.243 and IMR 7977

[dminn1]

I have been working on the Berger 105 Hybrid with IMR 7977 in a 26" Shilen 1/8 twist. I have been able to attain the velocity I am looking for without pressure problems but the extreme spreads have been disappointing to say the least. I started out with Tula LR primers and was getting es between 40 to 70 fps with all loads up to a well compressed charge I considered to be max. Thinking it might need a little more fire to get things started, I tried the Win LR primers as they have proven to be hotter by about 35fps in my .308 loads compared to Tula and CCI. The Win LR primers were indeed hotter than the Tulas, as I attained the same max velocity but with .6 grains less powder, but the es numbers did not improve at all.

Just to see if it was a powder or primer problem I loaded some H-1000 on top of the Tula primers and immediately got better velocity spreads with an es of 17 but considerably slower than the IMR 7977. My question is have any of you tried 7977 in .243 and what primer have you had success with? Would a CCI 250 be a good option?

Thanks
Darin

 

[msinc]

Are you annealing the brass???? If not, I would try that and also some neck lube. How close to the rifling are you seating the bullet??? Have you run a primer pocket uniforming tool into the pockets??? Flash hole de-burred??? Seating the primers with a good solid seating tool and check that they are all at the same depth??? All of the above together might show you the numbers you want to see. Those bullets usually like a run at the rifling of anywhere from .020" to .030"....they didn't want to group if they were jammed. FWIW, I had better luck with the VLD Hunting 95 grain bullets in my 243.
One other thing to have a look at...make sure you don't have a hard ring of carbon at the throat....the 243 is not above doing that to you!!!

 

[Patton243]

I tried that 7977 in my 7mm magnum and didn't like it. I'm pretty sure I was getting large spreads too like you mentioned and it wasn't very accurate. I run H1000 in my 243 I would suggest going with that powder. I heard RL 26 is good too if you want velocity but haven't tried it yet. What type of brass are you using? I run Lapua and I would suggest using that. That could be part of your problem too if you're using cheap brass.

 

[dminn1]

I'm running Winchester brass twice fired with necks turned, primer pockets uniformed, flash holes deburred, trimmed to the same length. Im using an old Lee Auto Prime tool that gives excellent feel when seating primers. Don't think it is a brass issue as I am getting good numbers with H-1000 with the same bullet. Just looking for any ideas with experience with IMR 7977 and primers used.

 

[B_Thomas]

Yea, also look at RL26 or VV N160. I am having very very good success with N160.

 

[Dgd6mm]

I run H1000 in my .243. I like it it shoots well and I would like to try the Rl 26. 7977 I believe I'd stay away from simply from some of the negative things I've read. I have shot IMR 7828 in my .243 and it wasn't half bad.

 

[dminn1]

Thanks for the replies. There's not a whole lot of feedback out there on 7977 but it looked promising in the Hodgdon manual. It burns very clean and gives high velocity but the accuracy and es numbers have not been impressive. I like the numbers i get with H-1000 but don't know if I'm going to reach my velocity goal. I will give RL-26 and V-160 a hard look as well.

 

[Dgd6mm]

What is your velocity goal?. With that goal what accuracy are you after, and at what distance?

 

[dminn1]

3080-3100, 1/2 moa, 100-1200yds

 

[Wingnut00]

RL-26! Yeah buddy. Makes a 243 a laser beam. Low es/sd numbers and excellent accuracy.

 

[Dgd6mm]

3080-3100, 1/2 moa, 100-1200yds

You should be able to achieve this.

 

[6milphil]

I tried 7977 in my 243 pushing 100gr sgk's. I managed to get 3090fps with an ES in the 30's out of a 20" barrel but the best it would shoot was about 1.5 moa at 300 yards. I abandoned it for h1000 and haven't looked back.

 

[dminn1]

I tried the Reloader 26 this weekend with a ladder test at 500 yards. ES numbers are much improved with most in the 5 to 15 fps range. Found two promising nodes at very impressive velocity. Seating depth test next but I think I am going to like this powder.

 

[dminn1]

I tried the Reloader 26 this weekend with a ladder test at 500 yards. ES numbers are much improved with most in the 5 to 15 fps range. Found two promising nodes at very impressive velocity. Seating depth test next but I think I am going to like this powder.

Went to the range yesterday to run a seating depth test on the Reloader 26 node I found in the ladder test I ran last week. I chronograph all shots in load development on a Lab Radar and noticed that I was getting 50fps more velocity than last weeks ladder test with all load parameters the same. Temp yesterday was 90 and temp during last weeks ladder test was 80. This gave me some concern about temp stability so me and the guy I shoot with decided to run a test.

