Home Forums Reloading Big Game Rifles Question on pushing the limits

Thank the Lord for the invention of the chronograph. I'm working up a load for a 7mm Rem mag. Powder-RL22, primer-Federal 215, bullet-160gr. Sierra SPBT, brass is RP once fired, off the lands about .020. My goal is 2950-3000 fps. with of course good accuracy. I started at 63.5grns. with velocity average of 2757fps. Next, 64.4grns. at 2810fps. and stopped with what was supposed to be a max load of 65.0grns at 2862fps. From what I've read I should be hitting close to 3000fps. now but as you can see I'm still short. No signs of pressure build up at all and accuracy continues to improve with each bump up. From your experience, if I move up to 65.5 and then possibly to 66.0grns. do you think I'll still be within limits? This is the first time I've ever had to push a load above and beyond published data. Thanks

my 160 gr load with a nosler part. is 67 gr. of RL22 the bullets are moly coated and the brass is PMC the vel. is 3078fps


Ed

My Nosler manual shows 63gr RL-223058fps in a 24"bbl. I'd go up .5gr at a time watching your chrono for any large increase in velocity or a drop in velocity. Also,of course,watch for any of the known pressure signs. I wouldn't exceed Noslers max veocity. I'd also chrono for a 5 to 10 shot velocity average backing off if need be. Of course optimum accuracy is the goal.

Dont think any animals will notice the 190fps "shortfall" in velocity. If you must go higher, I would start working in maybe .5 grain increments.

I don't use a chronograph in load workup because it doesn't really tell what the pressure is and I'm loading for accuracy rather than velocity. As long as I'm shooting a gun with a strong action, I will keep pushing a load until accuracy stops improving or pressure signs occur. When I approach what a manual says is a maximum load, I increase the load in smaller increments.

It's rare that I exceed a maximum published load when I go with the above criteria.

The world is full of blown guns and injured shooters who have to get the last 25 fps. You might just have a slow /tight barrel or loose one.Everyone is differn. All manuals reflect test done in a test barrel,not a commercial off the shelf one.
Of the two 7 mags I loaded for, a Rem and a Weatherby,I was never able to reach 3000 fops with a 160 gr bullet .However, I alwasys found top accuracy was just a tad under maximium.

It always amazes me how many reloaders there are who think they know more than ammo manufactures who test thousands of rounds of ammo

Remember that the books are general guidelines.

In my mind you're not really "pushing the limits" if you don't have signs of excessive pressure no matter where you are in relation to the listed max.

I find max and accuracy nodes and take the node a couple of grains below the point where signs of excessive pressure begin. I also do much of my testing in the heat of summer, so no surprises can pop up in extremes... except maybe a load that doesn't group as well in cool weather because of a drop in pressure... but nothing unsafe.

prredog,

Someone mentioned gun companies. The gun companies, like the loding companies, have a bunch of lawyers telling them what to do. Some one else mentioned lots of blown up guns. The rifles I have heard of blowing up have been from light loads of slow powders.

For about 30 years I have been a wildcatter. With wildcats there is no book to follow or lawyer to tell me to back off. I load till I see some sign higher presure and barely back off. I want maximum velocity with the best accuracy I can get. I do a lot of things alone so am not impressing others. I read my notes for more fun after the shooting session. If someone thinks I am running too hot, they can make a suggestion. If I haver heard it before, I politley let them know. If not, I give it a listen. Most of the time it is someone who believes the manual as much as I believe the Bible.

When the BOSS came out I did a home made version of one. They work! They don't need holes, but all mine, except on the rimfire, are adjustable brakes. Well, also the .375-.416 Rem Mag is not adjustable. All you do is work up to the maximum velocity and dial the brake or barrel weight. It's almost like cheating.

All great advice, thanks again.

Just use caution and observe what is going on while you're shooting and you'll be ok.

I've owned several 7 Rem Mags that would barely make it to 2950 fps with 65 to 66 grains of RL 22 depending on the lot. Other recommended powders did not get me over 2950 fps safely.

When your bolt is very difficult to raise, you know it's definitely time to stop and back down...

and they did show other pressure signs as in cratered primers, shiny ejector marks, etc. with the difficult bolt lift.

They would do the ususal 3200 fps plus with 140's with RL 22 without any pressure signs.

