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It's basicly a gauge that tells you whether or not the case is resized correctly. Some gauges measures head space but typically as long as the shoulder is correct and the case is the correct length, your good to go.
I use one and it works really well, there are ones you can use for after you load but I just use my mags and barrel, if it doesn't fit those, it fails. I load to my 5.56 and 7.62x51 to SAMMI spec and use a factory crimp die so I don't have to worry if the neck is a little shorter or if the bullet will come loose.
So if I'm loading to SAAMI specs, I don't need to worry about the jam/jump, they should chamber properly in any rifle right? I don't have any custom specifications for any rifles I'm shooting, so there's no custom rifling or anything. Is there a benefit to jamming to the lands, or is that the no-no I'm trying to avoid?
 
Possibly, but only if you can measure case head protrusion above the mouth of the gauge.

I'd think of case gauges as "does the cartridge meet SAMI specs".

Plunk everything (again, for straight / tapered), and learn what jump / touching / jamming for bottle-neck / rifle cartridges means.
I'll be honest, I'm a little confused. Headspace is the measure from the bolt face to the datum line where the shoulder contacts the mouth of the chamber, right? The gauges look like they all have a groove to indicate headspace tolerance in that regards. When I'm looking at seating depth, I'd be measuring for the jump/touch/jam to finesse my rounds for a particular rifle? I haven't gotten that far yet, I haven't seated anything, just making sure what I've gotten so far is safe to load. If I'm just putting together some plinking ammo for running through a few mid/low end rifles, do I need to really get that deep, or is SAMMI spec a good baseline?
 
I'll be honest, I'm a little confused. Headspace is the measure from the bolt face to the datum line where the shoulder contacts the mouth of the chamber, right? The gauges look like they all have a groove to indicate headspace tolerance in that regards. When I'm looking at seating depth, I'd be measuring for the jump/touch/jam to finesse my rounds for a particular rifle? I haven't gotten that far yet, I haven't seated anything, just making sure what I've gotten so far is safe to load. If I'm just putting together some plinking ammo for running through a few mid/low end rifles, do I need to really get that deep, or is SAMMI spec a good baseline?
Headspace, either by shoulder or case mouth, controls where the base of the cartridge is in relation to the breach face - get it wrong and the bolt won't close (inconvenient) / slide won't fully lock up (potentially much bad). Don't know if that answers your question or not.

Jamb / jump: If you strictly stick to book loadings then it shouldn't be an issue in SAMI chambers; when you're attempting to load long and jamb (with or w/o realizing it) then potentially dangerous spikes can happen in bottle necked cartridges (primer ignition starts the bullet moving, powder pressures are based on bullet mass having already broken static inertia).
 
So if I'm loading to SAAMI specs, I don't need to worry about the jam/jump, they should chamber properly in any rifle right? I don't have any custom specifications for any rifles I'm shooting, so there's no custom rifling or anything. Is there a benefit to jamming to the lands, or is that the no-no I'm trying to avoid?
Those two things are not the same. Loading to the lands is referring to the bullet seating depth and how close to the lands the bullet is or if it's touching, most will recommend not touching the lands.
Headspace is the space form the shoulder and neck of the case to the inside chamber walls. As mentioned, incorrect Headspace can lead to an out of battery firing which would be bad. To loose can lead to a case rupture and to tight can result is a jammed case.
 
Speaking of the rifle shooters.

Loading to the lands or loading to just short of the lands. Both schools of thought have their own cheering squads.

Though IMHO.......
I suspect that it depends on the individual, type of firearm that the ammo is being used in and what "discipline" is involved.

Aloha, Mark
 
Speaking of the rifle shooters.

Loading to the lands or loading to just short of the lands. Both schools of thought have their own cheering squads.

Though IMHO.......
I suspect that it depends on the individual, type of firearm that the ammo is being used in and what "discipline" is involved.

Aloha, Mark
I'd like to work my way up to better precision, but I also want ammo that will function in multiple firearms. I can respect the craft, but also understand a necessity for tolerances and thresholds. I'm not shooting competitively and I haven't gone hunting in years. Realistically, I only get out a couple times a year at best, and I'm not much of a good shot anymore. Being able to reload will hopefully put me in a better position to shoot more often. And I definitely don't want to do it wrong.
 
I'd like to work my way up to better precision, but I also want ammo that will function in multiple firearms. I can respect the craft, but also understand a necessity for tolerances and thresholds. I'm not shooting competitively and I haven't gone hunting in years. Realistically, I only get out a couple times a year at best, and I'm not much of a good shot anymore. Being able to reload will hopefully put me in a better position to shoot more often. And I definitely don't want to do it wrong.
Phew, read all this to make sure no one mentioned already. At my beginning I was led to use the comparator on a live factory round and then compare my sized/decapped cases to that.

