Hodgons 4831sc "Temp Sensative"

[Jick42]

I have been working on a load for my .260 and finally went out today and ran it through the Chrony. So, I've pretty much found my load that is shooting just a touch under 1/2 MOA @ 100yds. First 5 shots through the Chrony and the average was 2720fps, shooting 120gr Sierra Matchkings, lit up with 47.5gr of Hodgons 4831sc and an OAL of 2.80".

So, I take a break and shoot a few other rifles and come back to the .260. I'm in Middle Missouri and the temp today is 101. No biggie I figure because the 4831 is NOT suppose to be temperature sensative. So I string another 5 shots and was floored with the results. They averaged 100-120fps faster than the previous group. I am just wondering if this is normal and/or if anyone else has ran into this and seen this kind of variance when sitting out in the heat?
Thanks in advance guys.

 

[tigerfan_9]

Re: Hodgons 4831sc "Temp Sensative"

It was more likely due to the chrono, lots of errors from chrono's. the changing light and sun position can cause big swings in velocity readings on an optical chrono.

Was the ammo sitting in the direct sun? If so it would heat up much more then that amount the ambient temp went up.

 

[Jick42]

Re: Hodgons 4831sc "Temp Sensative"

Yes, the ammo was sitting directly out in the sun. I suppose I should have covered it.

 

[turbo54]

Re: Hodgons 4831sc "Temp Sensative"

Another thought is your powder selection.

Any reason you are using such a slow powder?

H4350 is just about right for the 140-class bullets. The lighter 123(ish) bullets oughtta use a faster, not slower powder.

Advise you to consider H4350, or perhaps even Varget with those light bullets.

 

[Paulyr450]

Re: Hodgons 4831sc "Temp Sensative"

The exact same thing happened to me the other day but it was with factory corbon 142 matchkings. I chronoed some of my handloads to see what was going on and just for shits and giggles had a box of factory ammo that they claim is 2700 fps. The first 5 shots were at 2710 average and 10 minutes later the second string at 2810 fps. The bullets were not in the sun and i let the gun cool down. I blame it in the chrono but it was also 100 degrees.

 

[Mark Walker]

Re: Hodgons 4831sc "Temp Sensative"

I've not found the H4831sc to be really temp sensitive, but I have found it to vary substantially from lot to lot. Be careful with it when going to a new lot, be sure to work up.

 

[shoot4fun]

Re: Hodgons 4831sc "Temp Sensative"

4831sc is a great choice for the 260 with heavier bullets, at least in my experience. My best accuracy has come using the 142 SMK with it.
I also think some previous posters are on the money. What chrono are you using? I found high, bright sunlight really affects chrono readings.

 

[Jick42]

Re: Hodgons 4831sc "Temp Sensative"

Hey guys, went back out this evening when the sun was going down, an the Chrony was right back to reading properly. The Chronograph is the Chrony Master F1. So the direct sunlight must really play havoc on the readings.

In regards to the powder selections, the 4831sc with the 120's has thus far been a very accurate load. But I have seen that the 4350 seems to be the powder of choice edging out the 4831. Will my velocities be a little higher with the 4350? Should i be running the 120's faster than 2720-2740? Once I jump up to the 140's will the 4831 be back on par for the heavier bullets?

 

[oldfatguy]

Re: Hodgons 4831sc "Temp Sensative"

Going to do OCW`workups with 107 SMKs & Varget and 142 SMKs & H4350. The H4350 is supposed to be right at case capacity while H4831sc would be seriuosly crunched. But, if the H4350 doesn't do it, then H4831 is next. The 107s and Varget are for the short course.

OFG

 

[turbo54]

Re: Hodgons 4831sc "Temp Sensative"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jick42</div><div class="ubbcode-body">In regards to the powder selections, the 4831sc with the 120's has thus far been a very accurate load. But I have seen that the 4350 seems to be the powder of choice edging out the 4831. Will my velocities be a little higher with the 4350? Should i be running the 120's faster than 2720-2740? Once I jump up to the 140's will the 4831 be back on par for the heavier bullets?</div></div>

Depending on barrel length, I'd expect the 120's to go 3000fps or at least really close to it. The 2700-2800 zone is pretty easily achievable with the 140's with H4350.

If you're happy where you are and getting good accuracy, no reason to change, but if you feel like playing some more I suspect you'll see a bunch more speed (and maintain excellent accuracy) if you tried H4350.

My 23" barrel 260 gets 2725-2750 from the Black Hills 139 Scenar ammo, and 2800 from a 140gr Hornady hpbt with 43.5gr H4350 in RP brass. I haven't shot much of that, so I don't know if the primer pockets are going to loosen quickly, but it sure doesn't seem to be a "stiff" load.

 

[Jick42]

Re: Hodgons 4831sc "Temp Sensative"

Hey Turbo, thanks for the insight. I do have some H4350, and was planning on trying it with the 123's. I noticed the BC difference between the 120's & the 123's, it's really not even close in comparison. The 120's have a BC of .421, while the 123's are .510. That is a serious difference.
So what i figure i will do, is keep the H4831 load with the 120's for my wife shooting our 250yd range, but develop a load for the 123's using the H4350.

 

[Niles Coyote]

Re: Hodgons 4831sc "Temp Sensative"

I run 4831sc in my 260 with the 139-142 class bullets and have not seen any temp issues (getting 2790-2835 depending on bullet ~47 grains). I have seen 100-200 fps swings in my shooting chrony due to light with several calibers.

Kombayotch posted a year or so ago a temp test and 4831sc did very well.