My .270 Chamber

Lee Q. Loader · Jul 31, 2019

I'm doing a little more experimenting with my .270, I bought some 150 gr Nosler Ballistic tip bullets. These are extremely long bullets, the bullet itself is 1.350", and I decided I want to try them with a very long OAL. So I finally measured my chamber length, (something I should have done long ago).
I used the method of using a fired case and seating a bullet in it just by putting it in the chamber and closing the bolt. I was able to do it and to my surprise I got a measurement of 3.51" with that bullet. Doesn't that sound wrong, as it way too long? To be sure the measurement was right I used a sized case and seated a bullet to 3.50", chambered the dummy round and extracted with no issues.
So as I'm doing this I think to myself that there is no way this OAL will fit in my magazine, I was right but 3.47 will fit the mag.
Guess I should mention that my .270 is a late 70's model 700 BDL.
So with all this new information, I guess I'll load these at 3.47 OAL to fit the mag and see if I can find a good load using RL 26.
I'd really like to hear some comments about this and some suggestions to find the most accurate load with these components.
Thanks in advance for sharing your knowledge with me.

LoonWulf · Aug 1, 2019

I've seen commercial rifles with everything from mile long throats, to basically none at all (how they pulled that one off I'll never know).
MY experience with 700s is they tend to run long. I used to load my 06 to 3.45 with a 165 balistic tip, my 7mag was similar tho for some reason I can't remember what it was right now.
unless your magazine is blocked, you should be able to get 3.7" out of a 700 long action magazine.

LoonWulf · Aug 1, 2019

LRDGCO said:
With a very long ogive, won't the bullet nose be well into the bore before the sides contact the leade and start pushing the bullet back into the case?

I'm not explaining myself well and I'm not sure whatever point I'm trying to make matters...

I guess a shorter, fatter, more traditionally shaped 150 grs bullet would make contact with leade or.lands earlier?

In any event, loading your bullet to 3.47 is probably the right thing to do, but I don't think it necessarily means that the chamber is outrageously long (unlike my rambling post...)

Good luck.

made perfect sense.

yes a bullet with a blunter nose shape/ogive will make contact with the lands sooner....unless it's got something unusual going on like a bore rider.

it's possible that part of the reason we see these long throats is that while a cartridge might have been spec'd with a med/light spitzer bullet (.30 Cal's 150s, or 7mms 140s), It used to be much more common to find long, heavy roundnose bullets than it is now.

that's just a thought tho, I've done no research on the subject as of yet.

MihiT · Aug 1, 2019

You can get a bit of throat erosion in 50 years shoot'n...

jmr40 · Aug 1, 2019

I don't really worry about OAL. I can't begin to tell you what any of mine are. I load a single cartridge to just fit the magazine. If it fits in the chamber without hitting the lands I know it is as long as possible in that rifle. If it bumps the lands then I'll seat it a bit deeper until it doesn't. Then I'll load up a batch at that length and go to the range. If I get the accuracy I want then I'm good to go. If not I can always seat the rounds I have a bit deeper to experiment. But this way I only have one direction to go while experimenting. But virtually all of the time the longest length possible is what I stay with.

Slamfire · Aug 1, 2019

Lee Q. Loader said:
I'm doing a little more experimenting with my .270, I bought some 150 gr Nosler Ballistic tip bullets. These are extremely long bullets, the bullet itself is 1.350", and I decided I want to try them with a very long OAL. So I finally measured my chamber length, (something I should have done long ago).
I used the method of using a fired case and seating a bullet in it just by putting it in the chamber and closing the bolt. I was able to do it and to my surprise I got a measurement of 3.51" with that bullet. Doesn't that sound wrong, as it way too long? To be sure the measurement was right I used a sized case and seated a bullet to 3.50", chambered the dummy round and extracted with no issues.
So as I'm doing this I think to myself that there is no way this OAL will fit in my magazine, I was right but 3.47 will fit the mag.
Guess I should mention that my .270 is a late 70's model 700 BDL.
So with all this new information, I guess I'll load these at 3.47 OAL to fit the mag and see if I can find a good load using RL 26.
I'd really like to hear some comments about this and some suggestions to find the most accurate load with these components.
Thanks in advance for sharing your knowledge with me.

I have not had good luck finding the throat distance with a spring loaded extractor plunger or a push feed type extractor in the bolt face. The spring will push the case forward and you lose sensitivity of feel when you cam the bolt down. I want to feel the moment the bullet touches the lands and back off a couple of thousandths. At least the bullet is not stuck in the throat when you extract the round. That has happened many times when the the OAL was too long and the bullet jammed in the throat.

I believe seating out the bullet as long as you can is a good thing, it made a heck of a difference in my pre 64 M70 257 Roberts. The factory reamer set the throat out at least two tenths of an inch further than any recommended OAL. The previous owner removed the short magazine box and bolt stop, and I set the bullets out to 2.921" with a max of 2.930", which is way longer than the 2.775" you see in manuals. The rifle shot very well after that, a long bullet jump is undesirable and leads to inaccuracy.

Captcurt · Aug 1, 2019

I'm with jmr40 on this. Most of the time OAL is governed by the magazine. If I was shooting benchrest I can see where it could make a difference, but for a hunting rifle it probably doesn't hurt accuracy that much. After all, Weatherbys have had long throats for decades and I have had some of them that shot well.

My .270 Chamber

Lee Q. Loader

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LoonWulf

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LoonWulf

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MihiT

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jmr40

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Slamfire

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Captcurt

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