Are Your Bullets "Pushing Inward" When You Rack The Slide?

[rcawdor57]

First I have to give credit to two people for making me think of this in more than just "it happens" and actually measuring my rounds after chambering them in my Glock 36. I want to thank Brokensprocket for posting in the past how he only chambers a round once and then it goes in the "Range Box" and to Matt (you may remember him and his wife on t.v. when concealed carry became a reality). Matt asked me long ago...maybe two years now if I had any issues with my bullets moving inward when I chamber the rounds in my Glock. Over and over...what happens to the bullet depth? Matt pointed out to me that the bullets will move inward ever so slightly and it may not be noticeable until it is too late. Keep in mind that as the bullet moves inward pressure inside the case will increase dramatically higher than expected and could blow up in your hand/face! I took what Matt and Gregg said and decided to follow their sage reasoning and measure bullet movement.

My gun: Glock 36, first model bought way back in 2002. Ammunition for this particular experiment is Aguila 230 grain hardball circa 2010. Calipers used are a Midway USA model (manual, not electronic).

This is not a scientific test but it is a test that proved to me that the bullets move in much deeper than I initially thought after only a few chamberings. The initial C.O.L. on these particular rounds (new) is 1.265 inch out of the cartridge box. I loaded them in my Glock magazine by hand (no loader) and then cycled them through my gun. I then measured the rounds again. Every round showed a measurable change in C.O.L. (Cartridge Overall Length) with the most change being 0.005 inch per cycle through the chamber. After three chamberings one of the rounds had a C.O.L. of 1.251 inch. Now that is something to think about.

I took the rounds apart and measured the powder charge (why not?) and it was consistent in all the rounds at 5.2 grains of ??? (looks like Titegroup). I then put the bullets back together and crimped them with my Lee Factory Crimp die. The rounds are all now back to their original C.O.L. of 1.265 inch.

Some observations: I am fairly certain the Aguila rounds are not crimped as tightly as U.S. made ammunition. I only had to use minimal force with one "whack" of my impact bullet puller to pop the bullet out of the case (new ammo..not cycled!). I am going to experiment with some U.S. made ammunition next and post my results.

Keep in mind that this isn't a controlled environment test done in a lab.

Something to think about for all of us that use autoloaders! Anything I chamber from now on goes in my "Range Box".

Thanks again to Matt and Gregg!

 

[64Impala]

My .02 worth...

Whenever I clear my firearm, for example in prep for dry fire practice, I strip the mag and then clear the chamber. I do not put the loose cartridge back into the mag. When its time to holster up, I manually load the cartridge into the chamber, close the slide and insert the mag. I don't rack the round off the magazine, to prevent "set-back" and to prevent repeated beatings of the bullet tip into the feed ramp. I've never experienced "set-back" or any damage to the nose of the bullet from repeated loadings on my handloads. However, on my carry ammo, I don't take chances.

I don't see an issue with tossing a previously chambered round into the "practice" bucket, but for $27 bucks for a box of gold dots, I try not to use them to much for practice.

 

[skidmark]

My .02 worth...

Whenever I clear my firearm, for example in prep for dry fire practice, I strip the mag and then clear the chamber. I do not put the loose cartridge back into the mag. When its time to holster up, I manually load the cartridge into the chamber, close the slide and insert the mag. I don't rack the round off the magazine, to prevent "set-back" and to prevent repeated beatings of the bullet tip into the feed ramp. I've never experienced "set-back" or any damage to the nose of the bullet from repeated loadings on my handloads. However, on my carry ammo, I don't take chances.

I don't see an issue with tossing a previously chambered round into the "practice" bucket, but for $27 bucks for a box of gold dots, I try not to use them to much for practice.

You may not get setback that way, but you do run the risk of the extractor not catching hold of the rim properly, as well as possibly breaking the lip of the extractor. Semiauto pistols are designed to strip the cartridge from the magazine and insert them into the chamber as the slide goes forward. It is possible to get the cartridge into the chamber in a different manner, but it involves minute wear that eventually will catch up with you.

I have very little reason to unload my handguns, but understand that others may have to do so several times a day. I offer the suggestion to them that they cycle their chambered round to the bottom of the stack in the magazine, and keep the other rounds in order. That way you will only rechamber your round once in every 8 cycles (using a 7-round magazine and 1 in the chamber as the example). This should avoid setback for several months' worth of loading/unloading. Taking everything out and lining them up on a flat surface and running a straightedge along the tops on the first of every month should warn you of possible setback. (You do perform monthly maintenance on your belongings (computers, keyboards, guns, etc. don't you?)

stay safe.

 

[Herr Heckler Koch]

I do rotate them but use an electronic micrometer - for its repeatability that is better than a mechanical vernier micrometer that we were taught to use.

When they do go Ka-boom, it'll be the whole magazine because I've never seen a set-back limit and just check that they're all within a standard deviation of each other - that they are all setting back at the same rate.

At a buck per round, I've quit practicing with my self-defense carry ammo long ago.

 

[Jason in WI]

When we use to have to reload every time we got in to the vehicle I did get setback. I posted this pic a year ago and warned everyone to check.





