bergers vs accubonds, barrel is super hot

[midnightmalloy]

so I just loaded about 60 test loads for the 160gr accubonds for my 280 ai and when i shoot them the barrel gets super hot! Im only shooting 3 in about 5 min and then letting the barrel cool for about 10min. its just that the barrel isnt cooling very well. its taking almost 20 min for the barrel to cool down to where its warm. Ive shot about 250 168gr berger vlds and never had this problem even when i shot more rounds in less time with less time to let the barrel cool down. I have a #5 contour benchmark barrel in a 1-9" twist 3 groove. And when im saying hot i mean 3 shots like i shot 3 mags full auto on an M-4! Im only getting 1.5-2.5" groups at 200meters with this gun and ive tried 6 powders, 2 primers and 3 bullets and nothing is very consistent. I just dont understand. Im loading with a chargemaster 1500, redding comp dies, nosler brass, cci BR primers or Fed 215m, berger 168 vld, 160 accubonds, 162 amax, I check for seating depth w/ hornady gaugues,...i just dont get it. I have looked at and verified multiple times my equipment, setup, and myself but its just not making sense why there isnt the consistancy. my rifle is a sako 75 action, mcmillan sako hunter stock, zeiss conquest 4.5-14 scope, benchmark 25" barrel, stress free bedded with devcon and aluminum pillars, barrel free floated... any solutions would be greatly appreciated.

 

[SpikeSniper]

MM-
Your problem may well be the chargemaster. Try verifying your loads with a balance scale. I Was having a lot of trouble with load inconsistency for my 7STW with a proven load. Upon checking the charges with a Hornady balance, I realized that many of the loads were off as much as .2 grains. I currently use a hornady dispenser/scale and double check with the scale. Are you loading other rifles with the same techniques and better results?

 

[J E Custom]

Different brands of bullets should not cause this, but powder,primer,seating debths if
different can.

If you are seating the Berger's and the Accubonds with the same die setting you will get
pressure differences and heat.

Each bullet type requires it's own die set up and load. Simply changing bullets can lead to
issues and should not be done.

J E CUSTOM

 

[rscott5028]

Ambient temperature is a big factor my barrels were scorching hot yesterday when I pulled them out of the trunk and hadn't even yet fired a shot.

The ammo rode inside with the AC and I kept it in the shade.

Did you shoot the Bergers on the same day?

Or, was that back when it was only 100F rather than 120F?

-- richard

 

[midnightmalloy]

I continually check my chargemaster with my hornady and rcbs balance beam scales and its always dead on. I live in western wa and the temp doesn't change much. It was only 10 deg difference outside. My gun and ammo are in the car and neither were even warm when I took them out of the vehicle. On the seating depth subject I have been jumping both bullets between 30-100 thou during load testing. Loads are at the same fps (within 80fps and well under max). I'm using the same primers and powder for both bullets also. My press is a hornady single stage and I'm using redding comp dies with the micrometer stem. So what gives? What could the problem be?

 

[SpikeSniper]

How about sticky bolt lift, cratered primers, or any other signs of overpressure? It's possible that the slimmer contour of the VLD's is producing less friction/drag. But I would think that could be checked with reloading manuals or programs.

 

[rscott5028]

What's your cleaning regimine?
Are you excessively copper fouled?

Have you compared the diameter of the bullets?

You could have a bad batch or even the wrong caliber. ...although you'd certainly see signs of pressure.

Ultimately, you need to try a different bullet. But, I'm sure the problem will continue to haunt you until you know the root cause.

-- richard

 

[Greyfox]

Try measuring the bearing surface and diameter of the two bullets to see if there is a difference in bearing surface. All other things being equal, particularly paying attention to bullet jump, it will be pressure and, or friction of the bullet in the barrel that will cause this. I have seen this happen in my 6mm when switching between Lapua Scenars and SMK's. The Lapuas are significantly smaller in diameter.