Primer Pictures -- Pressure Opinions? - The Firearms Forum

Josh Smith · 02-01-2012, 06:00 PM

Hi Folks,

I went from 0.318" bullets to 0.323" bullets in my Gew88/05 Commission rifle. The 0.318" bullets were just causing problems.

Here are some pictures of primers. The brass is 7.92x57mmJS (8mm Mauser) formed from Winchester .30-06 brass. Bullets are 150 grain Hornady. Powder charge is 43.5 grains of Varget, and primers are Federal Large Rifle. Published velocity for this load is 2400fps, which is just fine. Figure it might be a bit more with the tight bore.

Two different exposures with their inverted images on the right side

Macro uncut

The primers look like they're fine to me. Do you agree?

Data is from Hornady and the 43.5 grains Varget is their starting load. Hodgdon's starting load is 45.5 grains. Figure I'm safe using 43.5 grains as a start and 46 grains as max -- do you agree?

Also, this is effectively a squeeze bore. The initial slugging of the bore resulted in a groove measurement of a little over 0.318", but subsequent cleaning and shooting have been peeling off grime to reveal something a bit bigger. I still need to slug it again, but it may end up being 0.321" as they were playing with sizes of 0.318" to 0.321" while developing the rifle, and I have an original 1892 barrel. For now I'm assuming a groove diameter of 0.318" to be safe.

Would you have an estimate to what kind of velocity the barrel adds if it's 0.321"? I'm not trying to push the rifle's limits at all; just curious. I know there were squeeze bore barrels made for the .22LR before the advent of the rimfire .17 calibers, and they boosted by a few hundred feet per second.

Subjectively, recoil is about like a .30-30 with 150 grain load, maybe a bit less. Feels good to shoot and if I can find an accuracy node someplace under 46 grains Varget, I'll be a very happy camper.

Thanks!

Josh

cycloneman · 02-01-2012, 06:59 PM

Better give this some time and keep checking back. You should get some good advise before proceeding. LD will probably chime in tomorrow morning. I think something is amiss. But i dont have the knowledge some other have. Hang tight.

Josh Smith · 02-01-2012, 07:31 PM

Hello,

Will do.

I believe it's showing slightly low pressures, right where I want it in fact.

I'd love to have a piezo gun about now..!

Regards,

Josh

Bindernut · 02-02-2012, 10:42 AM

From how I'm reading the primers, you're just fine pressure-wise. They've got nice rounded pin impressions and edges...no flattening at all that I can see.
If the load is warm enough to seal the case neck so there's little or no soot-blow-by then I'd say you've got a good safe load.

JLA · 02-02-2012, 04:57 PM

Looks ok to me. There are no extrusion marks on the headstamp either and the primers have nice round edges. Id say that load is right where it should be despite the oversized bullet.

myfriendis410 · 02-02-2012, 09:04 PM

The primers look fine, but how does the neck look? Is it blackened? That would indicate low pressure and something to be leery of.

02-01-2012, 06:00 PM	#1
Josh Smith V.I.P. Member Join Date: Nov 2009 Location: Wabash IN Contributor Posts: 66	Primer Pictures -- Pressure Opinions? Hi Folks, I went from 0.318" bullets to 0.323" bullets in my Gew88/05 Commission rifle. The 0.318" bullets were just causing problems. Here are some pictures of primers. The brass is 7.92x57mmJS (8mm Mauser) formed from Winchester .30-06 brass. Bullets are 150 grain Hornady. Powder charge is 43.5 grains of Varget, and primers are Federal Large Rifle. Published velocity for this load is 2400fps, which is just fine. Figure it might be a bit more with the tight bore. Two different exposures with their inverted images on the right side Macro uncut The primers look like they're fine to me. Do you agree? Data is from Hornady and the 43.5 grains Varget is their starting load. Hodgdon's starting load is 45.5 grains. Figure I'm safe using 43.5 grains as a start and 46 grains as max -- do you agree? Also, this is effectively a squeeze bore. The initial slugging of the bore resulted in a groove measurement of a little over 0.318", but subsequent cleaning and shooting have been peeling off grime to reveal something a bit bigger. I still need to slug it again, but it may end up being 0.321" as they were playing with sizes of 0.318" to 0.321" while developing the rifle, and I have an original 1892 barrel. For now I'm assuming a groove diameter of 0.318" to be safe. Would you have an estimate to what kind of velocity the barrel adds if it's 0.321"? I'm not trying to push the rifle's limits at all; just curious. I know there were squeeze bore barrels made for the .22LR before the advent of the rimfire .17 calibers, and they boosted by a few hundred feet per second. Subjectively, recoil is about like a .30-30 with 150 grain load, maybe a bit less. Feels good to shoot and if I can find an accuracy node someplace under 46 grains Varget, I'll be a very happy camper. Thanks! Josh __________________ - Smith-Sights Adjustable Sights for the Mosin-Nagant - -->

02-01-2012, 06:59 PM	#2
cycloneman Advanced Senior Member Join Date: Dec 2008 Location: Louisiana Posts: 7,434	Re: Primer Pictures -- Pressure Opinions? Better give this some time and keep checking back. You should get some good advise before proceeding. LD will probably chime in tomorrow morning. I think something is amiss. But i dont have the knowledge some other have. Hang tight. __________________ Who are you going to serve today?

02-01-2012, 07:31 PM	#3
Josh Smith V.I.P. Member Join Date: Nov 2009 Location: Wabash IN Contributor Posts: 66	Re: Primer Pictures -- Pressure Opinions? Hello, Will do. I believe it's showing slightly low pressures, right where I want it in fact. I'd love to have a piezo gun about now..! Regards, Josh __________________ - Smith-Sights Adjustable Sights for the Mosin-Nagant -

02-02-2012, 10:42 AM	#4
Bindernut Advanced Senior Member Join Date: Oct 2007 Location: ND, USA Posts: 2,489	Re: Primer Pictures -- Pressure Opinions? From how I'm reading the primers, you're just fine pressure-wise. They've got nice rounded pin impressions and edges...no flattening at all that I can see. If the load is warm enough to seal the case neck so there's little or no soot-blow-by then I'd say you've got a good safe load.

02-02-2012, 04:57 PM	#5
JLA TFF Moderator/Host Join Date: Feb 2007 Location: Heart Of Texas Contributor Posts: 17,407	Re: Primer Pictures -- Pressure Opinions? Looks ok to me. There are no extrusion marks on the headstamp either and the primers have nice round edges. Id say that load is right where it should be despite the oversized bullet. __________________ It takes 43 muscles to frown, 17 to smile, and 3 for proper trigger squeeze. The latest caliber or gear is no substitute for experience and skill. Rifles and cartridges don't make hits -- shooters do. Fact of life: After Monday and Tuesday, even the calendar says WTF!

02-02-2012, 09:04 PM	#6
myfriendis410 Senior Member Join Date: Mar 2011 Location: Lompoc California Posts: 552	Re: Primer Pictures -- Pressure Opinions? The primers look fine, but how does the neck look? Is it blackened? That would indicate low pressure and something to be leery of. __________________ Life's too short to shoot an ugly gun.....