Now I could have measured with the micrometer but I didn't think it was necessary

These were cheap Remington UMC hollow points I was carrying. At the time I had setback with my .40 so I carried cheap rounds in the 9mm to see just how bad it would get and judge when I had to rotate. I don't remember how many times these were chambered anymore. I do remember that I rode the slide home and I still do to this day unless I'm at the range.

Now I only unload to clean the firearm and that round goes to the bottom of the stack.

 

[Jason in WI]

I manually load the cartridge into the chamber, close the slide and insert the mag.

Like skidmark said, be careful that's a good way to break the extractor in most pistols! If it works for you that's great but anyone reading be careful.

 

[GreenCountyPete]

i measured some interesting variations

8 rounds in gun
9mm rem golden sabers
1.128
1.136
1.128
1.128
1.134
1.129
1.125
1.134

so i took the 1.136 round and re chambered it 5-6 times measuring it each time no change
is it possible they are getting set back , maybe , i will have to watch it closer.

so i took 8 rounds out of a new box , different brand these were blazer brass but none have been chambered they varied by up to .007 between the shortest and longest

 

[davegran]

Different brands and types of rounds are affected differently by rechambering. Here is a comparison of different rounds and how they react to repeated rechambering. I usually just ride the slide closed to prevent it.

 

[rcawdor57]

Excellent Information!

Different brands and types of rounds are affected differently by rechambering. Here is a comparison of different rounds and how they react to repeated rechambering. I usually just ride the slide closed to prevent it.

Thanks for the link Dave. I think a lot of it has to do with the crimp. I crimp my rounds fairly hard and they are very difficult to take apart with my impact hammer. The factory Aguila rounds I used simply took one impact (and not a hard one at that) and out they came. My own loads take three to five HARD impacts to dislodge the bullets.

I am going to dig through some other factory ammo I have and do some more experiments.

Jason, I missed your post of those cartridges last year. That is some good information.

I also agree with Skidmark about racking the rounds in as designed. The extractors can break and usually do if closed on a round in the chamber. It's only a matter of time and then...when you need it most it will not work.

 

[Jason in WI]

Don't get too bent out of shape if your new rounds aren't exact, when they are seated the die doesn't push on the tip. All bullets vary by size and weight, it's really annoying when you have OCD and your reloading.

Another interesting experiment would be to measure your rounds and record them where they are in the mag and then fire a few off and see what happens to the rest, the reason we crimp isn't for the initial ride into the chamber but what happens during recoil. Granted a pistol isn't a kicker like a rifle but it might be interesting to see if there are any changes.

 

[Firearms Iinstuctor]

It is something to be aware of. I seen it happen rotating rounds in your mag helps. If you seen one that is set back I remove it and replace with a new round.

If it happens every time you chamber a round then there is something wrong with the ammo or pistol.

Be aware take a few Precautions.

 

[rcawdor57]

Don't get too bent out of shape if your new rounds aren't exact, when they are seated the die doesn't push on the tip. All bullets vary by size and weight, it's really annoying when you have OCD and your reloading.

Another interesting experiment would be to measure your rounds and record them where they are in the mag and then fire a few off and see what happens to the rest, the reason we crimp isn't for the initial ride into the chamber but what happens during recoil. Granted a pistol isn't a kicker like a rifle but it might be interesting to see if there are any changes.

I agree! Recoil can and does cause bullets to move. I've seen bullet jump in revolvers so much the cylinder could not rotate. I've seen 7.62X39 rounds crimped so lightly the bullets jumped in the magazine and could be pulled out by hand. They were reloads (not mine!) done by a newb who didn't know what he was doing.

I routinely weigh and measure a sampling of bullets when I load. Yesterday I weighed 5 bullets out of a batch of a thousand to see the variance between them. They are 185 grain .45 bullets and they varied by 1.3 grains on average. I can attest you get what you pay for. The higher quality bullets are usually spot on and have a variance of 0.1 to 0.5 grain between them and MIC alike as well.

 

[BROKENSPROKET]

First I have to give credit to two people for making me think of this in more than just "it happens" and actually measuring my rounds after chambering them in my Glock 36. I want to thank Brokensprocket for posting in the past how he only chambers a round once and then it goes in the "Range Box" and to Matt (you may remember him and his wife on t.v. when concealed carry became a reality). Matt asked me long ago...maybe two years now if I had any issues with my bullets moving inward when I chamber the rounds in my Glock. Over and over...what happens to the bullet depth? Matt pointed out to me that the bullets will move inward ever so slightly and it may not be noticeable until it is too late. Keep in mind that as the bullet moves inward pressure inside the case will increase dramatically higher than expected and could blow up in your hand/face! I took what Matt and Gregg said and decided to follow their sage reasoning and measure bullet movement.

My gun: Glock 36, first model bought way back in 2002. Ammunition for this particular experiment is Aguila 230 grain hardball circa 2010. Calipers used are a Midway USA model (manual, not electronic).

