How hot is to hot?

M

m1ajunkie

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Feb 22, 2010
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#1
Did a little shooting this weekend and my brass has me slightly worried about my load in the summer heat. I worked this up in about 70-75 degree temps and this weekend on the range it was 90-95 degrees all day.

Beleow is a pic of some of my brass:
IMAG0068.jpg


The load is 44gr varget with the 178 amax and a win wlr primer. I am shooting an lmt .308 AR so I don't want to be shooting a crazy hot load if not needed. I hate to back this load down due to my 16" barrel, and the groups I am getting with this load but safety is my number one concern.

My question is, how does this brass look to you other reloaders/ gas gun shooters? I am starting to get a slight black ring on my bolt face where the primer meets the case so I am thinking some gas is leaking by the primers. Should I continue to shoot this load, or would I be better off looking for a lighter load to shoot until it cools off?
 
#2
Re: How hot is to hot?

Lc brass is very thick, switch to win brass with the same loas and your pressure will go down a bit, i run the same load as you in an AR 10 with a noveske barrel and have no problems at all no matter what temp it is.
Varget is not very temp sensitive either, good choice there. I f you want to keep using the LC brass drop the charge to 43.5-43.7 and see what happens.
hope this helps.
 
#3
Re: How hot is to hot?

In spite of advice from those that claim you can't go by the flattened primers, I think your primers indicate at least a warm if not hot load? Doesn't look "crazy-hot" but I would not continue to use that load without reducing it a little.

I'm not in favor of tailoring a load based on today's ambient temperature. Find one that works throughout your expected temperature range and leave it at that.

My guess is that you are at least one full grain over what I would use, in that rifle. What's the velocity? BB
 
#4
Re: How hot is to hot?

Thanks for the replies guys. I'll try reducing my loads some so I can be confident in all temps.

Velocity with the 178 amax is 2460 fps from my 16" barrel.
 
#6
Re: How hot is to hot?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BLDTYLRY</div><div class="ubbcode-body">What is your barrel twist rate? </div></div>

I'm running a 5r 1/11.25 barrel.
 
#7
Re: How hot is to hot?

try heating up your ammo some more , see if you can get some case head marks or badly cratered/pierced primers to appear. If you get those to appear with little effort , maybe your ammo is to hot. If you try hard to heat up the ammo and you dont see any pressure signs, then maybe the load is pretty safe.
 
#8
Re: How hot is to hot?

I'm running an 18" barrel with 1:11 Twist and I'm getting similar results with 178gr A-Max and 44gr Varget. Primars are starting to show signs of flattening. BTW I'm using Winchester Brass.
 
#9
Re: How hot is to hot?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MALLARD</div><div class="ubbcode-body">try heating up your ammo some more , see if you can get some case head marks or badly cratered/pierced primers to appear. If you get those to appear with little effort , maybe your ammo is to hot. If you try hard to heat up the ammo and you dont see any pressure signs, then maybe the load is pretty safe.

</div></div>

My guess is we are hearing/reading sarcasm from one of those people that pay no attention to flattened primers?
What's the best method for heating ammo? Would a propane torch work?
 
#10
Re: How hot is to hot?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BuzzBoss915</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MALLARD</div><div class="ubbcode-body">try heating up your ammo some more , see if you can get some case head marks or badly cratered/pierced primers to appear. If you get those to appear with little effort , maybe your ammo is to hot. If you try hard to heat up the ammo and you dont see any pressure signs, then maybe the load is pretty safe.

</div></div>

My guess is we are hearing/reading sarcasm from one of those people that pay no attention to flattened primers?
What's the best method for heating ammo? Would a propane torch work? </div></div>


Sitting ammo in direct sunlight will get them plenty warm/hot.



Scott
 
#11
Re: How hot is to hot?

For heating up, I just shoot off a few rounds and then let the next round "cook" in the chamber for a minute or two to simulate excessive heat, if it shoots fine then with no blown primers or excessive bolt lift, then your load is safe.
 
#12
Re: How hot is to hot?

As far as the heat issue, these rounds were plenty hot. I spent the weekend at a competition where temps were ranging in the 90-95 degree range. Rounds were carried in a back pack or in mags in a pocket all day, The rifle was also outside all day.

This is about as hot as I can ever imagine my set up getting, and these primers are the results. It seems like the varget is indeed very temp insensitive, but these primers are certainly a little flatter than usual.

From what I can tell my brass is not showing extractor/ ejector marks except on the occasional case that has the excessively flat primer.

FWIW, all rounds cycled in the gun just fine all weekend.

ETA: Should the black ring on the bolt face that is starting to show up be a worry?

Like I say, I would really like to keep my loads where they are but if I am going to far I am going to back them down to see if I can get similar results. Judging from the replies in this thread I may try some loads in the 43-43.5gr range next time I make the range.
 
#14
Re: How hot is to hot?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rusty815</div><div class="ubbcode-body">A black ring on the bolt face could be a sign of gas leaking past the primer, are the primer pockets loose, it could also be a result from an excessively hot load. </div></div>

Primer pockets are not loose, seating a new primer still takes a little force even after I have fired my current load with the 44gr of varget. However it looks like some gas is leaking by the primers in my pic, there seems to be black coloring between the case and primer which would be evidence of gas leaking.
 
#16
Re: How hot is to hot?

Flat primers and gas leakage means something, in my world. Do not allow your ammunition to become heated laying in the sun, I don't know why I feel compelled to say that but it seems to me that you are getting some bad advice? Be safe, not sorry. BB
 
#17
Re: How hot is to hot?

