308 IMR4064 and IMR4895 ladder workup question

[mm9995]

I’m struggling with a ladder workup on my AR10 .308!

This is what I’m trying to do:

1: Ladder test workup for IMR4064 and Hornady 30 Cal 165 gr BTSP Interlock bullets.
2: Ladder test workup for IMR4895 and Hornady 30 Cal 165 gr BTSP Interlock bullets.

I have: AR10, .308, 20” midweight barrel, 1:10 twist

My problem is that the books are giving me significantly different load data.

IMR4064:
Lyman 39.0 - 44.5 gr
Hodgon 42.0 – 46.3 gr

IMR4895:
Lyman 38.0 – 43.2 gr
Hodgon 42.7 – 45.5 gr

What have you had success with using these bullets and powders?

Thanks in advance!

 

[Metal God]

I use both those powders A LOT and I rarely can get to Hodgdon max’s on either without pressure signs . In fact one of my best plinking loads using 4895 and the 168gr smk is 41gr which is right at Hodgdon’s start load .

My experience says Lymans is more realistic , but my start loads would be 1gr higher on both .

 

[otnot]

With my bolt gun 46 gr. of 4064 was max with a 168 gr SMK. Just start low and go up .3 grains at a time and watch for pressure signs. I use 300 yards for the test.

 

[mac86951]

AR work-ups take a little more care and variations in 308 chambers mean many books have different ranges.

Pressure signs are different for gas guns too; typically you'll beat up the brass on eject well before "bolt gun" pressure signs.

I seem to recall Sierra and Hornady have gas gun load recommendations search for those; otherwise I'd recommend starting with Lyman and working up. I'm at 41.5gr 4064 with a 175 in my AR.

 

[KMart]

Hodgdon online has a 308 service rifle loading data. I am assuming they mean M1a but may include AR-10

168 gr bullet

4064.........41.5 to 43.9 max
4895.........41.0 to 44.2 max

Those recommendations kind of falls in line what was posted by Metal God.

 

[Doom]

Remember that the AR10 and M1A/M14 were designed around the same ammunition so using powders and bullets recommended for the 308 Service Rifle work well in the AR10 and tend to be gentler on brass and rifle that max bolt action loads.

 

[JB10]

Imr4064 168 hornady or nosler does good with 42.0gr in a gas gun. I go more in my bolt action

 

[JFrank]

Both are good powders, I use 4895 with lighter 155 gr then 4064 under the 165 class btsp

Both really accurate..

 

[D-4297]

The "Gold" standard for a .308 Match round for decades was the Federal Gold Medal Match round . Developed for , and by the AMU for competition .
Federal .308 case - 2.005"
42.5 gr. 4064 ( brand not specified )
168gr. SMK
They had something figured out . Maybe buy a box and shoot them in your AR and see how they perform . Save one round and pull it , to weigh the powder and bullet . If it works , duplicate it .

My current TR load is 45.5 gr. of IMR 4064 behind a 185 Jugg OTM out of a 30" Krieger 5r bolt gun . Toasty , but works for me .

 

[Metal God]

The "Gold" standard for a .308 Match round for decades was the Federal Gold Medal Match round . Developed for , and by the AMU for competition .
Federal .308 case - 2.005"
42.5 gr. 4064 ( brand not specified )
168gr. SMK

Not anymore , IMR-4064 replaced with AR-comp . I think it was this forum but could have been another . A member posted a article or a correspondence with a tech at Alliant stating they switched a few years back . I then went and pulled some old ( 5+ years ) and new ( 1 year_ish ) Fed GMM and the powder is in fact different . Newer rounds have a much shorter cut powder then before .

Which is interesting because at some point in the last 5 years or so I noticed that Fed GMM did not shoot as well in a rifle I have as it did 8 years ago . I just figured it was throat erosion or general round count issues , then I learn the powder changed in that same time period . At least I know why it stopped shooting as well

 

[D-4297]

Good to know . Another case of ; It wasn't broke , So let's FIX it . That's okay . At least I know the "real" load , and can duplicate it if need be . Thanks for the update .

 

[mm9995]

I want to thank you for the input, I'm happy I reached out to the forum.

My plan will be to start the 4064 @ 40gr and the 4895 @ 39gr. I'll jump in .3 increments.

 

[Metal God]

My plan will be to start the 4064 @ 40gr and the 4895 @ 39gr. I'll jump in .3 increments.

.3gr is fine , FWIW I jump in 1% increments . So a likely 30gr charge would be .3 gr - 40 gr charge in .4gr etc .