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Posted: 8/30/2015 10:27:25 AM EDT
These cases are Widener's primed never fired Lake City Brass.  Bullets were lightly crimped with LEE Factory Crimp.

These were shot out of an Aero M5 with 16" Rainer Barrel.  Aero Bolt Carrier with JP Enhanced .308 bolt

It was about 95 degrees and the cartridges were around the same temp.  I was shooting, putting rifle down, writing down the chrono reading, then shooting again.
During the time between shots the round in the chamber was probably getting a lot hotter than 95 degrees.  

Left to right:

First two rows are 45.0gr Ramshot TAC behind 150gr BTFMJ - 10 shot avg 2741 fps
Next two rows are 45.3gr Ramshot TAC behind 150gr BTFMJ - 10 shot avg 2754 fps
Next two rows are 45.5gr Ramshot TAC behind 150gr BTFMJ - 10 shot avg 2759 fps

then you have an empty row followed by:

One row 45.3 Ramshot TAC behind 147gr BTFMJ
Next two rows are 45gr Ramshot TAC behind 147gr BTFMJ

I don't think ejector swipes are overpressure signs.  I get those on Federal M80 white box.

Not problems with ejection or sticking cases even with 45.5gr load

Ramshot lists TAC min/max 42.4-47.1 for 150g BT-FMJ.  
If I subtract 1gr for LC brass I get 46.1 and I'm under that.

I think I'm OK here but I'm open to second opinions.








Link Posted: 8/30/2015 11:04:33 AM EDT
I think they are all fine.  FGMM primers look much flatter than that out of the OBR.  I hand load 45 gr. of VARGET in m118LR brass and the primers are less flat than FGMM.
Link Posted: 8/30/2015 2:01:20 PM EDT
Are the ones with the color hue around the primer a trace of sealant or is that carbon?
I see you said these came new and primed, do they seal and crimp  their primers, or no crimp?

Occasionally you show ones that look like there is primer cup flow into the corners. Chronograqphing while developing a load helps to correlate the data to a speed range, but that is still only a rough guide when compared to strain gage data. It could be just the bulk photography effects, or it could be they are really samples of hight pressure signs. Your speeds appear to be about right, did they come out within less than 100 fps of the published data? If they are tracking well, there is less to worry about.

Depending on which 150 boat tail we are discussing, the TAC data shows a range of max loads. Looks like you are using the HDY example. Your speed isn't off by much. I'm not sure what test bbl they used for the data.

I would also ask why there appears to be flow back up around your firing pin? Depending on the diameter and finish of the firing pin hole on the bolt face, flow back down into the hole is also an indicator unless it is just an artifact of those finish details. Hard to say from the photos.

I would also look at the condition of the brass above the rim for additional signs of high pressure.

What would you say the headspace is like compared to the shoulder datum before and after? Sometimes the primer on semi-auto fired brass is affected by the headspace issues when compared to bolt rigs. If those primers are moving from a generous headspace, then there is nothing to worry about pressure wise.
Link Posted: 8/30/2015 5:43:01 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Are the ones with the color hue around the primer a trace of sealant or is that carbon?
I see you said these came new and primed, do they seal and crimp  their primers, or no crimp?

Occasionally you show ones that look like there is primer cup flow into the corners. Chronograqphing while developing a load helps to correlate the data to a speed range, but that is still only a rough guide when compared to strain gage data. It could be just the bulk photography effects, or it could be they are really samples of hight pressure signs. Your speeds appear to be about right, did they come out within less than 100 fps of the published data? If they are tracking well, there is less to worry about.

Depending on which 150 boat tail we are discussing, the TAC data shows a range of max loads. Looks like you are using the HDY example. Your speed isn't off by much. I'm not sure what test bbl they used for the data.

I would also ask why there appears to be flow back up around your firing pin? Depending on the diameter and finish of the firing pin hole on the bolt face, flow back down into the hole is also an indicator unless it is just an artifact of those finish details. Hard to say from the photos.

I would also look at the condition of the brass above the rim for additional signs of high pressure.

What would you say the headspace is like compared to the shoulder datum before and after? Sometimes the primer on semi-auto fired brass is affected by the headspace issues when compared to bolt rigs. If those primers are moving from a generous headspace, then there is nothing to worry about pressure wise.
View Quote


The color is sealant.  Primers are crimped.  These were Lake City Military cartridges that didn't pass QC.  They pulled the bullets, dumped the powder, and sold the primed cases as surplus.  They still have some tar residue in the necks.  I took the expander out of a full body die and resized the necks to snug them back down.

Can't tell you about the headspace other than the bolt passed the go/no-go gage tests and the cases look good in an L.E. Wilson case gage.
Link Posted: 8/30/2015 6:03:39 PM EDT
The rule of thumb is -2.0 grains when loading Lake City brass. Many times standard commercial brass starting loads are close to maximum in Lake City.

