300wm 208AMAX loads, 100fps difference?

[KiwiShtr]

Hi all.
Im brand new to reloading and have just finished putting together and testing my first loads. I was givin a load to work up to from someone, so started 2grns lighter and worked up in .5gn lots.
My work up Ive settled on:
AIAW 300wm
1/11 twist
27" barrel
Norma Brass, New
CCI 250 Mag Primers
H1000
76gn
208 Amax
from 2x5rd strings I was averaging 2670fps
Seated to 2.83 to Ogive (10 off the lands)
.5-.75 moa (mainly my shooting and ALOT of mirage so could have gotten it smaller).

The guy I got this from, using the same load was getting 100fps faster than mine. Is this a significant difference or could there be other variables I haven't considered? Im using Redding Micrometer seating dies and didnt do anything with neck tension. Would that made a difference?
Any advise would be great.
Cheers all.

PS. I had never seen any reloading setups or it done in person, so I have the Hide and a few books to thank for getting me going in reloading. Again, Cheers.
Anyone know where one can find "Published" load data for the 208's?

 

[MitchAlsup]

Re: 300wm 208AMAX loads, 100fps difference?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KiwiShtr</div><div class="ubbcode-body">The guy I got this from, using the same load was getting 100fps faster than mine.</div></div>

100 fps is within the things that can happen due to :: a) chamber size, b) barrel lapping, c) barrel grove diameter, d) ambient temperatures, and e) chronometer accuracy.

It is more important to watch for pressure signs and work up slowly and carefully than it is to hit any particular MV. Finally, accuracy trumps velocity any day of the week.

 

[jrob300]

Re: 300wm 208AMAX loads, 100fps difference?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KiwiShtr</div><div class="ubbcode-body">The guy I got this from, using the same load was getting 100fps faster than mine.</div></div>

100 fps is within the things that can happen due to :: a) chamber size, b) barrel lapping, c) barrel grove diameter, d) ambient temperatures, and e) chronometer accuracy.

It is more important to watch for pressure signs and work up slowly and carefully than it is to hit any particular MV. Finally, accuracy trumps velocity any day of the week. </div></div>

Having said all that... 2670 seems awfully slow for that load. FYI, I'm loading 76.2 gr H1000 .005 off lands (3.665" COAL)in a 22" barrel and getting 2870 fps. *Something* is strange... but the *something* may not be something you can do anything about.

Like suggested, work up your load and go til you hit SUBTLE pressure signs and then back off to the next accuracy node.

John

 

[Tribe]

Re: 300wm 208AMAX loads, 100fps difference?

I'd check your chrony vs real world data... shoot the thing at longer ranges, and see if those velocities pan out...

I shoot an AI 300WM, and I'm over 2,800 with 76gr H1000, win or nos brass.

 

[jrpilot]

Re: 300wm 208AMAX loads, 100fps difference?

That seems very slow for that load. For what its worth my 300WM load is. 208Amax 79gr H-1000 2955fps 12fps ES

No signs of preasure

 

[KiwiShtr]

Re: 300wm 208AMAX loads, 100fps difference?

Yea thats the MV that the other guy was getting, so was a little curious to the large difference. My barrel is still basically new, only 130rnd through it so far. Maybe it just needs a few more through it? I have a PR course this weekend so will take my chrono and compare it to others to check its accuracy (its new aswell).
Does neck tension affect pressure that much?

 

[RobertB]

Re: 300wm 208AMAX loads, 100fps difference?

It does affect it but I wouldn't think it would that much. Seating in or out of the lands to much will have a decent affect on it though.

 

[johndoe]

Re: 300wm 208AMAX loads, 100fps difference?

Do you have another cartridge you can check against your
chrono?

 

[KiwiShtr]

Re: 300wm 208AMAX loads, 100fps difference?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: johndoe</div><div class="ubbcode-body">Do you have another cartridge you can check against your
chrono? </div></div>

Yea I have some factory Hornady SST 180's that Ill take out. I have a PR course this weekend and will be chrono'ing loads there (using their chrono), so will do some comparisons and let you know how that goes. Cheers for you input guys.

 

[KiwiShtr]

Re: 300wm 208AMAX loads, 100fps difference?

Righto
Went to the course last weekend and re-chrono'd my loads. Turns out my chrono was off. Average speed was 2798fps with ES of 35fps. Was shooting (when I was on).5moa groups out to 300, under 1moa out to 500, then the wind had its wicked way after that. Something else to learn, all part of the fun.
Also I chrono'd my Factory Hornady 180 SST's, they averaged 3115fps with ES of 14fps (only 3rds).

Now I just have to figure out whats up with my new chrono.....

To be honest, as this was my first effort with reloading, having never seen it done before, I think I did ok. So now the learning and trialing wll really start. I have a base to work from, so let the fun begin.

Thanks for you input fellas.