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Which powder and how much of it do you have in your Sierra contol load?
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Rgr that. I thought there might have been some new feature for saving an entire multi-page thread in one whack. |
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If you know a little HTML it wouldn't be hard to edit the saved files so the previous/next page links take you to the right saved page. |
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Here's a little more information on my Noveske barrel. It is referred to as the "medium contour" barrel and it weighs 1.8 oz less than a 16" Colt HBAR. Here is a pic of the Noveske next to a 16" Colt HBAR for comparison.
The Noveske barrel with the Noveske gas block weighs 2 lbs 3 oz . . . and without the gas block it weighs 2 lbs 1.6 oz. For comparison, a 16" Colt HBAR without a gas block weighs 2 lbs 3.4 oz. |
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I've purchased the Black Hills Mk262 2nds from Cabela's and Fulton Armory. The HSM 5.56-17T naturally comes from The Hunting Shack. As far as I know, Hornady 5.56 TAP is still LE only. |
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Molon, That's exactly the answer I was hoping for! Thanks for your great work, can't wait to see the velocities. Regards, Justin |
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I am getting two of these Arsenal SLR-106FR's ( 5.56 x 45 NATO) in about a week. My question is what would be the better ammo for this AK (HSM-5.56 or HSM .223). We all know that the AK's are not as accurate as AR's, so why would be the reason for picking which ammo.
Should I go with the accuracy or the lethality for a self-defense weapon. Here is what the website states for info on the barrel.
k-varcorp.com/forums/index.php?showtopic=3848&st=0 TIA, AC |
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"Were going back in the f%&$ing tank" George Dzundza -The Beast (2001)
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Molon, Well, according to the following data, the velocity increase is in a 2:1 ratio from 16"-18" and 18"-20"; in other words, the velocity gained by moving to an 18" barrel from a 16" barrel is twice as much as moving from an 18" to 20".
Courtesy of Wes Grant at MSTN: VELOCITY AS A FUNCTION OF BARREL LENGTH. So if there is an increase of 45 yards of fragmentation range* between a 16" and 20" barrel, then according to the 2:1 ratio, the increase in frag. range from 16" to 18" is 30 yards, and 18" to 20" is 15 yards. *Based on your excellent frag. range chart: Conservative Fragmentation Ranges. In your opinion, if your Krieger 20" offers a 50 FPS increase over a Colt 20" chrome lined NATO barrel using 55 gr. ammo, then what would the velocity increase be using 5.56 75 gr.? Thanks again Molon. Justin EDIT: format. |
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Bump...looking for some input...
AC |
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"Were going back in the f%&$ing tank" George Dzundza -The Beast (2001)
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AC, You need to decide what it is you want from your rifle/ammunition combination. The 223-17T load is more accurate than the 5.56-17T load, but not by much. Is your rifle capable of exploiting the difference in accuracy between these two loads? The 5.56-17T will give you about 97 fps more velocity with a concomitant increase in fragmentation range of about 35 yards when fired from a 16" barrel than the 223-17T load will. Is fragmentation range your highest priority? Define your intended mission first and then choose the tools best suited for that mission keeping in mind that there is no perfect solution. Molon |
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Wait, let me rephrase that because it is somewhat confusing. If the 55 gr. round demonstrates a 50 FPS increase from the Krieger chamber, then what velocity increase is a 75 gr. round likely to demonstrate? Thanks Molon. You're really an asset to this community! Justin |
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If there’s one thing I’ve learned from chronographing, it’s that there is no set formula for calculating the muzzle velocity of one particular length barrel from a known muzzle velocity of another length barrel. There are just far too many variables involved. Every barrel is a law unto itself. The interactions between the barrel, bullet weight, powder, powder charge and the particular velocity spectrum involved all behave differently when a single variable in the equation is changed. When I attempted to give a questimate as to the possible difference in muzzle velocities between an 18” and 20” NATO chambered barrel based on the actual data for differences in the muzzle velocities between 16” and 20” barrels, I stated that I was making a big assumption in trying to correlate the two examples. The only way to really know is to chronograph the two barrels in question to compare the results. Even then, the results may differ from chronograph session to chronograph session. As an illustration of the points above, refer to the MSTN data to which you provided a link in your above post. You pointed out the 2:1 ratio for the velocity increase between 16” to 18” barrels and 18” to 20” barrels for the MK262 ammunition. The problem is, that the 2:1 ration doesn’t hold true for any other circumstance. If you look at the rest of the MSTN data, you’ll see that the same barrels have a 7:1 ratio with the M855 ammunition and a 19:1 ratio with the M193 ammunition. What I’m leading up to is the fact that I really can’t give you a solid number for the possible increase in the muzzle velocity for 5.56 TAP when fired from a Krieger barrel for all the reasons stated above. I’ll also probably never know the answer to that question because I’m just not comfortable with the idea of firing a NATO pressure round in my match chambered Krieger barrels. (I however, don’t have any reservations about firing 5.56 TAP from my Noveske barrel and I’ll be posting some chronograph data for that barrel soon.) Molon |
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I can give you one specific example. I chronographed the same lot of SAAMI pressure 75 grain TAP from a 20" Colt NATO chambered barrel and a 20" stainless steel, match chambered, Krieger barrel. Colt barrel: 2638 fps Krieger barrel: 2699 fps |
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Wow, I had no idea that velocity readings could vary so much. Thank you for enlightening me. Just one last question though, is it safe (i.e., would you feel comfortable) firing 5.56 pressure ammo from a .223 Wylde chamber? Justin |
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That's a lot more than I expected. Thanks again Molon. Take care and G-d bless. Justin |
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Could you publish all this in a bathroom reader format
Great stuff. Thanks! |
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ATTN: Arkansas Shooters!!!
Have you been to your Home Town Forum lately? Vist now for contest to WIN A MEMBERSHIP!!! ---------------------------------------------- I drink Kool-Aid...Or should i say COLT-AAC |
I don't personally own a barrel with a Wylde chamber, but it is my understanding that the Wylde chamber was designed to handle NATO pressure loads while delivering better accuracy than a NATO chamber. I've posted some information from various sources below on AR-15 chambers. Here is a link to a very good article on AR-15 chambers by Glen Zediker. |
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I'll assume you're referring to the shot highlighted in blue below. The beauty of using the mean radius for accuracy comparisons is that all 30 shots in the composite group are used as data points. Therefore, one or two outlying shots (notice I didn't call them flyers) don't have a major impact on the results of the mean radius. The mean radius for this 30-shot composite group is 0.37". If I remove that outlying shot from the group and calculate the mean radius using only 29 shots, the mean radius only changes to 0.35". |
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I have a wee bit of experiance with the Wylde chamber... about 3K rounds of experiance, all of it with 5.56 loads. Never had a hiccup. Shoots great though...continues to outshoot me.
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ATTN: Arkansas Shooters!!!
Have you been to your Home Town Forum lately? Vist now for contest to WIN A MEMBERSHIP!!! ---------------------------------------------- I drink Kool-Aid...Or should i say COLT-AAC |
Holy crap the Wylde freebore is horrible!!! I had no idea. Need to research it more but why would anyone want a freebore that long that is not using greater than mag length loads? Do you have Noveske's specifications?
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the wylde is based off the nato chamber with the freebore narrowed to help bullets get into the rifling straight. never seen specs for noveske, be nice though. |
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real men shoot bull barrels. its all about the girth.
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Originally Posted By DevL:
Holy crap the Wylde freebore is horrible!!! I had no idea. Need to research it more but why would anyone want a freebore that long that is not using greater than mag length loads? Do you have Noveske's specifications? Keep in mind that it’s not just the length of the free-bore that determines how far the bullet has to jump to come into contact with the lands. It’s the length (and angle) of the free-bore plus the length of the leade (and of course the shape and seating depth of the bullet.) Image from Hornady's reloading manual. Unfortunately manufacturers often do not list the length of the leade in their publicly available specifications. Clymer’s does. Looking at their specs one might think a bullet only has an additional 0.025” of jump with a NATO chamber as compared to a 223 SAAMI chamber. Now, look at the diagram below that actually notates the length of the leade: 0.045” for the SAAMI chamber and 0.164” for the NATO chamber. That’s an additional 0.119” of jump with the NATO chamber. Image from Rifle magazine #115. |
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OK, I promise this is my last question : Which of the above chambers would offer the most velocity while still being NATO pressure safe? CLE? Krieger/.223 JGS #514? |
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"Safety" is all relative. One can be safer than another, but nothing in this world is 100% safe. You must first define "NATO pressure safe".
Ammunition designed to be within NATO pressure specifications when fired from a 5.56mm NATO chamber is always going to be over pressure when fired from a smaller chamber. So before your question can have any hope of being answered you'll have to decide what average maximum and absolute maximum chamber pressures you will consider as safe and acceptable. Practice has shown that .223 Wylde tends to do well and be relatively safe with 5.56 NATO pressure ammunition. It also has the benefit of being well-known and wide-spread which helps keep support & sources high and costs low (as far as specially chambered barrels go anyway). Obviously all those chambers have been used with one measure of success or another, but has every one of them have been rigorously tested with 5.56 pressure ammunition? I don't know. |
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You should never try to solve your problems with handguns. Large automatic rifles work much better.
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The longer freebore is one way to allow the bullet to start moving early as pressure rises and gain some momentum before encountering the leade. This reduces peak pressure compared to a shorter freebore. |
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No. I think they're a military secret. However, using a 77 grain Sierra MatchKing and a Stoney Point gauge I measured the cartridge overall length with the bullet seated to touch the lands in my Noveske barrel. I did the same for a Colt NATO chambered barrel and a Krieger barrel with a match chamber. The results are listed in the table below. Here are a couple of pics of the Stoney Point guage. |
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you used an ogive bushing to get those measurements correct.
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real men shoot bull barrels. its all about the girth.
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Negative. When comparing the cartridge overall length necessary for the bullet to touch the lands in various chambers, the convention is to measure from the base of the case to the tip of the bullet, using the same bullet of course. (This is not the same thing as obtaining meaurements off the ogive of the bullet using some type of bullet comparator in order to set up a seating die.) The “standard” for comparing various chambers is to use an 80 grain Sierra MatchKing to measure the cartridge overall length needed for the bullet to touch the lands. My Colt NATO chambered barrel needs a cartridge overall length of 2.554” in order for an 80 grain Sierra MatchKing to touch the lands. For comparison, my Noveske Recon barrel needs a cartridge overall length of about 2.470” for the 80 grain MatchKing to touch the lands. |
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roger. that is how its always been done. i was just thinking that with the diff oal of bullets, going off the ogive would be a more precise measurement. it may be, but it doestnt really matter because thats how everybody does it. so the noveske needs an oal of 2.470", and the wylde 2.475" for the 80gr matchking. not too much longer in regards to earlier freebore question. seems the cle would have the least jump if it matters. |
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real men shoot bull barrels. its all about the girth.
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Chronograph Data for Noveske Recon Barrel
Here’s some chronograph data for the 16” stainless steel Noveske Recon barrel. The barrel has polygonal rifling and a Noveske Match mod 0 chamber. As usual, chronograph data was obtained using an Oehler 35-P chronograph with “proof screen” technology. All velocities listed are muzzle velocities as calculated from instrumental velocities using Oehler’s Ballistic Explorer software. I’ve also included muzzle velocities from a 16” Colt light-weight barrel with a NATO chamber and a Krieger 16” stainless steel HBAR with a match chamber for comparison. (The TAP FPD and 5.56 TAP muzzle velocities listed for the Colt barrel are from the original chronograph session for this thread. The rest of the data is from the most recent chronograph session.) Atmospheric conditions for the most recent chronograph session. Temperature: 67 degrees F Humidity: 45% Barometric pressure: 30.05 Elevation: 950 feet above sea level Skies: mostly sunny, Mercury turns retrograde |
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And there goes the polygonal rifling boosting velocity urban legend... right into the toilet.
