The Sammi Specs on the 9mm says to trim the cases to .754 minus .010 so that is .754 to .744, right? Should I trim all cases to .744 or they are good to reload at any length between .744 & .754? I am thinking about the pressures, it they are all trimmed the same length and using the same COAL length then the pressures will be the same, right? I don't load to the max but usually half way in between the start load and the max load, so I won't have anything to worry about, because they are mostly for plinking at paper. I think what is really important is placing your shot, that is what counts. Thanks, to all who respond, just wanted to be sure I am thinking straight.
QUESTION ON TRIM??
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Ironicaintit
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Unless you're super bored and a severe case of OCD kicks in, I wouldn't worry about it.
Docendo Discimus
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Yes, good to go.
barnfrog
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That is my understanding.
bullseye308
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I only trim rifle cases. I load lots of 9mm, more than many here per year, and I have not measured a pistol case in 30 years. I did when I started but was told it wasn’t worth the effort and that even factory loaded rounds varied which I verified Andy haven’t measured one since.
I’d only measure revolver rounds if I wasn’t using Lee dies and wanted a perfect crimp, but the Lee dies don’t seem to care about length and crimp right anyway.
I’d only measure revolver rounds if I wasn’t using Lee dies and wanted a perfect crimp, but the Lee dies don’t seem to care about length and crimp right anyway.
AJC1
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If it's a taper crimp case I don't crimp. If it's a roll crimp or bottleneck rifle I do... I trim 38 when most others don't because I roll crimp it....
GeoDudeFlorida
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The only time I "trim" 9x19mm cases is to make them into 9mmMak cases.
GeoDudeFlorida
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I didn't even know you COULD.
I haven't trimmed any auto cases, but as what I have is mostly Range P. U., I have measured some (couple thou) 9mm and culled, based on length.
Hardly any were 'too long' per Sammi. I kept 0.740-0.745 as it was the most-prevalent range I had.
Most of the culls were 0.739 or less.
Hardly any were 'too long' per Sammi. I kept 0.740-0.745 as it was the most-prevalent range I had.
Most of the culls were 0.739 or less.
Correct, load them to the same oal and the case mouth just lands wherever it does. Ho deep the bullet is compared to the powder/bottom of the case is all that counts in 9MM, .40, .45 etc.
My experience has been auto brass that head spaces on the case mouth is close enough, but with revolver brass manufactures are paying less attention to case length they can vary +or- .006" and be out of square. This will really mess with your crimp.
GeoDudeFlorida
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The case volume matters more and that's the volume BELOW seated bullet. Some folks match headstamps figuring that way the internal dimensions - therefore the volume - will be so close as not to matter. Other folks (hand raised) don't bother sorting or matching figuring as long as the powder column and air columns BELOW the seated bullet are close, that's good enough. Staying well away from MAX loads, using powders that don't tend to react badly to temperature changes, don't tend to spike or fizzle, and sticking with properly sized bullets for the bore all contribute to not having to worry. But, basically, these are turn of the last century designs that have stood the test of time because they're not finicky or hard to load.
Atavar
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Unless straight walled cases are so grossly long that you get unacceptable crimps I wouldn’t worry about it. I will trim my 9mm and .45acp cases if I am getting non-uniform crimps but many here have diagnosed me with unreasonable OCD.
Engineer1911
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Sort your brass, discard Berdan primed or cracked case/split cases. Load ammo per the load data you are using for bullet type, bullet weight, and powder. Use a slight taper crimp to hold the bullet.
Bullet weight is ± 3.0 grains, powder charge is ± 0.1 grains, loaded length is ± 0.020" (Yes, I mean ± 0.020"). There is nothing else to worry about or measure, just follow the directions that came with your reloading dies. Don't make loading those tiny cases any more difficult.
EDIT: If you use a factory round nose seater plug, overall length can vary 0.030" to 0.040" between the longest and shortest round. Round nose bullets do not have a common profile, vary by manufacturer, and dumping 3 bags of 125 grain RN bullets into one box can cause this variation. I loaded 50, measured OAL, sorted by length, and fired short round first up longest round last. There was nothing significant to report.
My solution for common length was to use a hex head 1/4" x 28 TPI bolt for a seating stem. I filed a hex head to 0.345" diameter, dressed the head off to a flat, installed it in the seater die. OAL is ± 0.005" . For clarity, I have never trimmed a 9 MM, 40 S&W, or 45 ACP case in the 47 years I have reloaded ammo. End EDIT
Bullet weight is ± 3.0 grains, powder charge is ± 0.1 grains, loaded length is ± 0.020" (Yes, I mean ± 0.020"). There is nothing else to worry about or measure, just follow the directions that came with your reloading dies. Don't make loading those tiny cases any more difficult.
EDIT: If you use a factory round nose seater plug, overall length can vary 0.030" to 0.040" between the longest and shortest round. Round nose bullets do not have a common profile, vary by manufacturer, and dumping 3 bags of 125 grain RN bullets into one box can cause this variation. I loaded 50, measured OAL, sorted by length, and fired short round first up longest round last. There was nothing significant to report.
My solution for common length was to use a hex head 1/4" x 28 TPI bolt for a seating stem. I filed a hex head to 0.345" diameter, dressed the head off to a flat, installed it in the seater die. OAL is ± 0.005" . For clarity, I have never trimmed a 9 MM, 40 S&W, or 45 ACP case in the 47 years I have reloaded ammo. End EDIT
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243winxb
Member
This. Head spacing is on the case mouth. Note SAAMI minimum chamber & maximum brass are both the same at .754"
Taper crimp is a must. Pressure not an issue using middle of road powder charges. I tested with 4 different powders.
I have found brass longer then maximum, needing trimming.
Skeptic13
Member
I have reloaded thousands of rounds of 9mm and I have never trimmed one of them. Never had and issue caused by case length.
Bazoo
Member
That’s correct. The oal will be the same and pressure will be the same.
AJC1
Member
I sort cases because of seating depth. When I deal with different brand I get a lot of variation. If I use the same brand I get around .001 and that makes me happy. My test batch of 357 gets every prep I am capable and hand trimmed because I run up to max and lots of loads I have no experience with... bullk 9mm for steel games in high volume is a mass production game and totally not my forte...
Did you mean loaded length +/- 0.002?
For me trying to make things consistent is a big issue, case tension on the bullet is one that gets over looked. Ever notice with Blazer brass some is easy to resize and some is hard? Separate easy for hard, then pay attention to the effort in seating the bullet between the two. I have improved accuracy and lowered ES and SD numbers by separating brass in this manner.
I too am in the "never trimmed a pistol/revolver case" camp. I guess if my revolver cases varied more than .010" in length, and if I got waaay different crimps, and I was shooting "Bullseye", I might trim some. But that hasn't ever happened. For semi-auto cases I plunk and just "deflare", no crimp...
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