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Just how much does temp affect RL15 and IMR4064?

Fatelvis

Sergeant
Full Member
Minuteman
Jun 15, 2003
304
4
Mokena, IL
I'd like to use these two powders in my accurized M1A (using 175 SMKs @ 2600fps), but have been leaning towards the "Extreme" powders to minimize temp sensitivity probs. I'll be shooting in 0*-95* temps at one time or another. How much actual difference in inches of POI (at say 300 yds) does a jump from 0* to 95* temp make with these two powders in 308 Win? Thanks guys!-
 
Re: Just how much does temp affect RL15 and IMR4064?

double base ball powders are the most temp variable - both of those are single base stick, so not much of a problem - from 0 to 95 F about 2-3 moa at 300

I take it you shoot at Bonfield? - I go to Waterman
 
Re: Just how much does temp affect RL15 and IMR4064?

So possibly 9" difference in POI @ 300 yds?! Yikes!
 
Re: Just how much does temp affect RL15 and IMR4064?

you can easily stabilize the the temp - keep the ammo in a cooler in the summer, inside the jacket in the winter - varget may cut the variance by half but it is still there
 
Re: Just how much does temp affect RL15 and IMR4064?

let me know if you want to check out waterman sometime, a similar drive for you, but we have 600 yds, it is also usually less busy
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: George63</div><div class="ubbcode-body">double base ball powders are the most temp variable - both of those are single base stick, so not much of a problem - from 0 to 95 F about 2-3 moa at 300

I take it you shoot at Bonfield? - I go to Waterman </div></div>

That seems excessive. More likely about 1moa at 300yd and about 2moa at 600yd. Likely less if you handle your ammo well.
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">More likely about 1moa at 300yd and about 2moa at 600yd.</div></div>
Isnt that impossible? wouldnt it be either 1moa or 2moa across the course?
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: buffybuster</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: George63</div><div class="ubbcode-body">double base ball powders are the most temp variable - both of those are single base stick, so not much of a problem - from 0 to 95 F about 2-3 moa at 300

I take it you shoot at Bonfield? - I go to Waterman </div></div>

That seems excessive. More likely about 1moa at 300yd and about 2moa at 600yd. Likely less if you handle your ammo well. </div></div>

probably is excessive for real life conditions as mostly no one will spend enough time outside a temp controlled structure/vehicle at the extreme of that temp spread to get the powder to those temps

more common would be 20 - 80 F and the variance would be 1-1 1/2 moa at 300
 
Re: Just how much does temp affect RL15 and IMR4064?

RL 15 is double base. all IMR rifle powder sans 4227 are single base.
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fatelvis</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">More likely about 1moa at 300yd and about 2moa at 600yd.</div></div>
Isnt that impossible? wouldnt it be either 1moa or 2moa across the course? </div></div>

No it's not impossible. At short range, velocity discrepancies are small compared to the MV and have very little impact on trajectory but at longer ranges as the velocity bleeds off the discrepancies become a larger percentage and have a larger impact on trajectory.
 
Re: Just how much does temp affect RL15 and IMR4064?

temperature is a double wammy - it affects the powder (MV) - but also the air density, which is the element that increases effect with distance
 
Re: Just how much does temp affect RL15 and IMR4064?

Is Varget too slow to use in a M1A/M14 pushing 175 grn bullets? I was always told IMR4064 was as slow as you should go.
 
Re: Just how much does temp affect RL15 and IMR4064?

varget is faster than 4064 - shows identical to IMR 4895
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: George63</div><div class="ubbcode-body">varget is faster than 4064 - shows identical to IMR 4895</div></div>

Varget is slower than 4064. It is fast enough to use in a gas operated semi-automatic, though.

It was also specifically optimized for using in a .308, even though it works very well in other applications.
 
Re: Just how much does temp affect RL15 and IMR4064?

My POI was approx 9" lower at 300 yards when firing in 20 degree F weather vs. 90 F and sunny, while using RL-15. 155 Scenar over 46.2g of RL-15 made as high as 3050 fps at 90 degrees and as low as 2850 in 20 degree temps - once everything was cooled down. Just my .02
 
Re: Just how much does temp affect RL15 and IMR4064?

Good thinking to be concerned about temp when pushing a 175SMK at 2600fps through an M1A. RE15 and IMR4064 can show variances of as much as 150fps to as little as 75fps from 0-95 degrees. I would slow the 175SMK down to 2500fps with either powder and bang away. Cheaper and safer to slow it down than replace your op-rod. My M1A gets the best results from VVN135
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> I would slow the 175SMK down to 2500fps with either powder and bang away.</div></div>
Normally I would agree, but I am putting a new PFI RR900 scope on it, and it subtends out to 1000yds using a 175 SMK @2600. I'd like to keep the load as close to that as I can to keep the BDC accurate, even if I have to use a grooved piston. (Which I'm thinking I might.)
 
Re: Just how much does temp affect RL15 and IMR4064?

I wouldn't try it in an M1A just too risky and op-rods aren't cheap. Besides that my face is ugly enough and my eyesight is getting worse with both eyes still in my head
 
Re: Just how much does temp affect RL15 and IMR4064?

