That 6.5x55 jump

Davee

Well-Known Member
Ok maybe I missed it but just how big is it? The reason I ask is that I started working out a load for Nosler 130gr Accubond, and I noticed their recommended OAL is 76.83mm. Now with this bullet, my rifle has a bolt-face to lands measurement of 78.14mm. Measured the length of the bullet from tip to contact point and found 14mm, if that is subtracted from the OAL you get 62.83mm length from the bolt face to the lands contact point. That gives a jump of 15.21 mm (599 thou)!! i.e. the bullet has all but cleared the case but not engaged the lands, the boat-tail is just in the neck. Now to me that sounds bonkers. So I have either made a mistake in my understanding, or I've a funny barrel -it's new only fired 60 rounds-, I've rechecked my measurements several times with two different verniers. n.b. I do seem to get more muzzle flip than my friends identical rifle. Any suggestions, a demerit point for everyone who suggest a different calibre!
 

Apthorpe

Well-Known Member
This isn't directly applicable because I have a 6.5x54 instead - and am very much a novice. I noticed that 140gr Hirtenberger factory ammo was 0.1" shorter overall than older 160 gr RN cartridges. The ogive was also more aerodynamic and I would think these cartridges also had at least 300 thou more before engaging the rifling...and quite possibly as much as or more than you calculated. I only test fired a few..and they're all over the place. I've just started reloading using 160gr Hornady interlocks and so far am pleased with their accuracy. (That said, they don't seem to have parallel sides and are only 0.264 at the base...tapering to .250-something )

Might it be that your Accubonds are intended for a more modern chambering, and that the swede wants heavy, long, parallel sided bullets? This is what the rounds it was designed for look like.....20161107_001433.jpg The pointier one is a 140gr and you can see how much ...well, pointier it is.
 
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flytie

Well-Known Member
Don't get wound up about seating close to the lands. The 6.5x55, 7x57 and the .308 have large amounts of "freebore." Concentrate on concentricty of your reloads, as Apthorpe so rightly says SAAMI chambered 6.5x55's are made to take the much longer 160gr bullets once favoured by our forefathers. The 6.5 can still be very accurate;


Simon/
 

Border

Well-Known Member
So how does it shoot?
plenty of them shoot just fine over here with saami c.o.l rounds.
dont get over excited about trying to seat the bullet near the lands, I presume it's for hunting rather than benchrest?
 

Muir

Well-Known Member
Stop measuring things other than the data manufacturer's recommended OAL. I never do it unless it's hi vel cast bullets. (where it is required, but for different reasons than with jacketed bullets.) My 6,5x55 shoots n the .3's with FL resized cases and the bullet seated to recommended OAL. (and crimped!) ~Muir
 

Davee

Well-Known Member
Many thanks to all. I have only just started to reload for this calibre. The rifle is a Sauer 202 and is probably more accurate than the driver, with Berger 130gr VLD I have shot a 14mm 5 shot group, last night I checked the Bergers, their contact point is 3 mm further back than the Noslers! I was somewhat aghast to discover that the bullet was floating at the start of it's travel. However I have answered another point, I read -somewhere- that the Swede shoots a heavier bullet with less powder, ie with the smaller bullets the expanding gases can pass around the bullet before it hits the lands and seals, ergo some of the powder is wasted, and the longer the bullet the less is wasted, so more of it goes into propelling the bullet. Maybe I'll try the 140's and 150's as well and see if there is any difference.

Muir how much crimp do you apply?
 

flipflop

Well-Known Member
I've started loading 160 RN for my Swede, though not for 'powder burning' reasons. I just got a great deal on the bullets and thought I'd give them a try. Though they chug out of the barrel at a pretty pedestrian 2450fps, they group tighter than anything I've reloaded to date and happily knock over Whitetail in the 25-200yd range in which I hunt.
 

Muir

Well-Known Member
Muir how much crimp do you apply?
That's a little like asking how much a duck weighs: It depends on the duck. Bullets with tougher jackets will get a heavier crimp -or it will be perceived as heavier. You need to experiment. You can look into the top of the die and see how much the die closes. (Lee Factory Crimp is the only die to use) I have used wire type feeler gauges to judge the amount of closure but mostly I use a sense of feel. If you crimp, trim to the same length at every reloading. I trim to the length of the shortest case in the LOT I'm reloading.~Muir
 

The tramp

Well-Known Member
Many thanks to all. I have only just started to reload for this calibre. The rifle is a Sauer 202 and is probably more accurate than the driver, with Berger 130gr VLD I have shot a 14mm 5 shot group, last night I checked the Bergers, their contact point is 3 mm further back than the Noslers! I was somewhat aghast to discover that the bullet was floating at the start of it's travel. However I have answered another point, I read -somewhere- that the Swede shoots a heavier bullet with less powder, ie with the smaller bullets the expanding gases can pass around the bullet before it hits the lands and seals, ergo some of the powder is wasted, and the longer the bullet the less is wasted, so more of it goes into propelling the bullet. Maybe I'll try the 140's and 150's as well and see if there is any difference.

Muir how much crimp do you apply?
Whoa, stop right there....

Just load up a suitable recommended bullet, and use it.

Vld's are not particularly suitable, but as you are getting decent results, bonus.

From what you said above, i think you have been doing too much googling, where the hell did you get the "leaking gasses" bit from ? I'd love to see the source of that !

End of the day,
Its a 6.5x55, it has a very long throat.
Normal ammo is in the 160gr area, thus very long bearing surfaces, which are great for a long throat.

If you want a 6.5mm that shoots the lighter stuff, sell it, and get a creedmore.

Sent from my SM-G925F using Tapatalk
 
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smokey

Well-Known Member
do not worry about this off the lands mullarky yes some rifles and bullet combinations shoot better this way but it is not the end of the world i see a lot of BR and F class shooters talking about 2 or 3 thou off the lands and they can talk it but not accurately measure it as for your 6.5 x 55 unless it is a custom barrel set up for your choice of bullet all factory 6.5 x 55 are chambered for the long heavy bullets that tend to be long round nose types so a modern sporting type bullet will fall out of the case if you try to do this
 

Davee

Well-Known Member
"where the hell did you get the "leaking gasses" bit from ? I'd love to see the source of that !"

"Simple my dear Watson", consider the following facts:
The freebore of any rifle has to be greater than the diameter of the bullet, if it was the same you would never chamber it. The freebore of the Swede is 7.87thou greater than the bullet diameter according to SAAMI.
The bullet loaded to Nosler specs has 6.2mm of the parallel section in the neck. After it has moved this much there is a direct passage from the case via the 3.98thou annulus around the bullet to the barrel. By the Laws of Physics gas will flow from a high pressure region to one of lower pressure. Thus gas will escape.
After the parallel section has cleared the neck, the bullet has to travel another 5.3mm before it is fully engaged in the lands and seals the expanding gases behind it.
Now I cannot quantify the volume that escapes, nor how many grains of powder this equates to. Insufficient data available, A PhD project anyone?
This will happen to any rifle when the distance to the lands exceeds the seating depth of the bullet.

If the bullet is crimped as per Muir's suggestion the pressure will be higher when the bullet is released from the case, thus the free flight time and losses reduced.
Now for my Swede -if I keep the same ogive- the bullet would have to be 11.55mm longer but would not fit into the magazine -probably could not be hand fed either- and so would have to be set 9mm further into the casing to do so, and would be close to 200gr, so the ogive has to go and be replaced by a rounder profile. So we have now come a full circle back to the 160gr round nose projectile it was designed for. Anything has to be traded against everything else.
 
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