Loading for the 185 gr LBT LFN bullet from Montana Bullets

[Spudmeister]

I've been shooting and hunting with 200 gr WFN very hard cast bullets in a G20 and G40 for years.  But the question came up... what is possible if I go to a somewhat softer and lighter bullet that is less invasive in the 10mm case?  This story attempts to answer those and other questions. 

The first decision was to go to a softer bullet.  Instead of a bhn of 20+ I went with the 15 bhn that Montana Bullets offers for some of their bullets.  A softer bullet (all things being equal) will obturate at a lower pressure, seal the bore and help prevent leading especially when there is no gas check.

The second decision was to shift from a WFN bullet design to an LFN bullet design.  This allows the bullet to be seated out to a SAAMI max of 1.260".  The bullet tested here is a 185 gr LBT design LFN.  The LFN design guarantees it will feed if anything will. 

Sooooo..... If I can pull this off there will be little to no leading, a nice increase in velocity or decrease in pressure, good accuracy in aftermarket barrels and a flatter trajectory.  In other words, read on and see if I got lucky.


All the accuracy testing and load development was done in a G40 with a 6" KKM barrel.  Testing began with 25 brand new Starline cases that were used over and over throughout the testing.  All primers are CCI large pistol std.  The bullets are the Montana Bullet works 185gr LBT LFN plain based bullet cast and air dried to a bhn of 15. I prefer Longshot with 200 gr cast bullets.  But I felt the 185 gr bullet would be too light/slick for this powder to get good ignition and switched to Power Pistol. Other velocity testing was done with a G20 with a 4.6" OEM barrel, a 5.3" Storm Lake barrel and a G29 with a 4.7" ported barrel.  In all the testing there were no failures of any sort.  All guns ran 100%.


Let's start with the basic load data.  G40.  6" KKM barrel and Power Pistol powder

POWDER                        MV                   ES

9.4 gr    PP                            1366 fps                       57 fps
9.6 gr    PP                            1366 fps                       52 fps
9.8 gr    PP                            1374 fps                       31 fps
10.0 gr  PP                            1382 fps                       23 fps
10.2 gr  PP                            1407 fps                       46 fps
10.4 gr  PP                            1420 fps                       48 fps


None of the loads tested showed any signs of excessive pressure (which is somewhat in the eye of the beholder) but the 10.4 gr load was showing some considerable slide velocity and slinging the empties quite a ways. A hot load in a G20 typically seems mild in a G40.  But you gotta settle somewhere so I settled on the 10.0 gr load of Power Pistol powder.  It has the lowest es which proves absolutely nothing and even less on a single test but... it looked like a good place to settle.  So on to further testing. 

Each load tested appeared to obturate the bullet in the barrel.  After each days testing some Ballistol and a tight patch was put down the barrel to remove any lube and residue.  In effect, it left only the leading behind.  It darned near took a microscope to see the slightest amount of leading and this was the case for all loads tested.  The barrel was thoroughly brushed/scrubbed clean then for the next days testing. 

Accuracy is tough for me to measure.  Mostly because I am not a great shot.  But it was about 2.5" at 25 yards and 5.5" at 50 yards. If I miss the hog it won't be the gun/loads fault. 

So it looks like a good load.  Now to test for MV and ES in some different guns.  10.0 of Power Pistol.


                                                                           MV                         ES
G20 with 5.3" Storm Lake barrel                        1381 fps                 39  fps

G20 with 4.6" OEM barrel                                  1312 fps                   46 fps

G29 with 3.8" OEM barrel                                  1243 fps                   60 fps
                 
G29 with 4.7" ported barrel                               1327 fps                   47 fps

G40 with 6.0" OEM barrel                                  1375 fps                   54 fps

The brass fired in the OEM barrel showed little difference from the more supportive KKM barrel.  No smiles. 

A total of 11 rounds was fired in the 4.6" OEM G20 barrel.  Leading was more than with the 6" KKM barrel but not bad. 


That about wraps up this phase of the testing.  I was looking for a good load in 10mm with the 185gr Montana bullet and found it. Velocities are up 100-150 fps vs the 200 gr hard cast loads I've been shooting. The G20 probably needs a heavier recoil spring with the KKM barrel.  It may go hog hunting next year.  But for now I'll load up a hundred and see how they do in the longer term. 


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[The_Shadow]

I have to laugh a little

Power Point powder

   Spudmeister I think you meant Power Pistol Powder...

[Spudmeister]

I have to laugh a little

Power Point powder

   Spudmeister I think you meant Power Pistol Powder...

