H4895 temp sensitivity

[roop]

Does anyone have any experience with the temperature stability of H4895?

I worked up a new hunting load for my .308win in the last 2 months using Berger 155 hunting bullets and 46gr H4895 and am wondering if I need to drop back a bit. I get acceptable accuracy (.75moa) and am well off the lands (+.100"). The primers look like they are right on the ragged edge, I definately don't think i want to go any hotter because my velocities are at or above the listed velocities for this load, but I am wondering if I need to back off a hair to allow for warmer temps in the upcoming months. The temps during workup were between 35 and 50 deg. F.

Has anyone out in the internets done any testing and found a substantial increase (like 50fps or more) using H4895 in summer vs. winter?

 

[918v]

Varget vs Reloader 15 in 308 ?? [Archive] - Benchrest Central Forums

Perhaps it is inverse temperature sensitive? I haven't seen any swings in the 308 but I don't shoot in the extremes, mostly 40-80 degrees.

 

[J E Custom]

Here is a comparison that may help.

http://www.hodgdon.com/smokeless/extreme/page2.php#top

I have had great luck and consistency with all of the Extreme powders from Hodgdon.

J E CUSTOM

 

[roop]

Varget vs Reloader 15 in 308 ?? [Archive] - Benchrest Central Forums

Perhaps it is inverse temperature sensitive? I haven't seen any swings in the 308 but I don't shoot in the extremes, mostly 40-80 degrees.

Most of my shooting will be in the same range, maybe up to 90 at the extreme high end. I took this quote from the forum you posted, pretty interesting:

Hodgdon Extreme powders mfg by ADI use and ethyl centralite coating instead of DNT or dinitrotolulene used by IMR and others. The burn rate of the powders using DNT to coat nitrolcellulose is given by the extruded kernel or grains size. With centralite, burn rate is also a function of the coating allowing smaller kernels for better metering. The centralite coating is more temp stable given a change in weather conditions. Even so the powders do have variances due to temps:

eg
Hodgdon
H4895 is tempurature pressure inverse as temp increases pressure decreases.
Good multi-use powder best in Desert Southern NM TX AZ etc.

 

[918v]

Here is some real deep thinking:

http://www.dtic.mil/dtic/tr/fulltext/u2/p004451.pdf

 

[918v]

Here is a comparison that may help.

http://www.hodgdon.com/smokeless/extreme/page2.php#top

I have had great luck and consistency with all of the Extreme powders from Hodgdon.

J E CUSTOM

I wonder how H4895 performed in their testing in the 308. Temperature sensitivity is cartridge dependent. I like H4895 for my 308 bolt gun is cuz it has a 26" barrel and Varget won't burn efficiently in the 2600 FPS sweetspot. H4895 works like a champ in this pressure range.

 

[Pdvdh]

Temperature sensitivity is cartridge dependent.

I'm experiencing this with Varget in .223 Remington. Some temperature sensitivity but even more so - large ES/SDs. Lots of folks love Varget. It must perform more consistently in other cartridges. The ES/SDs I'm experiencing in my AR-15 is poor. Still getting pretty good accuracy out to 300yds, but extremes of 100fps in MV. Following my recent experiences, I spent some time researching Varget on some Forums and learned others have had the same experience with Varget in their .223 Remington.

 

[918v]

Maybe your pressure us too low. What's your load?

 

[Pdvdh]

I tried 26.2 to 27.2 grains Varget behind a 60gr Vmax. After I was found good accuracy in 26.8 to 27.0 grain range, I chronographed 50-60 rounds in varying temperatures. More so than temperature sensitivity (MV variation with temperature change), my disappointment with Varget was the high ES even at the same temperature. A lot of my chronograph data was collected with 26.7 and 26.8gr Varget, Fed 205 primers, and 60gr Hornady Vmax.

I also tried Hodgdon BC-L(2) and again quite a bit of ES/SD, although better than with Varget.

Last powder I tried was Hodgdon Benchmark. That was the best of the three. But still obtain a few outliers that product ES up to 50-60fps.

I run a triplicate chronograph setup. I obtain four recorded velocities for each bullet fired. The chronograph data is solid.

I get good accuracy from all three powders out to 300yds. Just much larger ES/SD than I experience in 280 A.I., 7mm Rem Mag, 300 Win Mag, etc...

 

[918v]

and you tried jumping them various distances to the lands?

 

[Pdvdh]

and you tried jumping them various distances to the lands?

Nope. This is an AR-15 and I'm limited to 2.260" OAL by Magpul magazine design. So I don't have much latitude changing bullet seating depths.

I meant to include this information. After completing a lot of load development focused on finding a powder/charge/load combination that would lower my ES/SD without much success, I Google researched ES/SD with AR-15 .223 ammo to read what others' experiences were. I did read several Posts in threads stating that Varget was finicky in the .223 Remington compared to larger case capacity cartridges. I also read that some folks thought there was benefit to crimping bullets in their .223 ammo - for use in AR-15s.

So I purchased a Lee Factory Crimp Die in order to test the theory that crimping the bullets would produce more uniform powder ignition and reduce ES/SD. I tried this with two loads, 26.8gr Hodgdon BL-C(2) and 24.9gr Benchmark. I then shot crimped versus no crimp loads over the chronographs into 300yd targets.

I didn't see much difference one way or the other with respect to ES/SD. HOWEVER, believe it or not, the crimped Benchmark bullets printed a group about 1/2 the size of the same load with bullets that were not crimped. I fired 6 crimped shells into a group measuring about 2.5". I fired 6 no-crimp bullets into a group measuring about 5". I then fired another 5 no-crimp bullets to further verify the reduced accuracy, and the no-crimp group remained the same at about 5".

Crimping the bullets didn't cause much difference in ES/SD, which is what I was looking for, but the crimped bullets did shoot a group about 1/2 the size of the groups printed with no-crimp bullets. Again, this was with Benchmark powder.

With BL-C(2), I didn't see much difference between accuracy or ES/SD of the crimped/no-crimp bullets.

 

[Dgd6mm]

I run it in both my ftr rifles, .223, .308. I live in North Florida and use the .308 for 1000 yard long-range with a stout load pushing a Berger 185 Juggernaut, no temperature problems with it EVER.... The .223 is for midrange it's a little milder load, and also no issues.

 

[roop]

I run it in both my ftr rifles, .223, .308. I live in North Florida and use the .308 for 1000 yard long-range with a stout load pushing a Berger 185 Juggernaut, no temperature problems with it EVER.... The .223 is for midrange it's a little milder load, and also no issues.

How stout, just to satisfy my curiosity?

 

[Dgd6mm]

I'd have to check because it's been so long, but I believe it is within 200-300 psi from maximum what quick load is showing me. Where I shoot the temperature and humidity tend to get up, and during f class most times I will run my 22 shots between 12-15 minutes.