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Old May 31, 2011, 08:54 PM   #1
poline
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Crimp and increased FPS

I recently tested 5rds of 158gain rnfp jacketed bullets in chrome brass and winchester primers, with 6.1gains of V-3n37. This is the max load for that weight bullet, which I worked up too. All of this out of a 6inch barrel. The book calls for 915fps with this load.
The results were as follows:
one rd at 715 fps
one rd at 888 fps
one rd at 734 fps
one rd at 854 fps
one rd at 809 fps High 888
Low 715
Avg 800
Es 173
SD 74

The ES & Sd are terrible especially since the 6.1 gains were carefully weighted out on a Lyman Electric Scale.
My concern, at the moment is the High of 888 and the avg of 715 both are below the book 915fps.
I'm using a crimp between 1/2 to 3/4 turn because I found out that if I use the 3/4 turn that I use for lead bullets that It caused the case to buckle. So I'm thinking that if I use just a little more crimp turn, but not enough to buckle the case I might get more FPS. Any response or thought that forum has to this question and the one to follow is greatly appreciated.
Does anyone know the size of the test barrel that VihtaVuori uses for their
38spl ammo? Meaning that Hodgdon uses a 7.7 inch barrel to test their 38spl ammo.
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Old May 31, 2011, 09:33 PM   #2
Brian Pfleuger
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They show their barrel length at 6 1/2 inches and max load at 6.2 and 6.5 3N37 for 158gr bullets with velocities over 1000 fps.

http://www.lapua.com/en/products/rel.../relodata/6/28

The velocity would be less of a concern than the erratic results. They likely have a SAAMI minimum chamber and you do not, thus lower velocity.

I doubt that less than 1/8 turn crimp is going to have a dramatic effect. I'm inclined to believe that less flare would make more difference but that's obviously just a guess.

What is your OAL compared to their data? That can also have a large effect.
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Old May 31, 2011, 10:03 PM   #3
poline
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Rd one oal 1.431 715fps
Rd two oal 1.438 888fps
Rd three oal 1.438 734fps
Rd four oal 1.437 854fps
Rd five oal 1.438 809fps

The book calls for a oal length of 1.437

The flare was as I recall just enough to keep me from during a balancing act, even so, I could reduce it.
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Old May 31, 2011, 10:28 PM   #4
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Now, that I think about the flare. The brass, chrome, was not all of the same manufacturer. So m I not correct in thinking that the right flare on one case may not be correct on a case from a different manufacturer? Thickness of the case.
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Old May 31, 2011, 10:35 PM   #5
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1/2 to 3/4 turn of crimp is plenty. Adding more crimp as an afterthought may not be a good thing to do since you are at max. I suggest trying a different powder at this point.
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Old June 1, 2011, 08:03 AM   #6
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The mixed brass is probably your problem. Are they all trimmed to the same length? That will effect crimp. Neck thickness will also have an effect.

The biggest effect, I would guess, is varying case volume. With identical outside dimensions, various brands can have quite different internal dimensions. More volume equals less pressure, less velocity. Less volume, more pressure, more velocity.
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Old June 1, 2011, 08:06 AM   #7
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In the first place, nobody makes "CHROME" cases, or chrome plated. What you probably have is NICKEL plated brass.

Second, unless you have trimmed all the cases to the exact same length, AND they are all from the same manufacturer, you cannot expect velocity consistency.

Start over. Sort your cases, then measure them until you get enough the same length, or trim them all to the same length. Then when you crimp, you'll get the same crimp each time.

