I have only been reloading for a few months but am really getting into it and enjoying it. I went to the range yesterday with 3 loads for my 270 Using 130 gr Hornadys I have been firing with 53.2 Gr of Hodgdon Hybrid H100V. I tried 53.6 and 54.2. Surprisingly to me, I found that the 53.2 provided the greatest velocity. With 53.2 I got an average of 3040, with 53.6 2980 and with 54.2 3018.

My question is does this make sense?

Not a rocket scientist, but that's all the same speed. What might make sense is knowing the entire amount of powder sin't fully burnt. Maybe what's happening is that there's no linear relationship with that powder, your barrel length and the primer used between amount of powder and speed.

Be certain you didn't make a mistake with the powder charges, and repeat the experiment, while adding a third 54.8 gr load. Keep everything else exactly the same.

Also, lighting condition changes affecting your chronograph can cause changes in readings.

Man I must be getting old every time I turn around I see someone using a different powder I've never heard of or tried.

As they have said you have only 1 data set. Does it repeat? Your pressure is probably on the light side for a 270.

I've seen this before sometimes it repeats often it doesn't. Also seen loads where the extra powder was simply leaving the end of the barrel.

Welcome and enjoy your knew hobby.

Yes, there is a plethora of new powders coming onto the market,, that we definitely do not need. Especially when they can't produce the old standbys that us old guys know and love.
OP; yes, things like that do happen; do not be alarmed.
Reload and carry on.

You need at least 10 shots data for each load and preferably 10 groups for each load to be sure that you are comparing statistically valid variables.

I usually discard the data from the first 2 or 3 shots as the cold barrel velocity is always different to the rest. Similarly I do not shoot and take data from very hot barrels. I allow the rifle to cool down between strings.

The Std deviation of the string is also relevant as it will show any possible overlap with the next strings & loads with different powder charge.

I do not know that particular powder but 53 or 54 gr indicated it is quite a fast powder compared to 4350 or 4198 Oooops 4831 . So you velocities are already at the top end & possibly even hot if you are using a 22 inch barrel.

I would seriously check the case expansions are the head etc. & usual pressure signs. I would stop right there or do down a bit and just pick the most accurate load - 1.5 inch 5 shot group will do for all hunting out to 300 meters.

Smaller calibres on the 30.06 case e.g. 270W, 6.5-06, 7mm-06, generally perform better with a case full of a slower burning powder, such as those in the burning range of 4350 and 4831 not 4198 as Nakihunter has erroneously referred to as being slow, it is one of the fastest rifle powders so definitely do not use that in your 270.

quote:

Originally posted by Reload270:
My question is does this make sense?

No, it doesn't. Something is amiss. It could be your chronograph or the conditions (varying light) under which you chronographed. It could be your cases, which you don't specify as being all of the same brand and lot and prepared the same. It could be very high standard deviation produced by the combination powder, primer, and bullet. It could be that the number of shots in each string (unspecified) were insufficient to be statistically dependable. It could be . . .

Start over, making sure that you have controlled all of the possible variables. And use some H4831 or IMR 7828 SSC if you want consistent and high velocities.

Hi, I have had a lot of response and a lot of help. Thanks to all. I made up some new loads and had a more consistent result today. The Hybrid H100 V is a new powder from Hodgdon that is recommended for the 270. It is close in speed to H4831. The max load according to Hodgdon is 56 gr, I maxed out today at 55.2 gr and noticed that the primers may be a little flat compared to the 53.2 load that I have been using. My best results today seemed to be 53.6 although 54.4 may have been good as well except that I shot the rods on my Chronograph so I do not know what the speed was but the group was good. I fixed the Chronograph and got speed with the 55.2 load but the group was not so good.

I am planning to shoot 2 10 shot loads next time to compare 53.2 and 54.4. There does not seem to be much difference.

Thanks again for the comments.

Your Hybrid H100V is not close to the burn speed of H4831 if you are finding charges above 55gr are showing pressure signs.

59.0-60.0gr of H4831 was a good load for the 270W using 130gr projectiles and 58.0gr H4831 with 150gr projectiles.

The Australian produced AR2213SC powder which is marketed as Hodgdon H4831SC in the States has a maximum recommended load of 60.0gr compressed for the 270W (starting load 54.0grs).

All you have to do about burn rate is to check the Hodgdon website. I have no other answers.

quote:

All you have to do about burn rate is to check the Hodgdon website

I know nothing about H100V. But, looking at the Hodgdon site and QL burn rates H100V is a heck of a lot closer to H4350 than H4831.

I probably worked up loads for about 15 MKX 270s using 130s. Each gave the best group with the same stout load of H4831. Some of my $1/# surplus.

Going strictly by Swiss cheese memory I recall it be 59grs.

Either a standard overlap since your charge difference was less than 2% and you fired so few rounds or you had an "earlybird" shadow on your chronograph, which goofed up the reading.

That's to be expected, as the barrel heats up velocity changes, and all manor of other things can create your problem, and the bottom line is its a created problem only and may or may not be a consideration when you review the reloading manual that lists that sort of stuff. Reasonable variation in velocity has little effect on anything...Load your most accurate load, that's was your intention and 50 FPS or even a 100 FPS seldom makes much difference at the target, unless your after a gold medal at world match.. The size of the group and the ability of the bullet to do its intended job is all that counts when it comes down to the nut cutt'en.