9mm setback

[mnpfamily]

First post, sorry to have to bring up a topic that's been addressed before, however I haven't been able to narrow down the options for a solution.

I'm loading 147 grn. MG CMJ over 3.2 grns. Titegroup, once fired FC brass (my own), Fed Primers. I'm using a new 550B with Dillon dies.

I am a new reloader looking for solutions to setback. I initially set crimp to around .375, but was getting setback after hand cycling dummy rounds through my M&P JG after 2 times. OAL started at 1.125, after chambering twice, OAL was down to 1.119 or so. Thought I had the problem licked by increasing crimp to .368 or so, could chamber 3-4 times with virtually no setback, however, the visible crimp caused concerns. Made and fired approx. 100 or so rounds, no issues feeding or extracting, no apparent keyholing, and from what limited experience I have, no signs of overpressure. The amount of crimp bothered me, so I reduced flare, just enough to be barely visible, in hopes of creating more case tension, and reduced the amount of crimp. Crimp of finished cartride now at .374 or so. OAL was also increased to 1.130. Now I'm seeing setback after 2 chamberings, down to 1.128, and down to 1.126 after 3 chamberings. I will try to reduce crimp a little more, perhaps to around .378 or so, just to check if the crimp is the problem. Aside from changing to a U Die, are there any other suggestions that I might try? I am loading for minor PF. Am I being overly concerned about the amount of setback that I'm seeing? Does factory ammo also setback to a comparable amount, and I'm just not aware of it?

Thanks for any help you all may have.

[yoshidaex]

When you "crimp", all you're doing is removing the bell. Over crimping can cause all sorts of issues (mainly accuracy) because it starts cutting into the jacket. A "crimp" should leave only a slight to no mark on the bullet.

What's preventing setback is case size. A dillon sizer/deprimer die should be more than adequate enough to size your case to prevent setback.

Is your die adjusted accordingly (just slightly touching the shell plate)?

Do your completed rounds have a slight "coke bottle" look?

[mnpfamily]

Yes the finished cartridges do have the slight coke bottle shape. I tried to crimp just enough to "take the bell out" but that's when I noticed the setback. However, I was using a lot more flair initially and have cut it down considerably until its barely noticeable. The factory rounds I've compared them to have a bit more ledge and measure. 375 but those are 124 Gen FC. I would like to stick with the Dillon dies if at all possible. Thanks for the suggestion regarding checking the resizing die, I'll check before proceeding.

[Bob DuBois]

Crimp doesn't hold the bullet, the first stage sized has that task. If the bullets are pushing back either the sizer is adjusted to short or needs to be replaced.

I'm a fan of the Lee U die, it comes under sized and puts a tighter size on the case.

Adjust the sizer using a small strip of paper as a pull gauge. The sizer should go as close to the shell plate as possible without hitting. With the handle down get a feel on the paper as you pull it from under the die.

Adjust the crimp die two thousands under the measurement taken at the base of the bullet in the case.

The nine case I picked up measured .380, set the crimp at .378. Crimp helps feed the case in the chamber, it doesn't hold the bullet in an auto case.

To tight a crimp and accuracy will suffer.

In my guns the longer I load the better the group. I try for 1.140 but you might be able to load a little longer, just load ten and see if they will fit in the magazine.

If you still get set back and the die is adjusted correctly, I would purchase the U die, Dillon presses, first class, Dillon service, no one does it better. But there are better sizing dies. Seen this problem several times and the U die will fix it along with feeding issues in tight chambered pistols.

[Powder Finger]

First post, sorry to have to bring up a topic that's been addressed before, however I haven't been able to narrow down the options for a solution.

I'm loading 147 grn. MG CMJ over 3.2 grns. Titegroup, once fired FC brass (my own), Fed Primers. I'm using a new 550B with Dillon dies.

I am a new reloader looking for solutions to setback. I initially set crimp to around .375, but was getting setback after hand cycling dummy rounds through my M&P JG after 2 times. OAL started at 1.125, after chambering twice, OAL was down to 1.119 or so. Thought I had the problem licked by increasing crimp to .368 or so, could chamber 3-4 times with virtually no setback, however, the visible crimp caused concerns. Made and fired approx. 100 or so rounds, no issues feeding or extracting, no apparent keyholing, and from what limited experience I have, no signs of overpressure. The amount of crimp bothered me, so I reduced flare, just enough to be barely visible, in hopes of creating more case tension, and reduced the amount of crimp. Crimp of finished cartride now at .374 or so. OAL was also increased to 1.130. Now I'm seeing setback after 2 chamberings, down to 1.128, and down to 1.126 after 3 chamberings. I will try to reduce crimp a little more, perhaps to around .378 or so, just to check if the crimp is the problem. Aside from changing to a U Die, are there any other suggestions that I might try? I am loading for minor PF. Am I being overly concerned about the amount of setback that I'm seeing? Does factory ammo also setback to a comparable amount, and I'm just not aware of it?

