I am not a big fan of gain twist rifling because I saw it go around the first time and what it did to bullets, accuracy and barrels. Lapping the barrel may loosen it up a bit - less resistance should give you more velocity. My brother's 6"357 shoots my loads at an average of 100 fps slower.A slight freebore migh help too but it affects accuracy too. Faster burning powder is going to get the presshure faster and lose it quickly - what you want is a slower rise to pressure and to hold it as long as you can. If you are already using compressed charges then you are probably about as slow as the case will tollerate. I would still try the next slower powder and see what I could do with it.

The next slowest powder would be Varget and, for kicks, I might try it as I have a pound from some other testing. The next fastest is 4895. Your point about a slower rise to pressure is what I was referring to in my previous post and may be the key to the endeavor.

Two correspondents and a visiit to reloadersnest.com lead me to VV540 powder, a double based powder with a different pressure curve and temperature range (cooler burning powder). Duplicating the load found at reloadersnest.com, I still fell a few fps short of the goal, however, my second load got me the 5,000 fps I have been seeking, as follows:

Test 1: five shots, 100yds, 5,055 fps average, 11 SD, 66,635 psi, .95MOA

Test 2: SAA, 5,069 fps average, 13 SD, 67,182 psi, 1.2 MOA.

WW brass and WLRM primers were used. Brass was bench prepped. Accuracy was acceptable given that the bullets were spinning over 300,000 rpm! Note: this higher velocity was achieved with less pressure than previous loads.

Between test 1 and 2, the temperature had increased from 82 degrees to 91 degrees at Rio Salado Range, Mesa, Arizona.

Chronographing was with a Millenium CED, 4' screen spacing, set at 12' from the muzzle. The data is actual recorded data at 12' and not corrected to muzzle velocity.

Interesting #1: the brass used in these tests required one trimming and the primer pockets are tight enough for further useage, this after eight rounds of very high pressure loads. So much for the idea that the Swift round stretches brass beyond normal cartridges. My years of working with the Swift have shown me that it is no more difficult or finicky than any other round. Now, I shall go back to my standard Swift load of 41.5 gr of H414 and the Nosler 55gr BT, a load that works on all my Swifts superbly.

Interesting #2: the Swift was lauded by PO Ackley for shooting deer and antelope. With the 60gr Nosler partition and the Barnes TSX bullets, it has become an even better round for this task. I use a Remington Classic or a pre64 for hunting game with the Swift and it has made a believer out of many of my fellow hunters after witnessing the lightning effect on mulies and antelope even at ranges of 300yds. The same is probably true of the 22-250.

Next project: building a 220 Howell on a Ruger No1 with an 8" twist. This round was the brainchild of Ken Howell and is but one of a series of Howell cartridges that feature high case capacity. He did not design them for high velocity but for lower pressure while achieving normal velocity. The 220 should put 75gr 224 bullets downrange at around 3,450 fps @ less than 50,000psi. If so, it would be flatter shooting at 500 yards with less wind deflection than lighter and faster bullets while having less barrel errosion. A 28" Krieger barrel has been ordered.

PaulS: your idea of going to a slower powder was valid. VV540 is a few stages slower than the VV135. The load I used was compressed and I used an 8" drop tube to fill the cases nearly to the top of the neck. Test #3 was halted as pressures spiked with the first two shots and the primer pockets showed some leakage. This was with an increase of only .6gr. True to form, the velocity of those two shots hadn't increased at all from the other two tests. Your signature line of staying within the SAAMI specs is important and I am glad your posts remind us that safety is the key to a long and happy relationship with firearms and reloading. For those that experiment into the grey areas of pressure, top notch monitoring equipment and safety gear are mandatory for the shooter's safety and those around him.

Onward

Two correspondents and a visiit to reloadersnest.com lead me to VV540 powder, a double based powder with a different pressure curve and temperature range (cooler burning powder). Duplicating the load found at reloadersnest.com, I still fell a few fps short of the goal, however, my second load got me the 5,000 fps I have been seeking, as follows:

Test 1: five shots, 100yds, 5,055 fps average, 11 SD, 66,635 psi, .95MOA

Test 2: SAA, 5,069 fps average, 13 SD, 67,182 psi, 1.2 MOA.

