H414 and 7mm-08 Temp Sensitivity Concerns

[hct4all]

Hi guys, I am a newer reloader about 2 years now and I am little paranoid. I load for 7mm-08, 30/06 380 & 38/357. I am having a hard time getting my model 7 7mm-08 to group less than 1.75". A fellow at the range has the same rifle and is getting .5" groups. So he shared his load data and also mentioned that the powder was on sale at field and stream so on the way home I purchased a lb. The powder is H414. After doing some research online the words temp sensitivity came up. Some mentioned using a magnum primer. I called Hodgden about that and they did not reccomend the mag primer but did mention that the powder was temp sensitive. The tech told me a story about going over pressure when hot. So now I am seeking advice.

Other reviews said that the powder in certain calibers showed no sensitivity. What are your experiences?

So here are my questions.

At what temperature should I work up a load? As some may know in Pennsylvania know during our seasons there can be a 60 degree temp difference in a weekend. I would hate to be spot on on Saturday but low on Monday. Or overpressure if its hot. Orrrrrr am I just being paranoid. Sorry for the long post.

 

[Silent Sam]

A few things... H414 is the same powder as W 760. A lot of factory Winchester ammo is loaded with a bulk version of this powder. Many manufacturers use ball powders as they meter well. I wouldn't worry too much about it being overly temp sensitive. Ideally you should work up a load at the temp you intend to use it. If you worked up a max high pressure load in in extreme cold and used it in extreme heat you might have an issue. Who works loads up in extreme cold weather if they don't have to?. With the case size you are talking about you likely don't need magnum primers. Winchester LR primers are generally "hotter" than other std primers. Many loaders use magnum primers as a matter of course when using ball powders but you are working with a relatively small case and it shouldn't be an issue. Just because a fellow with the same rifle has a good load for his rifle doesn't mean your rifle will like it. Are you planning on using the same primer he does?

 

[Grumulkin]

H414/Win. 760 is temperature sensitive and so are pretty much all other powders. If you tested the "Extreme" powders, you would probably find some temperature sensitivity but probably quite a bit less than other varieties of powders. If you aren't loading on the bleeding edge of high pressure, I wouldn't worry about it. The dictum about always using a magnum primer with ball powders is one I've always ignored.

Also, though you think he does, your friend does NOT have the same rifle. Even in supposedly identical rifles, the chamber, throat and even the bore diameter can be somewhat different. One purveyor of guns/gunsmith had several "identicle" rifles with he tested with identicle ammunition and got velocity differences as much as 200 fbs between them so obviously they weren't identical even if he thought they were.

If your friend's load is conservative, judged by comparing it with one or preferably more manuals, then you could try as it is including the type of primer. If it didn't work as advertised, you could then work it up in the usual way starting at the lower end of recommended loads.

 

[GooseGestapo]

My Rem M7 7-08 only unpredictably shoots 1/2" for 3-shots. More like 1.5-2" 5-shot groups. But, it don't care! It does kill all out of proportion to expectations and is a "lucky" rifle. 30+deer, an elk, and several pigs.
I doubt that H414 is the answer but it's a good powder. You didn't say what bullet/weight you were going to use, but I can make some generalized recommendations.
47.0gr with 139-140, 45.0 with 150-154. Velocities are as good as you'll see, and accuracy is dependent on many other factors.
If hunting in Pa during deer season you'll be ok with standard primers. If temperatures run below 0deg F. use a "magnum" primer. The above loads are ok with magnum primers. If shooting/hunting in temps 100deg, keep ammo out of direct sunlight, magnum primers or standard...

You can try different primers, but in my 40+ years of loading experience, bullets and seating depth make much more difference.
I use RL17 or IMR4350 and Sierra bullets in my 7-08, seated to touch the grooves, if I want to see small groups. H414 doesn't agree with my rifle.

 

[ironworkerwill]

Rewrite edit* I initially misunderstood, your post.

If you're worried about temperature sensitivity, stay on the low end accuracy node. The sensitivity won't make that big of a difference unless your on the bleeding edge of pressure.

Want accuracy? Try Fed mag primers, Hornady 139gr flat base interlocks, and H380. It's shot fantastic in everything I tried. Not to bad at $0.36

 

[243winxb]

CCI thinks you need a mag prime for ball powders, and so do i. Even more if the powder charge is near the starting load. http://www.cci-ammunition.com/products/primers/primer_chart.htm and

We tested loads at both maximum normal pressures and at the starting loads (some labs calculate start loads—we shot them). Standard primers caused no ignition issues at the max load but posted higher extreme variations in pressure and velocity in the lower pressure regimes of the start loads. In extreme cases, the start loads produced short delayed firings—probably in the range of 20 to 40 milliseconds but detectible to an experienced ballistician. Switching that propellant to a Magnum primer smoothed out the performance across the useful range of charge weights and completely eliminated the delays.

Read more: http://www.shootingtimes.com/ammo/ammunition_st_mamotaip_200909/#ixzz4SmClYFv6

 

[ArchAngelCD]

Like said above, H414 is identical to W760 and a ball powder. It performs similar to IMR4350 & H4350 and that might be a better choice for loading for the 7mm-08. Rarely does the best accuracy come from a ball powder so 4350 might be your answer. If H414/W760 or 4350 don't work out it's possible H380 might do the trick.

Which powder/powders are you using in your other cartridges?

As for temp sensitivity I wouldn't worry too much about it. Usually the sensitivity is noticed below zero or above 100 degrees. Our hunting season here in PA is usually at moderate winter temps between 20 and 40 degrees. I have never had a problem with any powder in hunting ammo.

 

[eastbank]

my loads for my 7mm08,s has been varget with nosler bullets. and they have been moa or little less. eastbank.

 

[Bart B.]

While ball powders are popular because they meter very uniform in charge weights, they typically don't produce accuracy as good as extruded powders with 2 or 3 times the charge weight spread.

IMR powders 4064, 4320 and 4350 were favorites in the heydays of the 7-08 winning rifle matches at the Nationals.

Winchester primers are "hotter" than most. They know their ball powders are harder to ignite decently. Smart internal ballistics people are convinced ball powders slam bullets harder into the rifling and they're deformed too much. Stick powders ignited with milder primers push bullets more gently into the rifling; they're deformed very little or not at all.

 

[hct4all]

Thanks guys. I ended up selling the powder for what I paid and bought some IMR4350. I have tried work ups with IMR 4064 & Reloader 15. With 139 SST and 150 Nosler Partitons.. I use CCI std primers. The tech and some of the stories on the web made me parinoid

 

[Grumulkin]

Smart internal ballistics people are convinced ball powders slam bullets harder into the rifling and they're deformed too much. Stick powders ignited with milder primers push bullets more gently into the rifling; they're deformed very little or not at all.

That doesn't sound too smart to me. Now we need a powder that "gently" pushes bullets into the rifling and if you don't the bullets are "deformed?" I would call that theorey ridiculous.