Thanks for any help you all may have.

Are you sure the bullets are getting seated in? your biggest number is only 0.006. I would take a few cartridges measure them and write down the numbers. Then keep measuring them and see if you get different figures. In other words it's not super easy to get repeatable results on a loaded round with calpers, it may just be technique.

[FLSlim]

I agree with the others re: a possible problem with your resizing/decapping setup or die. The only other thing I can think of is a possible issue with your brass; I've read (but never experienced) that others have had problems reloading FC brass. So another option might be to try the same die settings on a different brand of brass. You didn't say, but I assume you checked the diameter of your MG bullets to make sure they aren't undersized (that certainly is unlikely, but don't ignore the obvious).

[Sarge]

Read this entire thread:

http://www.brianenos.com/forums/index.php?showtopic=103799&view=findpost&p=1181299

I, as well as others, have had the same problem. Might be your problem as well.

[G-ManBart]

Read this entire thread:

http://www.brianenos.com/forums/index.php?showtopic=103799&view=findpost&p=1181299

I, as well as others, have had the same problem. Might be your problem as well.

+1

Lots of good info in that thread...

[mnpfamily]

Thanks for the help, I appreciate it. I did check out that thread, found it while searching 9mm setback issues (the search function really works great here), but I was kinda hoping to avoid having to switch to the u die. If that's what it takes though I will pick one up. I will try to adjust the sizing die first though and see if that works. I haven't tried the paper method so I'll give that a shot. I'm pretty sure its setback, as the OAL reading on my calipers decrease after 2-3 chamberings. That's why I went with a longer OAL as the setback was putting me real close to the minimum when I started at 1.125.

Thanks again for the help.

[dsmw5142]

Make certain your decapping pin is not set any lower than absolutely neccessary as this reduces the case neck tension on the brass after it's sized. The decapping pin should only extend 3/16th of an inch below the die mouth, no more.

[juan]

Make certain your decapping pin is not set any lower than absolutely neccessary as this reduces the case neck tension on the brass after it's sized. The decapping pin should only extend 3/16th of an inch below the die mouth, no more.

I dont understand how, please explain.

thanks

[noylj]

If you feed the bullet enough times, you will always get some set-back. You should not ever have to cycle a round more than twice. From here, it sounds like you are over-thinking this. Your set-back does not sound like an issue. Normally, for bullet set-back, they are talking about 0.05" or more. All you need is a thumb "push" test for set-back. Also, this is why you should always aim for the longest COL that will work in your magazine and gun.

A taper crimp is really just to iron out the case mouth so it will feed smoothly. Your case needs to be at least 0.001" under bullet diameter before you seat the bullet. This is all the case tension you can get. A case any smaller will simply cause additional case expansion or bullet swaging to bring the two into the 0.001" difference. Pull a bullet and check the case ID and bullet OD.

For SD ammo, you are told to always take the chambered round and put it at the bottom of the magazine. Also, if the set-back is visual (not measurable, but visible), you should trash it.

[mnpfamily]

If you feed the bullet enough times, you will always get some set-back. You should not ever have to cycle a round more than twice. From here, it sounds like you are over-thinking this. Your set-back does not sound like an issue. Normally, for bullet set-back, they are talking about 0.05" or more. All you need is a thumb "push" test for set-back. Also, this is why you should always aim for the longest COL that will work in your magazine and gun.

A taper crimp is really just to iron out the case mouth so it will feed smoothly. Your case needs to be at least 0.001" under bullet diameter before you seat the bullet. This is all the case tension you can get. A case any smaller will simply cause additional case expansion or bullet swaging to bring the two into the 0.001" difference. Pull a bullet and check the case ID and bullet OD

For SD ammo, you are told to always take the chambered round and put it at the bottom of the magazine. Also, if the set-back is visual (not measurable, but visible), you should trash it.

I agree, shouldn't have to chamber more than twice, but with my luck, that'll be the round that keeps ending up in the chamber at the "unload and show clear" command by the RO. My wife and I have been picking the ejected round up (up until now factory AE 124 grn.), wiping it off, and loading it back up for the next stage. Neither of us really knew about setback until I started reloading and finding my OAL to be getting shorter after cycling. Anyways, I checked station 1, the die could be perhaps just a hair more off the plate but I decided to try reducing crimp first. Crimp is now at .378, setback seems to be limited to .002-.003 after cycling 3-4 times. Loaded approx. 40 or so rounds and will see how they shoot tomorrow. There does seem to be a bit more ledge to the rounds than the factory rounds, but all cycled without much hang up. Hopefully no feed issues tomorrow.