Have it throated differently or try another barrel. Even my custom barrels have been slow with 160's. Others have barrels that do 3050 w/o problems. I've had one that would do 3050 fps with 160 Partitions.

the nosler book lies about speede if everone dosnt know that they used a min spec barle to shoot faster. u should be aboule to go atleast a grain over max load

prredog:
I enjoy questions like this since I can run some ideas thru my copy of Quickload & see what it comes up with. Firstly, I've never loaded for nor shot a 7mm mag. so take the following info as you wish but here's some of what QL came up with: I entered your info into the Ql routine to calculate powder charge vs. velocity. Velocity I entered was 2950 fps along with your Sierra bullet.
Quickload predicts a powder charge of 66.2 grs. of RLDR-22 for 2950 fps at a pressure of 55404 PSI.
Looking at MAGPRO, it predicted 2950 fps with 69.4 gr. and 54532 PSI.
Finally, RETUMBO showed 2950 fps with 73.4 gr. and a pressure of 51523 PSI. NOTE - this is in PSI and NOT CUPS!
All of these powder charges returned a "NEAR MAX." warning.
QL says that the 7mm Mag. has a max pressure of 62366 PSI and recommends not going over 90% of that.
Just thought I'd throw this out to you & maybe give you some ideas. Good luck.
Bear in Fairbanks

I agree with the poster that asked, "what is the extra 150fps gonna do for you??" I just do not like to motor my rifles, especially hunting rifles, at the top end. The added stress of getting that last 100fps just isn't worth it. We know that any time something breaks or jams or comes apart, it's gonna do it at the most embarassing moment.
I've never used any R22 but I just checked my log and with several stick powders, my hunting loads for a 160gr bullet was 2900fps +/- 50fps. And my 7mag killed everything I pointed it at. While it's a nice number, 3000 isn't any sort of magic.

I have never gotten to book velocity with there loads, usualy Im 100 FPS off. As others have said I would not worry about 150 or so FPS, the critter wont care.

I agree with you 100%, why are so many people concerned with velocity then accuracy and bullet performance? Most hunting bullets perform and expand more reliably at around 26-2800fps. My advice for the speed demons is if you want the end all be all hunting rifle, get a 50 BMG, have it rebarreled and neck it down to 7MM or 30 caliber, then maybe you'll be happy when you go through a pound of powder every five rounds to achieve light speed and time travel at the same time with a hunting bullet. And don't forget to put a spiked metal recoil pad on it just to be sure it isn't least bit of fun to shoot as well.

Again, I continue to read and appreciate all the input. To answer the question about why worry about the extra 100-150fps, every cartridge has a certain capability to live up to and to maximize. At this point in my reloading for this cartridge and rifle, I don't believe I've made it to that point yet. Accuracy continues to improve as I bump up to the next level and there are no signs of pressure that would make me want to hold back other than the fact that by certain manuals and information I've pulled off the internet, I should have reached that point. Its a 7 magnum and I want 7 magnum performance, that sounds childish and I don't mean it the way it may appear. From all I've read here, proceed onward but with great caution. I've always worked up loads this way for many various guns and cartridges I have but this is the first time I've encountered a situation where it seems I'm so far off of where I should be. My hats off to all you guys that have been where I'm at or with the wildcatters that have had to rely on good common sense to keep pushing it a little further. That's why I posted here, I knew I would get the best suggestions!

I reload both ways. Moderate velocity and accuracy for my 9.3mm. And the max velocity that gives me top accuracy and long casing life in my .300 and .25-06. I'll pick the proper bullet for the application. Absolutely NOTHING WRONG in wringing out a SAFE maximum velocity if it fits your fancy. I'll pass on that 50 cal though. LOL

This is kind of a procedure I used that has worked fairly well for me.

I start somewhat low and check the case neck for soot, see what the chrony says and go from there.

I keep going up on the charge keeping an eye on the chronograph and looking at group size. When the soot on the necks is minimal, you are just about there.

The first signs of pressure I see is almost always the shiny mark on the casehead left by the ejector slot, or plunger.

If you reach this point and still don't have what you feel is acceptable velocity or accuracy, it's time for another powder.

I take my loading equipment to the range. That way, I can see just how much my primer pockets are loosening during the day. If you reach a load that you're happy with, load and shoot the same case 5 times and see how the case is afterward. If the primer pocket is still tight and it shoots a good group, that should be a very good load in your rifle.

+1 on watching that chrono. First caution sign I see when developing a load is an unusually large increase in velocity from what I've been getting per charge increase. That's worked for me since I bought my chrono back in the mid 80's. Except for the summer before last when working up a load for a friend's .257 Roberts. I was getting steady but gradual increases. Then a drop in velocity. Added .5gr and got the exact same low velocity. Added .5 gr and bingo I was over the max velocity in the manual. From pryor experience I knew to stop and back off at the first sign of an abnormal velocity change but since I had never had a drop in velocity before I decided to check it out. I had one of the members here run my data through quick load and low and behold it showed the max safe charge was the one before the first velocity drop.
Until someone comes out with affordable pressure testing equipment for us reloaders I'll use ANY and ALL available info or procedures to help me determine a safe load and hopefully keep myself in one piece. The more the better.