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Chambering issues in 9mm

XL105

Silver $$ Contributor
I’m having issues with chambering 9mm reloads. I cannot locate the issue.
147gr RMR actual diameter of bullet .355
OAL 1.15
Brass length .742-.748
Diameter of finished round that doesn’t chamber .388
Diameter of round that does .384
It appears the finished diameter is the problem. As you can see in the pictures, sometimes the issue is more pronounced, but the finished diameter is still .388, on both cases.
I have checked other chambers with similar results.
I don’t believe it’s a brass thickness issue, because it just seems random.
I haven’t had any issues with 115gr RMRs, but I can’t find a measurement on the 147gr that is out of spec.
What, in my reloading process am I doing wrong?
IMG_3930.jpegIMG_3932.jpeg
 
read this also from RMR's website:

This bullet requires a seating depth minimum OAL of about 1.10″ to chamber reliably in most handguns when loading 9mm. Most reloading manuals will specify a 1.13″ for a flat nose 147 and we’ve found that it works well in our guns. However, there are some handguns that have a very short leade that will not allow for the bullet to be seated that long. Glock Gen 5’s and CZ pistols are known for their short leades and this bullet may not work for them. For those guns we recommend the 124 grain MatchWinner.
 
Don't know your process/dies, but heavier (longer) bullet may be rocking and distorting brass at random during seating/crimping. Suggest picking up a cheap Lee Factory Crimp die to add as final process. Despite it's name (crimp), a key benefit to these dies is that they resize the outside of the case after bullet seating to ensure loaded rounds are within spec...
 
I have run all this brass through my Sig 365, using 115gr bullets, without an issue.
The 147gr are not chambering in my Canik, or my Sig.

I have tried seating them down to 1.10, also, the issue is still there.

I am aware of RMR statement, that doesn’t speak to the issue I am having, based on the pictures I posted. I may try the 124gr at some point.

I’m using Dillon 550, using Dillon dies. I cleaned the dies, and it didn’t resolve my issue.
I will consider buying the Lee crimp.
 
Out of 1000 rounds I probably had 25-30 that would not chamber, to varying degrees.
 
Post a picture of one of the offending rounds- this may be a crimping issue- sometimes the crimping/seating step can cause a bulge instead of the desired smooth, flat and tapered wall if the flaring is too little/much, and crimping die is set incorrectly.
 
Post a picture of one of the offending rounds- this may be a crimping issue- sometimes the crimping/seating step can cause a bulge instead of the desired smooth, flat and tapered wall if the flaring is too little/much, and crimping die is set incorrectly.

There are 2 pictures posted. What constitutes an incorrect setting?
 
The full round, showing the bullet and side profile of the case- if there is a bulge it should be visible
 
Do you have another 9mm gun to try the rounds in? Reason I ask, is that I've had a similar issue. I buy LAX remanufactured ammo for plate matches. About half of them won't chamber in my 9mm Springfield Garrison. They go in far enough to jam the slide. Factory new ammo is fine. I concluded it's a tight chamber because none of my other 9's have issues with the same ammo. So it seems that LAX reman is on the high side of spec and the barrel is on the low side; or one is actually out of spec.
 
The full round, showing the bullet and side profile of the case- if there is a bulge it should be visible
Sorry for the bad photo. But looking at the round, it doesn’t have a crimp on it, and is clearly bulging on one side of the case. The cases that do chamber, bulging slightly, all the way around the case, and has a crimp on it. The cases are the same length.
IMG_3933.jpeg
 
From that I would start by flaring the cases much more before seating.
More than this. I initially thought it was a flare issue, but tried a few different flares, to no avail. I thought it was FC brass causing issues, but found other manufacturers stamp having similar issues. It definitely something to do with the bullet being seated, or in the crimping process. I just tried adding more crimp, same issue. It’s just so random to me. Lee crimp might solve this problem.
IMG_3935.jpeg
 
The ones that do chamber, but looks like they have a bulge going all around- typically says you’re sizing too much, and the flaring doesn’t manage to restore the gentle taper - 9mm rounds are slightly tapered from head to mouth, but properly sized and seated rounds should not have an hour glass look to them. The ones that dont chamber and have a bulge on one side is most like the same starting condition, but because of the over sizing/inadequate flaring, the bullet is then seated skew because there is too much resistance during seating. Try slightly less sizing, slightly more flaring and see if you get better results.
 
The ones that do chamber, but looks like they have a bulge going all around- typically says you’re sizing too much, and the flaring doesn’t manage to restore the gentle taper - 9mm rounds are slightly tapered from head to mouth, but properly sized and seated rounds should not have an hour glass look to them. The ones that dont chamber and have a bulge on one side is most like the same starting condition, but because of the over sizing/inadequate flaring, the bullet is then seated skew because there is too much resistance during seating. Try slightly less sizing, slightly more flaring and see if you get better results.

I will raise up my sizing die, and add more flare.
I tried seating a 115gr into a case that wouldn’t chamber the 147gr. It chambers fine. I tried a couple different 147gr in that same case, none of them chambered.
 
I will raise up my sizing die, and add more flare.
I tried seating a 115gr into a case that wouldn’t chamber the 147gr. It chambers fine. I tried a couple different 147gr in that same case, none of them chambered.
I hope you come right! If you already sized all your cases it may be impossible to fix them now- the flare die won’t push the walls out to “fired” size, and even a mandrel would probably fail due to the tapered case design- you may need to fire a 115gr round in order to try and find the correct die settings for 147
 
I’ve seen these before many times when loading for USPSA. I found not seating the bullet square in the flare or not enough flare. The other thing was using the wrong seating stem.

Also some brands of brass are just out of specification on the small size.
 

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