Personally? I don't see any ejector marks, you say the primer pockets are still tight, I don't see any gas leakage between the primer and its pocket...this load is G2G. I can't explain the black ring on your bolt face, but is there any pitting? I'm betting the black ring is purely cosmetic and is nothing to worry about (absent any pitting, that is). If there IS pitting on the bolt face, you definitely have gas leakage and need to back down the load, and quite a bit. But I doubt it.

Edited to add:

I see about half your cases have flattened primers. Although primers aren't the most reliable at telling pressure, they can be an indicator. Maybe back off the load half a grain or so and see if they're still flat on a hot day, and there are plenty of those right around the corner.

Edited to add 2.0:

In end state, I think you're right on the edge of max pressure on a hot day. Is this too much? Thats for you to decide.
 
#18
Re: How hot is to hot?

Size 2-3 cases as you normally do, prime and fire them. If the fired primers are seated flush with the case head you have a pressure problem. However, IF the primers are standing proud of the case heads, you're sizing to much and setting the shoulders back by however much they are standing tall - and that's my bet.
 
#19
Re: How hot is to hot?

Fuzzball, next time I am out reloading I will try to fire a couple of primed cases and see what the result is. I didn't know firing just a primer like that would result in any kind of useful info. FWIW, I use a wilson case gauge about every 5-10 rounds when resizing to be sure my cases are in spec.

Also, I have decided to load up a set of test rounds starting at 42.5gr and working back up to see if I can't find a nice shooting load under the current 44gr.
 
#20
Re: How hot is to hot?

Went out last night to perform fuzzball's test. When firing 5 sized and primed cases I got primers "standing tall" above the case head on all five test cases. However all five were not protruding the same amount, some more than others. This has me thinking my lee die is not sizing consistently and could be a potential problem.

From the results of the test, it looks like I need to back my die out a little to reduce the shoulder bump, but what explains the slightly incosistent results? Should I be using a small base die for an autoloader?
 
#22
Re: How hot is to hot?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BuzzBoss915</div><div class="ubbcode-body">It would have been peachy if you had noticed this little detail a long time ago. <sigh> </div></div>

I agree, I simply did not know or did not think that to much shoulder bump would cause these flattened primers even on a safe load.

Now that I have learned this, I can't wait to get out to the range and see what the results are on a case properly sized.
 
#24
Re: How hot is to hot?

One thing to add: If you can't get 10 reload cycles out of hte case before the primer pockets open up, it is probably and arguably too hot.

Me, I'm getting 30+ reload cycles with 47.8gr Varget pushing 155 Scenars and have not lost a primer pocket in several thousand shots.
 
#25
Re: How hot is to hot?

M1aJunkie,

In looking at the photo and reading through the threads, i have deduced the following:
1. Your Load is 44gr Varget + 178AMAX in LC brass.
2. You stated that primers pockets are not loose.
3. I don't see any ejector marks in the photo.
4. I don't see primer leakage in the photo...the dirt around the primer comes from a dirty chamber.
5. Some of the primers are flat.
6. The velocity through your rifle is 2,460fps from a 16" barrel...

I'd say that given the above, your load is not at max pressure (max pressure = powder manf suggested max pressure).

Primers are not a reliable indicator of max pressure. I have gotten flat primers with starting loads before, so i have learned to not get too excited over these...ejector swipes are a more reliable indicator of max pressure in my opinion.

You posted a velocity of 2,460fps for this load. How was this determined? over a chrono? how does the load shoot?

What i have noticed is that during load development, as the powder charge is increased past the optimal charge weight (typically located above 90% of max pressure), accuracy starts to degrade(groups open up), velocity increase becomes very modest, sometimes actually dipping before rising again, while pressure increases dramatically. If you have access to a chrono, i would reshoot these groups and find out how they perform out of your rile. Let that be the deciding factor...but to my novice eyes & based on your responses, your caseheads look fine.

Regards,
 
#26
Re: How hot is to hot?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tx_Flyboy</div><div class="ubbcode-body">M1aJunkie,

In looking at the photo and reading through the threads, i have deduced the following:
1. Your Load is 44gr Varget + 178AMAX in LC brass.
2. You stated that primers pockets are not loose.
3. I don't see any ejector marks in the photo.
4. I don't see primer leakage in the photo...the dirt around the primer comes from a dirty chamber.
5. Some of the primers are flat.
6. The velocity through your rifle is 2,460fps from a 16" barrel...

I'd say that given the above, your load is not at max pressure (max pressure = powder manf suggested max pressure).

Primers are not a reliable indicator of max pressure. I have gotten flat primers with starting loads before, so i have learned to not get too excited over these...ejector swipes are a more reliable indicator of max pressure in my opinion.

You posted a velocity of 2,460fps for this load. How was this determined? over a chrono? how does the load shoot?

What i have noticed is that during load development, as the powder charge is increased past the optimal charge weight (typically located above 90% of max pressure), accuracy starts to degrade(groups open up), velocity increase becomes very modest, sometimes actually dipping before rising again, while pressure increases dramatically. If you have access to a chrono, i would reshoot these groups and find out how they perform out of your rile. Let that be the deciding factor...but to my novice eyes & based on your responses, your caseheads look fine.

Regards, </div></div>

Tx_flyboy,

Looks like your 1-6 facts are correct.

Velocity has been verified multiple times over my chronograph, as far as overpressure loads not shooting well I have seen that during load development for one of my other rifles. This 178 amax load I am shooting out of my .308 AR shoots 3/4 moa with ease. Once again, I have several months worth of data on this load and have been super pleased with it. Thats why I want to make sure it's within tolerable pressures because I don't want to change it if I don't have to.

However, after this thread I am going to drop back to 42.5gr and work back up to see if I can get the same results with slightly less powder. I am also going to work on my shoulder bump, after learning about my excessive shoulder bump I am confident that the flattened primers will be less when I get less shoulder bump.
 
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