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> 147gr. ELD-M in 6.5x55
147gr. ELD-M in 6.5x55
@ 04:08 am (GMT) |
Paul LevermanI have to replace my Swede's barrel. I've ordered a SS with the 1:8 twist. My smith says he has both the SAAMI and the AI reamers. I was going to go with the SAAMI.Will the 147gr ELD-M be a suitable choice? This is more of a bullet length question rather than a performance issue. My internal magazine length is 82mm (3.234"). There is about .100" of freebore with a 140gr. SST seated for concentricity, but I don't have an ELD-M to measure (on order). As well, will the SAAMI reamer have the suitable leade angle for the ELD-M? If anyone has an ELD-M handy, could you post the length? Thanks |
Replies
@ 08:17 am (GMT) |
Nathan FosterRe: 147gr. ELD-M in 6.5x55Hi Paul, the SAAMI specs for this are the same as the CIP specs. Neither differ from the original mil specs. A rifle built by Sako or Howa today, has the same specs as it did in the 1890's. I have however come across some M38 rifles with shorter throats (shorter max OAL's) but cannot accurately state why this was so.Max OAL with the ELD-M is typically right around 82mm. Optimal seating depth is around 78.5 to 79.5mm. Without the freebore, the Swede cannot produce full power. For your own math - The Creedmoor and Swede necks are both around 7mm long. An ELD-M protrudes around 24 to 26mm out of the case mouth of the Creedmoor when touching the lands. The .260 and Creedmoor are both designed with about the same level of jump using factory loads, but with a generous magazine, one can get relatively close to the lands. The same goes for the 7mm-08. Max OAL's with the ELD-M are up to 75mm for this entire crop. Note however that at 75mm or thereabouts, an ELD-M may be sitting just out into the case neck of the Creedmoor. Depending on the exact throat length, one may have to jump an extra mil or so in order to prevent a donut forming in the case neck (edit: Please see follow up post). The throat design of the 6.5x55 could possibly be tweaked a bit by taking the throat geomety from the Creedmoor and applying it to the Swede (everything from the case mouth forwards). Jump may be around .5 to 1mm depending on the final outcome. 55 + 26 = 81mm. In other words, the max OAL would be 1mm shorter than the max OAL in a CIP 6.5x55 chamber. If a throat loses or gains 50fps per mil of throat added or removed, expect your sweet spot to be about 2700fps rather than 2750fps when utilized in a Swedish Mauser action. This could be regained via the AI blow out. A further gain could be had by experimenting with Superformance or perhaps RE22 (e.g 2800fps at 24" playing it safe). If you want to increase downrange energy and wounding potential without trying to chase velocity (and therefore pressure), have a think about the 7mm-08. Even downloaded to 2400fps (.303 Brit speeds), the 162gr boasts excellent downrange performance (killing as opposed to paper). So do keep this in mind, especially if you are inclined to push the limits on things. Most guys are less inclined to push the seven once they have developed confidence in its abilities. Certainly a few ways to skin this cat. |
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@ 08:33 am (GMT) |
Paul LevermanRe: 147gr. ELD-M in 6.5x55Thanks, Nathan. Encouraging to know that the brothers had it right, right from the beginning. Sounds like the ELD-M will fit just fine and have a good jump to get going. Thank you as well for the numbers. As I said, all I had to work with were the SST lengths, but obviously, not very useful.With the SST hanging out of the neck, its COAL was 8 thou longer than the mag, so that wasn't going to work. Seated for concentricity, it had a good jump of .117". Worked well, good velocity, good pressure tolerance and for a barrel that looked like it was used for a water pipe, not too bad accuracy. Not bad, but not acceptable. Down side: 8 - 10 weeks for the new barrel, plus the time for the chambering, etc. Might have it for deer this fall. Up side: lots and lots of other project rifles to work with. |
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@ 02:33 pm (GMT) |
Nathan FosterRe: 147gr. ELD-M in 6.5x55Actually Paul, I need to put some clarifications around this as the Creedmoor is not all that uniform across the gun brands.Max OAL with the 147gr ELD-M runs from about 73mm (the design premise being a short jump / short OAL) but up to 75mm in many current factory rifles. Actually quite a disparity but not unusual compared to other cartridges. So if you use the math from the Creedmoor for a Swede throat, it needs to be max spec. But this may still not be enough. The major problem is that manufacturers use different datum points to establish reamer specs which can have a dramatic effect on lengths. Its not just plug and go as most folk imagine. Dave Manson currently offers a dummy reamer for establishing OAL protocols. It would be a good idea to go this way, if you want to try the Creedmoor throat geometry. Make a dummy cut, then add or remove freebore length, then order your final reamer. I doubt you would want to go much shorter than 81mm regardless of the jump, simply to ensure it achieves full speeds. I have worked with this COAL before. |
