From what I remember reading from Springfield, about 150 FPS is lost in going from the M1A to the SOCOM velocity with heavier bullers, and about 200 FPS with lighter bullets.
On the web I found an old magazine article (from one of those websites that archives them) where someone took some bolt-action gun, fired some shots with bullets of various weights, then cut off a few inches and re-crowned, then took some chrony readings again. I'd say the results were roughly close to the Springfields in terms of percentage of FPS lost, though slightly greater. So I'd say Springfield is a little bit optimisitic.
Due to the velocity variance caused by the difference in barrels/chambers (chronograph several rifles with the same barrel length and the same lot of ammo, and you will get a 150-200fps variance) it becomes very difficult to say becuse rifle 'A' gets xxxxfps with a 22" barrel than rifle 'B' will get xxfps less because it has a 20" barrel.
Further complicating this is tha the velocity loss/inch is non-liniar (although for the range usually discussed it's not far off), IE 12-15" may be 200'/" while 20-22 might be 30'/", 26-28 might be 20'/", but when you get out to 34-36 the difference might only be 5'/" while a 38" barrel might be faster than a 40". These numbers are for illistration only.
Side note, I personaly had a 26" barrel (30-06) that struggled to get to 2750fps due to a sloppy chamber/throat. Cutting it to 25" and putting in a tight 30-06 chamber/throat brought it up to 2995 with the same lot of ammo.
I have seen results from 3 different tests run on .308 rifles. One (a bolt gun, I think) chopped the barrel in 1" increments, and had a velocity loss of 100 fps going from 24" to 18", but lost another 200 fps (300 total) going from 18" to 16". (This is similar to another text done by a precision rifle mfgr, which said it was possible to get very close to peak .308 velocities in and 18" barrel.) Since this test controlled all variables and changed barrel length on the same barrel, this is probably the most impressive (and useful) test of differences due to barrel length alone.
A second test just compared a GI chrome lined 22" barrel and the unlined commercial Scout 18" barrel with 10 types of ammo. There was a difference of -178 fps, but this one used different rifles, barrel specs, and bore treatment (i.e., the chrome lining could have increased pressure and velocity, etc.).
A third test used an 22" M1A and a 16" AR10 with three types of surplus ammo (Hirtenberger, Radway Green and CAVIM) and recorded a velocity loss of 131fps, 141fps and 169fps between a 22" M1A and a 16" AR10. This one has lots of variables, and was on different rifle platforms, so it would not be appropriate to generalize from this test.
VA27-
Is that for a Socom16 or a 18" barrel SocomII?
By the way thank you very much for some real Chrono results. Lots of creative info flying about the 'net regarding the Socom velocity loss. I gotta get one of those dandy machines!
Mine's a SOCOM 16. The SOCOM II (with all the rails) is also 16". The Scout is the one with the 18" barrel. The load to use in the SOCOM is the HSM Police load. It matches the surplus NATO velocity in the M14.
In the real world, the velocity losses out of the SOCOM don't amount to much unless you're shooting past 5-600 meters. And if you are, just hold higher. Jeepers! You'd think it was the end of the American way of life just 'cause you lose a coupla hundred fps!
You guys gotta get out more. Go shoot a 45/70 at extended ranges. Then try a 30/30. Then pick up your SOCOM. See what I mean? No worries.
From what I remember reading from Springfield, about 150 FPS is lost in going from the M1A to the SOCOM velocity with heavier bullers, and about 200 FPS with lighter bullets.
On the web I found an old magazine article (from one of those websites that archives them) where someone took some bolt-action gun, fired some shots with bullets of various weights, then cut off a few inches and re-crowned, then took some chrony readings again. I'd say the results were roughly close to the Springfields in terms of percentage of FPS lost, though slightly greater. So I'd say Springfield is a little bit optimisitic.
Unfortunately, I don't have any links for you.
Since this post I made over two years ago, I have chronied my Socom II, and 150 FPS is lost versus a M1A using 150 grain bullets. The Springfield estimate is accurate.
