Working up a load with IMR4064---Check my math.

[Lrdchaos]

I have my rifle, brass and ammo. I am going to use the OCW to determine my best load. OAL will be the standared 2.800 for my 308. 175SMK bullets with Lapua Brass, Federal primers

Max load shows 45.6gr, I subtracted .7% which gave me 3.192 for a starting load of 42.4.

1st rd-42.4
2nd rd..+2%= 43.2
3rd rd..+2%=44.0

4-6 rds..+2%=44.8
7-9 rds..+1%=45.2
10-12rds.+.07=45.5

This will be my first shot at developing a load for my rifle. Should I load 3 rds in the 44.4 range and maybe a 3 rounds in the 45.0 range? It seems like there are some pretty big jumps in powder, I don't want to miss my accurancy node. Any advice would be appreciated.

 

[BC 6.8]

I use the OCW method to find my loads too, but I modify it a little to get shoot more groups over a wider charge range. Also, I always load up one group of cartridges over the max in case my OCW load is very close to max, but I don't shoot them if I see pressure signs earlier in the test. Another thing I change is I always increase my powder charges in the same increments (0.4 gr for .308 Win). See example below.

Bullet 175 SMK
Powder IMR4064
Primer Fed 210
Brass Lapua
# rds
Sighter 43.0 2rds
Load #1 43.4 3 rds
Load #2 43.8 3 rds
Load #3 44.2 3 rds
Load #4 44.6 3 rds
Load #5 45.0 3 rds
Load #6 45.4 3 rds
Load #7 45.8 3 rds
23 rds

 

[Darkside-Six]

Start at your 42.4 and increase by .3 grains for each load until you get to max.


Sent from my iPhone using Tapatalk

 

[bax]

Start at your 42.4 and increase by .3 grains for each load until you get to max.

^^^^^ what he said. Your jumps are 0.8 and that is too large, you might miss a node. With 0.3gr interval you won't miss a node.

Depending on your brass, you may find value in going below that starting point. I shoot 41.0 in LC LR brass and 42.2 in Lapua brass. I pay a velocity price for that but they are accurate and my brass lasts forever. I will be taking Darkside's advice and trying some hotter loads - in the meantime I'm pretty happy with what I have.

 

[mike.h.]

^^^^^ what he said. Your jumps are 0.8 and that is too large, you might miss a node. With 0.3gr interval you won't miss a node.

Depending on your brass, you may find value in going below that starting point. I shoot 41.0 in LC LR brass and 42.2 in Lapua brass. I pay a velocity price for that but they are accurate and my brass lasts forever. I will be taking Darkside's advice and trying some hotter loads - in the meantime I'm pretty happy with what I have.

I agree, my low node was at 41.7 and another at 42.6g. YMMV

 

[djarecke]

I am getting 2700 fps out of my M40A5 and 2650 out of my Harbinger with 42.1 grains of 4064 behind the 175 grain bullet. Those loads seem a bit hot...can you chrono them starting with a lower powder charge? How long is the barrel on your rifle?

 

[Brux]

With some of these loads mentioned,how do you even fit that much 4064 in a Lapua case with a 175SMK seated at 2800?

 

[arnie19]

I agree with Brux .I use 42.2 in my 308 ar with Winchester cases and its about all I can get in there .

 

[Lrdchaos]

I don't have a chrono, I will just start with the 41.5 min load and work up .3 from there. My rifle has a 23in barrel.

 

[djarecke]

That sounds like a solid load. I was using Lapua brass and the M40 loved anything from the upper 41 grains to the mid-42's. I tried up to 43 grains but the groups opened up. No pressure signs in my rifle (just for reference).

