mickb wrote:I didnt read the whole thread, got a headache this evening, but saw a coupe of points needing addressing,. Firstly Im assuming someone has pointed out AR2207 is a vastly too slow powder in 357.
I can understand using it in a pinch, aka no magnum pistol powders around, but that load is going to be running very low power, maybe only couple hundred fps above subsonic. No way anywhere near 2000fps with 140xtp, I would not be surpised if its 700-800fps slower than that.
As to accuracy Id say the slow powder, lighter bulets, very large bullet drop once you get to 100 yards and the fact the bullet is going transonic, dropping through the sound barrier to subsonic may all be playing a part in innaccurary.
Also a comment about a 357 being a more powerful 22LR for trajectory, no way, 357 far exceeds 22LR for flat shootingness, it beats 22Win mag as well with the right bullets. Not sure the OP realises while pistol loads run 1200-1600fps from a pistol barrel , they can run 500fps or more in the lever action. Again, the load of AR2207 is nowhere in this ballpark, in fact I reckon even out of the rifle barrel its still running slower than a short barelled pistol.
Also regards the 73 action, yes inherently much weaker design than the 92 and 94 etc....however, if winchester has seen fit to chamber one in 357( as uberti does as well) you have to assume it can handle factory 357 pressures.
I did some internet armchair research at one stage regards modern73 actions being used for magnum pistol chambering and didnt find any examples of rifles blowing up. What I did find reports of is after large QTY's of full house loads the headpace can increase over time necessitating gunsmith action, as the thrust is all agains the radius of those little toggle pins. That said , a lot of blokes are using 44mag and 357 in their ubertis and winchester 73's without even knowing what headpace is...
I wouldn't say AR2207 (H4198) is "vastly" too slow, particularly in rifle barrels. It's less than optimal, but it's what we have to work with. If I didn't have pistol powders I'd be getting my name on a list for some of this APS950 ASAP. I do agree that 2000fps is unlikely with 140gn bullets using AR2207, but I think they can certainly be pushed a lot faster than 1300fps, and certainly a lot faster than out of pistol barrels (they have so much more barrel volume to burn the powder in).
The 140gn XTP has a BC of .169. If it were only making 1300fps it would indeed have a fairly similar curve to .22LR. If it's making a more realistic 1500fps then it is flatter than .22LR, and still supersonic to around 125m. The OP is using 16.2gn (compared to QL's 14.7gn max in the data below) so I would figure it's a fairly stout load (we don't know his COAL). Without a chronograph, and with a degree of accuracy from the rifle you can shoot groups at 50m and 100m and measure the drop to get a decent idea of your velocity. If it drops 170mm going from 50m out to 100m then it's doing around 1300fps, 125mm drop would be around 1500fps, 90mm drop would be around 1700fps, 70mm drop would be around 1900fps. You need either very tight groups, or lots of shots to accurately measure your drop. Measure vertically to a fixed horizontal datum on the target (like the top of the page or rule a level line) for each bullet hole, then average them to get an accurate idea of your drop. Exclude any shots that you know where badly aimed though.
I Googled 4198 .357 loads and there are lots of people that have experimented with it for years, long before supply was an issue. It's a better choice when running heavier bullets, 158gn to 200gn, and longer barrels, but also works with lighter bullets and very short barrels. I found two people that had posted Quickload results for 1.590", 158gn, 4.8" pistol and 1.900", 180gn, 22" rifle loads. The pistol data is 11 years old, the rifle data was run last year. In both situations Lilgun gave the highest velocity, 1292fps in the pistol (30,625psi with 78% burn), 1703fps in the rifle (30,625psi with 97% burn). For pistol, Quickload placed IMR4198 in twentieth place (in the list of powders sorted by calculated velocity). For rifle, it placed H4198 33rd (later data so a wider choice of powders in QL's database I think). In the pistol, AR2207 (IMR/H4198) only made 25,221psi and 1073fps (83% of the Lilgun velocity with 49% burn), in the rifle AR2207 made 25,312psi and 1394fps (82% of the Lilgun velocity with 67% burn). So, less than optimal but definitely usable, and pretty safe too. But I would strongly suggest actually chronographing your loads if you want reliable data. The QL data didn't say whether magnum primers were used but I would assume not as it included all the pistol powders as well, mag primers would very likely improve the burn ratio.
Pistol:
https://forum.nosler.com/threads/357-mag-loads-starting-point.24409/post-239625Rifle:
https://www.go2gbo.com/threads/357-mag-load-with-imr-4198.129295/