Third, crimp does not equal velocity increase. Crimp is simply to keep the bullet from moving under recoil from the round that's being fired. If this is 38 special, then recoil isn't much of a factor, IN OTHER WORDS, a light crimp is all that's needed.
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Old June 1, 2011, 01:32 PM   #8
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With that kind of implied ignition irregularity, I'd try a magnum primer.
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Old June 1, 2011, 07:05 PM   #9
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Yes, you are correct about the NICKEL plated brass! I have been using the Lyman E-ZEE CASE GAUGE for the case length, but for this I will use the Lee case length gauge. I will sort the brass and expand the very minimum.
Thank all of you, for your advice and response.
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Old June 1, 2011, 11:02 PM   #10
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Quote:
a light crimp is all that's needed.
Would a heavy crimp increase or decrease start pressure, or have on effect ?
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Old June 2, 2011, 11:21 AM   #11
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Quote:
I recently tested 5rds of 158gain rnfp jacketed bullets in chrome brass and winchester primers, with 6.1gains of V-3n37.
Take a good look at what you are doing and what you are trying to achieve and see if they are close. A few things that jump right out at me:
* That is a very slow powder for a 38 Special. Slow powders with low pressure loads give lots of variation, as seen in your results. Use a faster powder like Bullseye, Unique, Universal, or W231.

* You only need enough crimp to keep the bullets from backing out under recoil. 3/4 of a turn seems like a lot to me, but not being there and seeing the loaded ammo first hand it's hard to say.

* As others have mentioned, sort your brass and find enough of one maker's brass to do your testing.

* 5 rounds is not a very good sample size for doing SD calculations.

* Reloading manual publishers use different guns than you do, so they get different results. Don't worry about it, they are just telling you what they got, not what you will get. Having chronoed many reloads, I often wonder if the reloading manual publishers are pathological liars, or if they have faulty equipment, or if I have faulty equipment.
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Old June 2, 2011, 12:29 PM   #12
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Quote:
Originally Posted by Scorch
. . . Having chronoed many reloads, I often wonder if the reloading manual publishers are pathological liars, or if they have faulty equipment, or if I have faulty equipment.
Heh, heh. The same thought has crossed my mind before.

One thing you can usually count on is that if they have pressure numbers associated with the load, then the gun was a test barrel in a universal receiver. Lyman is good about telling you when they've done that. Test barrel dimensions are specified by SAAMI to have minimum chambers and specific bore tolerances and cross-sectional areas. The idea is to tend to provide a worst case high pressure reading. That also means they get velocities that are optimistic compared to most commercial firearms.

I think Poline is trying to get maximum performance from the cartridge. Slow powders are the way you get that, but the lower the cartridge's allowable peak pressure, the less reliable their performance is, so its a trade-off; usually involving high extreme spread, large fireballs, and a lot of unburned powder. Even though this is not a magnum round, I suggested trying magnum primers because they sometimes can mitigate the irregularity. This article from a CCI employee mentions this. No guarantee, though, and you have to knock the load down at least 5% when you make the primer change.
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Old June 2, 2011, 02:46 PM   #13
poline
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"Poline is trying to get maximum performance from the cartridge."
I'm useing v3n37 because it is the one power that I have that the Lee Manual suggest for 158 gain Jacketed bullet.
Lee suggest 10 powers, which do not include Universal, Bullseye, or Unique.
These three powers are, indeed, suggested for 158 gain LEAD BULLETS.
Lee suggest HS6, Unuversal, and a few others for 158 gain XTP BULLETS, I tell myself that XTP is different from JACKETED. If I thought I could use HS6 for these JACKETED bullets I would, because I love what it does for my 158gain LEAD rnfp SWC. I get great FPS and my ES and SD are good and after I sort by manufacturer and reduce the expander, as the forum has suggested, I think they will get better.
I have not used magnum primers, because the book say not too, but I'm thinking about it now. With that 5% deduct thing.
If 5rds is not a good nbr to test FPS, ES, SD what would you suggest?

This is 38spl not 38+P....... my goal is to get the maximun I can and stay safe and I want it in a nickel plated brass with these 158gain JACKETED
BULLETS.
From the 10rds I tested, ......5rd from 6' barrel and 5rd from 2 1/2 barrel, I can tell you these are not target rds!!!!!
I thank all of you,very much, for your advice and response.
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Old June 2, 2011, 03:51 PM   #14
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As for a powder recommendation, have you thought of trying Autocomp? It's easily my favorite powder so far for 38spl. It's got great velocity and the accuracy from my Model 36 snubbie is outstanding!
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Old June 2, 2011, 04:12 PM   #15
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Poline,

Powders listed in the manual are only those tested by the writers. They are not necessarily "recommendations", though they may well represent those powders assumed by the writers to be most suitable. However, even that correlation is shaky at best.