 

[Road_Clam]

Here's some 178 AMax / 4064 chrono data shot out my R700 Varmint 26" bbl :

41 gr. = 2378 avg fps
41.7 gr = 2568 avg fps
42.3 gr. = 2637 avg fps
42.5 gr. = 2698 avg fps

 

[ArmyJerry]

I started at 41 with the Lapua brass, same start point with the LC brass, LC ended up 41.8, the Lapua ended at 42.2, 2605 +/- fps each. 26" Mcgowan barrel 10 twist on a 10 FP. I usually jump in 0.2 grain increments.

^^^^^ what he said. Your jumps are 0.8 and that is too large, you might miss a node. With 0.3gr interval you won't miss a node.

Depending on your brass, you may find value in going below that starting point. I shoot 41.0 in LC LR brass and 42.2 in Lapua brass. I pay a velocity price for that but they are accurate and my brass lasts forever. I will be taking Darkside's advice and trying some hotter loads - in the meantime I'm pretty happy with what I have.

 

[sib1948]

Reload my 308 168 and 175 gr SMK in Win brass and Fed 210 or 215 primers with OAL 2.86over 42.8 gr IMR 4064. Same with 185 gr Berger VLDs at 43.9 gr. IMR 4064. Good luck

 

[Greg Langelius *]

My generic 308/175 load is stolen from an article In Precision Shooting about a guaranteed 1000yd supersonic load for the M14/M1A.

Rem brass F/L sized, reamed flash holes
SRA 175SMK at 2.815" COAL, max mag length, this may not work in some magazines
Fed 210GMM, BR-2's work equally well
42.2gr IMR-4064 (at that time (late 1990's), this was a Sierra published max load).

This load has also proved accurate in some other rifles as well.

Greg

 

[Seandradamus]

I have an accurate load at 41.8 and 42.7
43 is getting hot in my rifle I use fed brass and lapua they seem interchangeable in charge weights

 

[pmclaine]

Tag.

Just did this excercise after screwing up an OCW and deciding to actually read Dans directions. Ill come back to compare what i did. Seems like I have more data points than the OP does.

 

[bruddah]

I had a great accuracy node at 43.0 gr of IMR 4064, but was getting ejector flow. The 175 gr SMKs were going over 2800 FPS out of my Savage model 10T using Lapua brass.

 

[Cowtown]

My IMR4064 ladder test for my 308 ended up at 43.5 grains with least vertical stringing... I chrono'd them last week and was at 2745 fps avg...

 

[Twoboxer]

I have my rifle, brass and ammo. I am going to use the OCW to determine my best load. OAL will be the standared 2.800 for my 308. 175SMK bullets with Lapua Brass, Federal primers

Max load shows 45.6gr, I subtracted .7% which gave me 3.192 for a starting load of 42.4.

1st rd-42.4
2nd rd..+2%= 43.2
3rd rd..+2%=44.0

4-6 rds..+2%=44.8
7-9 rds..+1%=45.2
10-12rds.+.07=45.5

This will be my first shot at developing a load for my rifle. Should I load 3 rds in the 44.4 range and maybe a 3 rounds in the 45.0 range? It seems like there are some pretty big jumps in powder, I don't want to miss my accurancy node. Any advice would be appreciated.

If you follow Dan's instructions, you can choose to use 46.5gr-10% and then either 0.03gr or 0.4gr increments from the 4th charge level on. Using 0.3gr (>0.7%) might look like this:

1 @ 41.0
1 @ 41.9
1 @ 42.7
=======
3 @ 43.6
3 @ 43.9
2 @ 44.2
3 @ 44.5
3 @ 44.8
3 @ 45.1
3 @ 45.4
3 @ 45.7
=======

While I'd prefer to use 0.3gr increments at this charge level, using 0.4gr (0.9%) increments would use 1 less 3-round group and end at 46.0. In either case, I'd advise sticking with one or the other increment beginning between the first and second 3-round group. Note that the whole range of 3-round groups can be shifted a tenth or three to suit your purposes, but the increments should remain constant to insure coverage.

