Reloading For The Thompson

[Grey Crow]

Being that the case of the .45 rests on its edge in the chamber, length is important.

The loading manuals call for a min length of .898" and a max length of .898" Tight tolerances!

Using once fired factory brass, I'm coming up with measurements all over the place. All being under the suggested length.

I'm getting a range from .852" up to .895" after resizing. At this point I do not plan on trimming any of the cases seeing that they are all under sized.

 

Too short of a case could cause a misfire, due to a light or no primer strike, too long and the bolt may not close quite far enough.

 

Then there is the OAL to deal with. I guess I'll seat the bullets to the cannelure irregardless of case length. With shorter cases there may be a slightly higher pressure.

 

Any suggestions, tips?

[PK.]

SAAMI specs for 45acp:

 

Case= .898 - .010

LOA= 1.200 to 1.275

 

[Z3BigDaddy]

"I virtually never have to throw away a case with a split neck. I have cases I first reloaded in the '60s. That seems strange to me also, but that's how it is."

That is the nature of straight wall cases... Sizing doesn't involve much reshaping of the case if any and the crimp is pretty much a little squeeze....

[Grey Crow]

PhilOhio,

 

Yes, I was referring to the cannelure on the bullet. I haven't loaded for over 15 years, and probably 25 for straight wall cases. LOL, I've owned .45 dies for about 7 years and just this Sunday 9/18/05 started setting them up.

 

In my reloading books there is no listing for OAL, thanks PK!

 

I have .357 and .38 casings that have been reloaded many times without any signs of fatigue. Although its a different story with those casings, as a roll crimp is used and placed on the cannelure for a more secure grip.

 

I haven't had the opportunity to observe any fatigue in the straight wall cases due to parting with my Colt Commander 9 mm, many years ago.

 

I'm not one to pick up brass of unknown origin and history. I guess I follow the manuals perhaps a little close. But then of course they want you to buy more casings.

 

Most likely I'll get 1k of hard cast bullets, and a few hundred of plated to use as chasers to scrub the lead out if any. From the 1911 boards its thought that plated bullets are not as accurate as FMJ or cast. The Jury is still out on that one, at least in this household.

 

My goal is to simply get more bang for the buck, and still maintain a good group.

 

Thanks for the tips and feedback!

[21 smoker]

Phil, Grey Crow,..I also have reloaded thousands of .45 cal and 9mm over the years and I`ve encountered problems with the case cannelure that you mentioned.Now several thousand .45s cases are of unknown history,so I expect some issues...mainly split cases...but several times they separate at the cannelure leaving .50 inches of brass in the chamber.I never leave home without my trusty 45-70 Trapdoor broken case extractor.This happens in my Thompsons and Reisings and causes a FTF, thanks to the floating firing pin that is all that happens.One other point on crimping the case mouth,..overall case length has to be consistant or the crimping won`t be uniform,and since these headspace on the casemouth,crimping is most critical,so I crimp as lightly as possible...FMJ or cast...hth.. http://www.machinegunbooks.com/forums/invboard1_1_2/upload/html/emoticons/wink.gif

[Grey Crow]

PhilOhio

 

I am currently using the RCBS three die set with carbide resizer die. According to the RCBS site the third die is bullet seater / taper crimp die.

Although the part numbers no longer match. I have Group B, part 18912

Their site lists it as Group B, part 18915.

 

Gun show this weekend, hopefully with a lot of luck I can get a deal on bullets.