Unfortunately, I had some issues with failure to extract, so I sent it back to Springfield. One of the changes done at the factory was a new bolt, and now the firing pin fails to detonate the primer sometimes, and it still fails to extract other times. I also got an extended top rail that goes over the bolt done at the factory, and occasionally the brass bounces off that and gets caught as the bolt pushes the next round into the chamber. The overall jam rate before I sent it in was about 1 in 60, and now it is about 1 in 50. Accuracy is a little better than the old Mini-14s. Overall I'd say the rifle is mediocre and would discourage anyone from plunking down the money on one of these, as they aren't cheap.
I must be understanding the measurement wrong. I just did the transfer on my Socom II, and was surprised when the dealer measured the barrel, and sure enough 18". The end is recessed with a larger bore where the comp ports are, but it looks like only an inch of recess. Not to say it really makes much difference. Maybe there were more than one SocomII. I'll take a closer look when the waiting period is up.
Just got it back 17 3/4" from nose to tail, but the compensator recesses about 1 1/2". So the beginning of the chamber to the end of the rifling is about 16.5". In otherwords, I guess I goofed.
It shoots pretty well. Muzzle blast is not much different from the scout from the shooter's position. It's significantly heavier than the Scout. The rear sight diopter isn't as much of a handicap as I thought it would be, but it is still too large for my liking. The BDC is a nice feature. I doubt I could shoot better than 3" without changing the rear sight. The trigger is really nice, though. I am starting to think this wasn't such a poor choice of a rifle.
Incidentally, I am still a little shocked that anyone can go to the range with other m1a shooters and every one has had problems. I do not personally know of anyone who has had a significant problem with an m1a. Maybe I just know a lot of lucky folks! I wonder if their quality has recently gone downhill.
CI, Sorry to hear your SOCOM hasn't been 100%. Have you sent it back again?
I guess I won the lottery on mine 'cause it's run fine and been a hoot to shoot.
I'm even more ticked now because I just cleaned it after shooting about 300 rounds of S. African surplus over the 4th of July weekend, and the bolt roller fell off when I pulled the bolt out. Apparently the snap ring that holds it on somehow fell off or just disintegrated. At least the rifle can still function, as the roller can't fall out when the rifle is assembled.
But man is ticks me off that a $1850 rifle jams about 1 shot in 75 (I don't think it is quite as often as I mentioned in my last post). Not to mention the fact the black paint flakes off the stock after minor contact. My friend bought an M1A too and it jams at about the same rate, even after it came back from the factory for service. And I have to call Springfield, because they didn't reimburse me for the cost of shipping my rifle for service, as they said they would. Everyone I've talked to at the range has had to send their M1As back too because of defects more serious than mine. I suppose I'll send my rifle back for warrant service again, but maybe I'll wait a while so whatever breaks next can get fixed at the same time. I don't understand how the M1As ever got a good reputation. The majority of recent owners I have met do not have a good opinion of them.
If I didn't know any better, I would say that M1As were made in China by cross-eyed machinists and sold by the pound.
Originally Posted by totalloser
I must be understanding the measurement wrong. I just did the transfer on my Socom II, and was surprised when the dealer measured the barrel, and sure enough 18".
No, you must be measuring from the wrong points. Springfield's own website says 16 inches. It is just as long as the Socom 16, and they call it "16" for that reason.
I stand corrected on the Springfield Armory quality. No longer impressed at all now that I own one. Poor metallurgy, and poor fitment of parts. Definitely not worth the money. Not if you expect good quality, anyhow.
VA27: Thanks for the FPS measurements on those .308 ammo types from different barrel lengths, it's very helpful! If you ever test any other types, please post the results here, as it gives a good idea of just how much speed you give up when shortening the barrel with various rounds.
How do you like your SOCOM M14? I've seen pictures and they look pretty slick.
totalloser: You say you've been somewhat disappointed with your Springfield Armory. Have you (or anyone else here) every tried a Fulton Armory M14? Or perhaps know someone who has one? What do you guys think of the quality of their M14's?
Have you (or anyone else here) every tried a Fulton Armory M14?
What do you guys think of the quality of their M14's?
I looked into a Fulton build, but luckily I was steered towards Ron Smith @ Smith Enterprise, Inc. (SEI).
