So I was out shooting my new BCM middy upper this afternoon. I have always had WW 748 around but it has always been a backup powder for me (.223/.308/.30-06 and soon to be 30-30). Only once have I had one weapon ever prefer it (a friends M1 no less) over something else. It has always done OK, so I keep it around. Today this upper really liked it in the lower power charges.
 I remember here back someone post that 748 was temp sensitive (with the implication in the post that it was at low temps that there was an issue), but I have can not find it now.  I had personally seen an undercharged hand load ww748 take apart an AR in a CMP match on the line next to me, but it was an extremely hot day. At the end of the match (the 20 round slow fire in 30 mins.) and he had his 20 laying out, in the direct sun, on his shooting mat for quite a while (as an FYI this was the second AR he KB with this load).
 I would be interested in anyone experience with WW748 especially with respect to temperature variations.

It is a serviceable powder for mid weight bullets in the 223.  It is not the Cat's Meow for the 223 as Varget, RL15, TAC, and N140 work well with mid to heavy wt. bullets.

Some ball powders are temp sensitive as that's the nature of the beast.  Speer recommends magnum primers with all ball powders, so keep that in mind.  I've used 748, but I'm in Miami and so temps are fairly stable.

Like the above fellow states, it's not my favorite powder, either, for 223 or for 308, but give it a whirl if you can get it for cheap.

Chris

W748 is said to temp sensitive at higher temps.

The "ball powder thing"............

It is generally said...........that ball powder needs a magnum primer to get it going.  But, even that is a "sometimes" affair.  Depending on cartridge and the named brand of powder.  Then, at lower temps.........yes, again.   Certain ball powders are said to be difficult to get going.   But, again YMWV.

So, trying to group all "ball powders" into a "one fit all universal truth" is problematic.

It's just easier to add words like, "generally or YMWV," to your statements.  

But having said that, ball powders generally do meter well.

Aloha, Mark

PS..............I use to live in Hawaii, the temps didn't fluctuate all that much.  I used W748 with my .308 match loads.........

I loaded some maximum loads with Hornady data using 748 powder. I worked up to the maximum and it showed no pressure signs at 55 degree outdoor temp in one specific AR. This same load in 95 degree summer temperatures showed pressure signs in the AR and showed scary pressure signs in a bolt action rifle the same day. This could be true of any powder, that if you work up a maximum load in cool temperatures it could be too hot of a load in hotter temperatures. With the powders I've used in .223/5.56 the Win 748 showed the most extreme difference. It's a good AR powder though and I've shot a lot of loads with 748 powder.  With 55 fmj or SP's I would recommend 25.9-26.4 grains of 748 but do consult your manuals and work up. I've used only RP 7 1/2 primers and they work well with the 748 powder.  I've only used it with 55-62 grain bullets and too would recommend another powder for heavy weight .223 match bullets.

I use 748 for reduced course match shooting in the winter, and for my varmint loads.  With a 50 or 55 grain bullet and using wsr primers it treats me pretty well with moa groups.  I do load to where my accuracy is the best, and that falls short of max, so if it creates more pressure on a hot day, no big deal.  I have read a lot of internet chatter about 748 being overly sensitive to higher temps, and it may be true.

I have a pretty damn good 150 gr 308 load for white tails with 748, but I have never shot them in very warm weather.

I have used 748 in my AR's for years now. Win SR primers. I use it with 55 gr FMJ or SP. It has been very reliable and pretty accurate. Never had a problem "getting it going" with the Win SR primers. I use middle of the road loads in all temps from the low teens to high 90's. I also use 748 (Win LR primers) in my 308 w Sierra 168 gr MK's and Hornady 165 gr SPBT. Very accurate. I will continue to use 748 for plinkers in my AR but am now using Reloader 15 for my match ammo. 748 has always done well for me but as I said, I will relegate it to practice and my M1 loads for now, as I really like the Reloader 15 for the accuracy stuff. JMHO.

Thanks guys. I am normaly a H335 guy for .223, but like I said 748 has always been on my reloading bench and I have a 748 load for all my rifle loads.

At 90 yards with (3 round group...I know a larger amount of rounds would have been better) Izzy 55fjms in once fired Remingtom brass and WSR primers. mid-70's for temp
BCM 16" middy on a LMT SOCOM stocked lower with LMT 2 stage trigger and 4x scope
748    25gr     7/8"
748    26gr     1"
748    27gr     1 5/8"
748    27.5gr  4"     ()

I am just target shooting with 55 gr fmj bullets from a 20" NM service rifle, and my accuracy load is 25.5 grs. of 748.
I have a Sabre defense 16"  middy that likes 26.0 grains of 748 with the same Hornady 55 grain fmj bullet.  I don't crimp most of my reloads, but these loads seem to do slightly better crimped in the cannelure.

Yup.  I load 25 grains of 748 for any bullet from 52 to 69 grains.  Hard to beat the accuracy with this charge and any bullet.  It is accurate enough.