Some days I just hate being human.  Thank you for the catch.  In my working career I wrote/gave many hundreds of Power Point presentations and have only been working with Power Pistol for a few years.  The crazy part is I proof what I write many times before posting but I could have proofed it 100 more times and not picked up what you did on the first reading.  Professionally I always got somebody else to proof my work.  It did not always make me look smart but it always made me look smarter 

[The_Shadow]

I hadn't tried Power Point Powder yet!      
I always look to see what people are using though!  The 6" barrels do help bring about good velocities!  Thanks for your report! 

[Taterhead]

Hah. Loved the Power Point powder reference too! Spent about 5 hours today working on a presentation for Friday and will complete it tomorrow. Corporate finance and all that.

Nice report and nice results. I think that some guys over emphasize the need to go with super strong alloy in 10mm.

15 should be plenty, and that would have been super hard by Elmer Keith standards.

[Spudmeister]

So I loaded those 100 rounds of the 185gr bullet with 10.0 gr of Power Pistol (or is it Power Point?) and fired them all yesterday.  They were fired in a gen 4 G29 with OEM and 4.7" KKM barrel, a gen 3 G20 with OEM and 5.3" Storm Lake barrel with 22# Wolf spring and a G40 with OEM and 6" KKM barrel.  While I was at it I filled in all the "holes" in velocities for all the barrels.

There were zero malfunctions.  Not even a hint of a problem.  That includes 1 handed mag dumps which just begs for trouble.  The 22# spring on the G20 seemed just right.  Brass flew 8-12 feet.  To be fair, the G29 with OEM barrel was quite the handful one handed but the 4.7" ported barrel made it a measure easier.  As usual the G40 eats up recoil like my grand daughter eats ice cream.  If something big and toothy were headed my way the G40 is the best though it carries the worst.

The updated velocities have been added to my original post.  I was surprised to see OEM barrel velocities so close (per inch) to the aftermarket barrel.  Just for the heck of it I got back 15 yards and fired 5 rounds with each barrel offhand to see if the bullets went to a different spot.  2 pics are below.  I don't think it proves anything but everybody likes pictures    .




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[The_Shadow]

Thanks for the added info Spudmeister... 

[5pins]

What size diameter did you get them in, .400" or .401"? I wonder if there would be any benefits with the 22 BHN bullet?

[Spudmeister]

5pins,

Sorry.  I should have mentioned the bullets are sized to .401" . 

All things being equal the softer the bullet the less pressure it take for it to obturate.  That is for enough pressure/push behind it for it to expand and fill the lands and grooves of the barrel.  At one end of the spectrum I load standard pressure 38 specials with 158gr bullets.  They are pure lead  (bhn 6 or so)being driven about 800 fps.  When done correctly I get zero leading.  A harder bullet would not have enough pressure pushing it to obturate the bullet and you may get gas blow by of the bullet and that leaves a lot of lead in the barrel.  In this example the harder bullet gives poorer accuracy and cruds the barrel up with lead quickly.

But when I had a 444 Marlin I shot 22 bhn 330gr gas checked bullets at 2,000 fps with no leading.  I am simplifying it some but the point is the hardness of a bullet is neither good or bad but whatever suits the need.  I've had really good luck with 21-22 bhn bullet in the 10mm and a few other guns but not much in lighter loads.   The 15 bhn with the 185gr is doing quite well and I don't see any advantage to making the bullets harder. 

[Taterhead]

5pins,

Sorry.  I should have mentioned the bullets are sized to .401" . 

All things being equal the softer the bullet the less pressure it take for it to obturate.  That is for enough pressure/push behind it for it to expand and fill the lands and grooves of the barrel.  At one end of the spectrum I load standard pressure 38 specials with 158gr bullets.  They are pure lead  (bhn 6 or so)being driven about 800 fps.  When done correctly I get zero leading.  A harder bullet would not have enough pressure pushing it to obturate the bullet and you may get gas blow by of the bullet and that leaves a lot of lead in the barrel.  In this example the harder bullet gives poorer accuracy and cruds the barrel up with lead quickly.

But when I had a 444 Marlin I shot 22 bhn 330gr gas checked bullets at 2,000 fps with no leading.  I am simplifying it some but the point is the hardness of a bullet is neither good or bad but whatever suits the need.  I've had really good luck with 21-22 bhn bullet in the 10mm and a few other guns but not much in lighter loads.   The 15 bhn with the 185gr is doing quite well and I don't see any advantage to making the bullets harder.

This is a really good post. It is a common misconception that all you need to do to avoid leading is to use harder alloy. As you explained, not so simple.