Seating and Depth and IMR 4350 really that sensative?

[ronedog]

I need some help analyzing my shot groups and helping me understand what happened.

3 days ago I finished my ladder test and settled in at 57.5g IMR 4350 Here's a pic of my group. Shots #16,#17, #18 with their respective FPS. It was 70degrees outside and this was shot at 57.5g of IMR 4350

So I thought I'd settle in at 57.5g of powder and then play with seating depth. This morning I went and shot those groups and it was all over the place. The temperature had dropped 11 degrees from the other morning. Here's a pic of the same 57.5g and 2.920 OAL (the first pick was also at 2.920 OAL.

What really has me confused is the velocities and how far apart this group was, considering 2 days ago I thought it was right on...either I loaded more powder than the scale said (but I'm very particular about this....using a lee powder scale...maybe this scale is not a good one to use?...it's not broken), or the temperature had a larger affect. Primers, brass, everything was all the same as it was 2 days ago.

I shot 6 different 3 shot groups at different OAL to figure out seating depth, and all of them were 4-6 inches at 100YDS...except this one:

This is the only group that that was decent, although not as good as 2 days ago. This was shot at 2.943 OAL, which is almost touching the lands. 2.944 is where it touches the lands.

I used to load with H4350, but I can't buy it locally anymore, so I went to IMR4350 and have been working my load up with that. I've never shot with IMR, and I'm still quite a newbie at this, is IMR4350 really this temperature sensative, or do I have some other problem? All my shots I felt good at where my aim point was and they were good shots, just all over the place with impact. I'm heading out hunting in 3 weeks and the temperatures in the morning will probably be around 45degrees, then in afternoon climb to 60 degrees...can IMR 4350 handle these temperature swings, or do I need to find some other powder?

I'm just not confident that if I load up some bullets at 57.5g and 2.943 OAL, or 2.920 OAL that it will be consistent.

I'm shooting a 300WSM Model 70, everything is stock, trigger pull is at 2.5lbs, Vortex Viper 6.5x20x55mm Scope...20MOA picitanny base with custom turret from CustomTurrettSystems.com ... its a hunting rifle, and my primary goal is to use it for hunting and I want to be in the boiler plate up to 800 yds...if my loads can get dialed in for that.

I'll take any input from you guys! Thanks.

 

[Mexico hunter]

You might try cleaning the barrel and checking all or the screws. I use IMR 4350 in loads for several of my rifles and get less than 1" groups for all of them. try going up or down on your load for my 300 WSM I am using 60 gr IMR 4350 / 180 Nosler BT FED 215 / 5 shot group 1 1/4" groups at 200 yards. My 300 Winchester load that I use I got from Gale McMillian with a 300 WIN mag rifle he built for me is 70 GR IMR 4350 / 180 Nosler it shots 5 shot groups at 200 yards less than 1" and 2 1/2 " groups at 500 yards. IMR 4350 powder works well in most magnum calibers

 

[ronedog]

thx for the reply...that's a encouraging to hear considering i just bought another bottle of imr 4350.

I checked all the screws on the scope, and everything was really secure...I loctited every screw and there was no movement in them. The scope also tracked true and has done throughout my testing, so I don't think there is anything inside the scope causing a problem.

However, I'm wondering if my powder charges actually weighed 57.5g. That large of a FPS in a bullet that has the same OAL and the same powder charge is suspicious to me. Let me explain some things I've observed with my powder scale and you tell me if it's normal.

I'm using the LEE Powder scale found here: Lee Safety Powder Scale - Lee Precision

I've had it for about 5 years or so. put maybe 200 bullets through it. Here's what has always confused me a bit. If I zero the scale, then go to weighing the powder at say 57.5gr I will make sure the scale flows back and forth smoothly without touching anything. Many times I'll get the powder charge exactly on the line and just for double checking sake I'll tap the scale to move up and down again, just to make sure it settles on the exact charge of 57.5 again. I've noticed if I change the "mountain" of powder, and distribute the granuals a bit, it can cause a fluxuation in the weight...I then have to add, or remove some grains to make it settle again at 57.5. This has always been weird to me, because I would think that if it settles in at 57.5 it should stay there, as long as I don't add any additional granuals, but it doesn't always do this. I've also noticed that the little powder plate (that hangs on the end, where I pour the powder into) can also cause the weight to change, even though I haven't added any granuals. For example, if I add 57.5gr of powder and get it all right, then if I tap the powder plate so it swivels to the left or right and make it stay to one side or the other, I've noticed that it will cause the weight to increase. I've been putting the plate in the middle thinking that would be the best place for it, and I try to make sure its always in the same place for every charge...anyway, I don't know if this is really a problem, or if I'm just overthinking it...but I still can't explain the increase in FPS, other than a problem with my powder scale. anyone use this scale and experienced the same things?

