Winchester 748 temperature sentive question

All powders have a tendency to get more 'explosive' in hot weather and especially if they are left in the direct sun or in a hot vehicle...

I use W-748 for most of my .223 & .204 loads and while I don't make a practice of 'loading hot' (usually almost a full grain under max), I always look very closely at the first couple of rounds fired on a summer day for excessive pressure signs...

I read somewhere that W-748 was the original powder developed for the AR in 1964 and will operate successfully under most normal 'extreme' situations...But, I always worry about those 'abnormal' situations..
 
748 will keep you happy year 'round. As mentioned above don't let your rounds bake in the sun /ubbthreads/images/graemlins/shocked.gif

My 223 sighted in with 748 in September holds zero in frigid January temps here in the Northeast.

748 will be very hard to beat in a 223.
 
It shoots great, I do most of my hunting in sub zero weather I just don't want the groups opening up or the zero changing. It shoots great now (60 degrees) can I expect the same groups when it gets cold out. It also shoots H335 good but not as good very close though.
 
I realize this is not exactly apples to apples, but I have
a W-748 load, with a 130 gr. Barnes bullet, in 308 Win.
It was originally developed for a Savage Striker(14"
barreled bolt action pistol), to kill Northern Whitetail
Deer. I developed the load in early Fall, in 50 to 70
degree weather, and hunted in the late November firearms
deer season, in northern Wisconsin. We see temps
occasionally below zero, and most often below freezing.
W-748 has always performed well, in this temperature
range.

Two things to mention about this load. First, it is HOT.
I am getting chronograph measurements averaging
2800 fps MV out of that 14" barrel. I expect if it is
much above 60 degrees, I will see signs of excessive
pressure, so I am careful with this load. Currently I have
not seen much for signs of pressure, other than a bit of
primer flatting. And the second point, is this load also
shots quite accurately(average groups under 1 MOA), in my
308 Win chambered BAR, also with no significant signs
of pressure.

I have had one scare with H-380, also a ball powder,
in a 22-250 load, with temperature sensitivity, so
I know what temperature sensitivity means. W-748 has
not shown me that sharp of rise in pressure, with a
rise in temperature, over the temperature ranges I
have shot W-748 loads over.

To you concern, about groups opening up in cold weather,
I have not seen that in this 308 Win load.

Squeeze
 
Thanks I just loaded up some more I am one grain below maximuim. I never shoot it when it is hot I start shooting about now on a frequent basis it doesnt get that hot here this time of year.
 
I've shot group's with a 223 & 748 in temp's of 12 degree's..to..90 degree's

With no problem's..my load was 26.5 grain's using a sierra 55 grain s.p. & a wsr primer.

I did notice a p.o.i. shift,Between the weather extreme's.

I've lost those target's so i can't say for sure how much though.

It seem's like it was an inch or two.

Heck coulda bumped the scope too.

It sure seem's to be a good powder.
 
Quote:
I read somewhere that W-748 was the original powder developed for the AR in 1964 and will operate successfully under most normal 'extreme' situations...But, I always worry about those 'abnormal' situations..



Yes Sir... that is the same thing I remember reading. I use it because I load it in my .223, .308, and 30-30. I have never had any issues out of 748 from hunting in negative temps in Erie, PA to the warmer temps of the Mid South. Great all around powder. /ubbthreads/images/graemlins/ooo.gif
 
Quote:
All powders have a tendency to get more 'explosive' in hot weather and especially if they are left in the direct sun or in a hot vehicle...

I use W-748 for most of my .223 & .204 loads and while I don't make a practice of 'loading hot' (usually almost a full grain under max), I always look very closely at the first couple of rounds fired on a summer day for excessive pressure signs...

I read somewhere that W-748 was the original powder developed for the AR in 1964 and will operate successfully under most normal 'extreme' situations...But, I always worry about those 'abnormal' situations..



Excellent advice!

Martyn
 
I wore out one .223, shooting 28.3 gr. of W-748 and 50 gr. Hornady SX bullets. Temperatures ran from -20, fox hunting, to over 100 in dog towns, w/o any problems. And it ran them out at 3450 fps. Only problem: thats a case full, and I cannot load them on the Dillon; it spills powder all over.
 
W748 will be just fine for what you are looking for. It is a great all year round powder. H335 also had this bad rap for having problems in extreme temps. Personally neither of these powders have ever given me a problem.

H335 is the only powder that my Stevens has ever seen. It has held the same zero in temps over 100 and at 15 below zero. BUTTTTTT I do not load really hot loads either.
 
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