Old Age & IMR powders for the .308

[M118LR]

M118LR hence it's time to open a .308 SMK conversation. Specifically the use of SMK 168 & SMK 175 .308 projectile and Old School IMR Powder.

Going back to Lymans 45th edition, there are a few extra Accuracy loads listed with IMR Powders than those listed in Today's current Sierra Manual.

Example: 45.0 grains of IMR 4064 for the 168 SMK in 30-06. IMR 3031 for the 175 SMK also in 30-06.
37.0 grains of IMR 3031 for the SMK168 in .308 Win along with 39.5 grains of IMR 3031 for the same projectile. While 41.0 grains of IMR 4895 for the 175 SMK is a good starting point for M118 but YMMV.

If there are still a few cans of IMR Powder on the shelf perhaps a couple of rounds of accuracy ammo can be crafted with it still Today?
What say Y'all?

 

[ChrisC]

4064 is an excellent .308 powder. I’ve burnt a lot of it. It is what Federal is using in their Gold Match ammo.

 

[Daezee]

IMR 4895, a classic powder for use in .308 target loads. I use it in my RPR, and M14.

 

[M118LR]

Now it's not like Vint N540, 550, Varget, RE 15, or RE 22 aren't also excellent powders. Yet they may be harder to acquire Nowadays than some of the Old School IMR powders.

As with every load each barrel will have it's preference, but I find the 11.25 :1 5R's are a bit more tolerant than some of the 10:1 2R or even current 6R barrels. Not that the 5R is inherently more accurate! Just that it seems to digest a greater variance of powders with nearly the same accuracy. (IE less finicky of what it is feed. YMMV) Just remember that this is with either the 168 or 175 SMK, small sample size of projectile. Flat based spire points may display totally different characteristics. JMHO.

 

[Capt. Dave]

I just finished loading up some 175 gr. SMK with IMR 3031. Was going to test them this morning, before the rain came in. I used 40.0 gr powder. Maybe I’ll get out tomorrow to try them out.

 

[M118LR]

I just finished loading up some 175 gr. SMK with IMR 3031. Was going to test them this morning, before the rain came in. I used 40.0 gr powder. Maybe I’ll get out tomorrow to try them out.

.308 Win or 30-06?
Love to hear how the string groups.

 

[Capt. Dave]

.308 Win or 30-06?
Love to hear how the string groups.

.308, I’ll post some results after testing. Will be fired from REM. 700 1-10 twist 26” heavy profile barrel.

 

[M118LR]

.308, I’ll post some results after testing. Will be fired from REM. 700 1-10 twist 26” heavy profile barrel.

4R, 5R, or 6R?
2R Barrels were 1942 War Modifications, although I've heard some folks have dabbled in 3R for competition use. Haven't heard much about how it worked out though.

That 1:10 twist started with the 30-40 Krag and 220 grain projectiles. For a 175 projectile it is a bit overspun especially out of a 26 inch barrel, but it's good enough for government work!!!

There is some eye opening info about the extended long range viability of the 1:10 twist vice the 1:11.25 twist rate available for Historic Reference mostly during XM21 or NM-M14 Data from Mil Test Proving Sites should you be interested? But the US Army/Remington settled on the 1:11.25 twist rate for the 5R M24, while the USMC Barreled the M40 with 6R Loosely 1:12 twist rate.

The History of 30 caliber twist rates

In 1892 the Army switched from the .45-70 Trapdoor Springfield Rifle to the .30-40 Krag-Jorgensen and there was much rejoicing. The .30-40 Krag was load with a 220 grain jacketed lead round nose bullet fired at around 2000 fps. This bullet required a 1 in 10 inch twist to stabilize this...

www.snipershide.com

M40 rifle - Wikipedia

en.wikipedia.org

 

[Capt. Dave]

4R, 5R, or 6R?
2R Barrels were 1942 War Modifications, although I've heard some folks have dabbled in 3R for competition use. Haven't heard much about how it worked out though.