 

[86alaskan]

I would say find a newer or nicer scale. I use an ancient Lyman but I can say that it will read accurately every time. you shouldn't be able to change the reading by moving the powder charge, it is what it is. Get a nice rcbs or redding that costs a few bucks, this is one of those places where more money does equate to higher precision. I also noticed that your fps spread is a bit high, you may want to keep tuning that load to get the spread down into at least the teens.

 

[ronedog]

Thanks for the reply. I'm thinking the FPS spread is due to charges not being constant at 57.5 from the scale problems. I found out my brother has a RCBS 750 loadmaster and a hornady concentricity gauge. I'm am going to do some comparisons to see how different the powder charges are for those scales. I also found that my bullets were .070-0.090 of runout, so I used that guage to bring them to within 0.010 of runout...I'll see what happens...bergers show up on thursday, so I'll shoot on sat.

 

[kcebcj]

You might have a scale issue as the FPS spread is considerable. In my opinion you should be testing at 200+ yards. 300 is better. It's very difficult to really tell what a load is doing at 100 yards.

I have used IMR 4350 with as much as a 40 degree swing and there was never a difference worth being concerned about. I actually work up hunting loads 45 degrees or colder in the spring or fall just to cover my butt no matter what the powder.

 

[Rick Richard]

I use IMR4350 in my 300 WSM and have not noticed in changes with temp variations. My load is around 59 grains under 185 Berger Hybrids. Savage shot 3/4 to 1.1 inches at 300 yards.

 

[ShootnMathews]

I'm using the LEE Powder scale found here: Lee Safety Powder Scale - Lee Precision

I've had it for about 5 years or so. put maybe 200 bullets through it. Here's what has always confused me a bit. If I zero the scale, then go to weighing the powder at say 57.5gr I will make sure the scale flows back and forth smoothly without touching anything. Many times I'll get the powder charge exactly on the line and just for double checking sake I'll tap the scale to move up and down again, just to make sure it settles on the exact charge of 57.5 again. I've noticed if I change the "mountain" of powder, and distribute the granuals a bit, it can cause a fluxuation in the weight...I then have to add, or remove some grains to make it settle again at 57.5. This has always been weird to me, because I would think that if it settles in at 57.5 it should stay there, as long as I don't add any additional granuals, but it doesn't always do this. I've also noticed that the little powder plate (that hangs on the end, where I pour the powder into) can also cause the weight to change, even though I haven't added any granuals. For example, if I add 57.5gr of powder and get it all right, then if I tap the powder plate so it swivels to the left or right and make it stay to one side or the other, I've noticed that it will cause the weight to increase. I've been putting the plate in the middle thinking that would be the best place for it, and I try to make sure its always in the same place for every charge...anyway, I don't know if this is really a problem, or if I'm just overthinking it...but I still can't explain the increase in FPS, other than a problem with my powder scale. anyone use this scale and experienced the same things?

I use the lee scale with very good results. Although you need to make some alterations to the pan arm. I use a pair of pliers to bend the part that hooks the scale so that when you set the pan on the bench the pan arm tip is parallel to the bench. Then take a file with a sharp edge and file a very very small notch in the arm tip about half way in the middle of the tip.

Now to using it. I use a lee powder measure that's set about .2 grains shy of my target load to dump a charge into the pan. I give the pan a little shimmy to make the powder settle out flat and evenly distributed in the pan. Now I set just the very tip of the pan arm on the scale and slide it over until I feel it set in the notch. Now you know the powder distribution and pan placement is Identical every time.

Here is the second important part. Trickle the powder up until the scale reaches the zero point. Note * if it goes over charge, take the pan and shake a couple grains into the trickle and repeat the weighing and trickling powder until scale reaches zero point.

The lee scale is not the most precise scale but by making my pan alterations and using my weigh method you can eliminate some of the inconsistencies in the scale. I use this scale and my weigh method to load all my ammo and my 6.5-284 shoots one hole at 100 and around an 1" at 500 yards, so I know that it definitely works.

 

[oregon logger]

could it be static disturbing the scales, ive heard of that. My gun jumped around like that. Cleaned it realy good and retorqued the action bolts and one was lose. Shot great after that.

 

[gohring3006]

My 30-06 did that with imr 4350 I switched primers from fed 215 to 210's and it settled down..