Possible noddie question: 155grn SMK vs 155grn Palma SMK

[User702]

Right, I've just completed my first big shooting competition using HPS 155grn .308 ammunition. It was decent enough and probably highlighted the fact that the rifle was new to me, I was tired, the light was all wrong, I had a bad back, etc. But... enough of the excuses for getting poor scores.

It got me thinking about ballistics and specifically about the differences and benefits of the "standard" 155grn Sierra Matchking and the Palma version of the same weight.

From the basic look of the two, the Palma round just seems better; more slippery shape, same price (roughly), more stable, so why do normal shooters of long range targets not use that particular round over a standard SMK? Will the Palma round stabilise in a shorter 1 in 12 twist barrel, or does it need a long 1 in 13 twist tube to make it work properly?

Sorry, but that was playing on my mind the whole of the trip back from Bisley at the weekend, so if you have the answer, please let me know!

[Steve E]

As a Target Rifle shooter, I use both.
The old 2155 SMK was the go to choice for many years and is a very good bullet and at one time was the only bullet allowed in Palma Shooting.
The newer 2156 Palma bullet is a much better bullet, particularly at long range when it can use 10-15% less wind than the old bullet. This is very important when shooting long range in fickle winds.
On a personal issue, I use the old bullet 2155 at short range (300-600yds) and the new 2156 Palma bullet at long range (800-1200yds).
At short range the new bullet does not seem to have any great advantage over the old bullet.
The question as to why do normal shooters not use the new bullet is vague. Who are the normal shooters? In my shooting circles the majority of shooters are using the new Palma bullet:- They load their own ammunition for the matches that allow handloads.
In matches where handloads are not allowed, almost all of the ammunition is loaded with the older bullet. It is a known and proven performer and is cheaper than if the newer bullet was used.

[ovenpaa]

Interestingly the #2155 is slightly more expensive than the #2156. My view is spend a little time batching the #2156 and you have an incredibly good bullet to shoot with and at under GBP26/100 what is not to like?

Tired? Hehe, I do remember the conversation we had first thing Saturday morning and trust me when I say you looked shattered Saturday evening, back to back comps are very tiring.

Well done on the 4/5/600 and don't forget to post the results up :goodjob:

Steve, did you find out how you did in the end?

[rox]

It got me thinking about ballistics and specifically about the differences and benefits of the "standard" 155grn Sierra Matchking and the Palma version of the same weight.

Take care when using the word 'Palma' to differentiate – the 'old' 2155 used to be called Palma too. For a given load the 2156 will retain a little more velocity and suffer a little less wind deflection. The meplat is a little more consistent (I believe they are pointed at the factory). In summary it is a better performer, but not by a huge margin. In TR small reductions in group size can be masked by the limits of eyesight and hold, besides which the target is plenty big enough to contain the 2155's grouping potential if shot well - the real challenge is not letting the wind take you out of the side. Consider the results of the English XX 1000 yard shoot yesterday - wise shooters converted 5-4 sighters, and many top class shots were mauled.

In UK TR/Palma shooting it is just 3 or 4 years since most domestic shooting was dominated by RG ammo. Since then the primary meetings in which ammo is issued (such as the Imperial, Inter-counties, club Open meetings etc) use commercial rounds loaded with the 2155 (the 'Old' Palma bullet) – this is reasonably close in behavior to the RG bullet, and actions that were designed for RG (like Swings) will handle it easily (it is not so easy to unload a Swing which contains VLDs). Many clubs and club teams also use HPS ammo loaded with the 2155. Fultons ammo is loaded with the 2155, and many individuals loaded it for their own use. Many folks do much of their shooting in preparation for the Imperial so they want to use ammo that is similar to what they will receive in the meeting, so that the all-import wind experience that they build-up will be valid in the main competition of the year.

Having said all that, it is a transitional period, so things are moving. Some clubs have taken to loading their own ammo using the 2156. Most teams travelling abroad use bullets other than the 2155. There are those who want to see more freedom, and those who want to see the emphasis remain on marksmanship and not determine the outcome in the loading room. Who knows where the journey will lead, but it is sure to be an interesting one.

Of course, outside of TR you probably just want the best ballistic compromise for the task at hand.

