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  #1  
Old 04-28-2012, 08:25 PM
SkippySanchez SkippySanchez is online now
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Bullet setback




Okay, I have my own thoughts on this, but, as my lovely wife points out on a regular basis, my thoughts are not exactly..... well, accurate.

So my question about bullet setback:

I carry a 1911 Colt Officer, loaded with Remington bonded Golden Sabers [but insert here any quality SD ammo]. At the range I practice with FMJ reloads or with a .22LR in a conversion on a full-size SA 1911. But I dry-fire practice 1-2 times a week and regularly lube if the gun has not been shot for more than a month (it's not my only gun).

Point being, I mark my SD ammo after it's been chambered & put it at the bottom of the stack.

So, how many times do you think a typical, quality SD round can be re-chambered before setback is an issue? I usually go for 2-3 times before it's marked for the bottom of the stack.
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Last edited by SkippySanchez; 04-29-2012 at 09:00 AM.
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Old 04-28-2012, 09:24 PM
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Rifter Rifter is online now
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Quote:
Originally Posted by SkippySanchez View Post
Okay, I have my own thoughts on this but, as my lovely wife points out on a regular basis, my thoughts are not exactly..... well, accurate.

So my question about bullet setback:

I carry a 1911 Colt Officer, loaded with Remington bonded Golden Sabers [but insert here any quality SD ammo]. At the range I practice with FMJ reloads or with a .22LR in a conversion on a full-size SA 1911. But I dry-fire practice 1-2 times a week and regularly lube if the gun has not been shot for more than a month (it's not my only gun).

Point being, I mark my SD ammo after it's been chambered & put it at the bottom of the stack.

So, how many times do you think a typical, quality SD bullet can be re-chambered before setback is an issue? I usually go for 2-3 times before it's marked for the bottom of the stack.
It has nothing to do with the bullet itself (assuming its the correct diameter). It has to do with 'bullet pull'. In other words, how tight the bullet/case fit is. But, absent some mechanical means like a cannelure that prevents the bullet from being pushed into the case, or some sort of cement is used like the military used to do, sooner or later you'll get some setback if you load a round often enough. It isn't a problem unless it gets to be excessive. If you limit it to no more than twice, you shouldn't have a major problem.
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Last edited by Rifter; 04-28-2012 at 09:26 PM.
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  #3  
Old 04-28-2012, 09:30 PM
superdude superdude is offline
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there is no objective way to put a count on how many times it has to be chambered before significant setback occurs. that's because it varies so much. it might be once, or ten times. the best way is to measure the overall length of the rounds, then set a criteria for being setback too far. you'll get different opinions from lots of people on what that criteria is.

ramshot published a figure in one of their manuals a few years back and they showed that an 0.010 shorter overall length in 9mm and 40 S&W produced from about 1,000 to 1,500 psi increase in pressure, respectively, using ZIP gunpowder.

so maybe a 0.010 decrease in length of your 45 ammo would be a reasonable figure.

realize that overall length can vary that much between different rounds in a single box of ammo, just in case you want to be confused by the realities of life.

i should add that i have no idea if the 9mm and 40 S&W math applies to the 45 ACP, but those are the only numbers i know of off hand. feel free to ignore it.

Last edited by superdude; 04-28-2012 at 09:40 PM.
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Old 04-29-2012, 10:12 AM
osageshooter osageshooter is offline
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I like your system. I think I will start using it. If you have a loaded gun and two spare mags loaded with defensive ammo you could run your ammo through your rotation two times for each round and have about fifty cycles before you exceed two chamberings per round. At this point you would be at about six months and a lot of people would say shoot the ammo and reload with fresh. Some experts say ammo stored in boxes will keep indefinitely, but ammo in and out of guns should be shot and replaced every four to six months. I think that exposure to oil, moisture, etc is the issue. I imagine that failure rates would be very low, but why take a chance.

