Low Velocity From 44 Magnum SBH 10.5”

[Hartkopf]

Two different loads have choreographed way lower than the load data from my SBH 10.5” barrel. Accuracy is good. The barrel slugged .430 and the cylinder throats measured.431.

Max load of IMR4227 of 20gr with a 300gr XTP chronoed 1060fps. The book called out 1312fps from 8” test barrel. Over 250fps slow. Grouped 1.75” at 25y from cheap plastic rest.

Max load of H110 of 19gr with a 300gr XTP chronoed 1180fps. The book called out 1325fps from 8” test barrel. That’s 145fps slow. Grouped 2” at 25y from cheap plastic rest.


Both of those loads chronoed right at 1000fps from a 2.5” barrel SRH Alaskan. Telling me the loads are ok.

What could cause low velocity in the SBH? Big chambers is all I can think of. Anybody know the specs and tolerances of a 44 magnum chamber? Anything else I should look at?

 

[WrongHanded]

How's the B/C gap?

I believe the XTP is a .429" diameter, so if your barrel slugs .430" (which would be the tightest spot on the whole barrel), perhaps you're getting gas pushing past the bullet. Try loading up some hardcast at .430" and .431" and see if there's a difference.

 

[Hartkopf]

How's the B/C gap?

I believe the XTP is a .429" diameter, so if your barrel slugs .430" (which would be the tightest spot on the whole barrel), perhaps you're getting gas pushing past the bullet. Try loading up some hardcast at .430" and .431" and see if there's a difference.

I’ll check the gap in the morning. The XTPs are listed at .430 but I have seen them measure .4295. The only bullets I have to choose from right now are .429 to .430, all jacketed.

The Alaskan 2.5” also slugged .430 and velocity from it was what I would expect.

 

[WrongHanded]

I’ll check the gap in the morning. The XTPs are listed at .430 but I have seen them measure .4295. The only bullets I have to choose from right now are .429 to .430, all jacketed.

The Alaskan 2.5” also slugged .430 and velocity from it was what I would expect.

I suppose in a barrel that long, it's possible the diameter varies a little. It could be larger than .430 at some point, but I don't know how you could check that. Other than lead smearing, maybe.

If you want to see if the chambers are appreciably larger than the Alaskan, you could always try swapping fired brass between the two and see how it feels in the chambers. Not very scientific, but if there's a large enough difference to matter, you may be able to feel it.

 

[Hartkopf]

I’ll try to measure both in the morning. I’ll also try to poke around in the barrel and see if there is an area where it opens up. I might have some expanding hole gauges I could work with. There would have to be an obvious problem for me find anything but never know.

 

[P5 Guy]

Standard or Magnum primers?

 

[bigpower491]

I’ll try to measure both in the morning. I’ll also try to poke around in the barrel and see if there is an area where it opens up. I might have some expanding hole gauges I could work with. There would have to be an obvious problem for me find anything but never know.

The best thing to use would be gauge pins in the cylinders. Much more accurate for those measurements.
How's the battery in the chronograph? Did you shoot both revolvers at the same day? That would eliminate a problem with the chronograph if you did.

 

[Richard Jay King]

In many "books" that use an 8" test barrel it is not vented to represent the cylinder/barrel gap....Your H110 load with the 300 grain XTP sounds spot on with respect to velocity to me...I have a SRH and shoot the same bullet crimped in the lower crimping cannelure loaded with WAY more WW296 and cannot get much more than 1300 fps.

 

[cfullgraf]

As said, "test barrels" are not necessarily vented to simulate the barrel/cylinder gap of a revolver.

Chronograph some factory loads that have velocity info from the manufacturer and see how it compares to your revolver. It will tell you if your gun shoots "fast" or "slow".

 

[Hartkopf]

The best thing to use would be gauge pins in the cylinders. Much more accurate for those measurements.
How's the battery in the chronograph? Did you shoot both revolvers at the same day? That would eliminate a problem with the chronograph if you did.

I don’t have access to gauge pins anymore but I’ll see what I can find to get a good reading. The chronograph batteries are 2 months old and both guns were shot on the same day. It was about 70dgs.

 

[Hartkopf]

Standard or Magnum primers?

CCI #350 Magnum primers.

 

[Pat Riot]

I am not a 44 Magnum shooter, but this thread interested me as it does relate to revolvers.
Anyway I did a little poking around and have found that you are not the only one to discover this very same thing @Hartkopf
I know we can post info from other forums on here but here are a couple of searches I did where people on other forums had similar experiences using Hodgdon load data. I am assuming you’re using Hodgdon data as it matches what you stated above.

Look for a link to “northeast shooters”
https://duckduckgo.com/?q=44 magnum 300 grain loads h110&ia=web

Look for a link to “AR15”
https://duckduckgo.com/?q=44 magnum H110 of 19gr with a 300gr XTP&ia=web

Screen shots of Hodgdon data and Shooters Reference that used Hodgdon’s data sans barrel length.




I am guessing you’re blaming your gun when you may have faulty data.

 

[WrongHanded]

Well the data got me thinking.

Hornady has 20.1gr of H110 as max for that bullet, and 19.9gr for W296.

 

[Hartkopf]

Ok I’m guessing the gun checks out ok. The B/C gap is .005 to .006. The chambers are .461 with a hair of taper down to .460, which is exactly the same as my Alaskan. The barrel doesn’t have any flaws and I was able to measure 4” from the muzzle with a snap gauge and found no difference in measurement from slugging. The snap gauge actually measured exactly what I slugged at .430.

 

[Hartkopf]

I am guessing you’re blaming your gun when you may have faulty data.

