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Posted: 6/24/2010 12:30:42 PM EDT
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So, being the NOOB I am with reloading for this rifle, the first loads I tried to work up were using 180 and 190 gr Sierra MatchKing bullets. I have since read that is not advisable since it can do damage to one's rifle, but I wanted to try and understand some of the results I got before I move back to the 168gr loads.
Let me preface this by saying that, not knowing what to expect, I started with low power loads based on the Sierra and Hodgdon manuals, which according to their publications were tested in long barrel bolt action rifles. Range temp was about 90F, cloudless sky. Shooting at 100yd, I first shot some factory FGMM 168gr (Pic. 1) to establish a baseline velocity and make sure the rifle was sighted in (I realize apples and oranges to the 180gr). With a 10-shot group out of a clean barrel I got a group centered +2.5" from POA. Muzzle velocity averaged 2670. According to ballistics software drop on this load is -2.5"@100yd, which gives me about a 235yd zero. Line of departure (angle of barrel to the POA) is 4.77 MOA. No elevation change from muzzle to target. Picture 1 - 168gr Federal Gold Medal Match 
With the first 180gr load (over 40gr of H4895), I got a good group, but it was centered about +4.3" from POA (Pic. 2). Avg MV was 2510. The ballistics software says bullet drop should be about -2.9". That tells me since POA and LOD never changed (didn't touch the scope) that this group should have been less than half and inch LOWER than the 168gr load. Instead it grouped almost 2" HIGHER than the 168gr load...?? Picture 2 - 180gr MatchKing over 40gr H4895 
Then I tried the 190 grain loads. First up was over 37gr of H4895 (Pic. 3). Avg velocity was 2300. Group center was +7" from POA....huh? BD on this load should be -3.5"@100yd. My calulations show that for this group, 7" above POA, the LOD would have to be a whopping 10 MOA. Picture 3 - 190gr MatchKing over 37gr H4895 
What does this mean? Is bullet timing the issue here? Could the rifle be recoiling/actuating prior to the bullet leaving the barrel? When I run the metrics for all 3 loads I get the following approx chamber pressures: 168gr=50,600 CUP; 180gr=48,300 CUP; 190gr=43,300 CUP. Without knowing exact volume and burn rate of the powder I cannot calculate what the port pressure should be based on these figures, but I would think that higher chamber pressures=higher port pressures if the burn rate of the powder remains roughly the same. Isn't this what would do-in the M1A'a op-rod or cause the action to cycle prematurely, causing potential bullet timing issues? Hopefully someone here more skilled and knowledgeable than me (that wouldn't take much) regarding this subject will be able to help me understand what's going on here. Thanks in advance. |
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Meh, M1a's and op rods are cheap. May as well follow your heart and forget the warnings. What could go wrong?
Schuster gas plug at the minimum. ETA- Your phenomena is a barrel time issue, Heavy slow bullets allow your rifle to move under recoil longer before bullet exit. |
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Quoted:
I think 175 is a safe max bullet for M1 Garand or M1A...cause if it were problem then why is LC loading M118LR with 175gr SMK? Or why was M118 Special Ball loaded with 173gr FMJBT? Or why was M72 loaded with a 173gr FMJBT? These loads were found to be to hard on the M14 when first used and have been toned down some. Pushing the envelop is where your bolt gun comes in. M1A's can and do blow up from improper reloading. These rifle's are not for beginner's when it comes to reloading. I posted the above group to show what can be done with the all time "Standard" M1A load. Reloading for gas guns should be approached with caution. And the M1A is the most finicky. There is a lot more to it than what bullet weight is too heavy. I stick with 168 as the heaviest. I don't usually shoot past 200 yards and if and when I can shoot farther the 168 can go out to 1000. If ultra long range is your game you may be better served with another platform. |
| If you are really curious about the external ballistics, it would pay to buy/borrow a chronograph and start with a known muzzle velocity. That would isolate the problem to the rifle internal ballistics or the flight mechanics. Then switching the gas on and off would isolate port bleed effects. |
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Quoted:
If you are really curious about the external ballistics, it would pay to buy/borrow a chronograph and start with a known muzzle velocity. That would isolate the problem to the rifle internal ballistics or the flight mechanics. Then switching the gas on and off would isolate port bleed effects. Don't switch the gas on and off on your M1A, it will only cause you headaches. Leave the switch alone. Standard match loads are fine with 150 through 180 grain match bullets. Stay away from the 190's. Don't run the ammo anywhere near what the manuals list for maximums. I use 40.5 grains of IMR-4895 as a maximum with 168's in a military case. 41.5 grains in a Winchester case. If you use H4895 reduce the charge to 40.0 grains even as max in Lake City, 41.0 grains maximum in Winchester cases. You can go over these loads at your own risk, it better be a whole lot better in the accuracy department to do so and it better be in the tenths or two powder wise. There is no reasonn to run faster than this. Most M1A's are running 168's at 2500 fps. Some people run them up to 2550 fps. That Gold Medal Match is too hot for your system. 155 grain bullets have come a long ways and should be tried in your rifle. The M1A fell out of grace on the high power courses before these little bullets became all the rage. Accuracy should be great and your powder charge need not be increased to get them to shoot well. Try the 168 powders and charges before bumping it up. Don't put more than a 1.0 grain increase for the 155's. Good Luck. |
| Well, having shot a M1A in HP Comp for many years....duplicating M852 with 41.5gr of IMR 4895 sparked with a WLR to launch a 168gr SMK that was held in LC Match brass.....and I had bbl that shot M118 just fine for many cans of ammo thru the gun...it did not beat the gun up....and in reality.....the 180gr SMK has the same bearing surface as the 168gr SMK. And, many of my fellow shooters were launching them out of M1A's. I shot a lot of 150gr SMK's for 200 yd league...great for lower recoil impulse and a bit cheaper then the 168gr. If you have concerns...work your loads up carefully.....and look for Nosler seconds in 30 cal to help with decreased costs.... |
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I shot NM with an M1A extensively in the 1980s and early 1990's before switch to an AR-15. I put a few thousand rounds of DCM provided Match M118 (173 gr FMJ) through it along with a few thousand rounds of handloads using DCM supplied 173 gr FMJ match bullets. This was iin addition to the Match M852 that we shot when it was available.