Just another quick question: I know that shortening OAL will increase pressure, is it reasonable to say that loading a longer OAL will decrease pressure? By loading to a longer OAL without increasing powder charge, could I be under minor PF? To be honest, I haven't searched this question, I apologize if its been answered before. Both my wife's and my M&Ps feed Fed AE 124 FMJ without a hitch, and they measured 1.152 or so OAL, so I am thinking about loading to at least 1.140 or so. I don't have a chrono yet, so I'm going by what results others have posted using the same weight bullet, powder and equipment.

Thanks again for all the suggestions, your help is truly appreciated.

[G-ManBart]

Just another quick question: I know that shortening OAL will increase pressure, is it reasonable to say that loading a longer OAL will decrease pressure? By loading to a longer OAL without increasing powder charge, could I be under minor PF? To be honest, I haven't searched this question, I apologize if its been answered before. Both my wife's and my M&Ps feed Fed AE 124 FMJ without a hitch, and they measured 1.152 or so OAL, so I am thinking about loading to at least 1.140 or so. I don't have a chrono yet, so I'm going by what results others have posted using the same weight bullet, powder and equipment.

Thanks again for all the suggestions, your help is truly appreciated.

Yes, loading longer will decrease pressure and velocity, but there isn't really a formula for how much change in OAL will cause a certain change in velocity.

Consider that by increase OAL, you are also decreasing the amount of bullet pull (neck tension), which can make setback more likely....less of the bullet is in contact with the case wall, so total tension is less.

I doubt that your load is even making Minor. Hodgdon's data shows 3.2gr of TG and a 147gr XTP at 1.100" being 855fps, which is 125PF. Going off memory, the XTP is a bit longer than the MG CMJ, so it takes up more case volume (at the same OAL). That means the XTP load would have higher pressure and velocity compared with the MG bullet, when seated to the same OAL. You're using a longer OAL, which will lower the pressure and velocity, and MG bullets frequently tend to need a bit more powder to get to the same velocity. You really need to either get a chronograph, or find a friend with one before you go much farther...even a $99 Shooting Chrony will work. R,

[mnpfamily]

Thanks for the info on that, I figured loading longer would affect pressure/velocity. I initially was aiming for 1.125 with 3.2 Titegroup as I had read it made 130 PF with 147 MG. I think I'll try 1.130 and see if I can get someone to help me with the chrono at first. Usually a couple of days before a match a bunch of the guys will show up at the range with a chrono. I know 1.130 works in both of our guns, so I guess I'll leave the OAL alone and adjust powder a tenth or two at a time and shoot for 130 PF. Makes sense that with less of the bullet in the case, less tension, hence more chance for setback. I didn't really think about it in that sense, just thought it might give me a little more margin of error in case setback occurred, and perhaps a little more accuracy (I need all the help I can get).

Terrific info here, thanks again for all the assistance, and for putting up with the newb questions. My wife and I have a bunch of factory ammo left, so I'm not in a real hurry to get the reloads dialed in.

[yoshidaex]

I'm wondering if the bullets you have loaded up will function properly in your gun.

M&P right? If your M&P is bone stock, it may cycle but fail to lock the slide back on the last round.

I haven't done any load testing with my M&P 9L but my box stock G34 would fail to run properly with 130 PF loads.

[tunakilla]

Yoshi,

M&P will run pretty much anything from Steel Loads to Major, you know which one i'm talking about.

[mnpfamily]

I just got back from the range and both guns ran flawlessly with the reloads. The Pro Series is stock, the JG has had the S&W M&P Action Job done. I sent the gun in hoping it would lighten the trigger enough that my wife would like it, but no luck. She still likes the Pro better. I was a little worried about the Pro because of the longer slide, but no issues whatsoever. If anything, as was posted in some of the suggestions, the rounds with the tighter crimp did print less accurately, however all the reloads were a lot more accurate than the factory ammo I brought along. At 25 yds, the vast majority of holes were 8 ring and in. A bunch were 9 and in. Not so much of a real grouping, but a lot better than I usually do. If its the ammo, I wish I would've started reloading a lot sooner. Either that or all the dry fire practice is finally starting to kick in. Either way, great deal all the way around.

Thanks for all the help, I know I'll have more questions as things come up. I'll continue to monitor OAL for setback every once in awhile.

[Erik S.]

I try not to crimp at all if my rounds will still feed flawlessly, less stress on the brass over time. I must admit I haven't read 100% of the responses here, so appologies for any duplicate suggestions. Maybe your dies are out of tolerance, shouldn't happen with Dillon, but I use Lee dies since they're cheaper and seem to have fewer problems with them than anyone else has with their more expensive brands. Try switching to lead bullets, they seem to "grip" the case better. If you do crip and you're using lead, you'll get a better grip there too. When crimping on a plated or jacketed bullet, you're just going to thin the rim of your cases reducing case life, when you crip on lead it actually DOES something for you since it cuts into the bullet (only slightly).

Good luck!