Used Win748 for years with 55gr. AR loading. Like the powder but it is temp sensitive. I’d limit maximum loads to Hodgdon’s level at 26.3 grains with. 55 gr. bullets. Hot summer temps or a round left soaking up the heat from a hot chamber will start to show pressure signs at some listed max’s of 27 grains or higher. Always got good accuracy with 748. I however have switched to H 335 for all my 55 gr loads. Higher velocity without as much temp sensitivity. Still use my supply of 748 for some 62 and 64 gr. bullets.
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W748
- Thread starter e-bear
- Start date
…I’d limit maximum loads to Hodgdon’s level at 26.3 grains with. 55 gr. bullets….
Perhaps, but understand that Hodgdon maximum is well below the SAAMI max pressure for the cartridge. The SAAMI maximum is 52,000 cup while the Hodgdon maximum is only 39,000 cup. I have no idea why they would reduce the cup to such a low value, other 55-grain cnc bullets show a maximum of 49,300 cup.
FWIW, I’ve used 27.0 grains of W748 for 40 years and have noticed no issues - but of course everyone should start low and work up. My own experience shows a large temperature sensitivity for H335, but my testing was decades ago.
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Unfortunately a lot of Winchester's early data (from one of their own pamphlets) was never updated, and several loads they list in 223 and 308 are unusually low. Further, this data was incorporated into numerous other data listings.
Am also using 27.0 gns for 55 fmjbt bullets, but might be careful of other bullet types with more bearing surface. This is above Win's own data using the lower cup pressure. And 748 is not too slow for a 55 grain bullet.
Am also using 27.0 gns for 55 fmjbt bullets, but might be careful of other bullet types with more bearing surface. This is above Win's own data using the lower cup pressure. And 748 is not too slow for a 55 grain bullet.
There was some fuss about it at one time. When Hodgdon took over distribution of the Winchester brand, the agreement included that Winchester's owners, whomever they might be at the time, would keep testing and load development up to date. They didn't, so a lot of old data still rides with the brand.
As to why that pressure is so low, that's going to be a matter of speculation. Cases have changed over time, and I note that if I use the smaller capacity found in some older cases and that is Quickload's default value of 28.8 grains of case water overflow capacity and use the 0.704" length of the Winchester Pointed Soft Point bullet in their original loads, then 26.3 grains of 748 has 99% loading density with QuickLOAD's default powder bulk density for 748. So they simply may not have wanted to get into compressed loads with it. More recent Winchester cases (post-mid '90s) have more volume (30.1 grains case water overflow capacity) and 27.6 grains of 748 would produce that same loading density in it.
Hodgdon had to substitute an available Speer Soft Point for the unavailable Winchester bullet in their data. They found one the same length but they have it seated deeper to 2.200" instead of 2.260" as is in the old Winchester data. That would partly compensate for more capacious cases. Gordon's Reloading Tool gives 748 a little bit higher bulk density than QL and says 26.3 grains would be 98.7% load density in the modern capacity case. GRT also gives higher pressure and velocity, so the modeling isn't a perfect match to the lot of powder used to accumulate the original Winchester data.
As to why that pressure is so low, that's going to be a matter of speculation. Cases have changed over time, and I note that if I use the smaller capacity found in some older cases and that is Quickload's default value of 28.8 grains of case water overflow capacity and use the 0.704" length of the Winchester Pointed Soft Point bullet in their original loads, then 26.3 grains of 748 has 99% loading density with QuickLOAD's default powder bulk density for 748. So they simply may not have wanted to get into compressed loads with it. More recent Winchester cases (post-mid '90s) have more volume (30.1 grains case water overflow capacity) and 27.6 grains of 748 would produce that same loading density in it.
Hodgdon had to substitute an available Speer Soft Point for the unavailable Winchester bullet in their data. They found one the same length but they have it seated deeper to 2.200" instead of 2.260" as is in the old Winchester data. That would partly compensate for more capacious cases. Gordon's Reloading Tool gives 748 a little bit higher bulk density than QL and says 26.3 grains would be 98.7% load density in the modern capacity case. GRT also gives higher pressure and velocity, so the modeling isn't a perfect match to the lot of powder used to accumulate the original Winchester data.
I shot 748 with Sierra's excellent 69 gr. MK for many years on the NRA's Nat'l Match course out to 300 yds. The load was 25 gr with the 69 gr MK seated to 2.255" for ~2800 fps through my Colt HBAR with its 1:7 twist. That load was consistently MOA out to 200 yds with the military sights.
The same load with Hornady's 55 gr FMJBT was nearly as accurate. I used Winchester Small Rifle Primers exclusively with no pressure nor ignition problems. Be advised that some shooters have noted temperature sensitivity using 748; but that was not my experience and I never pushed for maximum velocities (read pressures).
YMMv and be sure to check with a current manual for pressure implications etc. as data may have changed. Rod
The same load with Hornady's 55 gr FMJBT was nearly as accurate. I used Winchester Small Rifle Primers exclusively with no pressure nor ignition problems. Be advised that some shooters have noted temperature sensitivity using 748; but that was not my experience and I never pushed for maximum velocities (read pressures).
YMMv and be sure to check with a current manual for pressure implications etc. as data may have changed. Rod
Average Joe
New member
Been using W748 for .223/5.56 and .308/7.62x51 for years.
Crankylove
New member
I use it for 55 gr .223 loads.
Also for .338 Federal and .358 Win.
Also for .338 Federal and .358 Win.