I have been expermenting with 7mm Rem Mag loads with RL 25 and 160 Accubonds--yesterday, I was getting velocitys as follows--2813, 2912 and 2982. Assuming that I was accurate in my powder measuring and the other factors in putting a cartridge together, does anybody have any ideas about what would cause such wide variances? Thank you

Three shots is not sufficient to give you a valid standard deviation......but one don't have to be a rocket scientist to suspect something might be "awray".

Break out some copper remover and scrub the barrel well and go back to the range and start over again.

Check the brass length for "too long" brass, pull the bullets and dump the RL15 and load them with RL22. RL15 is too fast for that cartridge and 160 bullets.

Different cases, Different primers, your chrongraph, and your powder charges if you dumped with a powder measure vs weighting each charge.

Also was that the different random numbers you got in FPS or the string of shots, the low first one could be with a barrel nice and clean with oil.

Either RL-19 or 22, RL-15 is to fast for that cases and bullet.

Probably more likely cause is that you started with a clean barrel, as the barrel fouls, velocities will pick up, then stabilize. The other possibility is that the barrel was getting hotter, and you let the last rounds sit in the chamber and soak up the heat. If it's a clean barrel, they will progress in an orderly fashion like this.

Muzzle blast can alter readings. Back off another 10 feet and try again. Sometimes light shoning off the bullet tip will make a scoshi bit of change, try a diffuser.
Good luck!

All good points above. The other thing to check is neck tension. Is your brass all new, all fired the same number of times, did you remove the lube from inside the case neck? All these can affect vel. from shot to shot. Barrel temp. is another, if you are firing your first shot cold then rapid firing the next 2, the last shot could be as much as 100fps higher on hit days especially.

Thanks for the ideas. In fact it was new brass and I fired three different groups. I was very precise on my powder mearsurements, etc. More strange, two of the groups had reductions in the velocity and the last group had a medium number, low number and then spiked to the highest number. In addition, I was careful about allowing the barrel to cool. Actually, I am thinking that the chrono might be screwed up, but I am concerned that that kind of thinking can get a person into real trouble.

I am sorry that in my first post I didn't make it clear, but there was not a steady and progressive increase in velocity, but to the contrary with two of the groups the velocity progressively decreased. I had fired a fouling shot with no reading on the first.

What has me concerned is that I am at maximum loads. I am a little worried about increasing the powder if I the chrono is off. This is a new rifle for me. My factory loads have chronoed very slow for a 7mm Mag. Maybe, the better approach is to try RL 22 is see if I am still getting slow velocity and the wide variance.

quote:

Maybe, the better approach is to try RL 22 is see if I am still getting slow velocity and the wide variance.

R22 in the 7RM is like putting Mustard on a Hot Dog

I have seen terrible deviations w/ certain powders in certain rifles. You should probably try a couple of different powders and see which has the lowest SD.

The only thing about a good SD is that the harmonics may not be right so, a different powder may still be on the menu. Once you find a powder that gives great accuracy and low SD, you'll be set.

Some rifles will group well w/ bad SDs at all practical distances. Not often but, it does happen.

Good Luck

Reloader

quote:

Actually, I am thinking that the chrono might be screwed up, but I am concerned that that kind of thinking can get a person into real trouble.

Darn right.....BELIEVE that thing!!!!!

quote:

Originally posted by Schrodinger's Cat:
...does anybody have any ideas about what would cause such wide variances? ...

Hey SC, Back when the "RL" Powders first came out I tried RL-19 and RL-22 in one of my 7mmRemMags. Rather than messing with checking the Velocity, I checked the CHE/PRE values and found they varied way more than was acceptable for me. This indicated widely varying Pressure Fluctuations.

I believe I used three different Lots and never could get acceptable Pressure Indicators.

Time passed and a buddy gave me a couple of jugs of RL-25. So I tried it and had the same results.
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The strange thing about my results(and your results) are they are apparently a lot different than most people see with the RL Powders. A lot of folks who shoot them never mention wide variations in either Velocity or other Pressure Indicators.

I also saw the same thing with RL-15 in my 308Wins.

I gave it all to the same buddy and he tried it in two other rifles, a 270Win and a 25-06. Nothing good came from that. So, he gathered up what was left and gave it to a third buddy who is either using it for Fire Forming, or growing tomatoes.
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I use a lot of H-1000 in my 7mmRemMag(s) and am very pleased with it. I've not tried "Retumbo", but it appears to be about perfect for 160gr and 175gr in the 7mmRemMag.