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That was debunked a while ago, but the velcoity increase was real; wasn't about the rifling though, but the chamber. IIRC, Wes posted some figures that indicated the NMm0 chamber offers about the same velocity as a standard barrel of a two inch longer length. Steve from ADCO then posted that it was the chamber and then posted similar velocity gains from a WOA .223 Wylde barrel. This is really anti-climactic. I'm hoping it's just an anomaly, but knowing the quality and consistency of Molon's data, it's probably not. Although, a cold hammer forged polygonal bore barrel would cheer me up some. |
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If its not too much trouble; can I get the info for the rounds listed above using a 10.5" chrome lined barrel w/ a NATO chamber. Thank You, Marco |
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I wish I could give you that info. Unfortunately, here in the state of Michigan us peons aren't allowed to own rifle barrels less than 16" in length. (Might scare the sheeple, don't you know.) |
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Here are some pics of spent primers from Hornady’s 5.56 TAP load (which uses a mil-spec primer) that were fired from a Colt NATO chambered barrel. The primers show considerable flattening and even some riveting.
Now, I don’t for a minute believe that Hornady is producing overpressure ammunition. (I haven’t had a single malfunction in the two cases of 5.56 TAP that I’ve burned through in the testing for this thread.) What I do think that this shows is that attempting to use the observation of the condition of spent primers as a method to indicate an overpressure load is not really a very reliable one. |
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Molon,
According to Wes at MSTN, the Noveske Match mod 0 chamber yields a velocity increase equivalent to two extra inches of barrel length* and according to Steve at ADCO, a .223 Wylde barrel offers an identical increase (data here). But, these conclusions were all drawn based on velocity figures from Mk262, M193, and M855 respectively. Could it be possible that the NMm0 chamber does indeed offer a +2" velocity increase but just not with the 75 gr. TAP load? I'm just trying to figure out how two completely contradictory results could be achieved. On the one hand, I know your data is absolutely valid as your procedures leave no room for error, and on the other hand, I know that Wes' data has been confirmed by several other parties. *This was confirmed by another poster here. Best Regards, Justin |
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Originally Posted By CitySlicker:
Molon, According to Wes at MSTN, the Noveske Match mod 0 chamber yields a velocity increase equivalent to two extra inches of barrel length* and according to Steve at ADCO, a .223 Wylde barrel offers an identical increase (data here). But, these conclusions were all drawn based on velocity figures from Mk262, M193, and M855 respectively. Could it be possible that the NMm0 chamber does indeed offer a +2" velocity increase but just not with the 75 gr. TAP load? I'm just trying to figure out how two completely contradictory results could be achieved. On the one hand, I know your data is absolutely valid as your procedures leave no room for error, and on the other hand, I know that Wes' data has been confirmed by several other parties. *This was confirmed by another poster here. Best Regards, Justin Hi Justin, Unfortunately I don't have an answer for you on this one. There are just two many variables involved. As I've mentioned before, every barrel is a law unto itself. I looked through the threads from the links you provided and I thought this data from Bigbore was interesting: NOVESKE S/S POLYGONAL 1X7" 16" M855:.............3004 FPS WOA Wilson 16" 1:7 M855:................................... 3021 In that particular situation Steve also obtained results in which a barrel with standard rifling gave a higher velocity than the Noveske barrel. Looking at my results from above, the Noveske barrel had basically the same velocity as my 16" Krieger barrel when using 55 grain TAP, yet had a lower velocity than the Krieger barrel when using the 75 grain TAP FPD. Maybe my results are an anomaly, maybe not. When the weather warms up in the spring (it's snowing here in Michigan) maybe I'll repeat this test. Honestly though, I'm not really concerned about minor differences in the velocities of different brand barrels. I know what muzzle velocities to expect from my Noveske barrel and I know the accuracy it is capable of for 10-shot groups at 100 yards and that's really what one needs to know. Sorry I don't have a definitive answer for you Justin, but sometimes $h!+ just happens and that's just the way it is! Molon |
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No worries Molon. I guess I've learned that the study of ballistics is predictably unpredictable.
