Friday, June 4, 2010

Praxis: The semi-auto base of fire weapon.

A base of fire is a military term for a supporting force that provides overwatch and covering fire to other advancing units while they are executing fire and movement tactics. A base of fire can be a platoon during company fire and movement, by individual armoured fighting vehicles (esp. tanks) or infantry sections, in platoon fire and movement, or even by fireteams or individual soldiers, in the final stages of an assault. -- Wikipedia.

Suppress the Enemy.

a. The platoon leader determines if the squad in contact can gain suppressive fire against the enemy based on the volume and accuracy of the enemy's return fire.

(1) If the answer is YES, he directs the squad (with one or both machine guns) to continue suppressing the enemy:

(a) The squad in contact destroys or suppresses enemy weapons that are firing most effectively against it; normally crew-served weapons.

(b) The squad in contact places screening smoke (M203) to prevent the enemy from seeing the maneuver element.

(2) If the answer is NO, the platoon leader deploys another squad and the second machine gun team to suppress the enemy position. (The platoon leader may direct the platoon sergeant to position this squad and one or both machine gun teams in a better support-by-fire position.) -- FM 7-8 INFANTRY RIFLE PLATOON AND SQUAD, Chapter 4, Battle Drills.

Tricked-out SKS with bipod. This would make an excellent base-of-fire weapon when used with a large capacity magazine.

I have mentioned before in these pages that I was given a Yugoslavian SKS parts gun and that I am re-working it into a semi-auto base of fire weapon by modifying it to use AK mags, adding a bipod (which attaches to the bayonet lug -- bye bye pig sticker), etc. Why on earth would I do this? The project is a proof of concept experiment.

Based upon anecdotal evidence, it seems to me that the SKS remains the most common semi-auto rifle in militiamen's (and women's) hands today. And the 7.62x39 likewise remains the most common caliber found, in both AK's and SKS's. There are millions of SKS's out there, with the Yugoslavian M59/66s representing the latest (and perhaps last) big influx of the many Simonov variants.

The Yugo is a half-pound heavier than the standard SKS and almost four inches longer. The extra weight and length is not a bad thing for slinging grenades. Nor, I might add, is that a bad thing for a bipod-supported base-of-fire weapon. The bipod and extra-capacity magazine add even more weight. When your are counting on the bipod to provide a steady rest for accuracy and the 40-round stick or 75-round drum for volume, the extra weight helps defeat recoil and provides stability. This is a "goodness thing."

I like the SKS better than the AK variants for semi-auto aimed fire because I find them to be much more inherently accurate. (I make the observation here only, without wishing to get into the eternal argument about WHY this is so.)

So, if I am looking to create a semi-auto base of fire weapon in a commonly-occurring caliber, I could do a lot worse than the Yugo M59/66 for a platform to build one.

Why a semi-auto base of fire weapon? Because --

a. (and ask any old BAR man this) semi-auto can be manipulated from a bipod more accurately than full auto yet almost as rapidly;

b. unless you're fighting the Chinese People's Liberation Army in an alley, full-auto fire -- especially in the hands of a less-than-experienced shooter -- is most often wasted;

c. we lack the logistical tail to support full-auto weapons and must be sparing with ammunition expenditure;

d. Class III weaponry is (wrongfully) denied to the average person these days. Not much we can do about that at the moment but work around it.

Our fire teams need a base-of-fire capability. If we could expect to field entire squads of men and women, Appleseed trained, who could operate as designated marksmen and hit everything they aimed at with individual shots every time, then we would have far less need for volume-of-fire weapons. Since in the event the need will overwhelm the supply of trained marksmen, we can substitute the latter.

There is also the need for training buddy teams, fire teams and squads in the tactics and battle drills of base-of-fire. It may be that one day in the not so distant, we will find M240Bs and M249 SAWs lying about on the road, abandoned by their former Federal police owners or by gang members. (But then, I repeat myself.) If so, we need to have gunners used to the concepts and practices of base-of-fire. Better to get used to them on a substitute platform like a semi-auto, bipod mounted rifle now, so the transition is eased later, don't you think?

Now, one of the necessities of base-of-fire weapons is larger magazine capacity. In order to put out volume, even semi-auto volume, and sustain it you must have more ammo to call upon with slowing the process by changing out magazines. Therefore, to prove the concept with a Yugo M59/66 means modifying it to accept AK mags. This is hardly an undiscovered country. The Chinese SKS-M and SKS-D variants were manufactured to accept AK mags.

