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H4350 Temp/FPS change

deadnbrkn84

deadnbrkn84

Gunny Sergeant
Full Member
Minuteman
Jan 16, 2011
1,246
81
39
Portland, OR
So when I worked up a load for my match gun I settled on:

142SMK
43.5 H4350
etc.

The load chrono'd at 2812fps SD:4. Very accurate too. I did this load work in June up here in Oregon and it was about 85 degrees. Shooting yesterday I chrono'd it just for shit's and giggles and to my dismay it was shooting 2780 fps. About 30fps slower then usual. Yesterday it was about 40 degrees here. So 45 degrees colder then when I worked up the load.

Now my understanding is that H4350 is supposed to be very temp stable, so I could understand a a slight change in fps but this just seems extreme. This was done with a magneto speed chrono both times and it's all the same lot of powder, same load, length etc. Now the air was very thick out there yesterday but at the muzzle that shouldn't make that big of a difference.

I've got a ton of matches coming up and want to get this off my mind. Any help would be appreciated. Thanks so much.
 
Re: H4350 Temp/FPS change

How many rounds since the first chrono to the current chrono? As throats wear, pressure goes down, resulting in lower MVs.
 
Re: H4350 Temp/FPS change

I use that exact same load in my 260, and a little lighter in my 243. I can't tell you why, I don't think its the powder but I always check my dope at distance when it gets colder. Maybe because the DA is lower in the winter typically. But I equate it to shooting a stage in the morning and as the air heats up the bullets fly higher after lunch. DA is part of the equation, but like you at the muzzle? I don't chrono on cold days for the same reason, too much change when it heats up. Maybe an engineer or ballistic expert can add some info to the discussion.
 
Re: H4350 Temp/FPS change

To put it simply as possible. No matter the powder there's going to be some variance on extreme temp swings. Only losing 30fps avg on a 45 degree temp swing is pretty good.

Imagine if that was reloader 15 or 17.....willing to bet it'd be a hell of a bit slower....
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Poison123</div><div class="ubbcode-body">To put it simply as possible. No matter the powder there's going to be some variance on extreme temp swings. Only losing 30fps avg on a 45 degree temp swing is pretty good.

Imagine if that was reloader 15 or 17.....willing to bet it'd be a hell of a bit slower.... </div></div>

That was my thought. Just wanted to make sure I had a grasp on what was going on. I've gotta make a bunch of dope charts and wanted to make sure I did it at the correct fps. It's about .3-.4 mil difference at 1k.

As far as throat wear, it's about 400 rounds since last time. I have the barrel melonited and I did measure the throat. I couldn't measure any discernible difference in the throat wear from then until now. I will have every barrel I own melonited from this point forward. That is a simply amazing process.

Thanks for the help gents. Appreciate it.
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Poison123</div><div class="ubbcode-body">To put it simply as possible. No matter the powder there's going to be some variance on extreme temp swings. Only losing 30fps avg on a 45 degree temp swing is pretty good.

Imagine if that was reloader 15 or 17.....willing to bet it'd be a hell of a bit slower.... </div></div>
+1 ... I'd be taking notes on velocity shifts at different temperatures. FPS equates to +or- mil/moa down range.
 
Re: H4350 Temp/FPS change

This sounds like the load I use in my 260. I chronographed in two temperature extremes to check the temperature affect. I came up with .44 f.p.s. change/degree of temperature change. Your results are similar to mine. By contrast Varget in my 260 shooting 123 SMK has a MV variation of 1.26 f.p.s. change for each degree of temperature change. This does seem a little extreme for an "Extreme" powder but I chrongraphed this load in 80 degree temperature, checked it in forty degree temperature then entered the MV variation in Shooter. We shot a little match this weekend and I used the adjusted velocity for 30 degree temperature and I was dead on out to the stage limit which was 720 yards. I was good on one MOA targets from 100 to 720 yards. I wish I could use H4350 with this bullet but it is just not as accurate as Varget. I adjust my range cards and live with it.
 
Re: H4350 Temp/FPS change

Been using H4350 for years. When I first got my .243 I had to work up a load in New England winter at teens to 20's to get ready to shoot at Rifles Only in March in South TX in the 80s to 90s. The load I worked up was just as accurate in TX as it was at home and hit to 1000 yards on steel without a problem. I had chronoed it as well in my summer temps and there was a 15-20fps difference.

I am a big fan of the Hodgdon Extreme line of powders.
 
Re: H4350 Temp/FPS change

I did load development in the cold months and came up with a moderate load. When summer rolled around, the load was so hot the primers were falling out of Lapua brass. Your observation is in line with mine.
 
