Best cartridge for silhouette

DanDeMan · Post by **DanDeMan** » Wed Apr 18, 2012 5:23 pm

Meine Damen und Herren,

I filed-on a few bullets; man, I need to figure-out a better way. Any way, here are three that I think might of interest. Notice that the Cauterucio's have thicker jackets then the Walls. I've never lost a ram with either bullet even when launched to only 2,300 fps. The Lone Ringer will attest to this statement, "Back in the 90's the rams at San Louis Obisbo, CA were very tough." I never range a ram there when launching the 177 Cauterucios to 2,300 fps, with 31.0 grain of VarGet, out of a 7mm PPC Improved, never. Guys launching 190-gr, SMK's were ringing rams with 308 loads that most of us probably wouldn't want to touch-off. Exterior ballistic efficiency and bullet toughness are where it's at, given we have 1/4 MOA accuracy and moderate recoil for the ram loads.

!85 Wall 7mm VLD----------181 Cauterucio VLD--------Old 139 6.5mm Scenar (1998)

Trent · Post by **Trent** » Wed Apr 18, 2012 5:35 pm

Dan, can you go a little deeper on the tail of the Cauterucio and snap another photo?

DanDeMan · Post by **DanDeMan** » Wed Apr 18, 2012 5:41 pm

Trent wrote:Dan, can you go a little deeper on the tail of the Cauterucio and snap another photo?

Why???

Trent · Post by **Trent** » Wed Apr 18, 2012 5:51 pm

From the photo it doesn't look like it is sectioned to the midpoint. That will make the jacket look thicker. It looks like it's only cut about a third of the way through at the base.

Do you know if Cauterucio always used jackets from Sierra?

On the older Lapua bullets, is the only thing that was changed was the jacket thickness or was the profile also changed?

Jason · Post by **Jason** » Wed Apr 18, 2012 6:53 pm

This has me thinking that a .277 caliber 150-grain Hornady Interbond would be wonderful on rams. I just happened to have some of those for my 270 Winchester and filed half of one away. It's pretty impressive compared to the other pictures here. Anyone got a 6.8x47mm Lapua reamer?

Trent · Post by **Trent** » Wed Apr 18, 2012 7:02 pm

Jason wrote:Anyone got a 6.8x47mm Lapua reamer?

You must be talking about the 6.8x47J (for Jason). ;)

Varn · Post by **Varn** » Wed Apr 18, 2012 9:44 pm

Dan, MCA, Tony and others,
This has been a great discussion and I want to take the opportunity to thank everyone for sharing their hard work and information. Dan's 7TCU post prompted me to relay my experience with the 7TCU. In 2004 I had wrecked my GSXR 1000 streetbike and suffered a broken rib just under my right collarbone. I wanted to continue practicing and shooting but couldn't take the recoil of my .260 or 6.5x55 while my rib was healing. My friend, the late Mickey Wagner, graciously offered to let me use his 7TCU standard rifle with a 1-8 twist barrel. Remembering an email from Dan regarding high BC bullets I promptly ordered some 7mm 168JLK's. These had a .690 BC. I took it to a match and didn't lose a ram in practice or the match. Next week I took it to another match with the same result. They didn't go down fast but they always went down. This piqued my curiosity so Butch Bowersox and myself took the rifle to a range in Kylertown, PA where we would practice. We set up 25 rams and with Butch spotting I shot all 25 Rams from the bench. I tried them with center hits as well as low belly and low shoulder hits. Every one of them fell. We were both amazed at what that little cartridge would do with those bullets. I don't recall what the load was other than it was a case full of Varget. I also didn't chronograph them but it took 18 minutes to get to the rams so it must have been in the 2000 fps range. Another testament to the efficiency of high BC bullets on Rams. Again, thanks to everyone for their information and efforts. Mark Varner

Bob Mc Alice · Post by **Bob Mc Alice** » Thu Apr 19, 2012 9:11 am

More good info, thanks for sharing Varn. Are you coming out here to the Nationals this year?

