Pistol cases under case trim length in book

[Biggobob]

Hello Everyone,
I am very interested to find out from experienced loaders/reloaders to hear what they think about measuring pistol brass just purchased. I recently just started reloading and bought some 1 time fired 9mm brass online. I measured the cases and almost all of them were under the recommended minimum size in the book. Minimum is 0.749 and all fell under this and the closest was 0.748. I went to fire my first rounds and had a case separation and cracked the grip module on the P320. Note, these were probably too hot (lesson learned to start at minimum loads) also I used a powder from Shooters world(Ultimate Pistol D036-07). I did not have hard data like I would have if I had used something like HS6 or HP38. However, now being super cautious I decided to buy new brass from Winchester and only 3 failed. 97 were within limits at the bottom at 0.749. I measured all my new 300 Blackout brass from Star line brass and all failed measurement criteria. Way below book data. I will not use that brass as I am too new at this to take a chance. It seems as though they are saving money on brass by making them short or trimming off. I want to make sure that I am not an idiot and grossly missing something here. It appears that most comments I read are: I never trim pistol brass or I only trim rifle brass if needed. I have got that. It seems super obvious that you would not put a case that exceeds the book data on maximum length.There is almost nothing about using short brass that may cause pressures to rise etc…
I am not looking for comments that tell me to measure the brass using the rifle or chamber. I am needing info on pistols and using cases that are shorter than someone would expect, especially when using the book criteria. I would expect when buying new brass that it would be perfect or at least in this case from 0.749 and 0.754. I really did not like the case separation and would like to keep my fingers in the future. Any help would be greatly appreciated. BTW, I also bought Starline 38 special brass and now am wondering about revolver considerations when reloading. They were also under on size.

 

[Dub]

I am pretty sure your case separation is a result of another facet of your loading process and not brass that is minimally too short.

 

[DirtySteve]

I made 6.5 Creedmoor brass out of Lapua 22-250 brass.. It was so short I doubt I will ever have to trim it. I fired them about 5 times now and no issues. Short brass is seldom a problem in pistols. In rifles you can have carbon build up but even that is not a huge problem. There is no reason to hot rod any ammo you reload.

Also what do you consider way short??? .005???

 

[Biggobob]

Yep, that’s for sure. I have learned that and being careful. i just am trying to find out details on the using brass that is under limits. For instance, if I am using the book on a rifle case I could trim off up to 10 thou. What if I trimmed of 25 thou. Pitch It as a reject? My thought is yes. But, when it come to pistol brass I am reading that they just shrink? Its all good? That does not make sense at this moment. Thanks for the comment.

 

[dttheliman]

My 0.02c on your pistol brass: worry about your powder charge weight and focus on your OAL of the loaded round, make a few dummy rounds and cycle them through the firearm , like Steve said what are you considering short 0.005?

 

[Biggobob]

Thanks for the response Steve,
what I have been measuring is anywhere from .005 to .010 under the minimum trim length. The case on the 38 specials were coming in around 1.140 and the book calls for 1.145 and max case length at 1.155.

 

[dttheliman]

Thanks for the response Steve,
what I have been measuring is anywhere from .005 to .010 under the minimum trim length. The case on the 38 specials were coming in around 1.140 and the book calls for 1.145 and max case length at 1.155.

Would not worry about it - keep your oal correct and y’all be fine !

 

[Biggobob]

Ok, thanks

 

[1911nut]

The 9mm Luger headspaces on the case mouth

The 38 spl headspaces on the rim

 

[fkimble@charter.net]

New rifle brass will always be below or at minimum specs. It must go in any inspec chamber, even a minimum spec chamber. Pistol brass must also fit in any inspec chamber, so it must be a little on the short side also.

Frank

 

[Twicepop]

The separation you had is most likely a blow out at the unsupported part of the case that hangs out over the feed ramp of semi-auto pistols. It could have been caused by a number of reasons. Number one, an over-charge to much powder for a particular bullet. Another reason is that the bullet could have been shoved back into the case because of insufficient crimp (semi-autos are slam feed firearms) creating excessive pressure. Cases for semi-autos unless excessively short case length isn't critical (except for match ammo) because a taper crimp is applied after bullet seating (you are crimping after bullet seating, right?). Revolver brass should be held to as close to the same length as possible, this is because a roll crimp is generally applied after the bullet seating. To short of a case only means the crimp isn't as tight as those with the correct length cases. Too long of a case will generally cause the case to buckle/bulge right below the crimp and probably won't allow the round to be chambered.

 

[243winxb]

Look up the cartridge using SAAMI standards. https://saami.org/technical-information/cartridge-chamber-drawings/

Headspace on case mouth - .010" under maximum trim length. . 9mm Luger types.
Headspace on rim - .020" under maximum trim length. 38, 357, 44 mag types.

 

[358WCF]

It seems your case length questions have been answered above. Unsure what you mean by hard data, but Shooter's World data is available at the link below. They make the powder so I would imagine that it's reasonably good data as long as your brass is close to the same internal capacity & your bullets are of a similar weight & material.

https://shootersworldpowder.com/wp-content/uploads/shooters-world-manual.pdf

 

[GuitarmanNick]

I have also used SW Ultimate Pistol for 7.62x25 loads for my M-57 with good results.

The data was not available for the 110 grain, .30 carbine bullet, so I started very low and worked up slowly. The data is very limited for that powder.

OP, you might try Gordon's Reloading Tool to give you an indication of what to expect. Again, always start low and work up slowly looking for signs of over pressure.

On straight walled cases, as long as they are not too long, and you can seat a bullet to the desired COAL, you should be good to go. If they get too long, you may experience chambering problems and stuck/damaged cases. I usually check/trim pistol brass once before use, as part of the preparation process.

 

[DirtySteve]

Thanks for the response Steve,
what I have been measuring is anywhere from .005 to .010 under the minimum trim length. The case on the 38 specials were coming in around 1.140 and the book calls for 1.145 and max case length at 1.155.

Shoot them. Like others said just keep your overall length to what the manual states. I never have measured pistol brass. Never trimmed pistol brass. I used to shoot way too much of it for it to be feasible.
Steve

 

[Doom]

You are lucky you were not injured. Short cases have no effect on pressure. If too short the the cartridge is retained by the extractor instead of the case mouth on the chamber. Hard on extractor as it gets the impact from the firing pin.

If you didn’t have the SW data what did you use to pick your charge weight a COL?

 

[DGP4]

Did you do the plunk test on those 9mms that separated? If not you may have had an out of battery firing that caused the case separation. Always do a plunk test on reloads for semi auto pistols!