155s and H4895 in 308 gas guns

[jlorenzo]

What are some of your loads using this combo? I have Hornady 155 bthps, Sierra 2155 and 2156 155 smks and the best group my gun has shot was with the Berger 155.5 full bores and 42.8gr of 4895, 2.800 COAL. I am using Starline small primer match brass and Federal Gold Medal match AR primers.

For whatever reason neither of the Sierra bullets have shot very good so far. Just looking for data points to compare against my own.

Everything I've tried so far has been loaded at mag length. I have a Krieger 20" M110 barrel, 10 twist. JP high pressure bolt and SA adjustable gas block.

Is 2750 a realistic velocity goal with this setup and 155s? So far have only reached the high 2600s.

 

[kevinbritvec]

IMO, 2750 fps is fine for a 24" bolt gun, for a 20" gas gun, not so much. I used to get 2725 to 2750 fps with 150 grain bullets through my 22" M1-A barrels using Lake City brass. That would equal somewhere close to 2700 fps from a 20".

My .308 gas guns run best and group best using service rifle loads:

168 grain SMK's - Lake City or IMI brass
40.0 grains of IMR-4895
40.5 grains of IMR-4064
43.0 grains of WW-748
40.5 grains of AA-2460
41.5 grains of VihtaVuori N150

I don't worry about velocity. These loads run around 2500 fps from a 22" M1-A and work great.

My 155 grain loads are only a little higher and run around 2600 from a 22" barrel, that would average around 2550 from your 20" tube. Safety first, reliability second and tight groups last. In that order. You really want a 3:00 o'clock ejection pattern from an AR-10.

 

[SecondsCount]

The 155 SMK shoots really well in my Tikka Master Sporter, usually in the .5s

 

[mic2377]

I personally run them a bit slower, around 2650 out of a Criterion 20". I also use a JP bolt. There is obviously some lot to lot variance for H4895 - my go to load was 41.7 gr under either a Hornady 155 BTHP or Sierra 2155. This is with LC brass though hence the lower charge.

I have had surprisingly good accuracy with some other bullets including the 150 SST and 150 Accubond, basically equivalent to the Sierras.

Between my 20" Criterion and the 16" chrome-lined barrel in my MWS, the MWS seems to tolerate pressure better and also shoot better with hotter loads. I do not know why that is.

What kind of accuracy are you seeing?

 

[Phil McGrath]

Hmmm, most M80 ball runs pretty quick in 20/22in tubes…. I have never had much luck with any of the 155/156 bullets in my M-Guns no matter the load development.

I scored a good deal on some 155 Berger hybrids so I figured I would give them a try and possibly rule them out, 43.5 H-4895 or VV-135 in a LC case, any good primer 2.82 coal run ok in my M14 clones however in my 7.62mm M1 they shoot freakishly tight.

 

[searcher]

Using your same 155 bullet, primer and brass, my best results, by far, came with Reloader 15. N140 was second most accurate. The Reloader 15 comes onto the shelves every few months, then disappears. Unless you have some to try - have to watch regularly.

 

[tonyben]

I use 43.7 grains of IMR-4895 under a 155 Hornady ELDM. Fantastic performance! On par with 175 SMK's.

Tony.

 

[NZ_Fclass]

H4895 is in short supply down here and many of the sling shooters are moving to 8208. The "old" recipe was 44.1g to 44.5g - which may be too hot for a gas gun. I gather that 44.8g of 8208 is the current favourite for about 3000fps = but again, work up - that is a bolt gun recipe.

Anecdotally, many of the ADI powders supplied to Hodgdon's are slower than days of old ( I mean pre-Covid, when dragons walked the earth) I remember using a load of 44.1g of 8208, getting those kind of figures in my FTR rifle - and certainly, Hodgdon's reloading data for the 223 shows a max load of 28.7g of 8208 - for 2800 plus fps, which is a nonsense = I could only achieve 2700 in a 30 inch barrel.

 

[dixiecricket]

I run 40.0gr IMR4895 behind a 180gr SST at 2330fps 2.8"coal for mag feeding in 16" barrels. Its a mild load that is pleasant to shoot and adequite for 200yd hunting. Runs well in the 6x different gas guns ive tried it in and the relatively fast powder behind a heavy bullet plays well with high back pressure suppressors.

For high performance .308 loads i run stiff charges of CFE223 or Varget.