That 1:10 twist started with the 30-40 Krag and 220 grain projectiles. For a 175 projectile it is a bit overspun especially out of a 26 inch barrel, but it's good enough for government work!!!

The History of 30 caliber twist rates

In 1892 the Army switched from the .45-70 Trapdoor Springfield Rifle to the .30-40 Krag-Jorgensen and there was much rejoicing. The .30-40 Krag was load with a 220 grain jacketed lead round nose bullet fired at around 2000 fps. This bullet required a 1 in 10 inch twist to stabilize this...

www.snipershide.com

Sorry, I was mistaken. It’s 1-12 twist. I had had to go find my build sheet.

 

[M118LR]

Sorry, I was mistaken. It’s 1-12 twist. I had had to go find my build sheet.

4,5, or 6 lands & grooves?

 

[Capt. Dave]

I don’t even know the answer to that. Factory REM. stainless fluted heavy 26” 1-12.
’

 

[M118LR]

I don’t even know the answer to that. Factory REM. stainless fluted heavy 26” 1-12.
’

Next time you run a solvent patch down the barrel when rounds have been expended, it's easy to count how many grooves therefore how many lands by simply counting the marks on the dirty patch. A rocket scientist I'm not! But it's a pragmatic method to determine 4R,5R, or other rifling. JMHO.

Odds are that your Rem if is Older it's 4R unless it's a North American or X40 Build that the custom shop manufactures to the purchasers specifications. Nowadays the 5R used in the M24 is more customary.

Kind of like the guy at the bar who asked the Barkeep why the peanuts kept telling him how nice he was. The Barkeep said they are Complimentary Peanuts. LOL.

 

[Capt. Dave]

Not bad for very first time reloading .308 both flyers were on me. The SMK 175s were pulls, but in like new condition. I think the Norma 202 won out and has Great potential to shoot some really small groups.

 

[M118LR]

Not bad for very first time reloading .308 both flyers were on me. The SMK 175s were pulls, but in like new condition. I think the Norma 202 won out and has Great potential to shoot some really small groups. View attachment 110745 View attachment 110746

Did you manage to figure out if you have 4,5, or 6R once you cleaned the rifle?

 

[Capt. Dave]

I haven’t cleaned the rifle yet and know it’s not 5r, so 6 is the only other option from a standard REM barrel.

 

[Jhunter]

Don’t clean that barrel. The standard 4 groove seem to shoot the most consistent fouled. That barrel will let you know when it’s time to clean

 

[Capt. Dave]

Don’t clean that barrel. The standard 4 groove seem to shoot the most consistent fouled. That barrel will let you know when it’s time to clean

Yes, that’s true my gun shoots much better fouled. I can usually go 300 rounds between cleaning.

 

[M118LR]

Yes, that’s true my gun shoots much better fouled. I can usually go 300 rounds between cleaning.

I come from "The OLD School", a rifle with a day scope shall greet each sunrise with a clean bore/barrel.

Approximately what time period does it take for you to expend 300 rounds?
(i.e. 100 rounds a day is 3 days. etc.)

 

[Capt. Dave]

I tend to shoot in groups of days to maybe two weeks. Then in might be several months before shooting again. I don’t let a very dirty barrel sit for a long period, but a bolt gun doesn’t get very dirty anyway.

 

[M118LR]

I tend to shoot in groups of days to maybe two weeks. Then in might be several months before shooting again. I don’t let a very dirty barrel sit for a long period, but a bolt gun doesn’t get very dirty anyway.

All the manual operating systems (pump, lever, bolt) function without the influence of expended gas, so I'll assume that this is what you are referencing:

Gas-operated reloading - Wikipedia

en.wikipedia.org

"The M14 rifle and M60 GPMG use the White expansion and cutoff system to stop (cut off) gas from entering the cylinder once the piston has traveled a short distance.[4] Most systems, however, vent excess gas into the atmosphere through slots, holes, or ports."

Now when it comes to .308 group envy: