300 winmag load question

[pacomdiver]

im working up a load for my 300 win mag,1-10 26" hart heavy stainless barrel. im running h1000 powder, 220smk's ,cci lr , win brass and an oal of 3.50 and ogive of 2.916. 3.60 is the lands on this rifle. all loads were shot with the rifle in a leadsled shooting vice at 100 yards and were about 30 seconds between shots

on a previous rangeday, i found a sweet spot that had shown promise and loaded the same load, and a 1/10 grain over and under. the 3 loads i tried yesterday were 76.7, 76.8, 76.9.

all 3 loads had nice 3 shot cloverleafs but 2 shots lower and left that messed the groups up. what should i do? i rechecked to make sure all the screws were tight to rule out scope movement. should i try to get closer to the lands, or try a little more jump?. or are the 220's not quite stabalizeing at 100 and try them at 200+?

 

[300ATT]

Re: 300 winmag load question


FWIW, I have seen this same issue with larger .30 cal magnums.

The pundits at the time suggested that I do all my load testing at 200 or yards "in order to let the bullets settle down". Whether this is true or not I believe that doing load development at longer ranges (when the wind is calm) is a good thing.

Good shooting...

 

[ChadTRG42]

Re: 300 winmag load question

try thenm at 200 or 300, and lose the lead sled. I would also seat them closer to the lands, if you have the room in the mag.

 

[doc76251]

Re: 300 winmag load question

With a 300WM and heavies I would definitely consider backing up some. It is not too uncommon to find a great load that is 1" + at 100 and is 1" at 200 and 1" at 300. The concept 300 AT&T refers to gyroscopic stability (or in this case over stability) or "letting the bullet go to sleep".

I am partial to finding a good load via the OCW method which locates the same POI for a series of powder weights. The size of the group matters little. In the magnum you then move back and tweak the load to achieve maximum accuracy via seating depth and all the other usual suspects.

.02 for the pot.

Cheers,

Doc

 

[former naval person]

Re: 300 winmag load question

With a load that heavy, 0.1 grains shouldn't be detectable on the 100 yard target. Probably technique. Could be bedding/vibration issues.

 

[bench98]

Re: 300 winmag load question

I have a 300WM that would put three or four bullets in almost one hole and then throw out two bullets some where else, usually about 3/4" away from the other ones. I too thought that it was my loading, shooting technique, or rifle. After trying different powders starting out at a low pressure load and going up 1 grain at a time one powder and grain combo hit a sweet spot. Before that there were groups that were under.5 but I kept after it. It will now shoot .25 groups. It took a lot of time and a big powder selection to get there but it was worth it in the end.

 

[pacomdiver]

Re: 300 winmag load question

its got a single feed ramp and theres no mag, so i can load them as long as i want

the action was fully bedded by the previous owner and i have the action screws torqued to 65in pounds, which is what the m40 torque spec is. unfortunately i cant ask the last owner anything like what load he used as he died and i got it from an estate sale

barret,
thats almost exactly how far away they are on all 3 groups, any suggestions what other powders i should try with the 220's?i have imr4350,rl22 (didnt have much luck with it thou)and a couple others

 

[winxp_man]

Re: 300 winmag load question

Try 76.0 grains. This load give me the biggest 5 shot groups at .5 MOA. I have mine loaded at 3.550. The H1000 is a really good powder and it is also temp insensitive which is good for all year shooting. I dont know if you have a chrono but my 26" 1-10 Sendero pushes the 220 SMK at about 2830-40 with 76gr of H1000. The higher I went into the load with grains the bigger the group got.


Also are you annealing the cases? This will matter in shooting magnum rifles. Neck tension is important. One other thing is you might want to try the 215M Fed match primer. For me it did make a difference. I will be shooting some more with in these next few weeks and I will post some results.



Aron-

 

[cruzie27]

Re: 300 winmag load question

i have a Remington 700 5R with a 26 in 1:10 twist. i load H1000 at either 74.8 or 75.0 depending on lot for a AVG 2750FPS. i only use the FED 215M's. and seat them .010 off of the lands

dont forget to sort your bullets by weight.

 

[chain]

Re: 300 winmag load question

Mark you brass and see if you have the same two running amuck. I did that and changed to RWS brass. Problem solved. Are you trimming ? I had that happen once and the collar on my trimmer loosened a little. That is why I mark brass until everything smooths out. My 300 win isn't fussy about projectiles or powder as much as it is brass and brass prep. I have never shot anything heavier than 210 Bergers though. Good Luck

 

[22_250]

Re: 300 winmag load question

+1 on annealing and seating depth, though your bullet choice will affect that. I shoot 210gr bergers seated in the lands. 2 thousand of an inch off the lands my groups open up above moa.