XTPs are jacketed bullets and the appropriate data listed for XTPs of their weight should be usable for jacketed bullets.

As always, start low and work up. You'll be fine.
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Old June 2, 2011, 09:49 PM   #16
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Poline,

I've never seen a jacketed RNFP bullet. Are you sure you aren't confusing plated bullets with jacketed bullets? The XTP is jacketed. Plated bullets are softer and need to be fired like cast bullets, or at least not over mid-range jacketed loads.

Lee may not have the data you want, but Hornady has it for the 158 grain XTP's. This is one of the reasons you always look at several sources of load data. Another reason is possibly seeing significant pressure disagreements, as you'll see.

Hornady data:
158 grain XTP seated to 1.450" COL, Winchester WSP primer, Hornady/Frontier brass.

Bullseye: 3.4 grians to start, 4.2 grains maximum without going into +P range
Unique: 3.9 grains to start, 4.8 grains maximum without going into +P range.
HS-6: 5.1 grains to start, 6.2 grains maximum without going into +P range.
VV 3N37 5.0 grains to start, 5.8 grains maximum before reaching +P range.

Hornady says 6.0 grains of VV 3N37 is the maximum load and that it is already +P in their testing. Vihtavuori, on the other side of the pond, operates under CIP pressure limits rather than SAAMI. The CIP has no +P classification as SAAMI does. They use 150 MPa (21,756 psi) for all .38 Special loads. That's above current SAAMI +P. So if you get data from VV's online load data, keep in mind you are looking at exceeding current SAAMI +P, and will be operating in the vague, non-SAAMI region that manufacturers call +P+.

The +P standard has a complicated and confusing history. It was 22,400 CUP originally, then in 1993 it was, for one year, reduced to 20,000 CUP or 18,500 PSI, depending on which kind of measuring gear you had. The PSI number was then raised to 20,000 psi in 1994, because manufacturers complained they couldn't get adequate ballistic performance for +P at 18,500 PSI. Meanwhile, the CIP number suggests that no modern firearm should fail to withstand the higher pressure, anyway. Only some very old timers and early Airweights with their less-than-rugged early aluminum alloy frames need to be restricted to the SAAMI standard load limit (17,000 CUP and also 17,000 PSI).
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Old June 2, 2011, 10:13 PM   #17
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One other thing to possibly give thought to, is try those loads in braas not nickel and see if the variances stay. I shoot a lot of nickel and have noticed that they seem to be less cosistant than brass.Most of my best loads seem to be where brass is used, but that is in 40 S&W where pressures are higher.
I also shoot 45ACP and I can still notice it but not as much.
PS +1 on Auto Comp, it is a very good powder.
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Old June 2, 2011, 11:37 PM   #18
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Clay, what is this Autocomp? I can't find a listing, but I'm very interested. Peetzakilla, I did not know that XTP was jacketed, thanks.

Unclenick, When I look at the bottom of m jacketed bullet I see metal with a lead core. When I look at the bottom of my plated bullet I do no see lead core, but a plated core. Thanks for the SAAMI and CIP info.

Dunerjeff, Thanks for the brass vs nickel info.

Gosh, this forum just keeps giving and giving, fellows thank you!
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Old June 3, 2011, 08:19 AM   #19
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Almost all "copper" colored bullets are "jacketed" and some that we think are jacketed, like Speer Gold Dots, are actually heavy plating.

As far as I know, there are basically 3 categories of "other than lead" bullets. Plated, jacketed and all copper.

Basically, if it's not sold as plated, like Berry's, or copper, as Barne's X bullet, and its not lead, you treat it as jacketed.

The difference in the base, whether you see lead or not, is the difference between being a "full metal jacket" or a "complete metal jacket". "Full" having exposed lead, "complete" not. Though there may be exceptions. I've personally never seen a jacketed, hollow point, exposed lead base handgun bullet but I've never looked either and I don't doubt they exist.

The preceding information is not intended to be a PhD thesis regarding handgun bullet types. It contains generalizations that are likely not complete and/or 100% reliable.
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