AR Sponsor
Posted: 12/31/2004 9:37:11 AM EDT
|
There is just so much information here, that I need help answering my question (plus, it appears that there are many others who are much more "in the know" than I). Here is my dilemma. I have my 16" AR (1:9 twist) set up with the ACOG TA01NSN model. Even though it is designed for 62 grain FMJ's, the company states that changing the bullet weight does not affect the usage of the scope to any appreciable degree. Thus, I am searching for a combination of ammunition that will best serve my needs. I would like to have some mil-surplus ammo for training purpose (and on hand JIC the SHTF) but I would also like to find a "matching" duty type round (ie: ballistic tip, v-max, hollow point, soft point, etc) that I could typically load for serious social purpose. Does this make sense or am I asking for a lot or something that seems a little rediculous? Some might say that just limiting myself to a single round would be a better choice, but that can get awfully expensive with the non mil-surplus stuff. Given the fragmentation velocity for what it is, it seems to me that there are a number of other bullet designs out there (ie the ballistic tip or v-max) that would work better at longer distance than the FMJ's. I welcome your opinions, thoughts and knowledge. |
|
Normally, the recommendation is to first choose a duty load and use that to zero your irons and optics with. That ammo should meet all of your requirements, including terminal ballistics and accuracy. Then, shoot whatever practice ammo you like. While there is likely to be a small change in zero, it shouldn't be a problem at most common "training" ranges. And if, during training, you need to take a longer shot or for whatever reason, you need super accuracy, you can switch to your duty load for that portion of the training. Most 5.56 ammo shoots flat enough that the difference should be within the thickness of your reticule lines out to about 400m. There is no need to try to get an exact match, and it would be an especially bad idea to compromise your duty load in order to try to achieve such. For more info on selecting a duty load, read www.ammo-oracle.com -Troy |
|
Thanks for the info and advice. It makes sense. Next question as I don't have the time to research: What has been peoples experience with the 1:9 twist as far as bullet weight? I don't have the money to switch the barrel to a 1:7. What can I get away with in my 1:9, with say Black Hills ammo? The 75 or 77 would be great, but I don't imagine I would be able to get it to shoot from my 1:9. |
|
Some members have reported good results with their 1x9s and bullet weights in the mid to high 70's, others have not. Interestingly, the Kuleck & Duff AR-15 Owners Guide says optimum bullet weight for a 1x9 is 50 to 69 grains, while optimum for a 1x8 is 62 to 80. I have never shot anything heavier than 69 gr Federal Match in mine so I can't speak from personal experience. FWIW, I suspect that having good results with a mid/high 70 gr bullet in a 1x9 is a combo of three factors (1) a "1x9" that is actually a tad faster but still marked 1x9 by the mfgr, (2) a barrel in good shape with particularly high lands and (3) the danger of forming generalizations. Only recently I read that bullet length is the real factor in the stabilization formulas, not weight. I have found that truth out for myself. My DPMS 1x9 is deadly accurate with the Winchester 62 gr FMJ round, but has a harder time being as accurate using the M855 round, yet both are 62 gr. The difference is that the steel core in the M855 is lighter than the same volume of lead in the FMJ, and so the M855 bullet is longer than the Win 62. That difference is enough to influence accuracy. As someone said some time ago, each gun is different. You have to experiment to see what works and what doesn't with yours. |
|
For a Duty Load I might start with the Black Hills 68gr OTM as it is a good terminal performer and will likely do well out of a 1/9 barrel. For training you could use thier matching reloads when normal plinking/surplus rounds won't do. I would also consider a magazine of dedicated barrier penetrating rounds like the Federal Tactical in 62 gr for work behind glass. Contact the LE sales department of the ammo company you like. They will give you .gov prices for as little as one case and free shipping with as few as five. |
|
Okay, get ready for this one... I had requested a LE catalog from Hornady regarding their TAP line and finally received it today. According to the information, they tested their 75 gr. TAP from a 16" 1:9 (Bushy). Hornady doesn't quote accuracy tests that I see, however they do show that they did not test the 75 TAP in a 1:12 gun and noted that the 1:12 is too slow to stabilize the 75 gr bullet, which would lead one to believe that the 16" 1:9 gun was okay. How does this load compare with the heavier loads from BH in ("terminal") ballistics? Also, with the chart listed for the 16" 1:9 testing, they quote the 75 TAP to have a maximum performance range of 200 yds, while the 55 gr TAP is 300 yards and the 60 gr TAP is 275 yds. Doesn't this seem to contradict some of what I have read elsewhere on this site? Fed loads their LE TRU line to mil-spec, but doesn't have a heavy (70's gr) jhp loading (64 is the heaviest in their TRU line and doesn't fragment much according to their information). From what I understand, some of BH's loads are mil-spec (or is the only one the mk262 stuff?). Does anyone know if Hornady loads their TAP line to mil-spec...and if there are other loads by BH that are mil-spec? What else (if any...is there a 75 gr load like the 262?) is out there that loads mil-spec (ie: NATO pressure, military cases, etc) and has long(er) range fragmenting capabilities (that I can shoot in a 1:9 twist)? UPDATE: Looking through my info, I also found my LE pricelist for BH. According to notations they have there, 68 and 69 gr bullets need 1:10 twist, 73 and 75 gr bullets need 1:9 twist and 77's need 1:8. That helps a bit...but it still leaves some questions unanswered for me. Ideally, I would like something that fragments (out to at least 300 would be nice), which probably means a heavy jhp. I would like it loaded to mil-spec with NATO pressure and military brass that is sealed. Since I now have info that it needs to be 75 gr and lighter...is there such an animal out there? Or am I stuck with BH 75 "Heavy Match Hollow Point" or 75 TAP (which I THINK I have seen the 75 gr loading listed on some green/yellow/red tables fragging out to 200 yards)? And... Who makes the "Heavy Match Hollow Point" bullets that BH uses? And, I have seen a thread stating the Mk262 will drop about 2moa less than the equivalent red box from BH. How does the 75 compare to the 77 in terms of ballistics? By the way, what does "OTM" mean? I see that periodically, seemingly in reference to the heavy Sierra and Heavy Match loads and possibly in reference to the military stuff??? And is the Mk262 pretty much not available (or at least very limited supply)...with some special run of it coming via pre-order from one of the ammo websites? Whew. That's a lot to think about. I need help. |
AR Sponsor