Ruger Forum

TOMD1943 · September 3rd, 2012, 08:42 AM

my lee 9mm bullet seating isn't keeping the same oal. i can live with some difference in over all length but not as mush as i'm getting +/= 1.125 to 1.150. i'm not sorting my brass. will that cause the differance? thanks in advance for the help. TOMD1943

grandpabear · September 3rd, 2012, 08:58 AM

Mine varies also but not by .025. Sometimes by .003, or .005. I'm getting better at applying he same amount of pressure consistently. Most stay within .002.

tglazie · September 3rd, 2012, 09:05 AM

what type of bullet are you using

TOMD1943 · September 3rd, 2012, 09:24 AM

tglazie, using x=treme 147grfn platted. using titegroup powder. im a little worried about chamber psi. TOMD1943

grandpabear · September 3rd, 2012, 09:29 AM

What data are you using? charge, oal ect.?

mikld · September 3rd, 2012, 10:20 AM

Clean your seating die and make sure the primers are seated correctly. Look closely at the plated bullets and try measuring some. Bullet variation is common too.

Iowegan · September 3rd, 2012, 12:45 PM

TOMD1943. .025" variation in bullet seating depth is HUGE, especially with 9mm ammo where chamber pressure can skyrocket when bullets are seated too deep. The max variation should be +or- .005".

There are a number of things that could be causing your problem and it could be a combination of any of them. Let's start with the dies. Take your bullet seating die out and clean it thoroughly. Any case lube, bullet lube, or bullet shavings will corrupt the seater stem and result in inconsistent seating depth. Make sure the seater die is locked in tight. If you are using Lee dies with the rubber "O" ring in the lock nut ... get rid of it and replace it with a solid lock nut. The flex in the rubber can easily cause the problem. When you adjust your seater die, make sure the press handle is at the full downward stop. When you are running your press, make sure the handle gets pulled down to the stop each and every time for all operations.

Check several cases for length. After they are sized, they should not vary more than +or- .005". If they vary more than that, it would be wise to trim them to a uniform length. Always trim after sizing.

Next is loading procedures. If you are seating and crimping in the same handle stroke, cases that are just a few thousandths longer will crimp sooner and won't seat quite as deep when it feels like the handle is fully down. It's always best to seat bullets and crimp in two different operations. To do this, back the body of the seater/crimp die out a couple full turns then lock it down, making sure the crimp taper in the die does not touch the case. Adjust the seater stem for the prescribed bullet seating depth. Run the whole batch of ammo through the seating process. After seating, the case mouths should still have a slight bell. When the batch is complete, back the seater stem out several full turns then adjust your crimp for optimum and crimp the entire batch. Make sure the seater stem does not touch the bullet. By separating the two processes, bullets will seat to a nice uniform depth and because the seater stem has been backed out for crimping, it will not cause the bullet to change depth.

Hope this helps ... let us know what you find.

tglazie · September 3rd, 2012, 02:36 PM

I have not used this brand of plated bullets in the past, but I do load a 147gr LRNFP bullet that seats perfectly using Lee dies. I second what Iowegan said above about seating and crimping separately.

TOMD1943 · September 3rd, 2012, 02:57 PM

lowegan, Idid not know that you could do that with the die. I will try it on some pratice rounds to see if that does the job. like I did not like the way the bullets were coming out. done alot of adjusting of the seating as I was reloading the ammo. I will get the other locknuts. I did not like the rubber orings to begin with. It's been along since i've reloaded an I can remember what brand of dies I was using then but they did not have rubber orings in them. thanks for the help. will inform you how it turns out. TOMD1943

CHX77 · September 3rd, 2012, 05:52 PM

I'm a fairly new reloader, but have done around one thousand 9mm so far. I also use Lee dies, but seat and crimp separately. I have the four die set with the factory crimp die. I loaded several hundred using bulk Winchester hollow base 115gr FMJ and had no problem maintaining OAL within +/- .002". Then I loaded some Hornady XTP hollow points and had some rather large inconsistencies. Some would be .020" to .030" longer and were noticeably harder to seat. They also would bulge the case about .001" at the base of the bullet. Eventually, I realized this was only happening with Winchester brass. None of my Federal, Speer, or Blazer brass did this. I'm thinking the Winchester brass has a greater wall thickness. All the mixed brass had been sized and flared the same prior to loading either bullet.

Clovishound · September 3rd, 2012, 07:42 PM

All of my loads are consistent within a couple thousandths. I use the Lee die that seats and crimps. I do a light crimp.

My buddy had problems with inconsistent AOL. Found out there was a problem with the linkage on his press. It was not bottoming out properly. He replaced the linkage, and AOL tightened up nicely.

CtYankee · September 4th, 2012, 03:59 PM

Not to put too fine a point on it, but the important thing is bullet seating depth. If your cases vary by 0.01 (and I've found that in factory ammo) and your oal is within 0.002, you're still going have a lot of variability in your chamber pressure. Since I usually scrounge 9mm brass I don't bother to trim 9's; however I do check the case length and throw out stuff that is ±0.004 from my target length.

tglazie · September 4th, 2012, 04:31 PM

Quote:

Originally Posted by CtYankee

Not to put too fine a point on it, but the important thing is bullet seating depth. If your cases vary by 0.01 (and I've found that in factory ammo) and your oal is within 0.002, you're still going have a lot of variability in your chamber pressure. Since I usually scrounge 9mm brass I don't bother to trim 9's; however I do check the case length and throw out stuff that is ±0.004 from my target length.

You are confusing your measurements here. Case length has nothing to do with seating depth.

CtYankee · September 5th, 2012, 06:27 AM

Quote:

Originally Posted by tglazie

You are confusing your measurements here. Case length has nothing to do with seating depth.

Well no, you can seat a bullet to any depth regardless of the case length; however, if you take two cases of different lengths and set the same overall length you will have different seating depths (Sierra Reloading Manual, Ed. V; Seating Depth: the depth to which the base of a given bullet is seated below the mouth.)

If you have set your oal with a case of mean length, a longer case will have the bullet seated further in and the shorter case further out maintaining volume of the "combustion chamber" (an enclosed space in which an exothermic reaction takes place). The potential danger, it seems to me, is if you set your oal with a short case, in which case, you get a deeper seating depth with a long case.

The question is: does this reduce the case volume a significant amount, or not? I don't know, maybe I'm just stinking up this post with a Red Herring. Old reloading manuals (Hornady 2nd Ed. for example) gave seating depths not overall length, nobody seems to do this any more

Iowegan · September 5th, 2012, 05:25 PM

CtYankee & tglazie, If COL is set to spec, it should stay the same no matter the length of the brass. However, when you seat and crimp in the same operation, a longer case will grab the crimp taper in the die sooner and result in an over crimp. This will usually prevent the bullet from fully seating and end up with a longer OAL.