Best of luck to ALL YOU FOLKS with the RL Powders.

rl22, not 25 ...

bet you have a standard length barrel, right? 25 is slower than 22, and in a 22 or 24" barrel, you won't be burning all the powder.. and then compression or not, or even variance in compression raises it's ugly head.


what did the next 3 shots do?
jeffe

Cat
Try H-1000.. This powder works good in 7mm Mag.. Primers will have a big effect..Find a good load.. Then change primers.. Watch the mystery of changing one component unfold.. Make sure the other things are the same..As VapoDog said brass lenght will cause spikes..
AK

quote:

Originally posted by Hot Core:

The strange thing about my results(and your results) are they are apparently a lot different than most people see with the RL Powders. A lot of folks who shoot them never mention wide variations in either Velocity or other Pressure Indicators.

I also saw the same thing with RL-15 in my 308Wins.

I gave it all to the same buddy and he tried it in two other rifles, a 270Win and a 25-06. Nothing good came from that. So, he gathered up what was left and gave it to a third buddy who is either using it for Fire Forming, or growing tomatoes.
---

I use a lot of H-1000 in my 7mmRemMag(s) and am very pleased with it. I've not tried "Retumbo", but it appears to be about perfect for 160gr and 175gr in the 7mmRemMag.

Best of luck to ALL YOU FOLKS with the RL Powders.

Hey HC

Here is a string of 300 win mag loaded at the same time. I was testing distance from lands so all the loads were the same 74.5 gr RL22 with a 200 gr TSX CLOSE TO MAX, START LOWER AND WORK UP LIKE I DID)

1. 2952, 2994, 2972, 2987
2. 2968, 2985, 2962, 2985
3. 2966, 2998, 2972, 2975
4. 2972, 2970, 2985, 2982

This is typical of RL22 in the 300 win mag, no surprises.

Now for the 7 mag, here are velocities from a similar test in that caliber, varying seating depth .010" each load, 66 gr RL22 with a 160 gr TSX (CLOSE TO MAX, START LOWER AND WORK UP LIKE I DID)

1. 3052, 3089, 3054, 3073
2. 3053, 3069, 3055 (4th didn't read)
3. 3052, 3069, 3059 (4th didn't read)
4. 3031, 3027, 3039, 3030

That was pretty consistant!

Matter of fact, that 300 win mag load looks so good, I think I'll run and OCW sequence on that load!

How's them tomatoes?

I've not had good luck with RL powders in .22-250s, .25-06, .30-06, .308, and 7 Mag. Don't know why--but have generally ended up with best results with Hodgdon's or IMR propellants. As a result, I have several partial containers of RL powder in my magazine. Should I run up against a troublesome gun that doesn't perform to expectations with H or IMR, then I'll try the RL varieties if appropriate.

Not bad mouthing RL powders, just my experience.

My 7 Rem likes 7828 and H1000 with 160 grain Speers or Sierras. Also shot well with H870, but I never chronographed it.

IN a 6m Rem, I tested 15 powder combos with a 75 grain Hornady HP...

The most accurate load of all of them was 47.5 grains of H 414... by a long shot.. one hole at 100 yds...

The funny thing was tho... when I chronographed all of these loads later.. the one that had the widest standard deviation was the H 414 load.. by about 150 fps...

So much for theories....

hey what ever works best...

if it shoots accurately, don't worry about it..

load her up and go hunting...

seafire

quote:

that 300 win mag load looks so good, I think I'll run and OCW sequence on that load!

How's them tomatoes?

Hey Woods, RLPowders and the ocw do seem to be made for each other.
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As to the more pressing matter, tomatoes, I'm still under siege from the Rabbits. Getting some Tea as the sun was setting and noticed a small Brown Spot near them. Eased up the old 10x50s and sure enough it was a small genetically engineered Tomato Chewer easing in for a few chomps.

Hard to keep the Ortho Sevin Dust on them with the rain. And the Sevin Dust does slow them down.

But, it was time to break out the old 5mm Blue Streak.

Thank all of you for your input. This weekend, I am going to try a couple of different powders and will post the results next Monday. Maybe, there is a lesson to be learned in this.

Did you try weighing your cases and sorting them also debur flash holes and uniform primer pockets and neck thickness it all makes a differance case length,primers ect uniformity counts

I've noticed some variance in velocity with R-22 however it is still my go-to powder for the 270, 280, 30/06, 7mmRMag, and 338WinMag.

Can't explain why it's the most accurate in these rifles knowing it produces greater velocity swings than other powders.

On the other hands, I get consistent velocities with H4350 in several of these rifles but poor groups. ???

WN

I have never noticed any kinkiness with RL22 in the 7 Mag, and I haven't shot anything else in my old Sako for years. Every round I've checked through mine has chronoed within 65 fps regardless of temperature. For the last ten or twelve years I have shot nothing but RL22 and 175 NP in it.