Reloading Question

Richracer1 · Jun 6, 2009

Any of you ever worked up a load at cooler temps (50F), that gave great accuracy, but when shot at say 70F they showed slight pressure signs? Also, have you ever developed a load that just completely exceeded the velocity of printed loaded?

Reason I ask is that last fall, I worked up a 180AB load for my 30-06 using H414. Hodgdon listed max., 55.5gn gave me the best group size:

Well, I got a very big surprise today when I went to chrono some loads I have developed for a few of my rifles. My chrono gave the 30-06, 180AB, a 5 shot average velocity of 2922 fps. I always started low and work up in .5 increments. The above mentioned load showed absolutely no pressure signs when I shot it initially. Today, 2 of the 10 rounds (issues with chrony) had a little shiny spot on the headstamp but the bolt wasn't stiff to open. I developed this load in the morning hours, around 50 - 55F but the temps were arount 70+ when I was shooting these. I attribute the head stamp shiny marks to the temp difference.
Right now, I'm going to chrono this round again when the temps are back into the 50s and see what I get.

.405 · Jun 6, 2009

I have gotten some good groups in the winter.I live where it is hot as Hell in the summer and the humidity is super wicked. The mirage is unreal.
I haven't really notice any pressues changes on loads from one season to the next,but if you are running max loads I can see where there could be a problem with some powders.

YoteSmoker · Jun 6, 2009

I worked up a great shooting load with RL-22 and 160 grain partitions in 7 Rem mag in cooler tempertatures and tried to shoot the same load last summer in 85-90 degree temps one day and the groups came apart. With the same load, in the early fall, the rifle shot great groups again.

Antelope_Sniper · Jun 6, 2009

I have a load for my 22-250 that shoots great at 50 degrees, but will stick the bolt at 100 degrees.

What you are describing is what folks talk about when asking if a powder is "temperature sensative"

DrMike · Jun 6, 2009

Rich,

I think it is somewhat unusual that such a small temperature spread would generate such significant pressure. I have indeed had issues of pressure in loads, but they were usually developed mid-winter when temperatures were between -15 and 0 C (0 to 30 F). Then, when shooting in summer at 20+ C (70 F), pressure became an issue.

FOTIS · Jun 6, 2009

Yes but not that much difference.

old #7 · Jun 6, 2009

I don't think that 20 degrees in ambient temp is going to make a big difference. 50 degrees maybe. I have found that in the summer months barrels don't cool quickly and also the sun tends to heat the barrel just as much as the hood of a black truck. Also if you shoot a few rounds the chamber starts to heat up. If you decide to let the barrel cool while a round is in the chamber, that round will "cook" while the barrel is cooling.
When you say 2 of the ten rounds (chrony issue) had a little shiny spot on the head stamp..... What (exactly) does that mean?
I am curious why only two rounds displayed signs of a possible over pressure.
Where were these "rounds" in the shot string?

rick smith · Jun 6, 2009

What barrel length do you have? 2922fps for a 180gr bullet out of a 30/06 is way too fast.Rick.

JD338 · Jun 6, 2009

I had that happen. That is why I work up loads in the summer, don't have to worry about them in the fall. Clock your loads in the cooler temps to see where they are at.

JD338

Desert Fox · Jun 6, 2009

This happened to me with my 308 using BLC-2. Same scenario!!! developed the load around spring with no issue whatsoever but when shot on a hot day, it resulted in a sticky bolt and even blown primer. I called Hodgdon about this and was told that, all the spherical powder in their line are very temperature sensitives and that always exercized with caution when loading this powder on hotter days. I now had two different load for my rifle using this powder as a result.