WW brass and WLRM primers were used. Brass was bench prepped. Accuracy was acceptable given that the bullets were spinning over 300,000 rpm! Note: this higher velocity was achieved with less pressure than previous loads.

Between test 1 and 2, the temperature had increased from 82 degrees to 91 degrees at Rio Salado Range, Mesa, Arizona.

Chronographing was with a Millenium CED, 4' screen spacing, set at 12' from the muzzle. The data is actual recorded data at 12' and not corrected to muzzle velocity.

Interesting #1: the brass used in these tests required one trimming and the primer pockets are tight enough for further useage, this after eight rounds of very high pressure loads. So much for the idea that the Swift round stretches brass beyond normal cartridges. My years of working with the Swift have shown me that it is no more difficult or finicky than any other round. Now, I shall go back to my standard Swift load of 41.5 gr of H414 and the Nosler 55gr BT, a load that works on all my Swifts superbly.

Interesting #2: the Swift was lauded by PO Ackley for shooting deer and antelope. With the 60gr Nosler partition and the Barnes TSX bullets, it has become an even better round for this task. I use a Remington Classic or a pre64 for hunting game with the Swift and it has made a believer out of many of my fellow hunters after witnessing the lightning effect on mulies and antelope even at ranges of 300yds. The same is probably true of the 22-250.

Next project: building a 220 Howell on a Ruger No1 with an 8" twist. This round was the brainchild of Ken Howell and is but one of a series of Howell cartridges that feature high case capacity. He did not design them for high velocity but for lower pressure while achieving normal velocity. The 220 should put 75gr 224 bullets downrange at around 3,450 fps @ less than 50,000psi. If so, it would be flatter shooting at 500 yards with less wind deflection than lighter and faster bullets while having less barrel errosion. A 28" Krieger barrel has been ordered.

PaulS: your idea of going to a slower powder was valid. VV540 is a few stages slower than the VV135. The load I used was compressed and I used an 8" drop tube to fill the cases nearly to the top of the neck. Test #3 was halted as pressures spiked with the first two shots and the primer pockets showed some leakage. This was with an increase of only .6gr. True to form, the velocity of those two shots hadn't increased at all from the other two tests. Your signature line of staying within the SAAMI specs is important and I am glad your posts remind us that safety is the key to a long and happy relationship with firearms and reloading. For those that experiment into the grey areas of pressure, top notch monitoring equipment and safety gear are mandatory for the shooter's safety and those around him.

Onward

You guys fill me with a sense of awe.

Reading posts like these really brings home the fact that I have only scratched the surface of reloading. Of course not all people are made to do this type of experimentation-but I am darn glad some of you do.

Handloader, i sure hope you safely attain that 5000 fps. Keep it coming.

Handloader,

You got that round to just over 5000 fps with 67000 PSI on a strain gauge?
Was the gauge calibrated with some ammo or ?
How accurate do you feel the pressure readings are?
I am proud of you for two points:
1: you did the research to find a powder that could deliver your velocity with under MOA accuracy.
2: You documented every step of the way as a true experimentor
But what makes me really proud to know you is that you are going back to that old standard load that has served you so well over the years.

I looked up the SAAMI specs and the 220 Swift max is 54000 CUP and looking at other cartridges that have both pressures listed it looks like close to 65000 PSI is close to the same (There is no direct correlation between PSI and CUP readings - and the difference is more variable with the large volume and small caliber cases) I would tend to think that your loads , if the gauge had been calibrated with SAAMI /ANSI pressure test rounds, would be closer to 70,000 PSI than 65000 PSI. (This is only my guess)
Would you tend to agree or disagree with my guess Handloader? Just wondering... you don't need to answer.
Paul

PaulS wrote:

