fat ring in the brass that will not allow the loaded bullet to insert in my case gauge.

ric426
May 26, 2010, 02:03 PM
38 specials. I am using Missouri bullet 148G DEWC roll crimped at the crimp groove.

Exactly what I'm using too, though I'm crimping right at the top of the groove so my OAL comes out around 1.240" +/- .005". I'm using all Federal brass and haven't run into any problems

ReloaderFred
May 26, 2010, 02:30 PM
For years, Winchester made a special case for use with their excellent 148 grain Hollow Base Wadcutter bullets. It was thinner and made for the deep seating required with that bullet. The headstamp was WW and .38 Special, and there were two cannelures on the case walls. I still have about 1,000 once fired from when I was shooting PPC and I reserve those for loading HBWC bullets flush with the case mouth, just as Winchester and Remington did with theirs.

Some of the thicker brass won't allow full seating of such a long bullet without bulging, but as you've found out, most Federal .38 Special brass will allow it, even though you're loading the solid wadcutter and not the HBWC, which of course is even longer.

Hope this helps.

Fred

Sunray
May 26, 2010, 09:57 PM
Lose the crimp. .38 target loads don't need it and tend to shoot better without it. You can ignore any crimp groove altogether. Seat flush with the case mouth. OAL for WC's isn't an issue.

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