Thanks for your time. Justin |
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Lot-to-Lot Variation of 5.56 TAP
I was so impressed with the standard deviation and coefficient of variation of the original lot of 5.56 TAP that was used in the initial testing for this thread that I decided to do a side-by-side chronograph comparison of three different lots of the 5.56 TAP. I used a Colt 20” government profile barrel with a NATO chamber and chrome lining as the test vehicle. Chronographing was done using an Oehler 35-P chronograph with “proof screen” technology. All strings of fire consisted of 10 rounds each and all velocities listed are muzzle velocities as calculated from instrumental velocities using Oehler’s Ballisitic Explorer software. The results are listed in the table below. The average muzzle velocity of all three lots was 2823 fps. All three lots varied from this average by less than 0.5% with the individual results as follows: Lot #3060230: 0.18% Lot #3060234: 0.46% Lot #3060378: 0.28% atmospheric conditions temperature: 74 degrees F relative humidity: 59% barometric pressure: 30.09 elevation: 950' above sea level |
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Interesting thread. See your a detail man, or perhaps obsessive compulsive? Just ribbing you.
That would be David Emary. David handed me a box or two of Hornady 75 grain BTHP's at the Kansas Spring warm up match in April of 1996 in Salina Kansas. Also gave me his card and it states his job title as "Chief Ballistics Scientist". At the time the AR was just beginning to come into it's own in High Power, and the new bullet was quite exciting. Did ask dave about terminal ballistics, he told me it had a thin jacket and was a good fragmenter (is that a word). I was running a 1/8.5 twist barrel at the time and asked about it. David told me that the bullet was designed with a 1/8.5 twist in mind. I found that odd in that this twist rate is not all that common. I scribbled this on the back of his card: DON'T START MAX RL-15 25 VARGET 25 IMR 3031 22.8 2850 FPS Think I shot all of that up, would be cool if I still had it. Any how, just a bit of trivia. Got a question too. I was offered some 75 grain TAP ammo this past weekend. It was from a Y2K stash, probably 1999 vintage, in red boxes. This would be a 223 load right? Because Hornady did not sell a 5.56 load at the time? I did buy all of his IMI M193 and yellow box Remmy, and most of his IMI M855. Am not totally stupid. |
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A little bit of OCD can be a good thing.
WARNING! According to pressure test data provided by Hornady’s Dave Emary to John Feamster and published in his book Black Magic, the charges you have listed are all well above the maximum for the 75 grain BTHP bullet.
It sounds like you are referring to the 75 grain BTHP TAP PRECISION load which is a SAAMI pressure load and is basically the same as the TAP FPD load without the black nickel cases. |
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I don't doubt that. That is the numbers Dave gave me, wrote them down as he told me. He was adamant to start lower and watch for pressure signs, hence I wrote "DON'T START MAX".
Thanks for the tip. |
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That's a lot of Varget.
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In my pursuit of TAP and MK262 clones, the 24.6g to 25g is about the sweet spot for my 75g. loads. Flat CCI #41 primers, but no other problems detected. IMI cases seems to be soft brass and gives me loose primer pockets after two or so reloads of the brass at that powder charge. LC and other military brass has been fine. Accuracy has been excellent, but I have yet to get 75g to perform better than 77g. Maybe the T2 bullet will one day be released for sale to reloaders... Just my $0.02 Rmpl |
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"Our destruction... will be from another quarter. From the inattention of the people to the concerns of their government, from their carelessness and negligence..." ...Daniel Webster, June 1, 1837
What Would Yahshua Do? www.wwyd.org |
To dream the impossible dream...(sure would be sweet though wouldn't it) |
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Molon, How come the Mk262 77 gr. rounds are faster than the 5.56 pressure 75 gr.? Does Hornady download (for accuracy's sake)? |
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Awesome chart! I got some of the HSM 5.56 75g tactical to digest into my 20" accurized AR-15...
AC |
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"Were going back in the f%&$ing tank" George Dzundza -The Beast (2001)
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