This is far from a scientific test protocol but I think it showed some interesting info. I am shooting a .243 with Reloader 26 and he is shooting a Gap 6.5 4S with H=1000. We placed 3 rounds from each inside a plastic bag and placed in ice and then placed the other 3 rounds each in the direct sunlight for a 15 minute duration. We then shot the rounds over the chronograph with one shooter handing the other the rounds directly from the cooler or sun and shooting them about as quick as they could be chambered. From hot to cold the .243 with Reloader 26 had a 78fps difference in velocity and the H-1000 had a difference of 11fps. Reloader 26 is advertised to have excellent temp stability but my limited experience with it shows that may not be the case. I will say it is giving great velocity, and good extreme spreads but I don't know if I can keep it in the velocity window from week to week to maintain accuracy.

They Reloader 26 loads for the .243 that came out of the ice were right back on the velocity node that I found last week and they shot into a very nice .247" group. All of the other loads shot today not so impressive.

 

[Zero333]

Was the bore condition the same as last week

I had a 308 win that would pick up 30+ fps from clean bore to 150+ rounds.

 

[LitLBoy]

7828 SSC with BR-2's and Berger Hybrid .002-.003 neck tension 41.9 gr. in a 6XC is right at 3100fps. 1/4 MOA or better
LitLBoy

 

[dminn1]

Was the bore condition the same as last week

I had a 308 win that would pick up 30+ fps from clean bore to 150+ rounds.

Both sessions started on a clean bore and had about the same amount of rounds fired at each session. There is a lot of spread displayed between the hot and cold rounds fired in my informal test that led me to be concerned about the temp sensitivity of RL 26. Going to the range tomorrow in what is forecast to be similar weather to see if I get the same velocity jump.

 

[wedgy]

Temperatures in the mid 80's and up will affect RL26 and 7828. From LRH thread
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http://www.longrangehunting.com/forums/f28/temperature-sensitivity-alliant-reloder-26-a-187256/

I live out west where it gets hot in the summer when we pig hunt because nothing else is open, and I do testing also. The other week I got to test loads with a big temp swing to the "hot" levels. Speeds were with Labradar
Load is 7mm RUM 143 grain Hammer HBN 93.0 Reloader 26 CCI250 3.6"
On the 12th it was 68F and speeds were 3601, 3604, 3606, 3610
On the 16th it was 95F and speeds were 3649, 3650, 3651, 3655

So more or less a 27F rise gave about~ 50fps gain in velocity at the temp swing from 68 to 95F. That's 95F in the shade and yes I had the range all to myself. The rise puts this load to where primers really flatter and faint ejector marks. It boosts it a little over what a grain of powder increase would yield. I have a 6.5x284 load with IMR7828 that I cannot shoot in the hot temps (above 85F) as it sees a huge increase. A lower charge isn't accurate enough to keep.
So the term "temp stable" is within a range that most hunt but I think somewhere around the ~83F mark the fps per degree really starts to increase.
I know Shawn of Defensive Edge uses H1000 because he said it was the most stable powder he tested even though he got more velocity from others.
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[dminn1]

Temperatures in the mid 80's and up will affect RL26 and 7828. From LRH thread
-------------------------------------------------------------------------
http://www.longrangehunting.com/forums/f28/temperature-sensitivity-alliant-reloder-26-a-187256/

I live out west where it gets hot in the summer when we pig hunt because nothing else is open, and I do testing also. The other week I got to test loads with a big temp swing to the "hot" levels. Speeds were with Labradar
Load is 7mm RUM 143 grain Hammer HBN 93.0 Reloader 26 CCI250 3.6"
On the 12th it was 68F and speeds were 3601, 3604, 3606, 3610
On the 16th it was 95F and speeds were 3649, 3650, 3651, 3655

So more or less a 27F rise gave about~ 50fps gain in velocity at the temp swing from 68 to 95F. That's 95F in the shade and yes I had the range all to myself. The rise puts this load to where primers really flatter and faint ejector marks. It boosts it a little over what a grain of powder increase would yield. I have a 6.5x284 load with IMR7828 that I cannot shoot in the hot temps (above 85F) as it sees a huge increase. A lower charge isn't accurate enough to keep.
So the term "temp stable" is within a range that most hunt but I think somewhere around the ~83F mark the fps per degree really starts to increase.
I know Shawn of Defensive Edge uses H1000 because he said it was the most stable powder he tested even though he got more velocity from others.
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This tracks with my experience with RL 26. I am not seeing the big velocity jumps unless the temp is mid 80's and up. Thanks for posting this, Its good to read a firsthand account of how this powder performs in other cartridges in extreme temps. H-1000 does appear to be stable at the higher temps based on my testing.

I have done additional testing this week and think I have somewhat of a handle on how to stay on my accuracy node when the temps get above 85 with RL-26. I am impressed with the accuracy, es numbers, and the velocity is a step or three above any other powder I have tried with the 105 Berger Hybrids.