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[User702]

Rox, interesting points raised there.

From what you have said, I must have been using the 2155 bullet heads at the weekend, given that I was shooting the 155grn HPS ammunition and that was the primary driver for asking about this.

It may be that I'm just monumentally crap at reading wind and shooting at longer ranges, but I had a huge problem at 1000 yards and I was wondering if part of it was down to the ammunition going transonic between 900 and 100 yards and opening up my group sizes to barn door-like sizes. Given that I now have approximately 100 Lapua brass that will need filling, my plan was to obtain some of the 2156 bullet heads and do a comparative test to try and set my mind at rest.

Ovenpaa, I really do take it all back. I was certainly feeling a bit frisky and ken to get started at 7am, but I was really starting to feel the strain about halfway through the afternoon session. I started getting a sore neck, my left arm had gone to sleep and I swear I had the shape of the target burning into my right retina that night. The drive back was a challenge too and I was asleep as soon as my head hit the pillow. I will get the scores up in the next couple of days and I will try and get the plots scanned and posted as well.

[rox]

I was wondering if part of it was down to the ammunition going transonic between 900 and 100

HPS is reasonably pokey and I think it is unlikely to be transonic at 1000; there might be a small chance of that with very short barrels, but I doubt it.

It may be that I'm just monumentally crap at reading wind and shooting at longer ranges

Results from yesterday showed that plenty of world class shooters (including several Queen's Prize winners & Commonwealth Games competitors) got mauled by the wind at 1000x, so if conditions were anything like that for you then you were in good company. Improving at long range is easy - just devote more training time there. When conditions are very challenging you need to expect to loose more points, but be reassured that everyone else is dropping them too, and you can build the confidence to treat tough conditions as giving you an advantage over your opponents.

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[User702]

HPS is reasonably pokey and I think it is unlikely to be transonic at 1000

Fair point. I'm given to understand that it would have been leaving my barrel at about 2850 fps (only a 26" tube on my rifle!) and my ballistics calculator seems to think that things would have been fine from a velocity point of view at 1000 yards, but I was worried that it may have had something to do with the scores dropping off.

Alas, from what you are saying, it was just me being rubbish!

Never mind, at least now I have the excuse that I need to practice more at long range.

[IainWR]

Given that HPS 155 is made for the UK TR market and is CIP approved, I would be surprised if it exceeds 3650 bar MAWP under CIP test conditions. However, that's also the limit (it originates from an agreement with the Proof Houses) for the NRA RWS .308 ammo, which has a nominal velocity of 2920 ft/sec out of a 30" x 1/13" TR barrel with .297" bore diameter. That number was chosen as being sufficient to give >transonic velocity at 1000 yards under typical Bisley summer conditions. The NRA ammo uses the 2155 bullet, and the 2156 is indeed slightly less draggy, so will arrive faster for any given MV.

One (quite important) reason for using the 2155 in mass-market competition such as run by the NRA is that in a Swing, Paramount or RPA action, a 2156 round loaded to the same ogive length as the 2155 at 2.800" OAL (and thus to the same jump) will not extract live without taking the bolt behind the retaining catch. If someone has to unload a live round, I don't want them fiddling unnecessarily with the bolt catch.

Iain

[GazMorris]

It may be that I'm just monumentally crap at reading wind and shooting at longer ranges, but I had a huge problem at 1000 yards and I was wondering if part of it was down to the ammunition going transonic between 900 and 100 yards and opening up my group sizes to barn door-like sizes. Given that I now have approximately 100 Lapua brass that will need filling, my plan was to obtain some of the 2156 bullet heads and do a comparative test to try and set my mind at rest.

As someone who got taken to pieces by the wind at 1000x on Monday morning, you were in good company. The bracket was 10 - 17 minutes left, with shifts of 3+ minutes not being uncommon. I was just about staying in touch for the first half, but then an outer and two magpies in quick succession threw me before I regained something of a grip; however it was a bit late by that time!

I was using a standard batch of RUAG. Additionally, I shot with people using 2156s at 900x and 1000x. In both cases, they had significantly smaller, lower brackets that me as you'd expect.

Cheers,

Gaz