.300 Win Mag velocity concerns

[hntnnut]

I took my new CA ridgeline out last weekend for the first time to brake the barrel in and collect some data. my brake in procedure was 3 shots and clean, 3 shots and clean and so on. chronograph is a pro chrono 10 feet in front of the muzzle. The load is a 215 Berger .030 off the lands, 76.6 grs. of H1000, a federal 210M primer in new Sig brass. From other data found on the internet and else where, I figured I should be in the range of 2875 and no more than 2950 fps, also My ES is 42 and SD is 11. There is Zero signs of pressure, bolt lift is good, primers look good and no extractor marks. Should I be worried? Any reason I should back off?

Forgot to add that my average velocity is 3047fps
Richard

[kcstott]

My data shows you are backed off already, I'd start loading for accuracy

[longrange1]

first you do not mention what your actually velocity is just where you think you should be.

next you should be running large rifle mag primers not standard LRPs and that is probably part of the high ESs...another cause may be new brass.

if your looking for more speed you should try reloader 26....when i was shooting a 300wm i could not get the velocities i was looking for before high pressures with H1000...i shot RL-22 and 210g SMKs at 2920 out of 26 and 28" shilen barrels.

[J-cat]

No he should not be running mag primers. That is not the cause of his high es.

[pennstater]

No he should not be running mag primers. That is not the cause of his high es.

Curious. Why not the mag primer then?

[J-cat]

Because mag primers have proven to be unnecessary with H1000 in the .300WM. You want the mildest primer you can get away with for best accuracy. Our military’s MK248 Mod1 ammo uses H1000 and a FC210M primer.

[hntnnut]

Shoot for got to state my average velocity is 3047 fps. The high velocity was why I wrote this in the first place.


Richard

[J-cat]

Your chrono is not all that accurate depending on where the light source is. You should be around 2950 with that load assuming you have a 24”+ barrel.

[longrange1]

.300 Win Mag velocity concerns

No he should not be running mag primers. That is not the cause of his high es.

im not trying to argue but what is it then? ive loaded and shot thousands of 300wm rounds and every time i ran LRP it caused issues.

also even with a 26" barrel was NEVER over 3000fps or 2950fps with 76.5g of H1000 which was hot in 3 of the barrels i shot....75.5g of RL-22 was only 2925 with 210g SMKs.

Sorry I meant to put 73.5g of RL-22 not 75.5g.

[J-cat]

His high ES is caused by an incompatible combination of brass, charge weight, and OAL. It is not caused by the FC210 primer.

Not all standard LR primers are the same. 210’s and H1000 are so compatible it’s like they were made for one another.

[J-cat]

I run 77.5grs with 208’s in Hornady brass @ 3.660” in a 27” barrel and get 2950 FPS with single digit ES. Hornady brass weighs 233-242grs depending on the lot. I dunno what SIG brass weighs or it’s capacity.

[longrange1]

id be willing to bet if he ran everything the same and used a CCI250 primer his ESs would be lower. i agree its a combination of things but if you think a primer can not cause high ESs your wrong!

also in 4yrs and 3.5 barrels i never had a load in my 300wm that was in the single digits...teens to low doubles was the norm.

so your running 1g more powder than the OP out of a 27" barrel and your at 2950 so how could the OP be running a heavier bullet with less powder and most likely out of a shorter barrel and be at 2950?

to the OP...

your chrony is F'd up theres no way your at 3047 with that load.
i know a little bit about primers...i did a LOT of primer testing about 5yrs ago and the CCI250s were the mildest of the MAG primers.

get a better chrony or set yours up in a card board box without the sun shade at 15 feet not 10 feet and try the CCI250s.

[J-cat]

Tighter chamber, different barrel, possibly heavier case with less volume, that’s how. Stop arguing the primer issue. You’re wrong.

[MrElectric03]

Interesting to know on the primers, I hadn't heard that standard LR primers can Ben used with H1000 in .300 WM so I'll have to try in the future. I'm not even close to this point with my rifle but am taking notes.

[longrange1]

LOL ok.


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