m-1c/m-1d differences?
is the only difference the flash suppressor?
M1CGARAND_RifleLeft.jpgm1cm1d_sniper_rifles_800.jpg
also, i'm thinking that cone flash suppressor probably degrades accuracy what with it rattling around so much.
it might add to collector value
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I did find this:
LazyEngineer12-16-2012, 09:59 PM
Curious what affect this thing has on accuracy, I did some tests and compiled some data - both today, but as well as including some older data.
Equipment: M1D - both with and without a T37 flash hider. This is an aftermarket T37 - probably cast. (it is as pictured on the right)
http://www.billricca.com/trans/t37_bottom.jpg
There are claims that such aren't as good as the authentic military ones. But this is what I had. Visually, alignment seemed good.
Up until today, I had only fired w/out the flash hider. Below is a list of Average--to-Center performance data, in MOA. Note that average to center is not extreme spread. But is more statistically useful.
Most of this data is fired at 100 yards, from sandbags.
1.5
.529
1.18
2.23
1.01
1
1.18
.76
.738
.893
.548
1.25
.485
.657
.643
.748
.695
for an Average performance of: .94 MOA as the average distance of an impact to center of that grouping, for the M1D w/out the flash hider.
Let's toss the 2.23 and the .529 as outliers, taking it to 0.89 MOA
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Add the T37 flash hider.
2.5
2.4
1.8
1.3
1.16
1.1
.827
1.25
.638
1.958
1.087
.77
And the average of those is 1.4 MOA average to center point of grouping.
But, much of that was ball ammo. And for some reason, the gun really tightened up towards the end. So for the sake of bias, let's discard some data. Let's really try to push this with questionable subjective selecting. Tossing out the worst grouping of ball (that particularly lot wasn't shining in either case): so cut the 2.5, 2.4, and 1.8. And then toss the worst of the match ammo (Because it just started off bad as the gun was settling), that's the 1.96, and the 1.25. Now that any statistician out there has a very raised eyebrow, let's take a look.
That leaves me with an average to center of 1.01 MOA.
Still not as good as the gun shoots without the flash hider.
Conclusion,: this T37 detracts from the accuracy of this M1D rifle. A shame really, because it does look cooler with it on there.
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218bee12-16-2012, 10:12 PM
Wow...cool data...good job...I agree about the cool factor with it on...
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tank mech12-16-2012, 10:29 PM
I have a 10.5 barrel on an ar platform before I installed the 5.5 flash hider I set my scope after that the whole shot group moved about 1 inch to the right and the rifle was much louder.Go figure?
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AB9AD12-17-2012, 02:40 AM
I used a repo T37.
Took it off, I did not the gases leaking back out of the barrel splines.
I guess over time they could be cut.
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Brazos12-17-2012, 10:03 AM
I see a 10% variance as within the margin of error considering the quality of ammo you are using and the fact that you are using a repro FH. But the ammo is the largest variable.
Shoot it again using all the same lot of ammo. You would also have to let the gun cool completely between strings. Or fire each set (with and w/o FH) at the same time spacing to allow the rifle to heat the same overthe course of the string.
I do think they effect accuracy, after all is said and done.
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lapriester12-17-2012, 10:24 AM
Once zeroed I never saw an appreciable difference in accuracy with it on or off but, just couldn't stand the tuning fork ring on every shot that it produced so it went in the box. The early cast Hart threw the ballance of the rifle so far off I never shot it with it on figuring it would certainly have an adverse effect on accuracy. It felf like I put a 1# lead weight on the end of the barrel. Zeroe did change slightly on and off but that would certainly be expected with an additional appendage on the end of the barrel. It's a device that is either on or off and you should zero accordingly once you decide if you like the tuning fork out there or not.
As far as gas leakage as someone mentioned? The T37 fits and screws on just like any gas cylinder lock.....in fact it is the gas cylinder lock when installed. If you had one that leaked so much gas you worries about cutting the barrel threads you truely did have a repro that was a POC. My USGI T37 fits like a glove and, if anything fit tighter than any standard gas lock I have. I never once saw any evidence of gas leakage.
Larry
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LazyEngineer12-17-2012, 12:39 PM
I see a 10% variance as within the margin of error considering the quality of ammo you are using and the fact that you are using a repro FH. But the ammo is the largest variable.
Shoot it again using all the same lot of ammo. You would also have to let the gun cool completely between strings. Or fire each set (with and w/o FH) at the same time spacing to allow the rifle to heat the same overthe course of the string.
I do think they effect accuracy, after all is said and done.
Thanks, this was done, just not really shown in the above data dump. As a general rule, all side/by/side comparisons showed worse performance with the T37. However, M1's are just weird rifles. For example, two test methods were used, seemingly the same, but giving drastically different results.
Method 1. At a benchrest, place rifle on a pile of sandbags, pushed forward so the trigger guard touches the bag. Use left hand on the rear of the stock to adjust aim. Fire. Dismount from the rifle, lean rifle forward so it is balanced on the bag (10-20 degree down). Lean over to pear through the scope and mark the impact with both hands in score book.
Method 2. Same as 1, but keep rifle level, firing hand on it to stabilize, peak through scope to make sure nothing is amiss, lean back to the rifle, and fire. No recording of impacts until the string is done (so never had to take right hand off the rifle).
Method 2 had roughly half group size of method 1. We're not talking .25 MOA groups here either, some of the Method 1 groups had extreme spreads of 6" or more.
With that much error in testing, any 1 on 1 comparison of just one or two groups can be dominated by error. So I approached the analysis using as broad a data set I could get, and then compare the overall averages.
However, I did also do side/by/side comparisons. In pretty much all cases, the T37 shot worse. But, the T37 made the M1 muzzle heavy. So when using Method 1, the rifle had to be leaned forward between shots to prevent from falling off the bags. This either moved the forestock (let it rock forward), or was a significant enough disturbing of the rest and shooter mounting to cause affect - not really sure to be honest. I do know that when you do something like this with an AR, it doesn't go nearly this wild just by dismounting it - hence my suspicion of the hand guard. But I really don't know. I do know that when I used method 2, the groups tightened up - a lot (Those are the smallest numbers reported). Obviously I stopped using Method 1 when I noted this behavior.
AR's really spoil you. You can be pretty sloppy, and the damned things just shoot great. You can be careless about checking if the foresight is really centered in the peep, and the gun still shoots great. You can dismount them and remount them, and they still hit the same place. You can shoot it cold, fouled, clean, or hot, and they always hit about the same place. Not so much with an M1. Shoot a match with an M1 and they always move impact when they heat up.
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