I just loaded for my .300 WM the following loads and got the following velocities.

700BDL stainless w/24" barrel
Win cases
180 grain Swift Scirocco
RL-22
Rem 9 1/2 mag primers
74.5 grains - 3040fps avg.
75.5 grains - 3100fps avg.
76.5 grains - 3175fps avg.

The Swift manual says I should only be getting about 3030 fps at 76.5 grains of RL-22. I can't remember getting velocities this much higher than "book" with anything I have loaded in the last 5 years. I don't have any other experience with this particular rifle, as I just started working up loads for it.

What's going on? Is this normal, or at least not abnormal enough for me to be concerned with? I know enough not to push the envelope with my loads and will stay at the lower charge weights. I just expected my loads to be closer to the "book" loads.

Fast Ed

There are too many variables involved to figure out what's happening here IMO, except there is no free lunch with velocity. Match the velocity, not the charge. I've owned several rifles that have done that, most do not. One example is a .22 K-Hornet that achieved over 3400 fps with a Nosler BT of 40 grains, the charge being less than specified max charge for the cartridge. In fact it was the specified maximum charge for the Hornet at the time. No pressure signs, easy extraction etc. ad nauseum. I gave up trying to figure out why and just loaded to more sensible velocities for the cartridge, as indicated by published load data. Not going to say how high over 3400 fps it was, I doubt anybody would believe me, and yes, the chronograph was functioning properly.

Velocity too high clearly is a sign of excess pressure but in and of itself is not too much to be concerned with if it's not accompanied by other signs.
Chrony machines are warrantied to 5% accuracy...150'/sec in 3,000'/sec..... and who knows the other variables in play here.....If It were me and there was no other pressure signs and the load is a published load I'd just smile and keep on a shooting.

Both DD and Vapodog make valid points. I'd shoot 'em over another chrono and see what you come up with.

The last two of those load would be giving excessive pressures in my .300 WM, but no two guns are quite the same. The velocities are about what I would expect with that charge, bullet, and powder. Remember, the RL series tends to vary in speed more than most canister powders from lot to lot, so it is possible that you have a somewhat faster lot than was used by the Swift people in working up their manual loads.

My advice would be to load your 74.5 grain load for several shots in the same case to see if the primer pocket loosens after a few cycles. If not, then you could add a grain of powder and try the same thing again.

My rifles do this all the time - that is change velocity with the same load. Next time try this, when you're getting more velocity than you expect, clean the gun with a strong copper solvent like Barnes CR-10. If you have the same reaction mine do, your velocities will drop 100 to 150 fps and your groups will shrink. I think it is that a build up in the barrel will lead to more pressure and thus more velocity. If you've already cleaned your gun, then load the exact same load and chrony it and see if the velocity is the same.

Voodoo science, but I'd be interested to see what happens.

Not uncommon to have 100 FPS difference between barrels...

quote:

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Originally posted by Fast Ed:
I just expected my loads to be closer to the "book" loads.
Fast Ed

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Lots of good ideas. What is the barrel length from the Swift book? It is not unusual to have 75-100 fps diff on two different barrels, same caliber.

I load .300 WM for a buddy of mine who does not reload. He got almost identacle velocities with similar loads in his Ruger 77 Mk II with a 24 in. barrel.

Geronimo

quote:

Originally posted by vapodog:
Velocity too high clearly is a sign of excess pressure but in and of itself is not too much to be concerned with if it's not accompanied by other signs.
Chrony machines are warrantied to 5% accuracy...150'/sec in 3,000'/sec..... and who knows the other variables in play here.....If It were me and there was no other pressure signs and the load is a published load I'd just smile and keep on a shooting.

It was over my buddy's Shooting Chrony because I forgot the tripod for my CED. I think I will reload the rounds, and shoot over my CED. I have already cleaned the barrel down to bare stainless.

The worst part is that the 76.5 grain load shot into 3/4 MOA, substantially better than the other two loads. I am hoping my CED shows lower velocity, closer to book, so I feel comfortable shooting it.

Fast Ed

Fast Ed,

Some barrels are just fast. I have a 300WSM that is well over book velocities. I just use the book as a starting point and let the crony tell the rest. It has alot to do w/ the true barrel diameter. If it's tight, there will be more pressure and higher velocity. Not a bad thing. Some barrels will be 50-200 fps faster than book.

Hey, at least you can save alittle powder .

Good Luck!

Reloader

I had a can of RL-22 that did the same thing. It's lot number was posted on Alliant's web site and they said to be sure you used the start loads to work up with. I've still got a little of it but haven't fooled with it for awhile. BM

Bill

i use 73 grains... and break 3000, barely... and like a couple books say, 3100 with 180s in a winnie is asking for steel rain

jeffe

My 300 winnie does 3120 with 74.5 gr of RL22 and 180 sierras. Trouble is, the cases are then unusable as the primer pockets are enlarged. Really accurate too, had to drop er back a grain. Readings in this barrel seem to go on the high side. I had an identical rifle that was 200 fps slower with the same load, AND the bolt was stiff. You never know what you are getting when you buy RL22. Great velocity and accuracy but ya gotta be careful. I have never been able to get to max of 76.5 gr in any of my 300's. I do like it in my wsm cases also.

is it then possible to regularly push a 24" barrel 300 win mag to 3175fps using 180gr bullets, safely?

quote:

Chrony machines are warrantied to 5% accuracy...150'/sec in 3,000'/sec.....

Just for the record I have been researching chronographs a lot recently and Chrony guaranties 99.5% accuracy, or +-7.5fps (15 fps range) at 3000fps.

No as to the question of "Do they meet their accuracy guarantee?" I can not tell...