Re: H4350 Temp/FPS change

That's just it. The load is VERY accurate. I sub a .43" group at 300 yards with it at the slower speed and it's just as accurate at at both sides of the fps scale. So the accuracy is not something I'm concerned about. More just verifying with you guys what I can attribute it to so I know.
 
Re: H4350 Temp/FPS change

I don't know if this correlates with this or not. But I have a 6.5 creedmor Crusader. Same powder lot, same bullet lot , same everything. Since I first got the rifle it has freaking drilled tacks. But the more I shoot the faster it gets. No matter what temp. (+_30degrees). Since I first developed the load I have picked up 85 fps. Same charge weight same bullet 140 Berger. Same ect.... You get my drift. Today I shot at 520 yards practicing for a match only to find out I had yet again gained 25 fps. Ismh that it keeps getting better with speed. 2 " group today with 15 shots at 520 yards
 
Re: H4350 Temp/FPS change

AS,
Alot of barrels get faster after a certain number of rounds, just getting imperfections cleaned out of barrel. It's a good thing!
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: milo-2</div><div class="ubbcode-body">AS,
Alot of barrels get faster after a certain number of rounds, just getting imperfections cleaned out of barrel. It's a good thing!</div></div>

Damn skippy!!
 
Re: H4350 Temp/FPS change

Yes you will get some velocity differences with barrels usually after 150-200 rounds.

Question are you seeing the differences over a chrono or figuring it from data? Just wondering from this statement

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Aimsmall55</div><div class="ubbcode-body"> Today I shot at 520 yards practicing for a match only to find out I had yet again gained 25 fps. </div></div>
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Yes you will get some velocity differences with barrels usually after 150-200 rounds.

Question are you seeing the differences over a chrono or figuring it from data? Just wondering from this statement

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Aimsmall55</div><div class="ubbcode-body"> Today I shot at 520 yards practicing for a match only to find out I had yet again gained 25 fps. </div></div> </div></div>

Chronograph and trigger time. I only use my chrony to see Es sd, ect. Take my
real data from results behind the gun. I use ballistic AE. In custom mode. But in all honesty the chrony #'s are going up (velocity). According to my data I need 12.19 moa to put me on at 600.
But in simple terms I needed 42 1/4 moa clicks to put me on at 520. Now 125 to 150 rounds later I need 36 1/4 moa turns.
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Yes you will get some velocity differences with barrels usually after 150-200 rounds </div></div>
Here it seems like between 30-50 rds get the biggest jump and after 100 it has settled in.
 
Re: H4350 Temp/FPS change

Seems that way. I guess after 70 or so rounds at Saturday's match ill know. But I feel confident it's in it's "settling in" phase
 
Re: H4350 Temp/FPS change

Depends on barrel but I won't get a hard chrono number or run a rifle in a match until I have 150-200 rounds through it so I know it's settled in.

I asked about the chrono as if it was only dope made velocity other factors like scope tracking and environment can come into play.

And life is easier if you don't think in clicks.
wink.gif
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Depends on barrel but I won't get a hard chrono number or run a rifle in a match until I have 150-200 rounds through it so I know it's settled in.

I asked about the chrono as if it was only dope made velocity other factors like scope tracking and environment can come into play.

And life is easier if you don't think in clicks.
wink.gif
</div></div>

Well, It has seen a 35 degree temp change at the most plus or minus each way. I thought I answered what you were asking. Oh, btw I also think in mils.
smile.gif
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Depends on barrel but I won't get a hard chrono number or run a rifle in a match until I have 150-200 rounds through it so I know it's settled in.

I asked about the chrono as if it was only dope made velocity other factors like scope tracking and environment can come into play.

And life is easier if you don't think in clicks.
wink.gif
</div></div>


The rifle shot as I thought it would today at the match. Didn't win but I had 29 x's and a 580. Made a few bad wind calls.... Cost me the match. But I did get some hard #'s. master classification was achieved but the match was not a recognized one so I scored high enough, but am not formally categorized as master class. Was running the 140 vld at 2885.... Damn sure feel good about it though
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deadnbrkn84</div><div class="ubbcode-body">So when I worked up a load for my match gun I settled on:

142SMK
43.5 H4350
etc.

The load chrono'd at 2812fps SD:4. Very accurate too. I did this load work in June up here in Oregon and it was about 85 degrees. Shooting yesterday I chrono'd it just for shit's and giggles and to my dismay it was shooting 2780 fps. About 30fps slower then usual. Yesterday it was about 40 degrees here. So 45 degrees colder then when I worked up the load.

Now my understanding is that H4350 is supposed to be very temp stable, so I could understand a a slight change in fps but this just seems extreme. This was done with a magneto speed chrono both times and it's all the same lot of powder, same load, length etc. Now the air was very thick out there yesterday but at the muzzle that shouldn't make that big of a difference.