Norinco SKS-M "Paratrooper."

Chinese SKS-D.

Indeed, some of these rifles came into the country before the Clinton import ban with full-auto trigger groups. (These can be readily identified by the button on the underside of the trigger group which allows the operator to push it back and forth for semi-auto or full-auto fire.) Almost all of these were caught by either the importers at the time, or the various gun shops who sold them. (There was a rumor going around that the ATF was slipping these in to shipments just to test the compliance of gun store owners. Probably not true, but it is exactly the kind of sneaky shit that agency pulls from time to time.) Almost all were caught, but not all. I heard as recently as three years ago of a fellow who bought an SKS off an individual at a gun show in Kansas and didn't realize until he got the rifle home that it had the magic button providing low and high gears. I never did hear what he decided to do with his radioactive trigger group.

A Yugo M72 semi-auto RPK-style rifle with 40 round magazine. A base-of-fire weapon, even a semi-auto one, needs a larger magazine capacity than a rifleman's piece.

AK AES 10B heavy barrel with bipod and drum magazine. Note the carry handle, an excellent feature on a base-of-fire weapon.

During the 90s, before the ATF came out with their ruling banning the use of shoestrings, we used to practice base-of-fire in ambushes, etc., with semi-auto RPK-style rifles and Chinese 75 round drum mags (using blanks, of course). The rifle would run until you caught the bolt handle. Then you would cycle it by hand and start again. It made a dandy LMG substitute in FTXs. Alas, those days are gone.

The drums were very handy, and are just the thing for base-of-fire weapons. They are not as greedy of length as the long 40 rounders, allowing the gunner to get lower to ground -- a critical need when the rounds are flying both ways.

This is a Korean-made copy of the Chinese 75-round drum, opened and empty to show the mechanism.

Here is a loaded but open Romanian drum, showing how the rounds fit in.

Here is the back of a Chinese 75-round drum showing the wind-up key. The mag should be loaded, but not wound, until just before moving out for serious work.

My reworked Yugo will use drums and have a carry handle handle as well as a bipod.

Once you decide to use drums in a base-of-fire weapon, you need to decide how best to carry the bulky and heavy things. The Chinese issued this sort of drum carrier.

It is made of thin cloth and has a shoulder strap, but doesn't protect the mag from banging around much. It has the typical (but slow) Chinese wood toggle fastener.

This, however, is a much better way to carry drums on a combat harness.

This is the standard pouch for the USMC First Aid Kit. This pouch is MOLLE compatible and will attach to all DOD vest systems. It has an interior divider to separate your medic gear and features a color-matched low-IRR Fastex buckle closure. Its approximate dimensions are 7"H x 6"W x 1 3/4"D (expands to 5"D at opening).

You can find these boogers at various outlets on the web and often in surplus stores. My favorite local store, AA Surplus in Leeds, has them for example. (There I go pimping Darryl again.)

Be sure and get the original US issue pouch and not a knock-off from China. The tag stitched into the back of a USGI pouch reads something like this one I got from Darryl:


One final word. If you decide to go the route of a 7.62x39 semi-auto BOF weapon, you must become practiced with it firing from behind cover while prone with the bipod at targets out to 400 meters. Try for three round "bursts" on target. Take a look at the propaganda image of the RPD at the beginning of this piece. I put it there for a reason. (Ignore the moke with Chairman Mao's little red book.)

I will post photos of the rifle when I am finished.



Anonymous said...

"I was given a Yugoslavian SKS parts gun and that I am re-working it into a semi-auto base of fire weapon by modifying it to use AK mags,.."

The Yugo SKS is O.K. but adapting them for magazine use will prove to be a sticking point. Their followers are prone to binding which causes a FTF. Releasing the magazine allows the remaining rounds, which are no longer under spring tension, to spill to the ground.

Good luck with the project but have a Plan B.


Temnota said...

Be mindful of what the magazine mod will do to the compliance status of the rifle....I think, but am neither a lawyer nor an expert, that foreign parts-count rules will apply after the mag mod is done, and if you haven't removed the grenade launcher, that may prove problematic as well. Why give the feds a free bust?

Kevin Patrick said...

Tech sights would be a welcome addition to this rifle.

I don't work with or have any investment in TS, but I have two sets for rifles I own. Positive clicks and an increased sight radius are invaluable.