Handloader, PaulS: You got that round to just over 5000 fps with 67000 PSI on a strain gauge? Was the gauge calibrated with some ammo or ? H: No. The contacts were glued in place between specific points on the receiver and barrel. Incidentally, said glue is somewhat a challenge to get off these items. Part of the presumption is that the gauge is accurate per se and, at the very least, gives relative increases in pressure corresponding the increases in velocity. This is why CHE is a backup check, along with the other "normal" signs of pressure. FWIW, double based powers, such as N540, tend to spike rapidly in the pressure curve; as such incremental increases warrant very careful monitoring. PaulS 1: you did the research to find a powder that could deliver your velocity with under MOA accuracy. 2: You documented every step of the way as a true experimentor But what makes me really proud to know you is that you are going back to that old standard load that has served you so well over the years. H: This was simply an excursion into that grey area of handloading. Requisite are some guidelines and tools/equipment to monitor results. Anyone using a good chronograph will be able to watch the results of added pressure by the concomintant velocity increase and when that ratio is disrupted (ie marginal velocity gains per increased powder charge) one knows that the effective pressure limits of the powder are being approached. This is not the comfort zone of operation and my standard load allows respectible velocity below SAAMI max pessures by a considerable margin. I looked up the SAAMI specs and the 220 Swift max is 54000 CUP and looking at other cartridges that have both pressures listed it looks like close to 65000 PSI is close to the same (There is no direct correlation between PSI and CUP readings - and the difference is more variable with the large volume and small caliber cases) I would tend to think that your loads , if the gauge had been calibrated with SAAMI /ANSI pressure test rounds, would be closer to 70,000 PSI than 65000 PSI. (This is only my guess) Would you tend to agree or disagree with my guess Handloader? Just wondering... you don't need to answer. Paul

PaulS: Your observation could be correct, however, the variables that would allow us to pinpoint pressure are many. We can predict velocity from loading manuals, however, we are aware of the many things that can effect same. This is why we choose to use input from things such as chronographs, or in my case, the strain gauge -- to eliminate speculation. And, that is why the CHE and chronograph are aids in establishing reasonable progress toward one's objective along with the pressure gauge. We know a generally accepted max pressure for brass integrity is in the mid 70,000 psi range and, in fact, the beginning of pressure excursion took place by the addition of a mere .5gr of additional powder. All indicators, at that point, went "red", the goal was achieved and the remaining hot loads were pulled down.

One of the amazing products of the 60s was the Powley computer that could predict pressure based on numerous inputted factors. This "computer" was nothing more than a slide rule made of pressed cardboard, but, when combined with the Powley load computer would often give the handloader the best starting point for added experimentation. It was designed around the IMR series, which has a very progressive and predictable burn rate. Interpolation to other powders could be determined, however, one erred toward the conservative in such development. Powley wanted high load density, specific pressure at that density and the lowest possible pressure for the velocity desired. I prize my Powley "computers" as they have given me the basis for what has become many of my standard loads. It also gives me a tool to use to develop loads for any round whether existing data is available or not and to chart the changes that barrel length or case volume can have in theoretical loadings. Conversely, one can start by working backwards from a known velocity and predict accurately the baseline pressure if sectional density, ratio of charge to bullet weight, bullet weight and other factors are known. If you ever see a set of the Powley "computers", buy them and enjoy Powley's remarkable package.

That said, some baseline work with the Powley gauges have led me to want to try a Ruger 204. Theorectically, it should deliver on a number of levels and make it the 20 caliber equivalent of the 220 Swift. So, the search has begun for a good test platform, with the Remington VSSF being the primary choice. It comes with a 26" barrel which will allow shortening to the optimum 24" once testing has been done and for comparison purposes.

Recent prairie dog hunts have again impressed me with the much used and beloved Swift for the long range (400 to 550 yard) shots, however, the 204 Ruger is theoretically better. Maybe. . . .

Now, back to the loading room.

Hasta luego

This has been a very interesting post.

Handloader, in relation to the Powley Computer....I found this on the net and thought that it may well be useful to all of us that handload.....a computerised Powley Computer.

Powley Computer

Going to have a good long hard look at this as I feel that it may well help me solve a couple of minor dilemmas I have.

Cheers, Vince

Vince: thanks mucho for the Powley link; I had no idea it was computerized, however, I am not surprised. The website gives added information and changes terminology somewhat, the result, I imagine, of intervening use of the Powley computers. Those computers are wonderful tools to learn about basic interior ballistics.

Particularly, I enjoyed the references to Ken Howell. Ken lives in Quemado, New Mexico and I met him on a recent trip to Quemado. It shouldn't surprise me that he and Powley were friends as Ken has been a long standing force in the firearms area, has published books, and knows more than any living person about ballistics, I am certain.

If anyone is traveling through Quemado, a visit to Ken will be memorable and inspiring. And, always, welcomed.