Wow many determining factors in our Hobbie

[Ironworker]

Well went to the range today to celebrate our victory. Also to shoot some 90 gr Lupua bullets I had laying around. I'm shooting a 6x284 Hart 26" BBL with 10" twist. Rifling rate wouldn't stabilize 95gr Berger VLDs .But 90 gr Lapua 's it will. I step up various charges of H4831 SC and Re#22 . 56.5 grs of RE#22 produced higher velocity then same charge of H4831SC only about 50 fps. Why? Any how accuracy was best ever Re#22 produced under 1/4MOA at MV of about 3,475 and H4831 produced under 1/2 MOA at about 1/2MOA. with MV of about 3500. These were the most accurate loads of the day. All these loads arealmost 10% higher then what Sierra 5th edition says . What a difference in data. Plus I had no pressure signs and I'm jamming these bullets into the lands.SD was with in a few feet to 20 feet SD??????

[44 AMP]

Every gun is an indivdual to a certain extent. What is a safe working pressure in one gun can be max or over max in another, and vice versa. Loading manual max loads are those combinations of case, primer, powder charge and bullet type/style/seating depth, etc that produced max safe pressure in their test guns.

Your gun and its exact combination of variables (including chamber dimensions, case thickness, hardness, primer, powder, bullet shape/weight, seating depth, etc.etc) may have a different max limit. It may be higher or lower than the one found in the reloading manual's test rifles.

Sometimes you get best accuracy at max levels. Most of the time you don't, but again, every gun is an individual when it comes to that exact combination of factors that it likes to shoot the best.

Some folks load to get the most velocity and acceptable accuracy. Others load to get the most accuracy and acceptable velocity. Others load to have tolerable ammo to shoot, cheaper than factory ammo prices. And still others are somewhere inbetween.

[SL1]

44 AMP wrote:

Loading manual max loads are those combinations of case, primer, powder charge and bullet type/style/seating depth, etc that produced max safe pressure in their test guns.

Actually, the max loads are tested for PRESSURE in special barrels manuafactured to minimum SAAMI specs so as to create maximum pressure. The same loads are then shot in the "test gun" specified in the manual to give more realistic velocity expectations, but the pressure in that "test gun" is NOT measured. Thus, two manuals that come-up with the same max charge weights in their NEARLY identical SAAMI-spec pressure test barrels MAY have gotten the same pressures and velocities from their test barrels and STILL get different velocity values in their "test guns." That can be true even if they are the same model test guns. Not only do the dimensions of individual guns vary from the same manufacturer, but the amount of erosion in the throat can substantially affect the presure and velocity. It has been ALLEDGED that some earlier manual producers used their SAAMI-spec pressure test barrels for too much testing, significantly eroded their throats, and that accounts for some of the really hot loads for some cartridges in some manuals.

SL1