Temperature sensitivity question

[earl1704]

If I use a powder H414 which is not considered an "extreme" powder will just my point of impact change but retain a group with temperature changes?

I can hunt varmints with my 22-250 in the 20's or 70, 80, degree temperatures.

Load:
22 cal Hornady V-Max
41 gns. H414
Primer WLR
Remington 700
1:14 twist

I know the bullet falls below the gyroscopic stability formula but I cant seem to find a
bullet in the .224 category that meets the 1.4 minimum and will reach out (500 yds.)and smack a coyote. So I would like to try for the velocity this reload offers, but as I said will only my POI change or are there other things to consider?

 

[benchracer]

Temp Sensitivity means that the pressure and muzzle velocity generated by your powder charge changes with the temperature. In simple terms, when you tune a load for accuracy, you are tuning for an optimum velocity range with a given combination. If temperature sensitivity causes enough change in muzzle velocity, your load will be operating outside of the "sweet spot" you have tuned it for, and your accuracy will decline.

Another aspect of temp sensitivity, that is often overlooked, is that your primers can be temp sensitive. It is possible to use a powder that shows low temp sensitivity and still have temp issues related to the primer. That is one reason why you will see conflicting claims about the temp sensitivity properties of a given powder.

If you are concerned about temp sensitivity issues in your 22-250, you should consider powders like Varget or IMR 8208 XBR.

 

[earl1704]

Thank you for the information, I moved from California to Idaho messed up my reloads.
Back to the drawing board..............

 

[DocDoc]

Earl,
Sounds like the move from monometal only to ID will be a good one, especially resident status hunting. You will get the handholds sorted out for greater temperature fluctuation.

 

[barefooter56]

earl1704,
Benchracer has a great point ! Now as far as the twist rate stability issue . The Miller twist rate formula that all modern ballistics calculators use assumes that all modern bullets are shaped a specific way and that the boat tail of the bullet will have a comparative angle to the ojive. However, many bullets have flat bases or short boat tails in comparison to most modern bullets. For the flat base or short boat tail bullets the SG is higher that the stability calculator is predicting. Now unfortunately there isn't a different mathematical formula available that will work for these bullets. For this reason we have created recommended twist rates for these bullets base on live fire and extensive testing by our ballistician. You can find these at All Bullets | Berger BulletsBerger Bullets. We are working on a full list of these bullets that will be posted to our Twist Rate Calculator page in the future.
Take care!
Phil Hoham
Berger Bullet Tech

 

[barefooter56]

dont know where the ALL Bullets gibberish came from in regards to the link. Must be the North Koreans again! Here is the correct link All Bullets | Berger BulletsBerger Bullets
This corrects my previous post.
Take care
Phil Hoham
Beger Bullet Tech

 

[barefooter56]

Wont let me post correct link so email us and we can get you the correct link. Sorry.
Phil

 

[wbm]

If I use a powder H414 which is not considered an "extreme" powder will just my point of impact change but retain a group with temperature changes?

No way to answer that question. You just have to work up loads with the H414 powder and get your answer that way.

The Nosler 55gr Ballistic Tip can be used in your 1-14 twist barrel and get up to 3700fps with the right powder....that will most definitely "smack" a coyote at 500 yards.

 

[J E Custom]

H414 is definitely heat sensitive. I use it in my 7/08 with very good accuracy, the problem I have is that during the winter when temps are in the 20s and 30s my velocity is 3000 to 3010 ft/sec during the summer months it reaches 100o and the velocity goes to 3150, so I use this load only during the winter.

I have had very good luck with Varget but the accuracy cant quite match the H 414 loads (There is very little difference in the two) and the Varget loads will still shoot under ,200 thousandths so
it is my choice to continue using the H 414 loads for hunting.

I try to use only Extreme powders but it is hard to get away from some other powders that shoot and group so well.

J E CUSTOM