I never experiened any issues with bent op rods or other damage that would suggest the 173 gr bullets were beating up the rifle. However, powder charge and type is vital in an M1A or M14. In my experience, I got optimum accuracy and extremely consistent fucntioning using IMR-4064 and most of the shooters I knew who handloaded for the M1A used it as well. IMR-4895 ran a close second. If you get out of that range, you run into issues with the the pressure curve not being well suited to the gas system and that can cause serious op rod damage. I also agree that there are now some exceptional 155 gr bullets availbale. In terms of ballistics coefficients, the Sierra 155gr BTHP Palma Matchking bullet is superior to the 168 gr BTHP Matchking, is essentially equal to the 175 gr Matchking and gives up very little to the 190 gr Matchking. It's important to note however that the 155 gr Matchking and 155gr Palma Matchking are two different bullets. Personally, I don't think earlier availability of the 155 gr Palma Mach bullet would have made any difference in the decline of the M1A/M14 in NM shooting. One reason for the increased popularity of the AR-15 was that in the abscence of 5.56mm Match ammo, handloads were allowed, so it was far easier to get maximum accuracy out of the rifle. For example, in my M1A, I could get 3/4 to 1 MOA accuracy with handloads, but averaged about 1.5 MOA wth issued M852 or M118 Match ammunition. 1.5 MOA was about the lower limit in accuracy if you wanted to be competitive, so when it counted most the potential accuracy was at it's worst as you had to use issued ammunition. In essence, the switch to 5.56mm allowed me to tailor the ammo to the rifle and allow consistent 1 MOA accuracy. So when I switched, the 600 yard stage was more of a challenge (and it remains so even with 69, 77 and 80 grain bullets as they still don't buck the wind quite as well as a 168gr or 175 gr Matchking) but that was offset by higher scores in the 200 and 300 yard stages due to both greater accuracy of the ammunition and reduced recoil in the rapid fire stages. And, the far lower cost of practice ammunition was a major factor, especially when shooting 300-400 rounds per week. |
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Quoted:
The point of impact change is caused by the recoil of the heavy bullets. Seems counterintuitive, but it is the cause. When you go back to 168's or 155's those bullets will impact the target at a lower elevation. Thanks AeroE. You're the only person that actually read the post and answered my question. |
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Quoted:
Quoted:
The point of impact change is caused by the recoil of the heavy bullets. Seems counterintuitive, but it is the cause. When you go back to 168's or 155's those bullets will impact the target at a lower elevation. Thanks AeroE. You're the only person that actually read the post and answered my question. Welcome to AR15.com where people answer questions you never asked. |
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Quoted:
Quoted:
The point of impact change is caused by the recoil of the heavy bullets. Seems counterintuitive, but it is the cause. When you go back to 168's or 155's those bullets will impact the target at a lower elevation. Thanks AeroE. You're the only person that actually read the post and answered my question. Ahhhh.......But is it the correct answer. It does seem counterintuitive and is something I've never experianced |
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Quoted:
I think 175 is a safe max bullet for M1 Garand or M1A...cause if it were problem then why is LC loading M118LR with 175gr SMK? Or why was M118 Special Ball loaded with 173gr FMJBT? Or why was M72 loaded with a 173gr FMJBT? While not related to the OPs original post... ( BTW, ain't ballistics fun ?! ) Nothing personal, but remember Uncle Sugar can afford to spend vast amounts of money to keep their rifles running good....for the gov. , spending money on new op-rods,re-tuning etc. means diddly-squat to them. And if you haven't read these articles, they are very informative...http://www.zediker.com/downloads/14_loading.pdf.....and...http://www.zediker.com/downloads/oncefired.pdf |
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