Cam-over:

Lowering the die slightly(very little.1/4 turn+/-?) after the shell holder contacts the die. When your sized comparator measured case matches a live factory round it's what you want to see. If you match factory ammo with your sized cases your rounds should chamber and fire in any gun.
Regarding bullet setback/overall length (OAL/COAL). The book will give that spec and if you are using a similar profile/weight bullet you'll likely be okay. You could always drop a finished round in the chamber, with bolt-group removed, and make sure it seats properly and falls out freely. "Plunk Test".

On my bolt guns I learned that I didn't need to bump the shoulder back as far as factory rounds. Which means less working of the brass = better longevity of the brass
 
I'd like to work my way up to better precision, but I also want ammo that will function in multiple firearms. I can respect the craft, but also understand a necessity for tolerances and thresholds. I'm not shooting competitively and I haven't gone hunting in years. Realistically, I only get out a couple times a year at best, and I'm not much of a good shot anymore. Being able to reload will hopefully put me in a better position to shoot more often. And I definitely don't want to do it wrong.
Focus on reliable is a good place to start. A comparator or a case gauge is nice to have, but you're rifle chamber is the final word. If you make your ammo to fit the tightest chamber you have it should work in every other gun of that caliber. I always like to say if it fits it ships just like FedEx. You might be surprised by the accuracy in spite of focusing on reliability. Some guns like a lot of bullet jump, some don't. It's not as standardized as most people who don't make ammunition think it is. Be sure of your powder charge, make sure your primer is seated and make sure the case fits. Have you fired any of your own ammo yet? I'd be interested to hear your experience. I broke into a hell of a sweat the first time I pulled the trigger on one of my own cartridges. 😆 :p .
 
Have you fired any of your own ammo yet?
No, I haven't completed anything yet. I've been cleaning, sizing, and trimming brass a little bit. Been spending more time on it reading and doing a little research. I'll have Tuesday and Wednesday to actually spend some more time at the bench. After I've got some completed, I'll have to make some time to get out and test it.
 
No, I haven't completed anything yet. I've been cleaning, sizing, and trimming brass a little bit. Been spending more time on it reading and doing a little research. I'll have Tuesday and Wednesday to actually spend some more time at the bench. After I've got some completed, I'll have to make some time to get out and test it.
Dropping the hammer on your own ammo for the first time can be quite a rush... It'll be okay, just do it right. The first time I loaded for my 351 Winchester, I was extra nervous because there was no load data. I had to make it up off of the best available information and comparing data off of similar cartridges. 😬 . I'm not gonna lie. I got a little flop sweat, ha ha. You're doing it right. You are asking questions and seeking knowledge. You won't have any worries. Several of us here will be very interested to hear how your first rounds work out and see some pictures. We want a range report! It's very gratifying to see a new reloader have a successful first outing. We who have been doing this a long time forget what it's like to have that pride in your first handcrafted ammunition.
 
No, I haven't completed anything yet. I've been cleaning, sizing, and trimming brass a little bit. Been spending more time on it reading and doing a little research. I'll have Tuesday and Wednesday to actually spend some more time at the bench. After I've got some completed, I'll have to make some time to get out and test it.
Sending that first round down range is one of the best feelings. It's even better when you get to send a couple hundred down range at full auto that you've loaded.
It's a good feeling you can repeat for each caliber that you are loading for.
 
So... when seating, I messed up somehow... what causes this in the shoulder?

20240528_123640.jpg
 
Die is set to low, back the die out about a 1/4 turn and lower the seater stem about 1/2 turn. Start there and adjust accordingly.
I'll do that. I guess I'm not gonna crimp. On another note...
20240528_134735.jpg
I slowly ran one in the sizing die without the decapping stem to see if I could get it to take shape and I think I made a +p ... 😆 yeah, I'm gonna don't do that again...
I'm definitely learning what not to do.
 
I'll do that. I guess I'm not gonna crimp. On another note...
View attachment 1889575
I slowly ran one in the sizing die without the decapping stem to see if I could get it to take shape and I think I made a +p ... 😆 yeah, I'm gonna don't do that again...
I'm definitely learning what not to do.
You can crimp still, this is a common thing that happens when not crimping on the cannular ring. Make sure that at least half of the cannular is covered by the neck and you should be able to crimp, if you want to crimp off cannular than you'll need to back the die out further to avoid mushrooming the shoulder. If you want to do a separate crimp than I'd get a FCD(factory crimp die) and do the crimping that way, more forgiving with varying neck lengths than a roll crimp.
 
Is a .005 or a .01 difference in the case length going to matter? After resizing and trimming some of my cases weren't even up to 1.75 And spec is 1.76, I trimmed everything that was over 1.755, But they are not all exact.
 

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