9mm Seating Depth

C

cc1965

Inactive
I’m not new to reloading but I am new to reloading for 9MM
I’ll list the details first:
Ruger LC9S
Bullet - Remington 115gr FMJ 5.5gr Unique
Bullet - Missouri Bullets 115gr LRN 6.0gr Unique
I’m looking for “proper” depth and COL for these two bullets if anyone has any experience with either. I have shot factory PPU ammo and USA Reman rounds, both 115gr RN FMJ. No feed issues or jams. I measured the COL of the PPU at 1.150. The USA Reman is 1.140.
I loaded a box of both the FMJ and LRN. I couldn’t find any info or data on the Remington bullet. The Missouri website states “seat this bullet to APPROXIMATELY 1.08”. That seemed short to me so I loaded a little longer to 1.120. I seated the FMJ at 1.140 same as the store bought Reman. When I took them to the range I loaded five at a time in my Ruger. I had one feed issue in 15 with the FMJ. I had 4 or 5 feed issues out of 20 with the LRN. And suggestions or advice? Prior to going to the range, I loaded my clip full and cycled the entire box of both bullets through my gun. No cycle issues at all. But the LRN had multiple misfeeds when firing. Seemed like they weren’t riding up the ramp completely. The gun was purchased in September and has only had about 300 rounds through it. Spring tension shouldn’t be an issue yet. Limp wrist is also not an issue as I haven’t had any problems with factory ammo and only one misdeed in about 5 boxes of the USA Reman. I am wondering if I left them too long at 1.120 and am thinking of trying loading another box at 1.09 or 1.100. I’m not too familiar with 9mm reloading, but 1.08 just seems too short. Both loads were very accurate on bench rest. I’d like to keep the powder charge the same. Just looking to get a more consistent feed with the LRN as these will be my primary target loads. As far as carrying and reliability I will only use factory ammo. Any input would be greatly appreciated!
 
The bullet manufacturer gave you a seating depth.

You chose not to follow their advice.

Conclusion? Feed issues.

There ain't anything wrong with the cast bullets @ 1.080"

I have some home made cast bullets that I have to seat less than 1.080" in order for them to work in my guns.

Never had any issues in the 3 years that I have been loading those.
 
I loaded my clip
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Its called a magazine. Next do you do the plunk test with you reloads?? Take the barrel out of the gun and drop your reloaded round into the chamber. if it plunks you are good to go with regards to OAL. Start with the OAL on the long side. Drop the round into the barrel. If it does not go plunk remove the round and seat the bullet a little deeper. Drop it back in the barrel plunk,yes or no. If no seat the bullet a little deeper and try the plunk test again. Continue the process until the round plunks when dropped into the barrel. Now measure the round and that is your target OAL. Load a few up and try them at the range. If all is good great if not and feeding issues are presenting themselves you can adjust the OAL to cure it
 
Your chamber and magazine are the two pieces of equipment that will limit your overall length with any bullet in most auto feeders.
My CZ75B has almost no leade after the chamber. I have to load bullets deeper than most manuals list to get them to chamber properly. I look at the OAL listed in the book and use that for a starting point and then adjust the seating plug until the round drops freely into the chamber and turns in the chamber without any drag. I then record that OAL in my reload data.
DonP describes the process very well.
 
Yes, do a plunk test, but, that will tell you what your max oal is for that barrel. That may not be what oal you should use. That should depend on the function through the mag (clip-whatever) AND getting enough neck tension on the bullet combined with proper powder amount to achieve the desired velocity and accuracy.
115 gr bullets are not very long so you need a fairly short oal to have enough bullet inside the case to get good neck tension.
I'm not familiar with those specific bullets, but 1.108 to 1.100 sounds fine. But adjust your powder amount accordingly. Remember, start low and work up.
 
I have a 9mm pistol that when doing the plunk test I can seat a RN bullet all the way out to 1.175" and it will turn freely, only at that length the round will not fit into the magazine, it is too long.

Depending on the bullet used I will adjust the length in or out from the recommended length depending how it performs in my gun. I also adjust the powder charge up or down depending on where I set the length.

I also have more than one 9mm so I load all handloads to the shortest chamber so that I can use them in all the guns. I do not want to load a specific round for each gun.
 
Info that I have says RP 115 FMJ factory overall length is 1.110". Also it says Winchester 115 FMJ White Box oal is 1.160". The nose profile of FMJ bullets can be blunt or sharply tapered like the Win 115 and 124 gr. bullet. Blunt noses seat to a shorter overall length.
 
cc1965 said:
Any input would be greatly appreciated!
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Seat as long as possible so the gun will correctly function. Some guns require different OAL's. Testing at 1.10 seems logical.

