The chicken or the egg?

stralia

stralia

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Hi guys.

So...When you are developing a load for a new gun, do you firstly pick a certain powder and charge then adjust your seating depth in increments, then once you achieve a good group start playing with loads? Or vary loads first and depth after?

Cheers....
 
Pick a load of known accuracy. Sierra and Nosler list most accurate loads and most accurate powder or variations.
Incremental loading will show the formation of a desire to group.
For the 180 grain 300 Win Mag load, starting at 70.1 and proceeding to 73.6 of IMR4831 is still to be tested.
Using SAAMI specks, the overall length is starting at 3.330.
There are variations which you should make yourself familiar with.
Loading from a magazine may be a limiting factor for overall length.
Checking the overall length when seating to the lands is sometimes too long for the magazine however if that is not a condition that exists you can use that figure and seat a little deaper.
 
if your planning on jamming the lands ,you should always start jammed if not I load to my the max mag will feed.

I then do a ladder test 200m to 300m (video recorded)

I start 1 or 2 grains below recommended powder charge and work up in .5 increments to 1 or 2 grains above max. ALLAYS watching for over pressure signs. I wont shoot the weakest load first. i shoot the recommended start load first and work down to my weakest load to insure there are no negative signs, then shoot the rest of the ascending loads and stop at the first signs of over pressure.

once I find the node I wish to work with and the rough grain I wish to fine tune . I then shoot groups with shells loaded several .1 grains below and several .1 grains above my chosen rough grain. I find the load that groups the best at which point you mess around with seating depths. shooting groups again.


check out snipershide and 6mmbr websites for precision reloading info there is allot to learn and many different levels one can take it to, It really depends on what you wish to achieve and how much time you wish to spend.
 
horseman2 said:
Pick a load of known accuracy. Sierra and Nosler list most accurate loads and most accurate powder or variations.
Incremental loading will show the formation of a desire to group.
For the 180 grain 300 Win Mag load, starting at 70.1 and proceeding to 73.6 of IMR4831 is still to be tested.
Using SAAMI specks, the overall length is starting at 3.330.
There are variations which you should make yourself familiar with.
Loading from a magazine may be a limiting factor for overall length.
Checking the overall length when seating to the lands is sometimes too long for the magazine however if that is not a condition that exists you can use that figure and seat a little deaper.
Click to expand...

So if I start with an overall length say -.020 and then start at a charge of say 88.5gr H1000 (.338LM) and move up to say 91gr, then after I settle on a load then play with the length?
 
Last edited:
Depends if you are mag feeding or not.

If not, determine the length to lands of you gun (You really need to use a comparator to measure this properly)

Tangent ogive bullets I start with rounds touching rifling and work up powder from known safe starting point. If load is <40 grains I move in .2 grain encrements, over that I go up ny .5. VLD bullets I jam them 10 thou.

Find a node - and you will know this is a node, when you can see a definite trend towards and away from a tight group. One tight group in amongst a bunch of schitty ones is just a fluke.

When you have velocity mailed down, fine tune seating depth.

For mag feeding, set the bullets to the book COAL and find the ve.ocity node that works best
 
Since you mentioned 88.5 to 91.0 grains of H1000, I checked the Sierra Manual and assumed the 300 grain MK.

H1000 82.7 84.6 86.5 88.4 90.3 92.2

H870 89.4 91.4 93.3 95.3 97.2

Viht N170 84.3 86.0 87.7 89.4 91.1

Energy/ft.lbs. 4164 4332 4504 4679 4857 5038
Accuracy Load: IMR-4350/ 78.2grs. 2650fps/ 4679ft. lbs.

With all the unknowns, 0.020 may be too close to the lands. Bullet make, shape, and weight would help. I have never loaded the .338 LM so can only quote from book values.
 
horseman2 said:
Since you mentioned 88.5 to 91.0 grains of H1000, I checked the Sierra Manual and assumed the 300 grain MK.

H1000 82.7 84.6 86.5 88.4 90.3 92.2

H870 89.4 91.4 93.3 95.3 97.2

Viht N170 84.3 86.0 87.7 89.4 91.1

Energy/ft.lbs. 4164 4332 4504 4679 4857 5038
Accuracy Load: IMR-4350/ 78.2grs. 2650fps/ 4679ft. lbs.

With all the unknowns, 0.020 may be too close to the lands. Bullet make, shape, and weight would help. I have never loaded the .338 LM so can only quote from book values.
Click to expand...

Im loading for a Savage and using 300gr SMKs. I checked the seating depth with the Hornady gauge and it came to 2.965.
 
Im loading for a Savage and using 300gr SMKs. I checked the seating depth with the Hornady gauge and it came to 2.965.

So if you are going to seat at 2.945, using the same measuring technique, 5% below max would be about 87.7 for starters.

With the bigger case you increases might by closer to 1.0 grains until you get with 1 grain of max then proceed with great caution.
 
I always start with length. Seat a bullet in an empty resized case partway, insert in gun, and close the bolt. Usually, jamming into the lands will seat the bullet in as far as it needs to go. Check to make sure it feeds from the mag, shotren .005 or so, and go to town.
 
horseman2 said:
Im loading for a Savage and using 300gr SMKs. I checked the seating depth with the Hornady gauge and it came to 2.965.

So if you are going to seat at 2.945, using the same measuring technique, 5% below max would be about 87.7 for starters.

With the bigger case you increases might by closer to 1.0 grains until you get with 1 grain of max then proceed with great caution.
Click to expand...

Just loaded some rounds at the full length of 2.965 and they mag feed no problem. I'll start here with loads at 88gr and work up from there to 91gr.

Thanks for you advise guys!
 
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