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Joined: 08 Feb 2009 Posts: 1322 Location: Western WA

The latest chapter of my efforts to find a good 7/8 oz load for Red Dot has yielded an interesting finding on temperature effects. I had stowed some loads and gear in the vehicle which sat overnight in the driveway, during which the temps dropped into the low 30s.

Before I left for the range this morning, I loaded up an additional handful of identical 7/8 oz loads downstairs where the temp was about 70. I tucked them into my coat pocket.

At the range, the temp was about 36F. The difference between the cold soaked loads and the fresh warm loads was a consistent 105 FPS (1198 vs 1303 avg). The pressures are evidently affected by temps, which muddies up my lab testing plans.

My little Red Dot project seems to be morphing into a somewhat quixotic venture. Stand by for further results.

B.

Joined: 04 Mar 2019 Posts: 1853 Location: Central ND

Bruce,

FWIW, this is a tidbit I learned from Tom Armbrust.

A real solid load should only lose about 5% velocity when comparing a load's performance at 70 degrees F to the same load at 0 degrees F. It might seem a bit far fetched but it is actually very attainable. Sometimes all it takes is a primer change or a slight increase in powder charge to solve the problem. The drop off also exposes wads that may not fit a hull all that well.

Kinda why I don't care for loads that aren't at least in and around the 10,000 PSI chamber pressure number. Not saying that loads exhibiting chamber pressures lower than 10,000 PSI don't perform well when it's cold, just that the tendency to have a good all around load is better when the pressures are kept up towards MAP.

Kinda surprised that Red Dot is giving those numbers, usually it performs very well when cold.

One of these days, when I get brave (and foolish) I am going to set up my chronograph when it's -25 out and try a few loads, that I have left out all night, just for the heck of it.

Joined: 04 Mar 2019 Posts: 1853 Location: Central ND

I can't remember who posted or where I found the info, but there is a formula for what happens to chemical reactions (as in burning smokeless powder) as the temperature drops. I know chemical reactions slow down as it gets colder, but the info put a number to it. I should have saved the info......maybe a member here knows about it?

Maximum Smoke perhaps?

Joined: 09 Mar 2016 Posts: 757 Location: Mn.

When Kevin was just starting out as operations manager at Downrange I used to do cold weather testing for him often. It was before he got a commercial freezer and I could just set shells on the railing at a clubhouse for an hour or so. Used to shoot against Wi. during the blizzard league when I was young. And dumb. -25 below with Windchills of 50 below many times. Did I mention that I was young and dumb?! Although it was only ~15 years ago or so.

Even some factory shells will have problems with cold at those temps especially Euro shells. But most of them have gotten better over the years, for the most part.

With reloads what we found, and Kevin taught me, was crimp depth is critical. Crimp depth is critical to pressure and Mark is right (of course) and 10K PSI was always kind of our benchmark for cold weather shooting. Pressure is your friend in the cold. As long as it doesn't go over max.

Primers have more to do with pressure than powder in most cases. Old timers often switch to F209A primers in the winter. And know more than a few that say crimp them deep enough to eat chili out of. That can be dangerous however. Most of them are trapshooters so that explains a lot, just saying...

Tom Armbrust has a chart out there and article on crimp depth and pressure

As does Hodgdon (or did) on their reloading section. Their testing and published data is done with a .055 crimp depth

To accurately measure crimp depth Kevin had me cut a notch in my calipers. Measure the shell OAL then slip the notch over the lip of the crimp and the difference is your crimp depth. Accurate crimp depth. Anything else is just a guess.

The son and I went through 17K rounds that summer using F616 primers counting the box lids and Promo powder. Then it got cold and the wheels feel off the wagon. Fiocchi has since changed the composition of F616 primers and my understanding is they work better in the cold now.

But the first baseline measurement you need to do when working with cold weather testing is verify a crimp depth of .055 and as Mark said try to shoot for a load with ~10K PSI of pressure.

Joined: 04 Mar 2019 Posts: 1853 Location: Central ND

Cold Iron please do not take offense to this. It is no reflection on anything you have done or commented on. It is just my observation, opinion and quite frankly a pet peeve.

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I am not suggesting to do this with data that has been tested using a .055" crimp depth.

Every 12 and 16 gauge load I have ever developed has a crimp depth of .065". Why?

I measured 12 and 16 gauge factory crimps and they are NEVER set at .055" deep. Mostly .065" to .070" and sometimes deeper. As reloaders we are not using new hulls most of the time. Then why are we crimping to .055", when the factories are setting their depths .015" deeper using brand new hulls and using a spinning finish crimp die that probably imparts a bit of heat to 'set' the crimp?

I have no idea who or what decided that .055" is supposed to be the correct depth for 12 and 16 gauge reloads. Doesn't make a whole lot of sense to me.

Every reload that comes off my machines are set at .065". When you have a bit more depth, that crimp shoulder really rolls over nice.

Please remember this is only my 2 cents.

I completely agree with Cold Iron that good, consistent, solid crimps are very important to cold weather reload performance.

Joined: 08 Feb 2009 Posts: 1322 Location: Western WA

Replaced SG16S with SG16 (thanks to member MSM here) which snugged up crimps nicely in 2 1/2” hulls. Mild 7/8 oz Red Dot loads at 1200 FPS delivers surprisingly tighter patterns than 1 oz at 1300 FPS (800-X) through the M12 Mod choke. This 7/8 oz load definitely makes trap more challenging.

On the other hand, the venerable 2 1/2” A5 enjoys the light 7/8 oz loads with perfect cycling, and with the 26” Cyl barrel is ideal for skeet. Looks like a one size fits all load might not exist. (I got complaints from skeet competitors about the blast from the heavy 1 oz 800-X loads!)

B.

Joined: 04 Mar 2019 Posts: 1853 Location: Central ND

Brewster11,

Skeet shooters always whine about something, talking, too windy, the target setter, too sunny, too cloudy, someone a mile away started a Harley.......they might as well have a new one 800-X in a 1oz. load!!

They used to hate when I shot my ported guns!! LOL