178 grain .308 Loading Question....

[TNRobocop]

I picked up 200 rounds of Hornady 178gr A-Max Moly bullets and have a reloading problem with them powder wise.

The reloading charts show the two loadings listed below for use with IMR4895 (the powder I am using):

175gr: 41.0 grains

180gr: 40.5 grains

I am using once fired Federal GMM cases and Winchester LR primers for the other details. My "theory" is that I should load at the 175gr loading. What says the experienced hands?

[molonlabetn]

The most logical solution would be to start with the lower charge, and work your way up to the ballistics you're looking for, keeping an eye out for high-pressure signs. I'm no reloader, so I don't know if those are close to max charges... but it seems to me that jumping straight to a max load is ill-advised.

[strickj]

Im no reloader either but would you not use the difference?

bullet weight: 5gr = .5 grains

so wouldnt a 178gr use 40.7 grains?

[Marswolf]

I'd start with the lower powder amount. You want to end up around 2900 - 3000 fps. The slower figure is more accurate, but 3000 fps is recommended for hunting. Part of that result depends on the powder and part on your reloading technique. Different powders produce different results, of course. I like IMR-4350. That would be about 67.8 grains. The only way to find out which does better for you is to try them. If you have a ballistic chronograph, I'd use it to get the speed right and then play with stuff like seating depth and powder type to get the accuracy where it should be.

But all of my experience in 308 is with 168 gr moly coated MatchKings.

[Rock.45]

Go to www.hodgdon.com and or www.reloadammo.com/308load.htm and use the starting loads for the 175 gr with IMR4895 .

Edited March 4, 2008 by Rock.45
bad link

[TNRobocop]

Thanks for the replies. I am starting off with the 180gr loading since I found out that you should work from the closest heavier loading so so you don't have higher pressure loadings.

I went to the Hodgdon/IMR website and they didn't have but I used their load calculator and printed off the loading for all IMR4895 loads and am loading using the 180gr loading on there.

[Guest Crunchman]

From the Lyman 48th edition, (a reloader's best friend)

178 gr. Jacketed A-Max 2.780" OAL

IMR-4895, 37 gr (starting load), FPS-2292, P.S.I. - 39,500

IMR-4895, 41.0 gr Max. load, FPS-2600, P.S.I. - 58,500

If you use the max listed load for the 180 gr. you will possibly be getting into the 60,000+ pressure range. That's getting past my comfort zone.

Also, I'm not familiar with the Federal GMM nomenclature. If those are military brass, decrease your powder by another 10% starting, as military brass is thicker walled, thereby reducing case volumn.

Edited March 4, 2008 by Crunchman

[Marswolf]

Personally, I like the Sierra manual. It's accuracy load is normally dead on.

I find that slower burning powders keep the pressures more reasonable and rounds more consistent for a rifle.

[tn hp]

I agree with Marswolf, the Sierra manual accuracy load is generally "the load". Of course, match it to your barrel. It would appear that either load would be acceptable however, less is generally more when it comes to reloading.

When loading some of the G.I. .30 cal./.308 173gr. match bullets, I stayed with the 168gr. Sierra load data and it worked very well.