2750 fps is what I get from M80 ball ammo out of my 22" barrels. You should look at 2600 fps as close to maximum from a 16" barrel when using Lake City brass.
Link Posted: 8/30/2015 7:58:21 PM EDT
Then it is possible that those randomly dispersed primers that appear to have sings of high pressure induced flow might actually be due to dispersion in neck tension.

I would take a closer look at your chrono data for any signs that you were getting erratic behavior on ones where the necks may not be consistent with the average.

Is this stuff in the necks really worth playing with? Is this brass cheap enough to blast with when compared to the .308 brass floating around these days?

http://www.creedmoorsports.com/shop/Lake-City-.308-Brass.html

It is a good indicator if they don't drop too far down into the case gage.

Take a look at the firing pin details on your bolt face and the diameter of the firing pin. Those crater shaped dimples may just be a result of the detail on the bolt face.

To have a little experience with FGMM as a decent reference load is a good thing too. If you see how those loads perform and how that brass responds, you have a decent reference point to judge primers.
Link Posted: 8/30/2015 8:29:10 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
The rule of thumb is -2.0 grains when loading Lake City brass. Many times standard commercial brass starting loads are close to maximum in Lake City.

2750 fps is what I get from M80 ball ammo out of my 22" barrels. You should look at 2600 fps as close to maximum from a 16" barrel when using Lake City brass.
View Quote


I get 2700 avg from Federal XM80CL out of the box with a 16" barrel.  

Federal XM80CL 149gr FMJ thru my 16" barrel.

2684
2695
2706
2714
-------
2700

What kind of M80 are you shooting?
Link Posted: 8/30/2015 8:42:23 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Is this stuff in the necks really worth playing with? Is this brass cheap enough to blast with when compared to the .308 brass floating around these days?
View Quote


Probably not, but on the other hand, the tar probably will seal the bullets.  The tar is pretty dry.  Looks more like the inside of the neck is coated in soot... until you drag an expander ball thru it...
Then you'll have a sticky mess after a while.  But since this brass was never fired I think the only thing that's questionable would be the neck tension but when I resized the necks without an expander ball it
just squeezes the neck back to a consistent .330 I think.
Link Posted: 8/30/2015 8:53:46 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:


I get 2700 avg from Federal XM80CL out of the box with a 16" barrel.  

Federal XM80CL 149gr FMJ thru my 16" barrel.

2684
2695
2706
2714
-------
2700

What kind of M80 are you shooting?
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
The rule of thumb is -2.0 grains when loading Lake City brass. Many times standard commercial brass starting loads are close to maximum in Lake City.

2750 fps is what I get from M80 ball ammo out of my 22" barrels. You should look at 2600 fps as close to maximum from a 16" barrel when using Lake City brass.


I get 2700 avg from Federal XM80CL out of the box with a 16" barrel.  

Federal XM80CL 149gr FMJ thru my 16" barrel.

2684
2695
2706
2714
-------
2700

What kind of M80 are you shooting?


Surplus Lake City, Twin Cities and IVI (Canadian). M80 ball is loaded as hot as they dare with a margin of safety. The IVI Canadian was the fastest at 2770 fps. The Lake City and Twin Cities were closer to 2725 fps. Overall average was around 2750 from my M1-A's.

You are supposed to lose 25 to 30 fps for every inch of barrel you lose in a .308. My safe estimated of 2600 fps was based on the 6" difference between my barrel and yours. 6x25=150.  

Your primers are cratered. That doesn't necessarily mean you are over pressure. Oversized firing pin holes can cause this as well. Your velocity remains high IMO, try going another grain or two lower just to see if the cratering disappears. Each grain of powder in .308 loses or gains approximately 60 fps depending on whether you add it or reduce it.

I have never used TAC. It's a ball powder isn't it? Ball powders spike quickly on the top end, WW-748, BL-C(2), H335 all behave that way when at or near the top. I prefer Varget, RE-15, IMR-4895, H4895, VV N140, VV N150 or IMR-4064 for .308.

Different bullets, even though they weigh the same, can create as much as 12,000 psi difference fired from the same brass, same primer and same powder charge. Simply changing bullet brands can have a huge effect on pressures even though they are identical in weight.
Link Posted: 8/30/2015 9:04:11 PM EDT
OP, what you're asking us to do is compare all the ingredients in a bowl of goulash and tell you which one is best.

All your cases are of different lots of brass and primers within the same string. If we were making a comparison between same lots of brass and primer a better comparison could be made.

IMHO you're getting 22" test barrel velocities from a 16". I'd drop the charge down to 45 grains and load in bulk, you're not gaining much going another half grain higher.
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