9mm: FMJ vs. LRN Load Data

I don't think leading is the issue, excess pressure is.

Lead has less friction than a jacket so it will likely be going faster than the jacketed bullet, likely compounding any leading issue.

Peak pressure would be lower with a slicker projectile though, at least until the bore becomes constricted with the lead build up.

At some point the base of the bullet will be the weak link and accuracy will fall off substantially, this is why gas checks exist on some cast bullets.

Why?

There's a plethora of data out there for lead bullets in 9mm.

You are asking about two very different bullets. Different metals, different friction, different needs. If you are a newer reloader, don't try to extrapolate load data from jacketed to lead and as Texas 10mm says there is plenty of info available, use the proper data.

If you are asking just because you wanna know, see the answers above, and/or do some reading; http://www.lasc.us/castbulletnotes.htm http://castboolits.gunloads.com/

There's really no need to substitute or extrapolate data in this case. There's lots of 9mm lead info out there, I'd just use that.

Pressure should be lower with lead bullets, but, I don't have a pressure gage I only have physical indications to examine. Which are very unreliable at measuring pressures.

The best solution is to stick with mid range loads. Pushing the envelope will always create pressure future problems. There are simply too many variables, subject to change without notice, to be dancing on the edge.

Catpop said:

My current inability to find any 9mm 115 gr LRN for WSF data led me to ask the question.

If you have a source for this data please share it with me. I really need it.

In situations like this, I usually reduce FMJ data 10% as a starting point for same weight boolits.

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Try the Hodgdon web site. Their reloading data shows both lead and jackets bullets using WSF. I personally have no experience with it.

Catpop said:

My current inability to find any 9mm 115 gr LRN for WSF data led me to ask the question.

If you have a source for this data please share it with me. I really need it.


In situations like this, I usually reduce FMJ data 10% as a starting point for same weight boolits.

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I checked hodgens site found 124 lrn data. It is likely that was is too slow a powder for a 115 bullet. If that is the only powder you have it's better to use lead data from a higher weight bullet or try a different powder altogether. The Second is a better option.

Using a powder that is too slow can cause ringing, or bulging in your barrel and a 30 dollar can of powder is cheaper than blowing up a gun.

Catpop said:

Aside from the increased possibility of barrel leading, is there another reason to not directly substitute FMJ loading data for LRN reloading?

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Consider this.

Before the advent of jacketed bullets, all bullets were made from lead. And as velocity increased, to reduce leading, lead was alloyed harder and harder (BHN 10 all the way to BHN 22-24). But when harder lead alloy did not fully address the leading issue even after sizing the bullet diameter .001"-.002"+ larger than groove diameter of the barrel, gas checks that covered the bullet base were used to not only address leading issues but to prevent gas cutting/bullet base erosion from high pressure gas.

And what are modern jacketed/plated bullets? They are all lead/alloy bullets with full-length gas checks.

Catpop said:

My current inability to find any 9mm 115 gr LRN for WSF data led me to ask the question. If you have a source for this data please share it with me. I really need it.

In situations like this, I usually reduce FMJ data 10% as a starting point for same weight boolits.

Click to expand...

When I am conducting load development for bullet weight I cannot find load data for, I will reference load data for slightly higher bullet weight.

Here are Hodgdon and Speer lead/plated/jacketed load data for 115/124 gr bullets and WSF - http://www.hodgdonreloading.com/data/pistol

• Hodgdon 115 gr FMJ WSF Dia .355" COL 1.169" Start 4.9 gr (1,060 fps) 24,200 PSI - Max 5.7 gr (1,195 fps) 31,900 PSI

• Speer 115 gr TMJ WSF Dia .355" OAL 1.135 Start 5.0 gr (1041 fps) - Max 5.6 gr (1156 fps) - https://www.speer-ammo.com/download...m_caliber_355-366_dia/9mm_Luger__115_rev1.pdf

• Hodgdon 124 gr Lead RN WSF Dia .355" COL 1.169" Start 4.0 gr (945 fps) 22,200 PSI - Max 4.7 gr (1,055 fps) 27,300 PSI
  
  
• Hodgdon 124 gr FMJ WSF Dia .355" COL 1.169" Start 4.7 gr (1,015 fps) 27,700 PSI - Max 5.3 gr (1,115 fps) 32,700 PSI

Had you used 10% reduction of jacketed load data for 124 gr Lead RN, you would have ended up with start/max charges of 4.23 gr/4.77 gr when published lead load data start/max charges are 4.0 gr/4.7 gr. Using 12% reduction of jacketed load data produces start/max charges of 4.13/4.66 gr which I think better reflects published lead load data without going over max.

Another key factor is OAL, or more specifically, bullet seating depth as Lead RN bullets tend to be loaded shorter like 1.125" OAL compared to 1.130" for 115 gr FMJ/RN for me.

So using 12% reduction of more conservative plated load data that uses shorter 1.135" OAL, we get start/max charges of 4.4 gr/4.9 gr. If your OAL of 115 gr Lead RN is shorter (and likely larger sized at .356" - Note that Hodgdon used smaller .355" sized 124 gr Lead RN for their testing), I would just reference published lead load data that uses longer 1.169" OAL with start/max charges of 4.0 gr/4.7 gr.