Looks like you’re right. I have some other good loads I can try. They were not what I wanted to use in this gun but I’ll chrono them and see if they match up to other load data.

 

[buck460XVR]

I know we can post info from other forums on here but here are a couple of searches I did where people on other forums had similar experiences using Hodgdon load data. I am assuming you’re using Hodgdon data as it matches what you stated above.

Yeah, I have found that Hodgdon's velocity numbers are many times are unrealistically high. Hornady, using the same components, shows about 200FPS less with similar powder charges than Hodgdon, using a real revolver(7 1/2" Redhawk), as opposed to a test barrel.

 

[Hartkopf]

Ok I did more testing. 180gr XTPs over 31.2grs of H110 chronoed 1879fps out of the SBH 10.5” barrel. This is very much in line with Hodgdon’s data which is 31.5gr out of a 8.25” barrel gets 1896fps.

Also a near max 240gr load chronoed right about where it should.

@Pat Riot called it;
Looks like my gun is fine and Hodgdon’s data for 300gr XTPs has unreal velocities.

 

[JohnKSa]

Max load of IMR4227 of 20gr with a 300gr XTP chronoed 1060fps.

• Hornady's Manual (7th Edition-2007) states that a max load of 19.2gr of IMR4227 should drive a 300gr XTP to 1100fps from a 7.5" revolver.
• Sierra's Manual (Edition V, 7th Printing--2003) puts 20gr of IMR4227 behind a 300gr bullet (not a max load) at 975fps from a 7.5" revolver. That is NOT with an XTP, but with a Sierra 300gr JSP.

Max load of H110 of 19gr with a 300gr XTP chronoed 1180fps.

• Hornady's Manual (7th Edition-2007) states that 18.8gr of H110 (not a max load) should drive a 300gr XTP to 1100fps from a 7.5" revolver.
• Sierra's Manual (Edition V, 7th Printing--2003) puts 19gr of H110 behind a 300gr bullet at 925fps (not a max load) from a 7.5" revolver. That is NOT with an XTP, but with a Sierra 300gr JSP.

 

[bigpower491]

Ok I did more testing. 180gr XTPs over 31.2grs of H110 chronoed 1879fps out of the SBH 10.5” barrel. This is very much in line with Hodgdon’s data which is 31.5gr out of a 8.25” barrel gets 1896fps.

Also a near max 240gr load chronoed right about where it should.

@Pat Riot called it;
Looks like my gun is fine and Hodgdon’s data for 300gr XTPs has unreal velocities.

Good onya.

Thinking about that after reading @Pat Riot post, I went thru one of my logs and compared their data to my own real world.....twas off a bit from my numbers.

I personally stopped using 296/110 last yr in 44 Mag. Ramshot Enforcer was more consistent in my SBH 7.5.
Of course I still use 296/110 in 454 Casull, and it's become my go to powder for 450 Bushmaster rifle, so the 5 pounds of it I have on hand certainly won't go to waste.....

 

[Hartkopf]

What was strange to me was how the IMR4227 max loads were off so much more than the H110 loads. With a long(ish) barrel and a heavy bullet I thought 4227 would be very near H110. The data indicates a velocity difference of 13fps where I got over 100fps slower. Basically 10% off.

 

[bigpower491]

What was strange to me was how the IMR4227 max loads were off so much more than the H110 loads. With a long(ish) barrel and a heavy bullet I thought 4227 would be very near H110. The data indicates a velocity difference of 13fps where I got over 100fps slower. Basically 10% off.

For sure. The data out of my Hornady book was pretty damn close to what I was seeing on the chrony.
Never tried 4227, was thinking about picking up a pound to try when my lgs had some in stock but grabbed Accurate 9 instead. Probably should grab some next time it comes around, if it ever comes around again.
Glad you got it sorted our, if you ever get a chance to try some Enforcer, give it a whirl. It doesn't really care as much as 296/110 over a wider range of loads. They both meter thru a measure about the same, so no trickler involved... set it and throw at will

 

[WrongHanded]

If you're open to trying different powders, you should consider 300-MP for that 10.5" barrel.

 

[Hartkopf]

If you're open to trying different powders, you should consider 300-MP for that 10.5" barrel.

I’ll keep 300-MP and Enforcer in mind but right now I’m locked into H-110 with several pounds. I actually got pretty good groups with H-110 and the 300gr XTPs so I’m going to fine tune that a bit and see where it goes.

 

[Hartkopf]

For sure. The data out of my Hornady book was pretty damn close to what I was seeing on the chrony.
Never tried 4227, was thinking about picking up a pound to try when my lgs had some in stock but grabbed Accurate 9 instead. Probably should grab some next time it comes around, if it ever comes around again.
Glad you got it sorted our, if you ever get a chance to try some Enforcer, give it a whirl. It doesn't really care as much as 296/110 over a wider range of loads. They both meter thru a measure about the same, so no trickler involved... set it and throw at will

IIRC, Enforcer was less expensive than most powders. I’ll keep it in mind for later.

 

[Gordon]

Ok I did more testing. 180gr XTPs over 31.2grs of H110 chronoed 1879fps out of the SBH 10.5” barrel.

I used 31 Grains of H110 under 180 grain bullets in all my longer barreled .44 Magnums and that load gets 2100+ Fps from a 16"+ Carbine (my 20 " Browning B92) and is one heck of a load for light/med deer to 150+ yards out of the Carbine and 100 yards with a 7 1/2-8 3/8 pistol I can attest to. I don't go for the last tenths of a grain in hot loads like that with my Dillion 1000 or 650 progressive turret presses . H110 and Win 296 are almost identical in load density and performance BTW in .44 Mag and a lead 240 grain bullet can hit 1500 fps in those longer barrels with near max loads.