270 Winchester Magnum???
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QL estimates that 3400 is obtainable at a predicted pressure of 65k given the 27" barrel length. Of course this is an estimate. Originally it estimated that it would take 63.5 gr of powder to get there whereas your seeing that same velocity at 61.5 gr. The difference could be in the powder, the chamber volume or whatever. This isn't an exact science but learning about your gun and load as you go is important.
Dogleg,
I'm not sure how you can quantify the excess pressure needed to see a sticky or heavy bolt. Other than being over. Some actions will show a sticky bolt quickly (Remington, Sako), others hardly at all (Winchester).ime
Dogleg,
I'm not sure how you can quantify the excess pressure needed to see a sticky or heavy bolt. Other than being over. Some actions will show a sticky bolt quickly (Remington, Sako), others hardly at all (Winchester).ime
My gun maker advised me that he had never worked on a model 700 before with such tight tolerances. I wanted to purchase an older Remington (1985 to 1995) for the build because they were the years of best production........I guess it showed. Furthermore the chamber has a short throat, possibly this has an effect on pressure with load development. Regardless, this is what my journey was all about, it exceeded all expectations and quite pleased that I have a 270 Winchester Magnum.
Yes thanks for sharing all this. The 270 case is nearly 100 years old. Modern powder with a long barrel and bonded bullets, it is now revitalized as the new King of open country cartridges.
Yes, I'm so pumped that I'm going back to the range in a couple of days. Furthermore, I know this powder is NOT temperature sensitive. During the first load data, temperatures were between +20 to +24 Celsius and with the 61.5 load there were no signs of pressure. During second load data the temperature was -4 Celsius: POI and velocity were the same and no pressure.
It's rather ironic or coincidental that this cartridge arrived on the market in 1925, and my 300 H&H is near completion, and that cartridge arrived on the market in 1925 as well.....go figure.
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- sudbury, ontario
so this is a regular 270..win.... but is running at 270 win short mag velocities....very nice and impressive.....way to go and nice job fellolw shooter
cheers
cheers
As I side note I had a 1:8 twist 270 Win put together this summer on a model 700. My dream was to shoot the 170 Berger EOL. I thought (QL was consulted) I could get them to 2900 using 7828 and a 26" barrel. I couldn't get there. Although I didn't blow myself up, I may have blown a primer. I didn't see the accuracy I was looking for either after I backed it down to 2800 and change. It now sits there, waiting for my motivation to figure it out.
Looking back the 1:10 is perfect. 150's are plenty. The 270 was figured out long before I came along.
Looking back the 1:10 is perfect. 150's are plenty. The 270 was figured out long before I came along.
track : My gun maker advised me that he had never worked on a model 700 before with such tight tolerances.
What exactly does that mean or as compared to what ?
RJ
What exactly does that mean or as compared to what ?
RJI can't recall what the specifics were, probably the allowable boundaries of space tolerance was limited between the receiver, barrel thread, bolt head and barrel.track : My gun maker advised me that he had never worked on a model 700 before with such tight tolerances.
What exactly does that mean or as compared to what ?
Brass starts flowing at 75,000 psi more or less. Hard bolt lift and extractor marks show up around that point. Proof loads don’t blow primers.
You are right that some rifles don’t show much for pressure signs. Some of my builds on custom actions don’t show much of anything for signs, but would cream the primer pockets first time out. Oops
Yes thanks for sharing all this. The 270 case is nearly 100 years old. Modern powder with a long barrel and bonded bullets, it is now revitalized as the new King of open country cartridges.
and This is a spinner for me, i got a freakin 7 rem mag and i feel like a 26 inch barreled 270 win with a Re powder, would get me proberly just as good if not better results to 500m on game!!?!
how much advantage do you think a 160gr "? eldx" has over a 140gr Accubond say..... SFA id rekon....
the Question about how hard that velocity is on brass relates, as the 7 rem mag isnt over doing it, whereas sounds this 270 in particular is almost over doing it at times... hmmm
I have loved the 270 win for about as long as I can remember(reading stories from outdoorlife as a kid) and have had many over the years.Times have changed but the old 270 keeps on selling.The 170 bergers caught some interest a few years back,some day I will build one for long range target with a 1-8 or 7.5 twist or a gain twist.Might do a AI version or maybe a Gibbs.Good speeds with the 130,I would be interested to see what a 140 or 150 gr. would do.
The 270 win will never be a caliber for African or North American dangerous games. It has always killed elk and moose effectively here with 150 and 160 grain at a mv of 2900 fps and 2800fps respectively, not to mention deer. With 150 going at 3100 and 160 going at around 2950 from 24 in barrel with Rl26 or MRP, it will 'kill better' and shoot farther so one wonders why the caliber should be pushed even further..and for what barrel life....If I needed a magnum I would get one.
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Then put a 27 inch barrel on your 7 mag, and enjoy the same advantages. - dan
I was just online comparing 280AI with 7MM mag, 28Nosler etc. There really is no such thing as a free lunch in order to shoot bullets fast. Also, a 150gr bullet at 3100fps doesn’t care what cartridge launched it. Powder efficiency is a very minor factor considering the rest of the cost of shooting. A smaller diameter bullet that weighs the same as a larger diameter one could penetrate slightly better, but bullet design has more impact.