Make sure your seating die isn't migrating out. The seating stem on my LEE die will back out occasionally and i'll start with rounds at 1.10 and after loading 50 rounds i'll magically be at 1.12.
 
Bullet - Missouri Bullets 115gr LRN 6.0gr Unique
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That load appears to be 0.5 grain over max according to Lyman's Cast Bullet Handbook for a 120 grain lead alloy bullet. I'd check your data source and be very careful of your OAL. 9mm rounds are especially sensitive to shortened OAL's.
Best Regards, Rod
 
The max over all length WITH BULLET listed for the 9mm Luger is 1.169"

COAL = Cartridge over all length

This is the industry standard max length that SHOULD work through all guns, but "should" does NOT mean "will" in every case. All factory ammo is loaded to a slightly shorter length than the max, to promote reliable function in the broadest range of guns.

The "plunk" test is fine, and a good way to tell if your rounds will CHAMBER, but won't tell you if they will FEED acceptably well.

But the LRN had multiple misfeeds when firing. Seemed like they weren’t riding up the ramp completely.
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Compared to copper jackets, when it comes to rubbing on steel, lead is "sticky". The softer it is, the "stickier" is it (higher friction).

Lead that is too soft, doesn't slide up a feed ramp, it sticks, and wants to stop, and in extreme cases, does stop. A rough feed ramp increases the degree of the problem, if the bullets are too soft, and a "too soft" lead slug can stick even on a mirror smooth feed ramp.

Don't know how hard the lead slugs you have are, but they could easily be borderline hard enough for proper function (since you are getting some feed issues)

Depth of seating matters, more in a 9mm than some other rounds, you should have at least one full caliber (.35") of the bullet in the case for proper grip on the bullet, and more doesn't hurt, providing you are using a powder charge appropriate to the available volume of powder space.
 
Don't know how hard the lead slugs you have are
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It is very tough to find a commercial cast bullet softer than BHN 18 in this day and age.

The website shows that these are an 18.
 
When I did the PLUNK test, i used a fired case and marked where the bullet was pushed into the case when I inserted it into the chamber.
 
For most rounds that are loaded for a semi automatic gun. The maximum COL is listed as a guide. It tends to be the length that is the longest that it can be, and still reliably load into a box magazine. They also have a minimum length listed. That is the one that you do not want to go shorter than. The deeper seated bullets increase the pressure in the case.

For revolver round they give a max length that if you go longer than that it may stick out the front of the cylinder not allowing the cylinder to close, or turn if it somehow manages to close.
 
I too have battled with 9mm in the beginning. I've loaded rifle and revolver ammo for over thirty years, but only started 9mm about eight years ago. Definitely a learning curve for me. So here is my method. First, seat a dummy round at max COAL and plunk. Then keep seating a little deeper if it doesn't pass, until it plunks. Then I go another .01 deeper to allow for inconsistencies in the bullets. Then at this point I work up a load for accuracy and reliable function. Then I load up a hundred more as a final test, and if all is fine load away. Of course, all the while watching for any signs of excess pressure. If at any time I experience a failure, go back to square one and start over.
 
In all these discussions I don't believe anyone has ever brought up the extremes of OAL. Such as with very heavy long bullets Like 147gr. one can actually seat too deep and increase case pressure to a dangerous lever. While with light weight short bullets I suppose it could be that they are loaded so long as to reduce the amount of bullet inside the case to a point it effects neck tension and the ability of the case to hold the bullet in place, yet is still with-in the max length.

The big difference being that most revolver bullets I've seen have a crimp groove while the Semi do not.
 
Such as with very heavy long bullets Like 147gr. one can actually seat too deep and increase case pressure to a dangerous lever.
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Seating depth really isn't the problem everyone seems to think it is, IF the powder charge is correct for the volume available.

That is what isn't mentioned enough.

Yes, the 9mm is extreme about this, and yes, seating deeper than specified can raise pressure dramatically, and possibly dangerously.

UNLESS you adjust the powder charge to compensate for the reduced case volume created by deeper seating. IF you do, then there's no pressure issue.

How much do you adjust? I can't tell you. That, you will have to figure out on your own. ;)
 
44AMP, well put and in expanding my thought!

I have found when working up loads with the 9mm and 380acp I'll start with the length suggested by the bullet maker and then when I reach a powder charge that appears to have tightened up to the best group I will then start to play with the length to see if I can tighten it up a bit more. Going both longer and shorter with mid range loads. With light starting loads I can usually go much shorter but not much longer and then just the opposite towards Max loads.
 
This is why my method eliminates the danger of too high pressure. Determine your OAL first, then work up your load. Works every time.

Why I do not load to max and work up loads slowly.
 
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