I hope this helps.

I hope things work out.

Side question: Which data do you guys guys use for plated bullets? Somewhere between LRN and FMJ?

I usually erred towards LRN data, but maybe that is not correct.

LiveLife said:

Another key factor is OAL, or more specifically, bullet seating depth as Lead RN bullets tend to be loaded shorter like 1.125" OAL compared to 1.130" for 115 gr FMJ/RN for me.

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Read and heed! In my early days of 9mm reloading... for a BHP... I got into trouble loading Unique to max or near max. I would get primer cratering and primer flow with what should have been a safe load. Hindsight being 20/20, I'm sure it was combination of factors, but largely bullet seating depth.

Fite Man said:

Side question: Which data do you guys guys use for plated bullets? Somewhere between LRN and FMJ?

I usually erred towards LRN data, but maybe that is not correct.

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I've always used jacketed data, but stay at least 10% below max, and below the max rated speed for the bullet.
When I used to chrono everything, plated bullets always seemed to match up closer to predicted jacketed velocities.

Fite Man said:

Side question: Which data do you guys guys use for plated bullets? Somewhere between LRN and FMJ?

I usually erred towards LRN data, but maybe that is not correct.

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Depends on the brand and thickness of the copper plating.

Way back when plated bullets started, plating thickness was thin and often plating would fail when pushed to jacketed velocities. Then companies started increasing the plating thickness and started selling "thick plated" bullets that could be driven to jacketed velocities without plating failure.


FYI, gilding metal thickness used for jacketed bullets are thicker than .015". And unless things changed, these are plating thickness for various copper plated bullets - https://www.thehighroad.org/index.p...ng-at-25-50-yards.808446/page-3#post-10470195

"Regular" plated bullets typically have around .004" plating thickness with 1200 - 1250 fps max velocity rating. However, max velocity rating applies to plating failure, not accuracy. For me, regular plated bullets, even with 1200-1250 fps rating, when pushed to jacketed load data velocities start to lose accuracy around mid-range load data.

"Thick" plated bullets typically have around .010"+ plating thickness but some companies call .008" thickness "thick plated". Thick plated bullets are rated to 1500 fps max velocity and can be driven to full jacketed load data velocities.


Many published and online load data now include various brand plated load data and if that's the case, I would use plated load data. If you are using regular plated bullets and can't find load data for your brand bullet, I have used lead load data with regular plated bullets with good results.

If you are using thick plated bullets rated to 1500 fps, you should be able to use jacketed load data.

FYI, if you reference Speer load data, you will see TMJ and Gold Dot HP bullets. Total Metal Jacket is Speer trademark for thick plated bullets with around .015" thickness and Gold Dot HP bullets have around .018" thickness and their load data will often show higher start/max charges than some jacketed load data. If you are referencing Speer TMJ load data and using regular plated bullets, I would be conservative and consider reducing max charges - https://www.speer-ammo.com/reloading/handgun


BTW, whether using regular or thick plated bullets, exercise care to not use too much taper crimp or you may end up cutting through the plating or deform/reduce the bullet diameter which will decrease neck tension to increase bullet setback. Since case wall thickness averages .011", I usually add .022" to the diameter of bullets for taper crimp amount.

And not all 9mm bullets are sized the same - https://www.thehighroad.org/index.p...re-sized-the-same.818806/page-2#post-10567453

So for .355" sized X-Treme plated bullets, you want to use .377" taper crimp.

And for .3555"-.356" sized TMJ/Berry's/HSM/RMR plated bullets, you want to use .378" taper crimp.


As to accuracy, many reloaders found plated bullets often do not produce the accuracy of jacketed bullets and like Berry's MFG, started increasing bullet diameter to improve accuracy of their bullets. Berry's pushed the accuracy further by developing hollow base bullets with thick plating that produce accuracy on par with jacketed bullets. Speer TMJ and other brand plated bullets have used dished or concave base to help with bullet base deformation.

Picture showing Berry's regular 124 gr "solid base" plated bullet next to 124/115 gr "hollow base" plated bullet. (Notice 124 gr solid base bullet with similar bullet length to 115 gr hollow base bullet)

Catpop said:

My current inability to find any 9mm 115 gr LRN for WSF data led me to ask the question.

If you have a source for this data please share it with me. I really need it.

In situations like this, I usually reduce FMJ data 10% as a starting point for same weight boolits.

Click to expand...

Hint; this is why I always find a load in my manuals before I buy any components. Saves a lot of time and frustration. A bunch of years ago I wanted to try a specific bullet in one of my 44 Magnums, bought the bullets but found no data for the powder I wanted to try. Those 300 gr (?) bullets sat around my shop for quite a while and were eventually melted and cast into 150 gr DEWCs for my 38s...

PO2Hammer said:

I don't think leading is the issue, excess pressure is.

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Exactly.
EVERYTHING we do in reloading is to control chamber pressure.
.