Reloading for the 300 win. Results Questions

[Firecat]

So I set out today with my new trusty Ruger Hawkeye 300 Win Mag. I had worked up some test loads to find what my new rifle was going to shoot best. The bullets that I had chosen were 180 grain Sierra Gameking spire point boat tails. I like these bullets for their design and the fact that they are one of the few 180 grain bullets that breaks .500 for ballistic Coef. I loaded these bullets with IMR 4831 and CCI 250 Large Rifle Magnum Primers. Here are the results. My question is what is going on with these groups?

This was the lightest load that I had loaded at 71.8 grains. decent group three shots at right at 3/4 of an inch

This is my second load at 72.4 grains. the group of three is 11/16 or just under 3/4 of an inch

Then this happens. Load threeat 73 grains opens way up top three shots measure 1 13/16 of an inch

This is load four at 73.5 grains. Here my group goes horizontal. The three shot pyramid is gone and is replaced with a horizontal string. What is going on?

Lastly load five at 74 grains. Even more dramatic horizontal spread. What makes a group change shape like this?

It is clear that my rifle likes a little lighter load. the 72.4 grain group that i shot will most likely be the one I load with. It is a medium to hot load but well under the max load in the sierra manual. None of these loads showed signs of pressure and would feel safe loading any of them, however the lighter two loads of the five yielded the best results. What is my rifle trying to tell me by the change in the group shape? Is there any way that i can use this data to further my progress in my load developement?

 

[ICANHITHIMMAN]

Well there are alot of things going on. I dont know you or your shooting abilty If you where shooting a proven load and rifle I would say its trigger pull.

But sence it looks like you shooting a ladder test I would say its normal. Take your best load and switch the primers try a LR primer and see if it shrinks anymore. Also you can try some hotter charges just dont go over max. Im shooting a 185g bullet and 81g of powder.



Jon

Also I am no expert but I hope this helps

 

[RockZ]

I like the lack of vertical in the 73.5gr load.
Is your barrel free floated and how far off the lands are you?
You may be able to coax the 73.5 gr load together with a seating depth change.
Also what were the wind conditions?

 

[Firecat]

Rockz, the rifle barrel is free floated. I was shooting at around 7:00am and the temperature was around 60 with absolutely no wind. Unfortunately like most production rifles the throat is long. I would run into magazine length issues long before I was ever able to reach the lands. Not only that, but the 180 grain game kings have a HUGE boat tail and I would not ever be able to have enough seating surface for the bullet in the neck. I can come forward with the bullet an estimated .050 and still be okay with things though. What would you recommend?

 

[RockZ]

I'd load up some at 73.5 and shoot groups
loaded .025 and.050 longer to see how it groups

 

[bigngreen]

Usually when I'm getting the flier that is jacking up my group a little primer test will take care of it. I load the best groups powder charge with all the same seating depth then change the primers. I try to do a Mag and LR primer in every brand I have on hand. The results can be amazing.

 

[Firecat]

Well here's what I decided after hearing what you guys had to say. I took a load between the lightest two and loaded it with varying bullet depths. I loaded five different loads at an even 72 grains. The first seat depth is 3.340, 3.355, 3.375, 3.395 and lastly 3.410. Five different loads with a total span of .070. I would have perhaps Tried for even more but I ran out of neck tension with the bullet and magazine length. I also took the 73.5 grain load and switched up Primers. I also tried a couple of different seat depths with this hotter load. I also like the fact that there is very little vertical variation. I will see what happens early Saturday and post my results.

 

[mmmooretx]

While using a different bullet and powder I got a .38" 5 shot group at 100 yards. I talked to a Sierra bullet technician, great people and love to talk loads, I moved up to the 200 gr. SGK that has a better BC and I think stabalizes better due to longer length. It will sound funny but I have a Kreiger 24" barrel on a Ruger 77 Mk II but it shoots pretty good. My load is CCI 250 primers, 78.5 gr. of H1000 and the 200 gr. SGK is seated .010 off the lands. Oh yeah around 2900 fps MV.

 

[Firecat]

Mr. Moore,

Thanks for your input. I will look into the 200 gr. SGK's. I have been very pleased with the sierra bullets that I have used up to this point. I have had great luck with Ruger Rifles also. I've had to float the barrel in each one, but they(220 Swift, 25-06, 7mm Rem Mag, and 300 Win Mag) will all shoot sub moa at 100 yds with handloads. They shoot a heck of a lot better than the factory Remington I have. If you can get 2900 fps with a 200 grainer, that is very attractive. Sounds like I need to do some more research.

 

[mmmooretx]

Give the Sierra Tech people a call, link below. They will take all the time it takes to resolve any issue with Sierra bullets/loads. I talked to them 2-3 times and for as much as 30 minutes at a time. They call back and do email too. I talked to Robert Treece.

Sierra Bullets - The Bulletsmiths

 

[mmmooretx]

I am also doing a load work up with the Berger 210 gr. hunting bullet. The BC is even better but I have not found the sweet spot for the distance off the ogive. I have three sets of three at .030, .035, & .040 for my next test groups. I tried close to the ogive, .008 off the ogive but my groups were 1.2", not good enough. Once the sweet spot is found I expect them to be even better than the SGK, but if they match I'll be happy.

 

[Firecat]

Mr. Moore,

I am doing like you and trying several new loads with varying seat depths. I would have shot them last Saturday, however the range was closed for the day. So hopefully this Saturday. I would be interested to hear how the 210 Bergers do for you.

 

[mmmooretx]

It is only 9 rounds but I am going out to my new hunting lease this weekend to set up my feeders and stands so it may be a week and a half. I do have a CED M2 chronograph so I should have data too. I do not have a meplat trimmer and my primary range is limited to 300 yards, plus my spotting scope is still on the wish list....

 

[Firecat]

I have thought about a meplat trimmer. How effective are they? It seems sound in theory.