Also, Appleseed is a marksmanship and heritage organization (

However, it does not maintain or endorse any connection with any groups outside of those goals, or militia outside the context of April 19, 1775.

It's good education and instruction, and I highly recommend it, I'm an Instructor in Training with AS, for full disclosure.

--- KP

Dutchman6 said...

"Tech sights would be a welcome addition to this rifle."

Already in the gunsmith's hands. The whole point of creating a BOF weapon is accuracy at distance, since support fire is by definition stand-off. Lengthening the sight radius is critical to that.

The leaf sight base will be used to install the carry handle.

-- Mike

Dutchman6 said...

"The Yugo SKS is O.K. but adapting them for magazine use will prove to be a sticking point. Their followers are prone to binding which causes a FTF. Releasing the magazine allows the remaining rounds, which are no longer under spring tension, to spill to the ground."

The bolt must be modified to strip the rounds reliably, deep and clear of surrounding metal including especially the feed lips. The magazine catches -- forward and rearward -- must be done precisely by someone who knows what they're doing. Of course you lose the bolt hold open on the last shot. When completed, we will have a narrative, with pictures, of what was done so it can be imitated.


d'Heat said...

Speaking of Appleseed, how does one progress from learning basic marksmanship to learning how to shoot, move and communicate? I assume the answer is to join a group of like-minded, knowledgeable individuals and practice. (If that's not the answer, what is it?) Nevertheless, how does one find a group to join? I live in NE FL and have searched in vain for such a group.

Wyn Boniface said...

I do not think modifying the SKS will help. BTW keep 992r compliance in mind when changing the SKS. IMHO it would be better to use an RPK clone or a belt fed semi-auto clone of some type. That or go all the way and get a tax stamp on a M60 in the NFA registry pre-86.

J. Croft said...


I'd have the bipod a little further back to improve the arc of fire.

I've owned a couple SKS-D's and several regular SKS rifles with the zytel duckbill magazines. I've seen TWO conversions of the standard SKS to the AK mag feed so I know it's possible. It's also possible to find a SKS-D but that's a 16 inch barrel. No I don't know the exact thread or if it's simply pinned but perhaps a longer Yugo barrel could be mated to the SKS-D receiver.

On the Tech Sight, if it's the 200 model you can do elevation adjustments it's just that you will have to do some shooting and some math to figure out where it shoots at longer ranges, if you give up the tangent rear sight.

I've suggested an improvement to the 7.62x39mm cartridge's downrange performance by using a sabot for a streamlined 6.5mm bullet-essentially a Poor Man's Grendel. That's HERE:;f=12;t=000257

The Infamous Oregon Lawhobbit said...

Not to unduly widdle on your choice of an SKS w/mag for a base of fire weapon - you need to work with what you have, and the price/utility curve is always an issue - but.....

Been there, done that, on this sort of thing and the much shorter description of "suppressive fire" is "to keep the other guy's head down while your maneuver squads come around and whack him." That said, by using 7.62x39 as a caliber, you're restricting your range to 3-4 hundred meters, which is also within range of any likely opponent's weapons.

I'd suggest, just for discussion purposes, that you'd be much better served with a 7.62x51 NATO (i.e. .308, sorta) platform - the HK comes to mind - and be able to provide effective suppressive fire from 8-9 hundred meters away. And now that there are (relatively) inexpensive drum magazines on the market, heavier caliber supporessive fire becomes much more feasible - vis a vis trying to find some of those belt-fed semi-autos out there.

Anonymous said...

For some reason, I cannot get too about the 7.62x39 round. How about an AR10 instead in 7.62x51?


Dennis308 said...

For rapid semi-auto fire Mike you might want to see if you can attach a muzzle brake to your SKS. I know the 7.62x39 does´t have much recoil.But for long range sustained fire to be accurate it will need to be steady and a muzzily brake will be a big help in that goal.Especially out to the 400 yard mark


Jimmy the Saint said...

Of course, all of this presupposes that you live in an area where you can legally have a high-capacity magazine. If you're stuck somewhere like the People's Respublik of Kalifornia, your options are very, very limited.

Anonymous said...

Two friends and I went in on a PKM package a few years ago. I also own an RPD, as does another member of the group. So, we are pretty well covered for our numbers.

Anonymous said...