@ 01:40 am (GMT) |
David LenziRe: 147gr. ELD-M in 6.5x55I’ve found this to be a good place to start looking for bullet lengths:http://www.jbmballistics.com/ballistics/lengths/lengths.shtml#Hornady 1.440 listed for the 147 ELD-M (and 143 ELD-X) Saves me the trouble of scouring the internet about 90% of the time. |
@ 01:05 pm (GMT) |
Kevin JensenRe: 147gr. ELD-M in 6.5x55Hi Guys. For what it's worth. I am reloading the 147 grain ELD M in an old Sako AV. My seating depth is 81.7mm which gives me .3 mm jump.COAL in this rifle happens to be 82mm. I have found it really easy to work up accurate loads with this projectile in this particular rifle, & am averaging just over 2700 fps with AR2209 powder with no pressure signs. |
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@ 02:12 pm (GMT) |
Nathan FosterRe: 147gr. ELD-M in 6.5x55Thanks Kevin. What Paul was inferring, is how to set about a chamber that works harmoniously with a COAL that allows the boat tail / body junction of the bullet, to be seated flush to or below the shoulder / neck junction of the case as opposed to being seated out into the case neck. This will help to prevent a donut forming in the brass and will help ensure the lowest possible ES.In this sense, he is asking how much freebore is required to get to speed or what is acceptable and especially what type of leade angle should be used versus the secant ogive. All of this has been inferred rather than asked and in turn understood by me as I answered him. Sorry for any confusion. I learned the language of inference when I was raised by people I call the clan who mostly used hand signals. Later I moved to a valley in the Ukraine, met a horse, married a cave lion, then traveled to France where I now reside. Those where the good ol days, class of 89000BC. |
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@ 02:19 pm (GMT) |
Nathan FosterRe: 147gr. ELD-M in 6.5x55More here for novice tinkerers: https://www.youtube.com/watch?v=qyrmBhaqXtMOn the topic of Manson reamers: https://www.ballisticstudies.com/Knowledgebase/Foster+Manson+Reamers.html |
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@ 02:39 pm (GMT) |
Nathan FosterRe: 147gr. ELD-M in 6.5x55Just another thing to clarify for novice readers. Increasing the COAL does not decrease the freebore. The freebore is simply an area bored out of the chamber (barrel) ahead of the case mouth. It does not matter whether you seat forwards and have some space behind the bullet or seat back and have space / jump in front of the bullet, the freebore remains the same -its a part of the chamber dimenions. The less freebore you have, the less room there is for gas expansion - again whether the bullet is seated back or forwards. Hope that makes sense.In Kevins example, his load is working well with close seating. His rifle has the typical freebore of a 6.5x55, but he has got everything working well by adopting minimum jump. The brass may however form a donut with repeat loads. In the 7x57, it can be useful to seat out towards the lands and simply let a donut form, then bin the brass after so many loads if the donut starts to push forwards or act as a crimp (high pressures) with other projectiles. The Swede does not however have quite the same long neck. Ideally, it pays to seat at least one caliber into the case neck. But further to this, it can help to seat down to the case shoulder junction to prevent donuts. But ultimately, we each do what works. It is however good to be mindful of consequences, especially the crimping aspect should a donut form. This is my main concern (pressure), especially in the older rifles. This topic is discussed further in my reloading book. I hope that helps explain things a bit further. |
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@ 11:17 am (GMT) |
Paul LevermanRe: 147gr. ELD-M in 6.5x55I received the ELD-Ms and made up a collet style dummy case. Inserted a bullet just enough for the case to grip and chambered the round. COAL to the lands was 3.343" (84.92mm). However, I'm not sure how much erosion has taken place and the barrel is in really bad shape. Loaded to optimum concentricity, the COAL is 3.180" (80.77mm). Which, if I am reading the numbers from SAAMI correctly gives a jump of about .170" or 4.5mm.If the barrel throat is really truly bad, I'm hoping this is still enough of a jump with a standard SAAMI reamer, if not, the AI might be the way to go. |
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@ 05:50 am (GMT) |
Paul LevermanRe: 147gr. ELD-M in 6.5x55Just received confirmation that my barrel is ready and on its way.6.5mm, 1:8, 1.250"X3.000" at the chamber/knox, .875" at the muzzle, 6.5# Just like Christmas! |
@ 07:39 am (GMT) |
Magnus VassbotnRe: 147gr. ELD-M in 6.5x55Hi.How did this project turn out? Did you land on the AI version? If so, what freebore/ jump/ coal/ velocity/ accuracy did you end up with? Magnus |
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