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Old March 28, 2012, 07:32 AM   #1
jwrowland77
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Newbie question on LRN vs FMJ-RN OAL

Ok have a pretty simple question. I completely understand the difference between a LRN and a FMJ-RN.

My question is when looking at manuals if they say LRN and there is no FMJ-RN in the manual, can you use the data for the LRN for the FMJ-RN, and assume the same powder charges and OAL? Assume everything is the same (ie powder to be used, weight of bullet).

I will be loading 9mm 115gr FMJ-RN. I ordered the Winchester, mainly because that's what I'm used to shooting off the shelf.
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Old March 28, 2012, 08:16 AM   #2
ScottRiqui
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In general, you can use lead data for your jacketed loads, assuming the same bullet weight, since the recommended charges for lead bullets tend to be a little bit lighter than for the equivalent jacketed bullets.
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Old March 28, 2012, 08:19 AM   #3
jwrowland77
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Thank you! I'm getting ready to begin my first reloads and I just want to be as safe as possible. A little nervous if you know what I mean. Lol
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Old March 28, 2012, 08:55 AM   #4
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I don't like using lead data for jacketed loads as lead can be higher than the recommended max for jacketed. Not always but there are examples out there. I'm only talking about powder charges, I'll get to OAL in a sec. And the thing that stumps me is 115 FMJ is a really common bullet, and every load manual covering 9mm should have a load for it. It may not say "FMJ-RN" but nose profile means essentially nothing when it comes to powder charge.

For OAL if you want to use the recommended for LRN, go for it. Other people use a round of factory ammunition, which is fine also. OAL is a guideline, not a rule. Accurates manual says it best,

SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must be seen as a guideline only. The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination. This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of the barrel, 3) ogive or profile of the projectile and 4) position of cannelure or crimp groove.
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Old March 28, 2012, 09:11 AM   #5
jwrowland77
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Well I have two manuals that have loads for 115 FMJ RN but I've also been using loaddata.com to try and see as many different loads as possible for the powder I will be using.
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Old March 28, 2012, 10:47 AM   #6
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Every manufacturer of powder is going to have some load data for a 115 jacketed bullet. For example Hodgdon only lists one single load for 115 FMJ (for WSF), but has a dozen or so loads for a 115gr GDHP which most people use as a basis for their FMJ loads as well.

I just don't care for the advice that you can/should use load data intended for lead and jacketed bullets interchangeably. In 9mm lead bullets are practically synonymous with less than full power target loads, but when you get into other calibers lead will often have a higher max charge than jacketed. Given that this a public forum where anyone, with any level of experience and reloading any caliber can come here and read that, I figured I would say something.
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Old March 28, 2012, 10:51 AM   #7
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That brings up another question, wouldn't a HP and a RN have different OALs? I'm just trying to make sure I don't seat it to deep and cause over-pressure and cause something to happen to the gun or worse, myself.
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Old March 28, 2012, 10:55 AM   #8
ScottRiqui
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Quote:
I just don't care for the advice that you can/should use load data intended for lead and jacketed bullets interchangeably.
Note that I didn't say you could use lead data for jacketed bullets and vice versa. I specifically said that I was making the recommendation to use lead data for a jacketed bullet because lead data usually prescribes lighter charges than jacketed data for the same weight bullet.

In fact, I haven't yet seen otherwise in my manuals. But if you say it's out there, I'll defer to you.
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Old March 28, 2012, 10:57 AM   #9
Adamantium
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Quote:
That brings up another question, wouldn't a HP and a RN have different OALs?
Yes they will, I am strictly speaking about powder charge. For new reloaders I recommend just using a similar round of factory ammunition and basing your OAL on that. For me I can't remember the last time I searched for a recommended OAL as I determine that myself based on my needs.
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Old March 28, 2012, 11:05 AM   #10
jwrowland77
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Ah ok. Believe it or not I have been reading the ABCs of reloading but some of it just brings up questions, and then when I go to search for loads for specific bullets and powders I see stuff that doesn't match exactly.

I have read that you can find what the OAL is of your specific gun. I had thought about trying that and seein where that stands and then start out with the lowest charge I can find and work up.

Thoughts?
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Old March 28, 2012, 11:34 AM   #11
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In a way there are three OAL's for your 9mm. The first is your magazine length, IE the longest bullet you mag will hold. The second is the chamber length, which is the longest your gun will chamber. The third is the longest bullet your gun will feed between the two. I generally go with the shortest of the three for my OAL. Or for my 9mm as that is the only caliber that I reload for more than 1 gun, I base my OAL on the more picky gun.

Generally with round nose bullets the magazine length will be the shortest of the three.

Some of us like to experiment a bit more, others just stick to the numbers the manual provides. Nothing wrong with either approach as long as you are making safe and functional ammo.
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Old March 28, 2012, 11:39 AM   #12
jwrowland77
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Yep, keywords there are safe and functional.

I really appreciate y'alls input.
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Old March 28, 2012, 08:43 PM   #13
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Please don't interchange cast/lead and jacketed bullet data. They can be quite different in terms of pressures developed -- especially in the 9mm/40mm cartridges.