Setback can be measured easily with a micrometer, but the degredation of components cannot be. The bonded gold saber that I purchased yesterday is 82 cents per round, so it costs a little over $20 to replace a 25 round defensive set up for me. (Eight plus one in the gun, and two spare eight round mags). Every six months, twenty bucks, and I still get to shoot the old stuff.
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Old 04-29-2012, 10:33 AM
400cor-bon 400cor-bon is offline
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just ease the slide into battery instead of dropping it
and those chambered rounds will last a whole lot longerbefore they set-back
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Old 04-29-2012, 06:08 PM
SkippySanchez SkippySanchez is online now
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Quote:
Originally Posted by 400cor-bon View Post
just ease the slide into battery instead of dropping it
and those chambered rounds will last a whole lot longerbefore they set-back
What a concept! I didn't even think about that. The only time I've ever noticed setback was with a reloaded FMJ round (duhhh), and I have a cheapo micrometer but have not used it just to check on rounds that have been re-chambered two or three times. Another good idea.
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Old 04-29-2012, 07:28 PM
GT40DOC GT40DOC is offline
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Originally Posted by 400cor-bon View Post
just ease the slide into battery instead of dropping it
and those chambered rounds will last a whole lot longerbefore they set-back

+1 There are a whole lot of folks, me included, that have been doing this for a long time with good results. Some may disagree, but that is common when you have a large group of people like this forum.
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  #8  
Old 04-30-2012, 08:38 AM
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Quote:
Originally Posted by 400cor-bon View Post
just ease the slide into battery instead of dropping it
and those chambered rounds will last a whole lot longerbefore they set-back
Doing this works unless your chosen ammo has a fairly sharp, square edge. Easing the slide into battery rather than dropping the slide as it was intended to can cause some ammo types to jam against the barrel feed ramp because the slide is not pushing the bullet with sufficient velocity to enact feeding the way it was intended.

As to setback, it's a good idea to rotate and avoid rechambering rounds more than a couple of times no matter what method you use. In general, it is a better option, if you must eject the round, to set that round aside in your range pile and load a fresh round from the magazine.
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Old 04-30-2012, 10:21 AM
M4finny M4finny is offline
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Here's a thought: If you are concerned with setback and are taking the time to actually "rotate" a once-thrice chambered round to the bottom of a magazine for carry, why keep the bullet at all? If it isn't suited for battery as the first bullet on hot standby, perhaps it shouldn't even be fired at all?

Here's my solution and it does take some time to do:

First, I check the COL for a factory fresh round and take note of it. Write it down if you have to. Or, measure ten of them and write down the average if you want to go that far.

Each week, my carry guns get field stripped and wiped down. If I were concerned so much about setback, I would and have removed every round from the magazine and measure the COL for each round. Any round that exhibits a major change in COL from my factory fresh COL measurements gets removed from the rotation for carry completely.

Personally, a compressed round should be visible by eyesight and I tend to lean toward the school of thought that some folks are worrying way too much about a change of
.010-.020 change in COL.

YMMV,

Fin
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  #10  
Old 04-30-2012, 10:51 AM
gkos59 gkos59 is offline
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Solutions to bullet setback has been discussed many times before and as I've always said I just hand cannelure all of my carry ammo with a Corbin tool and then I don't worry about it.
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Old 04-30-2012, 10:54 AM
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Quote:
Originally Posted by M4finny View Post
Here's a thought: If you are concerned with setback and are taking the time to actually "rotate" a once-thrice chambered round to the bottom of a magazine for carry, why keep the bullet at all? If it isn't suited for battery as the first bullet on hot standby, perhaps it shouldn't even be fired at all?

Here's my solution and it does take some time to do:

First, I check the COL for a factory fresh round and take note of it. Write it down if you have to. Or, measure ten of them and write down the average if you want to go that far.

Each week, my carry guns get field stripped and wiped down. If I were concerned so much about setback, I would and have removed every round from the magazine and measure the COL for each round. Any round that exhibits a major change in COL from my factory fresh COL measurements gets removed from the rotation for carry completely.

Personally, a compressed round should be visible by eyesight and I tend to lean toward the school of thought that some folks are worrying way too much about a change of
.010-.020 change in COL.

YMMV,

Fin
I generally agree, I go my visual inspection. Cartridges that show visible setback and damage are worth pulling anyway.
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