I still want to see those Cauturucio bullets filed down to centerline. I suspect they are nothing more than heavy VLD Match Kings. I agree they are a clear advantage over the regular factory Sierras, though.

Snake · Post by **Snake** » Thu Apr 19, 2012 9:35 am

All us old guys shot 308 in this game at one time. I never got no satisfaction from190's on rams...BC and sectional density aside...the 168 or 175 7mm had the better length and less recoil. Looking at those photos I agree with Trent that the sectioning was off center; further more there are only a few jacket makers available for the custom maker...J4 and Sierra are two. i do not believe Hornady Nosler Norma or Lapua sell jackets. As for JLK I have them and i have used them. They are excellent and not too 'spensive for a custom pill (they make a nifty 180 7mm VLD)
As far as TCU's are concerned I have already commented and described our experiment with the 7mm PPC 40 degree ...but 2350 with the 175 was the best we could ever get and if it was a 90+ degree day primers pierced...Its a lot easier to load down a standard case than to fool with sizing/fireforming etc

cslcAl · Post by **cslcAl** » Thu Apr 19, 2012 10:03 am

Re: Best cartridge for silhouette

by cslcAl on Tue Apr 17, 2012 9:07 pm

Guy's, Lots of good info posted here. Dan the Man great to hear from you again. I have a ram related question for you. I have been shooting a lot of Cowboy silhouette and we too are playing the recoil vs. knockdown game. I know you have done extensive tests on momentum. I am not an engineer so what is a signifigant gain in momentum? I have recently done some testing with 170 Sierra 30-30's reduced to 1928fps. and the momentum at 200 meters is 1.08 (Lb-sec.) Energy is 778.1 (Ft/lbs). Comparing that to a more standard load producing 2137fps. with momemtum at 200 meters of 1.19 (Lb-sec) and 937.5 (Ft/lbs) of Energy. I used Sierra's V6 program to get these figures. Is a gain in momentum of .11 (Lb-sec) a big gain? I know from experience that the faster load will work better, that's a no brainer. I just have no experience with the numbers and would like to know for future reference how much it takes to make a significant difference.

I posted this the other day and didn't get an answer to my question. I hope you all don't think this is a stupid request, but I am a plumber by trade and my formal training with velosity and momemtum deals with sewage; and that don't apply here.

Thanks,
Al Foust

Trent · Post by **Trent** » Thu Apr 19, 2012 11:04 am

Al, mathematically you are looking at a 10.2% increase from 1.08 to 1.19.

Real world... how much performance difference is 10% ?

Bob Mc Alice · Post by **Bob Mc Alice** » Thu Apr 19, 2012 11:20 am

That last statement was funny Al. Yes, your question was good and I hope you get an answer, too.

Varn,
Dave B. and I did the same ram experimenting early this year with two of his 6.5's. He was bench testing three brands of bullets hitting them in a 3-4 inch diameter zone over the front leg. Conditions were very calm. Our rams are perched on top of a reversed RR rail as most are. We have to put our targets away after each match so the general membership wont wreck them. They also get hammered by our long range pistol shooters and now by the recently started up centerfire lever gun group.

No two rams of ours are perfectly alike and their placement on the rail will almost never be the same. Add in that we occasionally have to cycle in a spare to replace a broken foot one. I felt we had a typical representation of what to expect at most any silhouette range. Of the 18-20 targets he hit in that zone, all fell. But in AZ he lost two with more desireable body hits. What do you do. Shrug it off and keep shooting.

Snake · Post by **Snake** » Thu Apr 19, 2012 11:22 am

I love those calculated energy levels. Fact is the transference of energy is dependent on the nature of the transmitting medium ( da bullet)....so if that bullet is weakly constructed and explodes too rapidly on the target..energy is transmitted inefficiently ...thus the wobbly old maid ram! The correct balance of velocity and hence impact speed and bullet construction factoring in approach angles and one can probably definitively come up with ultimate ram tumbler. But like i told the guy at our BPCR match who just lost a ram with his 45/70 450gr lead bullet when he asked if there was something wrong with our rams....sometimes stuff happens. (The wind grasshopper...the north wind)

DanDeMan · Post by **DanDeMan** » Thu Apr 19, 2012 12:40 pm

Trent wrote:......Do you know if Cauterucio always used jackets from Sierra?

