Barnes 200gr XPB and 275gr TSX

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Re: Barnes 200gr XPB and 275gr TSX

Postby mcb » Tue Jul 25, 2017 6:30 pm

Bmt85 wrote:Resized Remington 405gr?


Yeap

I don't have a set of micrometers so I did the best I could with my good Mitutoyo calipers.

Once fired Hornady brass fresh out of my sizing die:

.4990
.4995
.4990
.4995
.4990

The 37.5 gr Lil'gun, 200gr PBX load:

.5005
.4995
.5000
.5000
lost one

The 39.0 gr Lil'gun 200gr PBX load

.5010
.5000
.5005
.5010
.5000

I have not trimmed my brass at all yet so I am not sure case length data will help much here. I have never tried to monitor Case Head Growth. I have done a ton of reloading but to date is almost all pistol (to feed my USPSA addition) and shotgun so I would be grateful for an interpretation of what the above data might indicate. Always looking to learn. Thanks!
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Re: Barnes 200gr XPB and 275gr TSX

Postby Hoot » Tue Jul 25, 2017 7:51 pm

Were those resultant case head growth numbers before or after resizing? They usually get a little narrower and a little longer after resizing. Now, if those dimensions are after resizing, you have about one more repeat of those 39gr loads before the cases will start binding in the chamber on the next reload. I'm guessing they were before resizing. You have a learning opportunity if you're up for it. Mark them and also measure the length. Wipe them off with a rag with a little mineral spirits or other mild solvent on it, dry them, lube and resize them. Then take the diameter and length measurements again.

All that having been said, You strive to keep the case head diameter growth to less than .005 increase that doesn't resize back at the most. Otherwise, you'll hit the diameter wall in about 4 reloads. Tamer loads don't cause such irreversible growth. I myself, do not reload 1st fired brass more than 4 times or for a total of 5 reloads. As their diameter grows, that metal has to come from somewhere and where it comes from is often less length length. Usually around 5 reloads, I hit the 1.685 length or .5015 diameter threshold which lands them in the "charity" peanut butter jar. I know bolt action enthusiasts don't have the same issues as the AR platform in this caliber.

Hoot

EDIT: Don't ever trim 450b cases.
In Theory, there is no difference between theory and practice. In Practice, there is.
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Re: Barnes 200gr XPB and 275gr TSX

Postby mcb » Tue Jul 25, 2017 8:30 pm

Those where measured as fired. I have not resized them yet. I will measure their length and resize them and measure them again.

ETA:

The five cases fired with the 39 gr load:

Fired: .5000 1.688 Sized: .5000 1.691 Change .0000 .0030
Fired: .5000 1.690 Sized: .5000 1.694 Change .0000 .0040
Fired: .5005 1.692 Sized: .5050 1.696 Change .0000 .0040
Fired: .5010 1.687 Sized: .5010 1.689 Change .0000 .0020
Fired: .5010 1.691 Sized: .5010 1.692 Change .0000 .0010

I found it interesting the diameter at just above the extractor did not change.
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Re: Barnes 200gr XPB and 275gr TSX

Postby Hoot » Wed Jul 26, 2017 8:21 am

mcb wrote:Those where measured as fired. I have not resized them yet. I will measure their length and resize them and measure them again.

ETA:

The five cases fired with the 39 gr load:

Fired: .5000 1.688 Sized: .5000 1.691 Change .0000 .0030
Fired: .5000 1.690 Sized: .5000 1.694 Change .0000 .0040
Fired: .5005 1.692 Sized: .5050 1.696 Change .0000 .0040
Fired: .5010 1.687 Sized: .5010 1.689 Change .0000 .0020
Fired: .5010 1.691 Sized: .5010 1.692 Change .0000 .0010

I found it interesting the diameter at just above the extractor did not change.


That's the heartbreak of Case Head Growth. One thing I did, was customize one of my RCBS #3 shell holders by milling off some of its height in the interest of sizing further down the case. Kinda akin to the effect that AR Small Base sets have. It'll buy you back a little diameter, but it's not a miracle worker.

Hoot
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Re: Barnes 200gr XPB and 275gr TSX

Postby mcb » Mon Sep 18, 2017 7:49 am

Finally got back to do some shooting. I had loaded up the remaining Barnes 275gr bullets I had on hand as that is the bullet I am planning on hunting with this year. The load was as I loaded early in the thread.

Bullet: Barnes 275gr TSX
Brass: Hornady (once fired)
Primer: Winchester Small Rifle
OAL: 2.260
Crimp: .475
Powder: Hodgdon H110
Charge 2: 33.5gr
Average: 1923fps (2257 ft-lbs)


This time my scope stayed tight. Still not shooting as good of groups as I would like but certainly minute of deer vitals.

100 yards, 8-shots. ~2.8 inch group.

Image

Not sure why I get the occasional flier high. I am measuring every powder charge on my scale. What else should I be looking at?
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Re: Barnes 200gr XPB and 275gr TSX

Postby Al in Mi » Mon Sep 18, 2017 8:15 am

How long between shots were the 8?

barrel might be getting warm
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Re: Barnes 200gr XPB and 275gr TSX

Postby mcb » Mon Sep 18, 2017 8:48 am

Shot where fairly slow with two short breaks. Three shots, pause, three shots, pause two shots. I could still grab the barrel without discomfort when I was done so I don't thing heat is very likely in this case.
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Re: Barnes 200gr XPB and 275gr TSX

Postby plant_one » Mon Sep 18, 2017 11:25 am

if you're breaking contact with the rifle on those pauses, you may be getting a different cheek weld when you reposition on the rifle. however without knowning the order of the shots on paper thats just a possible.

however that alone can move your groups around on you.


accuracy = consistency ------ both at the reloading bench and the shooting bench
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Re: Barnes 200gr XPB and 275gr TSX

Postby Hoot » Mon Sep 18, 2017 1:26 pm

This thread is getting a little long in the tooth so I forget if you covered this already: Those .475 crimps. Were they down into a driving band groove? That would require a COL that would allow you to line up a driving band groove with the mouth. I may be repeating myself but I seat Barnes so that the driving band groove is mostly buried beneath the mouth and just a little of it peeking out. That allows the taper crimp die to drive the mouth down onto the groove as much as possible. The sharp edges of the groove hold on very effectively. Much more positive than driving a taper crimp down into a cannelure. Usually, that keeps the velocities close and subsequently the vertical component of the POI. You can safely drive those 275's 200-250fps faster. That benefits their ballistic performance due to their length.

Hoot
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Re: Barnes 200gr XPB and 275gr TSX

Postby mcb » Mon Sep 18, 2017 1:57 pm

I will double check tonight but I believe I was seating them just beyond the front most driving band grove so the crimp was coming down on the bearing surface of the bullet not into one of the grooves. I will have to set the bullet out just a touch longer and try crimping into the groove on a future batch and see if that helps. -thanks
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