On the other hand, jacketed military-caliber FMJs tend to be very similar in design for similar weights. If you have powder/OAL listings from a manual for the FMJ weight you want to use, I suggest you stick with those.

BTW: What powder(s) are you using?
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Old March 28, 2012, 08:46 PM   #14
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I'll be using Unique since I also have a 9mm, .380 and .38 Special I'll be loading for.
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Old March 28, 2012, 08:59 PM   #15
mehavey
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Sierra 5th
9mm Luger
4" barrel
115gr FMJ
OAL 1.100
Unique Powder
Min 4.9gr/1,000fps
Max 6.6gr/1,250fps

Speer 14th
9mm Luger
4" barrel
115gr TMJ
OAL 1.130
Unique Powder
Min 5.6gr/1,161fps
Max 6.3gr/1,244fps

I'd split the differences all-round: OAL=1.15",** Min=5.2gr, Max= 6.4 and stay in the middle of that loading range until comfortable w/ what you are getting.

** assuming the bullet will pass both the magazine length and the full chambering "plunk" tests at that OAL.

Last edited by mehavey; March 28, 2012 at 09:04 PM.
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Old March 28, 2012, 09:07 PM   #16
jwrowland77
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Now would it matter that I have the Walther PPS 9mm with the 3.4" barrel? Does that make a difference when the data shows for a 4" barrel?
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Old March 28, 2012, 09:10 PM   #17
jwrowland77
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Sorry for all the questions, I just want to be as safe as possible. I've been looking at loaddata.com along with the Sierra 5th and Hornady 8th manuals, is what prompted the original questions. It wasn't showing a whole lot of 115 FMJ loads on the loaddata.com site.
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Old March 28, 2012, 09:22 PM   #18
mehavey
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Quote:
I have the Walther PPS 9mm with the 3.4" barrel? Does that make a difference...
No effective difference in loading data.
Velocity will be lower by about 40fps.
No big deal.

Start at 5.2gr

.

Last edited by mehavey; March 28, 2012 at 09:28 PM.
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Old March 28, 2012, 09:25 PM   #19
jwrowland77
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Oh ok sweet. I can handle that difference. . I have a tendency to be a little OCD. I'm an accountant, it comes with the job. .
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Old March 28, 2012, 10:06 PM   #20
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Using a minimum lead load with a FMJ bullet can lead to a squib... bullet not leaving the barrel, especialy in a revolver, but it can happen in a semi auto too... I wouldn't do it......
The problem is that, depending on the caliber, often you will be fine, then you will tell your friends its ok, but sometimes, it isnt....

Advice to follow published load data is like advice to wear your seat belt.... Lots of people do it without ever having a problem, then there are others who do have "problems"..... You can take your chances without a seat belt because your buddy says its OK, or you can wear it because you know its safer, its up to you, just know that chances are good you wont come out unscathed 100% of the time.....

Here is my biggest problem with treating them as interchangeable, or even interchangeable just one way (lead>jacketed):

Ive noticed that sometimes when the same powders are listed for both, the MAX charge for a lead bullet is less than the MIN charge for a FMJ bullet....

Other times I see the powder recommended for lead loads are completly different than those for FMJ loads....

And still other times you will see the lead bullet data exactly the same as FMJ.....

All depending on caliber.....

If nothing else, stay with slower powders if you are going to go "sans belt".... faster powders are often recommended for lead than are suitable for FMJ... for example, in a 357 magnum, tite group is recommended for 158gr lead bullets, but would be way too fast for a FMJ bullet of the same weight, you would almost certainly end up with a squib if you tried to substitute a FMJ for lead using titegroup....
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Old March 28, 2012, 10:18 PM   #21
jwrowland77
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Brings me to another question. In the Sierra 5th manual, for Unique for 115gr FMJ min at 4.9 max at 6.6 COAL 1.100", do people move up with the numbers shown or can I move up in my loads starting with 4.9 and move up by .1 until I find one I like? Or go as manual say from 4.9 to 5.2 to 5.6 etc. or would it be smart to 4.9,5.0,5.1 etc?
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Old March 28, 2012, 10:29 PM   #22
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no you dont have to go up in the increments in the manual, they just show them to give you an idea about how fast you will get with about how much powder... you can go in between if you want...
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Old March 28, 2012, 10:59 PM   #23
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.1 grains is a such a little bit. I tend to move up by at least .2, it just saves time.
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Old March 29, 2012, 06:19 AM   #24
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always start low, or you can be 'surprised'

Find three data sources that show your components, or as similar as possible;

average the START data;

use THAT to start;

THEN work up slow.

Yeah.
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Old March 30, 2012, 01:30 AM   #25
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You have asked some very good questions and I applaud you for your diligence to the detail in your questions. All of the advice given has been a big help to me as I am sure it has been to you.
This forum has some great people on it that are willing to share their knowledge. I am more than grateful.

Thank you all.

Shoot Safe and Often
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