To the the best of my knowledge. For his heavy, 7mm VLD's he swaged down Sierra 30-cal jackets. That's what makes them thicker. I don't know if he still does, though, given Sierra now makes long 7mm jackets for their 175 MK.

On the older Lapua bullets, is the only thing that was changed was the jacket thickness or was the profile also changed?

I don't know if the profile has changed since I last purchased 4,000 rounds of the 139-gr, 6.5mm Scenars. The place in Atlanta that imported Lapua bullets, before Kaltron Pettibone, Inc. became the sole distributor, sold them in wooden ammo boxes of 2,000 per box. I've smashed the new 139's for a couple of guys the past few years, but I did not compare the profile to my older bullets.

DanDeMan · Post by **DanDeMan** » Thu Apr 19, 2012 2:12 pm

Snake wrote:..... As far as TCU's are concerned I have already commented and described our experiment with the 7mm PPC 40 degree ...but 2350 with the 175 was the best we could ever get and if it was a 90+ degree day primers pierced...Its a lot easier to load down a standard case than to fool with sizing/fireforming etc

Snake,

I designed a 7mm PPC Imp reamer back in 1996 (40 degree shoulder and body with less taper) for the 180 JLK's (BC = 0.735.) Out of the 8-twist Hart barrel, launched to 2,325 fps with 31-gr of VarGet I never rang a ram. And, back then we had some very suborn rams out here. Those JLK's were made when Jimmy Knox still owned the company; bullets made in 1996. Because of the very high BC, that bullet was still going about 1,746 fps at the ram line. Terminal momentum was 1.40 ft-lb per sec. Recoil, using a 10 lb rifle, was 10.1 ft-lbs.

One of the metrics I created, after purchasing my first exterior ballistics program on a PC, assessed recoil vs terminal momentum at the ram line. So, the ratio for the 7mm PPC Imp was 1.40 / 10.1 = 0.1389 ft-lbs of momentum per ft-lbs of recoil. Another interesting metric looked an recoil vs wind deflection at the ram line. It was those equations that drove me to go with the 7mm back then. For comparison, here's the ratio for my 6.5-08 Hunter rifle's ram load that consists of the 139 Scenar over 43.5-gr of N160 producing an MV of 2,825 fps. For the recoil calculation I'll use 10 lbs so we can have a fair comparison. So, the ram-line momentum is (139/(7000x32)) x 2,015 = 1.25 ft-lb per sec. Recoil from a 10 lb rifle for that load is 11.4 ft-lbs, so the ratio is 1.25 / 11.4 = 0.109. So we can say that the 7mm load delivers (0.1389 - 0.109) / 0.109 = 27 % more terminal momentum per ft-lb of recoil. And that, ladies and gentlemen is why, IMHO, the 180-gr, 7mm VLD's rule the ram line; with the old JLK's and Cauterucio's sitting on the Ram-Knockdown Throne. I still have 3, unopened boxes of the old JLK's and several thousand of the old 177 Cauterucios.

Damn, now I have to run another series of computer simulations and calculations to determine how much terminal momentum the 7mm PPC Imp would deliver if the load produced 11.4 ft-lbs of recoil......OK....if the 180 JLK is launched from a 7mm BR with 33.0 grains of VarGet the MV is about 2,475 fps. Out of a 10 lb rifle the recoil will be 11.4 ft-lbs. Terminal velocity at 500 meters is about 1,873 fps. Terminal momentum = 1.51 ft-lbs per sec. Now, how much more terminal momentum is the 7mm delivering to the ram compared to the above 6.5-08 load? Here's the answer: (1.51 - 1.25)/1.25 = 20 % more terminal momentum for the same recoil. And, the dwell-time for the 7mm bullet will be greater, so the actual ram-knock-down performance is more than the calculated 20 %.