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If it were my rifle I wouldn't use anything over 175 grain bullets. Obviously you can use heavier bullets but heavier than 175 gr isn't recommended by Springfield or most experts on the M1A. Personally I don't worry about the op rod bending or cracking but I feel that the pressures that it takes to move the heavier bullets are getting to the top end of what the M1A is capable of handling so you are putting a lot of strain on the receiver. You didn't say which Berger 185 gr bullet you are using but regardless of which one it is at 41.5 gr of Varget you are probably pushing 55,000 psi and when you go up to 42.5 gr you are probably upwards of 59,000 psi. Thats getting up to some pretty high pressures for an M1A.

You mention that once in a while you get a primer strike with no ignition. There are several things that can cause that, a dirty bolt (on the inside where the firing pin travels) and a incorrectly shaped safety bridge are the two things that come to mind.

Then you say that the cases are getting stuck. It sounds to me like they aren't stuck, rather they aren't being ejected due to the bolt not traveling far enough back; that's a classic symptom of short cycling and that usually implies low operating gases. A stuck case is usually a situation where you have to pound the case out rather than just manually cycling the op rod. Since your load is hot enough then it would be more likely that there is a gas leak somewhere like a loose gas cylinder plug or something adding a lot of resistance to operating system. Try to doing a tilt test (you can look up what that is on this forum).

But I have one other idea that would explain both the firing pin issue and the lack of gas. If your cases are not being sized correctly you can have problems with the head space being too long. That could cause the bolt to not close completely and that can cause the firing pin tail to not rotate all the way in to the safety bridge slot. That could cause misfires. That would also allow gases to escape around the case which would reduce the amount of gas getting in to the gas cylinder which then could cause short cycling which causes the bolt to not move far enough to eject the fired case and strip a new one off the magazine.

To check this you need to either measure the head space of the chamber and compare the case to that dimension or you buy a Wilson style case gauge. The case gauge is the easiest way to check the case dimensions and the least expensive option. There is also a quick way to check you cases. You remove the parts from the bolt and remove the op rod spring and guide. Re-install the stripped down bolt. Insert a resized case in to the chamber and then close the bolt by hand. You should be able to close the bolt without any pressure. The roller on the bolt should rotate all the way down to the right side receiver rail. If the roller wont go all the down to the rail then the bolt isn't closing all the way and that means that the case isn't resized properly. You can then try turning the resizing die down in to the press a little further which will push the shoulder back a little or you can try a small base resizing die which resize the case closer to the head. You would still have to adjust the small base die for proper head space dimension but the die will ensure that the diameter of the case is sized back to SAAMI specs further down toward the base.
 

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I always adjust the die down to the shell holder with the ram all the way up, to the point where you get a little spring in the ram. hodgens website says that the start load for varget with a 190 grain is 41 grains and max is 44 grains. They show 49,000psi on the max load with a 190. Im using the 185 long range not the vlds. It doesnt feel like normal cycling to me when I have to bang on the charging handle with a glaved fist, or stand up and push against a table to unchamber the round. But i do suspect its a resizing issue.
Depending on the manufacturer of the die you may or may not be moving the shoulder when you setup the die to their recommended standard. My RCBS die wouldn't move my shoulder where I needed it so I bought a Redding die set and that solved my problem. They also make case holders that are designed to move the case up deeper in to the die so that you can adjust the shoulder bump. Also a small base die makes the diameter smaller closer to the base of the case. I have heard of several people that have had issues like yours and they were resolved by moving over to a small base die, I'm one of them. My SOCOM had problems until I changed from a full length die to a small base. Most experts recommend using a small base die with all semi autos to ensure proper operation. It isn't always needed but for some rifles the cartridges just wont work until you use the SB die. And since it doesn't hurt anything why not use the small base and eliminate the sizing issue as a potential problem.

As for the powder issue, what rifle did they test those loads in? My guess is they used a universal receiver (they don't tell you what barrel or rifle they used) and they list the barrel as being 24 inches long. In which case the top end that they list is hotter than would be recommended for the M1A. As for pressures and such, the specifics of your case volume, seating depth, bullet length, etc. all play a major part in determining the calculated pressures and muzzle velocities. So without that info I can't be as accurate as I could otherwise but I'm just saying that anything over 175 gr is pushing the design of the rifle beyond it's original intent by a huge margin.

The 49,000 "psi" that you mentioned is a "CUP" value and not a "PSI" value (they switch between the two). PSI values are normally higher than CUP values. It would not be unusual for a CUP value of 49,000 to have a 55,000 - 60,000 PSI equivalent. There is no absolute conversion between the two so nobody can say exactly what PSI that 49,100 CUP represents but I can tell you from experience that it would be somewhere in the area of at least 55,000 PSI. I use QuickLOAD software to predict the performance of my loads and while it isn't perfect it is better than just guessing. I can tell you that if you load 190 gr bullet and use 44gr of Varget you had better be prepared for some nasty results. My bet is that the least that will happen is that you will destroy your rifle and you might end up severely injured.

QuickLOAD predicts that a 185gr Berger BTHPLR over 41.0gr of Varget, in a case with a volume of 56gr of water, and a COAL of 2.81" will produce approx. 52,288 psi and produce about 2490 fps at the muzzle. That's not a bad load as far as I'm concerned but I can get the same speeds with lower pressure using some other powders. The 42.5gr load (which is a pretty common hot load for distance shooters) would produce about 58,271 psi and a muzzle velocity of about 2560fps. And the top end of 44 grains would produce about 64,976 psi and a muzzle velocity of 2640fps...as long as the rifle didn't explode.

I didn't say it was normal cycling, but there is a difference between the case being "stuck" and short stroking. Originally you described your action as just having to use your gloved hand to work the action, to me that isn't a problem with a "stuck" case. But now you added the description of having to push against a table to extract the case then I would agree that it is a stuck case. In which case you might have too hot of a load, a rough chamber (that means there are machine marks in the chamber), a tight chamber (they reamed it on the short side of the specs). or improperly sized cases.
 

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Please take your rifle to a trained RifleSmith in the M14. It may be simple, then again
the gas system, powder, primer & bullet choice can be a danger to you & other
shooters. If I learned anything from the Master Builders who trained me it was to
save your guesses for marbles in a jar. When it comes to the M1 & M14 please
err on the safe side, find a trained builder/RifleSmith.
There is the best answer so far.
 

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Does a small base affect accuracy any?
I haven't ever read or heard anything about accuracy issues and I've never really paid any attention to any differences. But I know that I can get some pretty tight groups using a small base die. I am getting 1" - 1.25" groups with my SOCOM16 and I get under an inch with my Loaded, both at 100 yds from a bench.
 

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I don't agree, Varget is not too slow. It's burn rate is very close to or the same as IMR 4064 depending on weather and powder lot. There are an awful lot of professional long range shooters that use Varget and have for years. The main advantage of Varget is it's temperature stability. Under actual firing conditions using a 22" barrel and 168gr bullets there will be less than 100 fps (more like 50 fps in most cases) difference in muzzle velocity between Varget and IMR 4895 and the chamber pressures will be very close to the same.
 
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