Double base powders tend to be the most susceptable to temp changes. Re-15 is a double base powder. It does have a coating to help with that, but not much more.

FWIW, 4064 was like the first powder ever to be coated in the hopes that doing that would make a more consistent load in temperature extremes. To a certain point it did. It was better at least than the rest of it's contemporaries.

If you want the best year-round performance, look to the newest powders out there that specifically handle that. Hodgdon extremes and RE-17. While Re-17 IS a double based powder it's manufacture process (and ingredients, I'm sure) keep it to be a lot less temp sensitive than a lot of other single base powders. Re-17 works well with 175 gr. and up due to it's speed.

IMO, the best powder right now in that weight is IMR 8208XBR. That was specifically formulated to handle the broad temperature extremes. It works well with bullets up to and including the 175 gr. The next best is Varget. They are heads and shoulders above anything else out there specifically for your reasons. After that I would use H4895 Extreme. I use it all the time as I don't need Varget so much that I'll pay the premium around here for it. I did get some 8208 cans while they were on sale.
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Something else you may want to know. My experience with temp sensitive powder is that the lowest difference is obtained when you have a case full, or as full as you can get, of a powder that is near the upper end of the pressure range for that cartridge. Fill the case to the uppermost accuracy node you can find.
In the case of Semi-auto's, it is sometimes impossible to get a case full of the powder you need to even out the temp issues. The M1 Garand in .30-06 is a classic example. To fill a case you need a powder that will bend an op-rod because it's too slow.
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sandwarrior</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: George63</div><div class="ubbcode-body">varget is faster than 4064 - shows identical to IMR 4895</div></div>

Varget is slower than 4064.
. </div></div>

do not know where this comes from

they are close enough that lot variations may have them overlapping but here:
http://www.reloadbench.com/burn.html

and here:
http://www.accuratepowder.com/wp-content/uploads/2010/12/burn_rates.pdf

show varget as faster than the IMR variety of 4064

edit: I see the lyman manual shows varget as slower
 
Re: Just how much does temp affect RL15 and IMR4064?

George63,

It's been my experience that I've always been able to load more Varget than 4064. I've only used IMR 4064 as I haven't had the need, <span style="text-decoration: underline">or found on sale,</span>
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the AA4064.
 
Re: Just how much does temp affect RL15 and IMR4064?

All bullshit and assumptions aside. Imr 4064 is the Shit. F vargay in your M1A. From 85- 33 degrees accross my chrony absolutely no velocity difference. NONE!!!! 41.7 IMR4064 grains behind 175 SMK. Is my bolt gun load 41 for my M1A or until u get to 2550fps. Thank you very much. Love RL-15 too as well as IMR4895. These Two powders are temperature sensitive. However they're extremely accurate.
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 2clicks</div><div class="ubbcode-body">All bullshit and assumptions aside. Imr 4064 is the Shit. F vargay in your M1A. From 85- 33 degrees accross my chrony absolutely no velocity difference. NON!!!! 41.7 IMR4064 grains behind 175 SMK. Is my bolt gun load 41 for my M1A or until u get to 2550fps. Thank you very much. </div></div>

I'm glad the IMR4064 works for you. As it should. That's what it was developed for. But insinuating Varget wasn't formulated later and with more properties isn't correct. It was a formulation to help load the case of a .308 completely and remain as stable as possible in all temps. Because of it's makeup, it does that better than IMR4064. But, it is slower.

Along that line do keep in mind IMR 8208XBR is slightly faster than 4895 (any brand). But, it has a softer pressure ceiling so you can use more of it than you would normally expect.
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">But, it has a softer pressure ceiling so you can use more of it than you would normally expect.</div></div>
I've been using 8208 in a whole gaggle of cartridges, but figured it produced too high of pressure for the M1A. What do you mean a "softer pressure ceiling"? Is it suitable for the M1A?
 
Re: Just how much does temp affect RL15 and IMR4064?

The OP was asking about imr4064 and Rl-15 for his m1a. And the temp sensitivity of these two powders. I think he's looking at two of the best four or 5 options. Considering the M1A's pressure limitations. I do have varget but don't use it for my gas guns. And honestly the most accurate powder for me has been vvn140, and imr4895. Maybe he has only has IMR 4064 & RL-15? Are you saying that Varget was made for the M1A?
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 2clicks</div><div class="ubbcode-body">The OP was asking about imr4064 and Rl-15 for his m1a. And the temp sensitivity of these two powders. I think he's looking at two of the best four or 5 options. Considering the M1A's pressure limitations. I do have varget but don't use it for my gas guns. And honestly the most accurate powder for me has been vvn140, and imr4895. Maybe he has only has IMR 4064 & RL-15? Are you saying that Varget was made for the M1A? </div></div>

Varget was made to optimize the .308's capacity with heavier than standard bullets, i.e. 168's/175's. Standard caliber in an M1A is .308. <span style="text-decoration: line-through">Although, they do come in other flavors</span>. I stand corrected on that statement.
 
Re: Just how much does temp affect RL15 and IMR4064?