Mike, I have a Russian SKS that I'm thinking about converting per this info. Thing is, I've read some some stuff online about converting the rifle to accept AK mags. There is some question about it's legality, which frankly I don't give a shit about, but also about its practicality. Main thing is, when I'm done with it all I want a rifle that will function. Some folks will tell you that if you're practiced enough, you can lay down enough fire almost as quickly with 10-rd stripper clips as you can with a 30-rd mag. And others say that the after-market SKS drum mags are only so-so as far as reliability.

So, soliciting your comments.

Dave_H said...

It could work. Actually this reminds me of a story I read on the internet some years back. It was complete with pics documenting the after effect on the rifle. A fellow and a buddy of his got the notion to do something similar with an SKS. They had it set up with a bipod, one guy was firing as fast as he could, the second was loading stripper clips as quick as he could. Even with the low cap fixed mag, they achieved a rate of fire sufficient to heat that SKS up so much that the synthetic stock actually melted and sloughed off the front of the rifle.

Allen said...

in the early days of paintball, when the semi-autos were just starting to be available, we did something similar to this.

(yes, I understand paintball is not really analogous to real firearms, and not 100% effective as a training aid. it can be helpful in basic tactics and principles if used properly and the limitations are taken into account)

we had 3 loader/gunner "BAR teams". each team had 1 semi-auto (all PMI-3's if I remember right set up with a long barrel, bipod, and a good sized hopper) and a pump-type gun for the loader.

loader had 2 jobs..keep the semi-auto full and to cover the gunner's ass...a gunner can get "tunnel vision" and get surprised.

it was very effective. pick a target and pin it. distract a target (whack the bunker they are in from one direction) by making them look one way when you are moving in another.

now, paintball isn't combat. the ranges are a lot shorter. people have no fear of death. but some of the principles (like this one) can cross over and be tried out in a limited fashion.

Shy Wolf said...

OK, Mike- NOW you done it!
Not (formerly) being one who really "saw" a need for an MBR, let alone one capable of semi-auto DM capability, you have whet my competetive appetite.
Being poor, I'm going to find an SKS and see what I can do along the lines of your thinking. Couple of comments from my perspective on the conversion...
Being old and somewhat opinionated, I'm going to not put the bipod on the bayonet lug since it will put added weight/stress on the barrel and change the point of aim/impact from non-prone positions. Tack it to the far end of the forearm on a sling screw instead.
Not really fond of the Dragonov style stocks, either, so a conventionally shaped stock will be my choice. Weight will be slightly more, but not a problem.
Dunno if I'd worry about putting a carrying handle on it, either, since the weapon will be light enough to pick up by the balance.
Reading the SKS blogs, no one has any really good things to say about magazines with more than 20 round capacity, so I'm thinking of holding with those- just carry more, they change easily enough. The TAPCO mags seem to have the concensus on reliability.
I have an old AimPoint Red Dot to hang on it for optics, but may end up putting on a low-power (4X max) scope. (Will have to wait and see about that, though- it helps to have the gun in hand before getting too carried away.)
Also, even as low-cost as they are, if one gets too carried away with accoutrements for this SKS-DM, the cost may get so high as to be impractical and having bought an M-forgery may've been the wiser move.
Too, who the hell's gonna care if the SKS-DM isn't "922 compliant" when the SHTF? Sheesh, people: we gotta think outside the "legal box"- we're fighting a friggin' war!
PS: Will send pix and range results when completed.

Anonymous said...

Base of fire? dont forget that the yugo SKS is a grenade launcher too.

I think home made rifle grenades could be made from 1 inch commerical tubing or pipe. they call it a 22.5 grenade launcher so 1 in ID tubing or pipe would leave 2 mm total clearance between the grenade and the spigot (what is the thing on the end of the barrel called?)

to blank off the portion over the rifle barrel you could use a 1X 1/4 pipe reducer with a pipe plug.

To attach the explosive part weld another pipe plug, back to back, to the pipe plug in the reducer. This could also be a solid pipe thread nipple although I am not to sure those are available.

Now add another reducer to what could become a pipe bomb or an open 2 inch pipe to stick maybe coke bottle gasoline cocktail in.

look up the bursting pressure of schedule 40 pipe, it's in the low thousands of psi,,you could wack em pretty hard with out them bursting.

The orignal rifle grenades came with a shell with a special slow burn powder. I don't know where to get it or how much to use. I have also heard the original used a lot of powder and where hard on the guns. don't know.

I have been meaning to do the above for years now , no time.Please try and tell us.

your heavy weapons platoon could have 2 SKS for base of fire and two for grenade launching.with another 4 rifle men with sks to carry ammo and support.