Any .308 pet loads?

The only primer test I've seen isn't recent, but it's here. It agrees with Rocky on a choice for milder, and KVB (Wolf and Tula) were even milder. It suggest the Federal was closest to the Remington 9 1/2, but had almost half the standard deviation. The CCI200BR is another possibility from the chart. The KVB is quite impressive on SD, but lots of folks complain they are hard to seat.

Also have a look at these flame shots, though I'm not sure that tells you anything about pressure. Fuel content maybe (see this primer on primers).

I pulled a bunch of Federal GM with 168 grain SMK's once about 10 years ago. It contained 43.5 grains of IMR 4064. They claim 2650 fps from a 24" barrel, and this is one of those instances in which QuickLOAD, with 57.0 grains of case water capacity (my Federal cases) seems to be about on the mark, predicting 2648 fps and 52,600 psi in a tight chamber.

For Rocky's 41.0 grain load it shows 44,350 psi, but that may be low (see pressure behavior below). I would suggest running a 30 shot round robin between 40.7 grains and 43.4 grains to see what your rifle likes. Depending on its chamber size, it should find something favorable in there.

The QL model does not take odd pressure responses into effect and 4064 may be a bit odd, and Rocky's load may run a bit warmer than shown. In the Precision Shooting Reloading Guide, Dave Milosovich presents and experiment in which 4064 seems to have special pressure immunity. Comparing it to 4895 as to the amount needed to achieve a given velocity from a 180 grain bullet in a match rifle (24" tube), he had:

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <wunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <wontGrowAutofit/> <w:UseFELayout/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--> This shows less 4064 needed for 2200 fps, indicating it is the faster of the two powders, while 2500 fps and up show it takes more, indicating it is the slower of the two powders (assuming same energy content per unit weight). This would explain (to my mind) why it is a popular accuracy powder, as that behavior would make it less temperature sensitive and more tolerant of small charge errors than most.

QuickLOAD put your first load at 2520 fps and 41,700 psi with the default powder model. For 748, I have three models. One is the default, one I worked out for some load and pressure data of my own, and one is simply half way between the two. The burning rate differences in Winchester seems to be a bit greater than some other brands. I don't know whether it's just that the ball process is harder to control. At any rate, the inbetween model matched your measure performance pretty well. The latter also gave 2520 fps, and almost an even 40,000 psi. Given the velocity and the energy level, that shouldn't be too far off. With that same 748 model, Rocky's load is predicted to get 2697 fps in your gun and barrel length at 48,800 psi. It will be interesting to hear what you actually measure?

If I play with Chris Long's optimum barrel time numbers, I get 45.2 and 47.2 grains as being on timing sweet spots, so you might search in that range. For H4895 it's giving 42.6 and 44.7 grains. For IMR 4064 I get 42.9 45.0 grains. Those are all well within Hodgdon's listed maximums for Winchester cases, but should be safe for other cases, as well. Your exact fired case size will determine actual finals, but based on the predictions from your gathered data, I may be fairly close. Anyway, work up from low to high and see what you get by way of results.

Rocky Raab said:

I used known accuracy loads in .308 Win and in the .223, changing only the primer. I ranked primers in order of the velocity produced, averaged from 20 shots. (It was so long ago, I have no record of the loads used or the velocities, only the resultant rankings. Here they are from hottest at the top down to coolest: . . .

Small Rifle

F205
R7½
WSRM
F200
WSR
CCIBR4/CCI400 (tie)
R 6½. . .

Click to expand...

It's fascinating to me how these kinds of things can differ. Charles Petty had an article in Handloader 248 (Aug-Sep, 2007) in which he did the same experiment. He ran a 52 grain Hornady Amax bullet over 24 grains of Reloader 10X in new Winchester brass in a .223 bolt gun (Cooper Pheonix). His result had the Federal 205 and 205M at the bottom of the velocity list and Remington 7½ at the top of the heap. Others inbetween.

I put Petty's results in Excel to sort by the 25 shot average velocity from hottest to coolest, and got:

I like this article on primers by a former CCI employee. He points out that primers get changed without notice or fanfare by their makers. It's yet another reason you back your loads off when a component lot number changes.