My experience with varget is the accuracy/powder charge range is hotter than I want to run in my M1A. Seems to me varget likes to be run on the hot side. Plus my velocity spread is lower with the other powders. There's more to accuracy than speed. Especially when we're talking about the M1A platform. Given the fact that IMR 4064 is temp stable and runs well with lower powder charges with low velocity spread its on the top of the list for my M1A loads.
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 2clicks</div><div class="ubbcode-body">My experience with varget is the accuracy/powder charge range is hotter than I want to run in my M1A. Seems to me varget likes to be run on the hot side. Plus my velocity spread is lower with the other powders. There's more to accuracy than speed. Especially when we're talking about the M1A platform. Given the fact that IMR 4064 is temp stable and runs well with lower powder charges with low velocity spread its on the top of the list for my M1A loads. </div></div>

I agree with what you are saying.

Now we need to break down why. As I mentioned earlier, Varget was initially developed to maximize heavier bullets in the .308. What is true of the .308 is almost without exception true of the .223. Heavier bullets are the best choice when using varget as a powder.

The M1A was designed around a 150/155 gr. bullet. Pushed at a nominal speed of 2800 fps. (50 fps faster than than the then current .30 Cal U.S.) When accurized for a heavier bullet, it then gets a little finnicky as to how you arrive at that.

4064 was developed as a target/match powder post WWII. As I mentioned above it was the first 'coated' powder us civilians had ever seen. It pretty much amounts to original formula 4895 that was coated. Remember, DuPont made the first 4895 that Bruce Hodgdon pulled down and sold. They then duplicated the recipe and sold their own. When Hodgdon ran out of pull-down 4895, he contracted with an Australian company to start making it for him.
Anyhow, an interesting read on 4064:
http://en.wikipedia.org/wiki/Improved_Military_Rifle#IMR_.23_4064

All that said, no matter how you arrive at a workable load in an M1A, stick with it. There are a lot more parts in that rifle that need to be accounted for in comparison to a bolt gun. If your rifle likes 4895, then stick with that. If it likes a load with 4064, stick with that. I recommend Varget for heavier bullets in the .308 as it works well. I <span style="text-decoration: underline">don't recommend </span>it for the lighter bullets <span style="color: #000099">{added: in gas guns}</span>. I do apologize if I wasn't clear on that from before.
 
Re: Just how much does temp affect RL15 and IMR4064?

Thank you Sandwarrior. Now do you recommend a grooved piston, or Schuster plug when using Varget and 175s?
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fatelvis</div><div class="ubbcode-body">Thank you Sandwarrior. Now do you recommend a grooved piston, or Schuster plug when using Varget and 175s?</div></div>

No idea on those. It's a matter of balancing the speed and pressure to match the distance and size of the port. The grooved allows excess gas to bleed off during they cycling and the Schuster bleeds excess off as it first actuates.

If you have either then you can reload up to the full potential of a slower powder. It would seem to me that with speed and pressure you might see best results with those by using RE-15 or RE-17.

I don't have an opinion on how much better one works than the other.
 
Re: Just how much does temp affect RL15 and IMR4064?

FWIW, awhile back imr4064 was tested here on the hide against Varget for temp stability in the 308 with 175's, in that test I remember reading it (imr4064) was actually the better of the two. YMMV
 
Re: Just how much does temp affect RL15 and IMR4064?

Yeah I remember a test awhile back that had varget vs 4064 and 4064 actually looked like it was a little slower.

I use Varget in my garand all the time, it works fine.

Also I'd throw H4895, 8208 and Alliant AR-COMP out there. I especially want to try AR-COMP when my zillion pounds of varget runs out.
 
Re: Just how much does temp affect RL15 and IMR4064?

I am having a difficult time locating it to share the link, I remember reading it as I had just bought 16 pounds of varget and remember thinking "Thats nice to know now"
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I think it was in a m118lr clone thread or a link there in.
 
Re: Just how much does temp affect RL15 and IMR4064?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Niles Coyote</div><div class="ubbcode-body">FWIW, awhile back imr4064 was tested here on the hide against Varget for temp stability in the 308 with 175's, in that test I remember reading it (imr4064) was actually the better of the two. YMMV </div></div>

Do you have a link?
 
Re: Just how much does temp affect RL15 and IMR4064?

You might go with what Hodgdon says:

http://www.hodgdon.com/burn-rate.html

85 <span style="font-weight: bold">IMR, Co IMR 8208 XBR</span>
86 Ramshot TAC
87 <span style="font-weight: bold">Hodgdon H4895</span>
88 VihtaVuori N530
89 <span style="font-weight: bold">IMR, Co IMR 4895</span>
90 VihtaVuori N135
91 Alliant Reloder 12
92 Accurate Arms 2495BR
93 <span style="font-weight: bold">IMR, Co IMR 4064</span>
94 NORMA 202
95 <span style="font-weight: bold">Accurate Arms 4064</span>
96 Accurate Arms 2520
97 <span style="font-weight: bold">Alliant Reloder 15</span>
98 VihtaVuori N140
99 <span style="font-weight: bold">Hodgdon VARGET</span>


Keeping in mind of course that double base powders usually end up at about the same load weight as a faster single base powder because of the extra pressure they produce.