.50 BMG Reloading--Primer Setback Problem--Need Help.

larphred · February 18, 2007, 21:46

I have been reloading for decades, but am new to .50 BMG reloading. I have a Barrett 99 and one of the first things I noticed was that when I chambered an empty brass case, the extractor didn't engage the rim and extract the case, whereas my other bolt guns do extract an empty cartridge.
Next, I shot some tracers to break in the barrel and they functioned flawlessly--I thought they were AP, because they had a black tip but turns out they were tracers. Then I shot some HSM reloads both ball ammo and AMAX. Surprisingly bad groups at 100 yds.: 1.5-2 in.
So I tried reloading some 700 g. AP bullets (which I resized) using Hirtenberger primers and H5010 powder (surplus). A reloader friend who has shot/reloaded .50s for years recommended 220g H5010, which checked out as okay in the Barnes reloading manual. The first round fired backed the primer our 0.020" and significantly flattened (almost mushroomed) it. I pulled those bullets and dropped back to 205g H5010 and the primer setback was the same. I haven't measured the case with a micrometer, but it does appear slightly bulged about 1/4" from the head.
The only two options I can come up with are either the surplus powder was mismarked and is not H5010 or maybe the headspace of my rifle is out of spec.
Anybody have any other ideas?

kycrawler · February 18, 2007, 22:46

sounds like your oversizing (actually making them too small) your cases in effect creating an excessive headspace problem because the case is too small for the in spec chamber

February 18, 2007, 21:46	#1
larphred Registered FALaholic #: 1555 Join Date: Nov 2000 Location: Sandy, Ut. Posts: 3,098	.50 BMG Reloading--Primer Setback Problem--Need Help. I have been reloading for decades, but am new to .50 BMG reloading. I have a Barrett 99 and one of the first things I noticed was that when I chambered an empty brass case, the extractor didn't engage the rim and extract the case, whereas my other bolt guns do extract an empty cartridge. Next, I shot some tracers to break in the barrel and they functioned flawlessly--I thought they were AP, because they had a black tip but turns out they were tracers. Then I shot some HSM reloads both ball ammo and AMAX. Surprisingly bad groups at 100 yds.: 1.5-2 in. So I tried reloading some 700 g. AP bullets (which I resized) using Hirtenberger primers and H5010 powder (surplus). A reloader friend who has shot/reloaded .50s for years recommended 220g H5010, which checked out as okay in the Barnes reloading manual. The first round fired backed the primer our 0.020" and significantly flattened (almost mushroomed) it. I pulled those bullets and dropped back to 205g H5010 and the primer setback was the same. I haven't measured the case with a micrometer, but it does appear slightly bulged about 1/4" from the head. The only two options I can come up with are either the surplus powder was mismarked and is not H5010 or maybe the headspace of my rifle is out of spec. Anybody have any other ideas? __________________ Michael O'Sullivan was my great friend. But I don't ever remember telling him that. The words that are spoken at a funeral are spoken too late for the man who is dead. What a wonderful thing it would be to visit your own funeral. To sit at the front and hear what was said, maybe say a few things yourself. Michael and I grew old together. But at times, when we laughed, we grew young. If he was here now, if he could hear what I say, I'd congratulate him on being a great man, and thank him for being a friend. -------------------------------------------------------------------------------- --the forty-four spoke and it sent lead and smoke, and seventeen inches of flame. ----Marty Robbins

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February 18, 2007, 22:46	#2
kycrawler Registered FALaholic #: 19787 Join Date: Apr 2006 Location: Crawfordsville IN Posts: 1,274	sounds like your oversizing (actually making them too small) your cases in effect creating an excessive headspace problem because the case is too small for the in spec chamber