This is not a scientific test but it is a test that proved to me that the bullets move in much deeper than I initially thought after only a few chamberings. The initial C.O.L. on these particular rounds (new) is 1.265 inch out of the cartridge box. I loaded them in my Glock magazine by hand (no loader) and then cycled them through my gun. I then measured the rounds again. Every round showed a measurable change in C.O.L. (Cartridge Overall Length) with the most change being 0.005 inch per cycle through the chamber. After three chamberings one of the rounds had a C.O.L. of 1.251 inch. Now that is something to think about.

I took the rounds apart and measured the powder charge (why not?) and it was consistent in all the rounds at 5.2 grains of ??? (looks like Titegroup). I then put the bullets back together and crimped them with my Lee Factory Crimp die. The rounds are all now back to their original C.O.L. of 1.265 inch.

Some observations: I am fairly certain the Aguila rounds are not crimped as tightly as U.S. made ammunition. I only had to use minimal force with one "whack" of my impact bullet puller to pop the bullet out of the case (new ammo..not cycled!). I am going to experiment with some U.S. made ammunition next and post my results.

Keep in mind that this isn't a controlled environment test done in a lab.

Something to think about for all of us that use autoloaders! Anything I chamber from now on goes in my "Range Box".

Thanks again to Matt and Gregg!

Now that I have picked myself off the floor.....thank you and your welcome.

I don't remember who taught me about bullet set-back, maybe it was Hubert or discussion on this forum, but the thought of a gun blowing up on me created enough reasonable fear to do something. I got one of those cartridge cases that holds 50 to keep in my center console. I have 49 in it. After one has been in the chamber, it goes in this case, bullet up, and I take another out of the same case, sitting primer up, that has never been in a gun. When there are no more sitting primer up, and they all are bullet up, that case of 50(49) goes in my range box at home.

Since I don't do the dance anymore, I use alot less JHP's at the range, which my wallet loves.

 

[64Impala]

thanks for the heads ups on the issue of dropping the slide on the a round in the chamber. I didn't know that was hard on the extractor. Live and learn. I'll have to re-evaluate my proceedure. I guess the only real option here is to go out and buy another G19 just for dry fire practice

 

[GreenCountyPete]

Don't get too bent out of shape if your new rounds aren't exact, when they are seated the die doesn't push on the tip. All bullets vary by size and weight, it's really annoying when you have OCD and your reloading.

Another interesting experiment would be to measure your rounds and record them where they are in the mag and then fire a few off and see what happens to the rest, the reason we crimp isn't for the initial ride into the chamber but what happens during recoil. Granted a pistol isn't a kicker like a rifle but it might be interesting to see if there are any changes.

I cast my own , if i don't like it back in the pot it goes , i don't crimp much at all or it swags the boolit down which causes leading , i haven't loaded a ton of them yet but the are stuck but good without any extra crimp mostly because the bullet is already .402 and it would really have to squeeze down or the brass expand to go in any deeper. and they hardly ever go in and out , just in and out as empty brass.

next on the list is a mold for 9mm

 

[Captain Nemo]

I reload all my ammunition. I reload the following calibers. .32ACP, .32S&W short, .38S&W, .38Special, .357magnum, .45ACP, .45Long Colt, .22Hornet, 30-30, 7.62 X 39, 30-06, .303British, .303Savage, 8mm Mauser, .762 X 54, .755Swiss. There are a number of factors that affect the OAL and crimping. Some of the most importaant and not always thought of are: case length, bullet length, smooth bullet v canellured, lead v brass jacketed v copper jacketed, case thickness, type of powder used.

Case length and case diameter and bullet type is more critical in semi-auto's than in revolvers. Semi-autos require a straight crimp because they headspace on the case mouth. The selection of components are therefore critical in semi-auto ammo. Revolvers aren't dependent on headspace so they can be roll crimped. Most semi-auto ammo crimps .001 smaller than the diameter of the bullet. How well that crimp holds depends on all the conditions I mentioned in paragraph 1.

OAL is a fickle thing. It too must take into consideration those factors mentioned but it must also be concerned with the combination of bullet type and powder used. That is the critical combination in order to determine the minimum AOL of any ammo. Factory ammo walks the middle of the road in order to have a margin of safety. The actual safe OAL can be quite different. For example: The minimum factory value for OAL of a 9mm parabellum round is 1.169. The actual safe minimum OAL for different powder/bullet combinations can be quite different. The critical factor being the amount of pressure produced. The safe minimum OAL range for a 147 grain XTP bullet varies from 1.142 with 6.2 grains of N105 powder to 1.130 with 4.7 grains of IMR 800X.

What does all that useless data mean? It means that there is probably .039 wiggle room built into factory ammo for safety reasons. The only way to determine the real minimum safe OAL is to determine the components of the ammo and research a good reloading manual.

None of this information is to serve as advice. Each must make their own conclusion. I present it only as information. My personal opinion is that within reasonable limits setback is not as big a safety concern as it is a reliability concern. Reliable semi-auto operation is dependent on the bullet sliding up the bullet ramp of the magazine at a precise angle. That angle is controlled by the lips on the magazine which are usually calibrated on the typical factory OAL. A differing OAL can affect that angle so that feed reliability can be affected.