Another newbie looking for direction

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Re: Another newbie looking for direction

Postby Hoot » Tue Jul 12, 2016 5:02 am

Bmt85 wrote:Thanks guys, appreciate the help.
I think I'm going to put the 230gr with Rem brass loads on hold for a bit. I really need work up hunting loads. I picked up some 200gr xpb for deer hunting, so ill work on those, then the 275's, using hornady brass. Hopefully get a base down on this.


Excellent choice on the 200 XPB. The near perfect bullet for white tails in the 450b. Lots of documentation on load recipes also.

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Re: Another newbie looking for direction

Postby Bmt85 » Fri Sep 16, 2016 9:45 pm

Ok, so I did some work up and even did some hunting. But have a question.
200 TSX, worked up to 42.5gr lilgun on once fired Hornady, no pressure signs, and pretty good accuracy.
275 TSX, worked up to 41.0gr lilgun (have a carbine length gas system, so thought I might run lilgun instead of 296) on new Hornady brass, primers were perfectly fine, very, very light ejector marks, and chg between .0011 and .0020".
However, I went on a bear in Maine a couple weeks ago with the 275 TSX load and don't know what happened. I fired 2 shots, one during sight in and one to kill the bear. Lost the one that I shot the bear with, but saved the one during sight in. It had pretty heavy imprinting of both ejector and extractor, chg was .0030", and brass grew from 1.697" to 1.7". Primer look good though. Kind of wondering what happened. Temp was a about 5-10 degrees cooler than work up temps, the rifle wasn't sitting in the sun, and it was a cold bore. Kind of at a lost. Only thing I can think of is that it's new brass and really soft, but it should have showed something in the work up loads, especially since it was a hair warmer, and I wasn't working with a cold bore during work up.
What happened?
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Re: Another newbie looking for direction

Postby Al in Mi » Sat Sep 17, 2016 10:41 am

I haven't played much with the 275gr Barnes in the AR, but 41gr seems a little high with Lilgun.
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Re: Another newbie looking for direction

Postby Hoot » Sun Sep 18, 2016 8:13 am

When you tested your ammo prior to being out on a hunt, which is a bad place to discover issues, was that batch from the same lot number of Lil Gun as the ones you hunted with?
Powder does vary somewhat from lot to lot.
To what C.O.L. were the 275s loaded in order to get the taper crimp to catch a driving band groove?
I ask because if you look at loads modeled using the Quickload software, As you get to max load, a variance in .05 inches COL can sometimes run the pressure from upper safe to whoa baby!
41gr would be up near the top of the range at 2.18 COL from my experience with the 275 XPB, but the XPB is not the TSX. Bullets can have very similar looks to one another and still be physically different inside. Have you mic'd the 275 TSX bullets? Emphasis on measured with the more accurate micrometer as opposed to with calipers.

The enigma is that the load issues you encountered in the field, should have shown up in practice as well, all else being equal. That's a head scratcher.

Bottom line is when you're loading up near the top, it doesn't take much variation in any of the contributing factors, to step over the line.

I'll throw this out there despite it not getting much airplay on this forum. Bore humidity can impact the resistance to the bullet traveling down it more than you might think. Resistance contributes to pressure.

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Re: Another newbie looking for direction

Postby pitted bore » Mon Sep 19, 2016 7:13 pm

A question, possibly irrelevant:
Was the rifle operated similarly in the load testing and hunting situations? If not, is it possible that the slam-bang of semi-auto loading might have altered the bullet seating depth of the bullet, and changed the pressure response of the powder? If the bullet was seated so that the bullet was pretty close to the lands before loading, a good slam into the chamber may have jarred the bullet so that it contacted the lands, which would likely raise pressure.

Could a bullet hitting the feed ramp during the loading cycle have forced the bullet deeper into the case, which might also increase pressure?

I'll readily admit ignorance about fine (and not so fine) points of AR operation.
--Bob
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Re: Another newbie looking for direction

Postby Bmt85 » Thu Sep 22, 2016 4:58 pm

Sorry I didn't get back sooner, I've been extremely busy lately.

All components are from the same lots.
C.O.L : 2.335-2.34", that's to crimp into the front of the first groove. I cut out part of the front of the mag to load that long. Bullet is into lands at 2.4175"
Max case fill at that C.O.L is about 43.2gr for lilgun.
Taper crimp - .473
Stab crimp - .473
Bullet diameter is .4502-.4510, most measurements .4504.
Brass used was between 1.6955-1.6970" long, same as when doing load workup.
Temp difference was 5-10* cooler in Maine
Humidity was about the same, humid here, humid there. No exact numbers.
Elevation is about 500' lower in Maine.

One thing I thought about today, I don't remember cleaning the barrel after load workup. Some people have an issue with Barnes bullets copper fouling quickly, so maybe?
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Re: Another newbie looking for direction

Postby Bmt85 » Thu Sep 22, 2016 5:37 pm

Pitted bore, as to operation it's usually the same. Normally I load all 3-4 rounds for one charge weight into the mag and fire slowly. When hunting I load 5 in the mag and charge the weapon, I don't add another round after, I just carry 5. When sighting it in before the hunt, it was just the one round in the mag, charged the rifle, and shot.
After the kill shot, I didn't see any length change, but I should check them again to make sure.
I have the taper crimp into the front of the driving band, so length shouldn't get shorter. Might get longer, but that should reduce pressure shouldn't it (as in more case space)? I could be wrong.
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Re: Another newbie looking for direction

Postby Bmt85 » Sat Nov 05, 2016 4:06 pm

So I found my problem, the bore was horribly copper fouled. Took forever to clean it and finally got to the range. I shot 3 rounds with new brass (loaded from bear hunt) and 4 rounds with twice fired, all running 275gr TSX and lil gun. The new brass chg was .0008", .0009", and .0012". The twice fired brass chg was between .0005" and .0009". Only one of the new brass showed very, very light imprinting. Primers looked good for the most part, a couple slightly flattened.

Going to work on other loads, then come back to the TSX's with 296.
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Re: Another newbie looking for direction

Postby Al in Mi » Sun Nov 06, 2016 6:33 am

I had a 30-378 Weatherby that was a tack driver with 180gr Barnes to about shot #35 then things went bad bad in a hurry. Clean the barrel, and yes it was a chore, shoot 3 foulers and was ready to roll again.
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