 

[Pinecone]

Here is an Excel spreadsheet to automate the charge weight increments for OCW load development -

http://www.snipershide.com/shooting/snipers-hide-reloading/193057-ocw-excel-template.html

 

[pmclaine]

I used Nosler, Hodgdons, Lyman, and Hornady data to find my max. The Hornady data seems/is known to be very conservative so I weighted toward the others. I screwed up to OCWs so far, hoping for advice if it looks like Im ready to fail again.

IMR 4064

175 max 43.4

1@ 39.1
1@ 39.9
1@ 40.7
3@ 41.5
3@ 42.3
3@ 43.1
3@ 44.0


168 Max 44.7

1@ 40.2
1@ 41.0
1@ 41.8
3@ 42.6
3@ 43.0
3@ 43.4
3@ 43.8
3@ 44.2
3@ 44.6
3@ 45.1

155 Max 46.6

1@ 41.9
1@ 42.7
1@ 43.6
3@ 44.5
3@ 44.9
3@ 45.3
3@ 45.8
3@ 46.3
3@ 46.8

Varget

175 max 44.1

1@ 39.7
1@ 40.5
1@ 41.3
3@ 42.1
3@ 42.5
3@ 42.9
3@ 43.3
3@ 43.7
3@ 44.1
3@ 44.5


168 Max 45.4

1@ 40.9
1@ 41.7
1@ 42.5
3@ 43.4
3@ 43.8
3@ 44.2
3@ 44.6
3@ 45.0
3@ 45.5

155 Max 46.6

1@ 41.9
1@ 42.7
1@ 43.6
3@ 44.5
3@ 44.9
3@ 45.3
3@ 45.8
3@ 46.3
3@ 46.8

 

[Twoboxer]

IMO, your 175s' spread is too wide to give you any info - the rest look OK though the 0.4gr intervals and some 0.5gr tics aren't my preference.

That's a lot of shooting from one barrel - remember Dan's advice about cooling and cleaning intervals.

Good luck!!

 

[wxl]

I have my rifle, brass and ammo. I am going to use the OCW to determine my best load. OAL will be the standared 2.800 for my 308. 175SMK bullets with Lapua Brass, Federal primers

Max load shows 45.6gr, I subtracted .7% which gave me 3.192 for a starting load of 42.4.

1st rd-42.4
2nd rd..+2%= 43.2
3rd rd..+2%=44.0

4-6 rds..+2%=44.8
7-9 rds..+1%=45.2
10-12rds.+.07=45.5

This will be my first shot at developing a load for my rifle. Should I load 3 rds in the 44.4 range and maybe a 3 rounds in the 45.0 range? It seems like there are some pretty big jumps in powder, I don't want to miss my accurancy node. Any advice would be appreciated.

No one answered your question. Your math is wrong. 3.192 gr is 7%, not .7%. Again 42.4 gr starting is probably OK if you are using a bolt gun (you never said). If a gas gun like an M1A, I would start maybe 0.5 gr lower. Good luck.

 

[pmclaine]

IMO, your 175s' spread is too wide to give you any info - the rest look OK though the 0.4gr intervals and some 0.5gr tics aren't my preference.

That's a lot of shooting from one barrel - remember Dan's advice about cooling and cleaning intervals.

Good luck!!

Yes just noticed the 4064 175 grain string looks short. Ill recheck my math on that one.

The only loads I have loaded are the 168s and I think thats a 24 shot session. Im doing two strings of the same load one to fire in a 24 inc Rem 700 the other for an LMT MWS. Posted an OCW about two weeks back and I thought I had good data for both rifles at 41.9.

At 300 I wasnt imoressed with the M40 results and a second reading of the MWS rounds showed I picked one that probably was a perfect vertical string and it showed at 300.

http://www.snipershide.com/shooting/snipers-hide-reloading/265702-2-ocw-2-rifles-1-load.html


OP apologies if you consider this a thread steel. Seems like we are both looking for similiar things and I hope my mistakes/trials are helpful.