SEI builds M14s for our military and they build civilian rifles to the same high standards when time permits.
So far, SEI has built 4 M14s for me and the results have been nothing short of outstanding.
I also got more bang for my buck by choosing SEI over FA.
I have no experience with other manufacturers, but was EXTREMELY disappointed to find that none of the parts in my SA rifle were case hardened. And the fitment of parts made it hold the bolt open when fired due to the angle on the bolt hitting the hold open lever even with a full mag. Plus the front part of the op rod was impacting the reciever, dinging both. I have heard tales of the op rod sailing off the gun, and I suspect it is due to poor fitment at this point. The op rod is pushed sideways from the impact. Oh, yeah, and they stuffed the receiver into the stock with the fitment too tight, and it cracked the stock. It was really difficult to spot the cracks, but when it got a little oil in them you could see it following the cracks on the right side of the stock.
I corrected all the fitment issues, and it's an apparent reliable, accurate shooter, but I am SORELY disappointed that it won't have the resistance from wear that a properly heat treated rifle would. I've toyed with the idea of stripping it down and case hardening all the parts myself, but it is a HUGE hassle, that should have been done at the factory.
PS were I to do it over, I'd get an LRB rifle www.lrbarms.com I may do that yet, as my buddy want's my Socom (knowing what I know). LRB not only heat treats everything properly, they offer a receiver with two dovetails in the reciever and a picatinny rail to fit in it. This gives you the best scope mount I HAVE EVER SEEN on an M1A, and it won't have a bolt on the left side of the receiver to dig in your spine when the rifle is slung, like most m1a scope mounts do.
Hi guys:
Just wanted to post my 2 cents. I have an M1A National match that was built by the custom shop at Springfield Armory about 15 years ago. I have literally run thousands of rounds through it. Although it no longer will hold sub-MOA groups it will shoot 1 MOA groups with my special recipe. I have only broke it down completely once for a full servicing. It has never done anything but operate flawlessly and it ALWAYS hits what it is aimed at On a scale of 1 to 10 I rate this firearm an 11
Welcome!! Your 2cents is identical to what mine would have been before buying my Socom. I am not new to m1a's I have a couple buddies that have had m1a's for about... I guess about 15 years. One a NM with a bedded stock bdc/ranging scope etc, the other a service style. These rifles' quality is what led me to my purchase. I think things have changed at SA.
Incidentally, an easy way to see if your parts are case hardened it to nick a small part (other than the barrel) with a file. If it nicks, it's not case hardened, as the case hardening will be harder than the file.
My chagrin is due to the fact that if all the parts are case hardened, you can't wear it out. The barrel may wear out, but then you can rebarrel. Quality of yore. Machines to built a lifetime- or many lifetimes.
He has a lot of fun and from I have seen compared to other assault rifles, excellent accuracy and results with this rifle. Like they say here, back in the day, I wish I would have had one in Vietnam. It is a great rifle.
It's really interesting how only about 150 fps is being lost by going to a 16 inch barrel on the M14 and semi-auto variants. Still leaving the .308 with plenty of punch, but making the M1A's with these shorter barrels easier to maneuver in close quarters. For really reaching out, you want the full barrel length, but from close to medium range, it will work great with the 16 inch barrel for most things.
It's really interesting how only about 150 fps is being lost by going to a 16 inch barrel on the M14 and semi-auto variants. Still leaving the .308 with plenty of punch, but making the M1A's with these shorter barrels easier to maneuver in close quarters. For really reaching out, you want the full barrel length, but from close to medium range, it will work great with the 16 inch barrel for most things.
Information I've been able to gather:
The 16.25" barrel will deliver approximately 140 less FPS than a 22.0" barrel.
The 16.25" barrel delivers about 40 FPS less than the 18.0" barrel.
Thanks for the info. So unless you're going with the full length 22 inch barrel, you might as well just go right to 16.25 inches, not much point of anything in between. Unless maybe the shooter wants to load high pressure ammo and can get more out of the 18 inch barrel than just 40 fps higher. But in that case, the 22 inch barrel would be the best choice most of the time (unless the shooter really wants to keep the rifle more compact), because it can benefit the most from such hot ammo.
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