Unique with X-Treme HPCB 180gr bullets

[sparkyv]

I was gifted a pound of Unique, so I'm planning working up range loads with the X-Treme HPCB 180gr bullets.  I've found load data, but have not seen much discussion about this combo.  Any advice or pitfalls of which i should be aware?  Thanks.

[sqlbullet]

Not with these bullets.

I have used Unique with berry's plated 180 grain, which I would consider very similar/comparable.

6.7 grains of Unique with a COAL of 1.260"  using starline brass and Winchester large pistol primers gave 967.5 fps from my glock 29, 1042 from my Witness full size and 1041 from my Para P-16/40 converted to 10mm.  All velocities are an average of 10 shots.  Extreme spreads were 58, 50 and 61 respectively.  Likewise, case heads were .431", .429" and .426" average of 10, respectively.

Alliant lists 8 grains as max with a 180 grain JHP.  I would expect to get a bit above that with these bullets since they are shorter.  Velocity at max load with Unique is going to be between 1150 and 1200 fps.

[sparkyv]

Thanks for the info, sqlbullet.  Pretty much what I thought.  With this info and all RDub01s work, I'm confident that I can work up a decent range load.  Regarding measuring the case heads, can you point me to some online source on this technique?  I've read positive and negative comment on thus technique, but can't find a "how to".  Thanks.

[sqlbullet]

http://www.hodgdonreloading.com/reloading-education/tips-and-tricks/simple-trick-monitoring-pressure-your-rifle-reloads

This is about the best guide I have found.

That said, I have found the chamber makes a big difference in how much expansion occurs as well.  I know for each of my guns what happens with factory ammo, and I look for those values.  For instance, as you can see below, my glock has a much more "generous" chamber than my Witness or Para.  As a result I see lots more expansion in these chambers.  This is the same reason push through sizing dies have become more common.

[tommac919]

"generous" is a nice way to said it...

In my G20 (stock ), I've noticed that .432-.4325 expansion is on the low loads for my gun/barrel. Mid range+ loads for me at .433
Highest I've seen is .4335 at book maxes and slightly above. ( never seen a .434 )

Take these same loads in the Sig 220/10mm and I'll only see .425-.427  ( .427 were the hottest comm rounds I could find )

Each gun is different and it takes time to learn what is normal for each.

[sparkyv]

I'm a bit confused sqlbullet and tommac919. The Hodgdon article says that this technique works only on new brass.  For me, this may not be too useful as I plan to mostly use brass fired multiple times.  Are you using new brass that was associated with the reported expansion data?

[The_Shadow]

sparkyv, you can recondition your brass with pass through sizing before resizing and depriming with standard dies.  I use a LEE FCD with its guts removed as the BULGE BUSTER pass through die and it gives me a complete sizing top to bottom that includes the casing rims at 0.4225"-0.4230".  This process gets where standard dies can not reach because of the radius inside the sizer die and the shell holder occupying the area that is expanded.

I have found this process of pass through sizing top make more uniformed cartridges, and primer pockets even benefit too.

When your cartridges are shot in various firearms the area at the feed rams can be out of round and less supportive allowing casing brass to expand or stretch to its limits or even exceed them.

Glock factory chambers the expansion is around 0.4340" and any thing exceeding that number is likely starting to "SMILE" which exceeds the brass strengths.

[tommac919]

sparkyv...

you can get these measurement from new factory ammo to start with ... compare the 'new' brass to all your others.
this is where i got my first measures from.

Or if you need, PM me your address and I'll send you a dozen new Starlines for Christmas 

[sparkyv]

Your idea makes sense The_Shadow.  Up to now, I was using my bulge buster only to iron out the few loaded rounds I produce that won't drop in my cartridge gauge.  I will start running fired brass and monitor case expansion, and determine my baseline using new brass, tommac919.  Thanks for all the advice.

[sparkyv]

sparkyv...

Or if you need, PM me your address and I'll send you a dozen new Starlines for Christmas 

Thanks for the offer tommac919, but I've got some new Starline cases that I'll be loading up soon.  BTW, have you evaluated new SIG brass? I have some of that too, but wonder how it compares to Starline.

[tommac919]

Have fired some of the factory Sig ammo....pretty good for factory.
But that brass went into the mixed brass bucket and hasn't been reloaded yet.

Can only say that Starline is a nice brass for reloaders as it's malleability is on the high end