I've got a ton of matches coming up and want to get this off my mind. Any help would be appreciated. Thanks so much.</div></div>

What primer are you using? In colder weather its recommended that you use a magnum primer. Just somthin you might try.
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Shadowofjudgment</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deadnbrkn84</div><div class="ubbcode-body">So when I worked up a load for my match gun I settled on:

142SMK
43.5 H4350
etc.

The load chrono'd at 2812fps SD:4. Very accurate too. I did this load work in June up here in Oregon and it was about 85 degrees. Shooting yesterday I chrono'd it just for shit's and giggles and to my dismay it was shooting 2780 fps. About 30fps slower then usual. Yesterday it was about 40 degrees here. So 45 degrees colder then when I worked up the load.

Now my understanding is that H4350 is supposed to be very temp stable, so I could understand a a slight change in fps but this just seems extreme. This was done with a magneto speed chrono both times and it's all the same lot of powder, same load, length etc. Now the air was very thick out there yesterday but at the muzzle that shouldn't make that big of a difference.

I've got a ton of matches coming up and want to get this off my mind. Any help would be appreciated. Thanks so much.</div></div>

What primer are you using? In colder weather its recommended that you use a magnum primer. Just somthin you might try.</div></div>

Wouldn't that throw off his #'s meaning Es and sd. For instance the fgm210m
Give me 25 to 30 fps more than the cci br2's but my #'s are way down with Es in the single digits. Hell, I might have a mag primer just to try it. What do you think a Fgm215m would do in a .308 or 6.5 creedmor in terms of velocity?
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Aimsmall55</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Shadowofjudgment</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deadnbrkn84</div><div class="ubbcode-body">So when I worked up a load for my match gun I settled on:

142SMK
43.5 H4350
etc.

The load chrono'd at 2812fps SD:4. Very accurate too. I did this load work in June up here in Oregon and it was about 85 degrees. Shooting yesterday I chrono'd it just for shit's and giggles and to my dismay it was shooting 2780 fps. About 30fps slower then usual. Yesterday it was about 40 degrees here. So 45 degrees colder then when I worked up the load.

Now my understanding is that H4350 is supposed to be very temp stable, so I could understand a a slight change in fps but this just seems extreme. This was done with a magneto speed chrono both times and it's all the same lot of powder, same load, length etc. Now the air was very thick out there yesterday but at the muzzle that shouldn't make that big of a difference.

I've got a ton of matches coming up and want to get this off my mind. Any help would be appreciated. Thanks so much.</div></div>

What primer are you using? In colder weather its recommended that you use a magnum primer. Just somthin you might try.</div></div>

Wouldn't that throw off his #'s meaning Es and sd. For instance the fgm210m
Give me 25 to 30 fps more than the cci br2's but my #'s are way down with Es in the single digits. Hell, I might have a mag primer just to try it. What do you think a Fgm215m would do in a .308 or 6.5 creedmor in terms of velocity? </div></div>

I wouldnt think the mag primer would change the velocity. But what it should do is make the load more consistent in fps. Im thinkin that if there is an increase in velocity with a mag primer then you are having an ignition problem. So once you get enough fire to light the powder you are now maximizing your powder burn.
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Shadowofjudgment</div><div class="ubbcode-body">

I wouldnt think the mag primer would change the velocity. But what it should do is make the load more consistent in fps. Im thinkin that if there is an increase in velocity with a mag primer then you are having an ignition problem. So once you get enough fire to light the powder you are now maximizing your powder burn. </div></div>
Switching to a magnum primer could very well increase pressure in your case, thus affecting velocity. Not very sound advice.
Any change in a component could change velocity.
 
Re: H4350 Temp/FPS change

I tried the exact same H4350 load in my creedmoor with fed210m primers and cci200 primers.The 210m average 35fps faster than the cci200. It was about 30 degrees and I shot them within an hour of each other. I have some loaded up now with cci250's that I am going to try this week with the same load (my load is not too hot).
 
Re: H4350 Temp/FPS change

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 8nbait</div><div class="ubbcode-body">I tried the exact same H4350 load in my creedmoor with fed210m primers and cci200 primers.The 210m average 35fps faster than the cci200. It was about 30 degrees and I shot them within an hour of each other. I have some loaded up now with cci250's that I am going to try this week with the same load (my load is not too hot). </div></div>

42.4?? If that's what your loading then we r the same. I'm getting 2885 fps with out the slightest indication of op. not a single primer flattened or ejector mark. I would have no problem bumping it up a few tenths but I see no reason for changing what is ultimately the best shooting round I've ever Developed. Only thing I may do is start loading with br2's after this bullet lot runs out. Got another 500 140 vlds in the mail and 30 fps is nothing if it lowers my es
 
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