Built a 7.5" pistol from a m1sales kit. Firing 62grain wolf ammo it will cycle pretty good, maybe one soft primer strike out of 20 rounds aslong as I hold it firm. 55grain will get soft primer strikes every shot after firing a manually chambered round. If I hold the buffer tube up against my cars tire it will cycle fine with 55grain. I'm thinking the bolt carrier isnt getting enough gas pressure to cycle all the way back so its not going completely forward?

Maybe drill a bigger gas port hole in the barrel? Polish the chamber? any ideas?

Quoted: I'm thinking the bolt carrier isnt getting enough gas pressure to cycle all the way back so its not going completely forward?

It's not that you're getting too little gas, it's that the length of the gas pulse is too short. You need to figure out a way to slow down the action. Normally I would say just to use a heavier buffer but I don't think you can in this situation. I would try an adjustable gas tube or a fat tube. But then there's another problem, I don't know if the companies making these kinds of gas tubes make them for a 7.5" barrel.

If it was a complete upper from Model 1 Id be sending it back or selling it and finding another dealer. M1s customer service sux.

You might also be getting "bolt bounce".  The AR pistol buffer/tube set up is known to be weak.  I built a 10" barrled pistol using a model 1 kit and I experianced "light primer hits", but the carrier cycled fine each time it fired.  Loaded, fired....and "click".  

I'm gonna clean my barrel and gas tube to make sure that isn't a part of the equations.  As of right now, I have a CAR type tube on order, to use the CAR buffer/recoil spring.  This *should* solve any of my problems.

I also noticed that "limp-ing" the AR pistol it affects it also.  But I think the problem is the recoil spring.... too weak to keep it closed.

Any chance the Model 1 pistol recoil spring is like what Duncan Long referred to, i.e. a Colt 1911 style so various weights could be used, until the correct one was found?

Can someone post a picture showing the details of the Model 1 buffer setup?  Thanks,

Paladin

Quoted: Any chance the Model 1 pistol recoil spring is like what Duncan Long referred to, i.e. a Colt 1911 style so various weights could be used, until the correct one was found? Can someone post a picture showing the details of the Model 1 buffer setup?  Thanks, Paladin

I haven't read D. Long's book...so I don't know.



But what you say about it similar to 1911 spring is quite true.  I'm just not sure how long it is.  I never measured mine when it was "new" and I'm sure that it has been compressed a little...

If it is similar, the best thing to do, according to the wolf spring site, a 1911 long slide spring, number 1 might be best.  All depends on how long the stock spring in the AR pistol buffer is...

who sells fat tubes or adjustable gas tubes?

I have the same buffer and it is complete garbage.  I am going to try and shave down a car buffer and use a cut down CAR spring and tube and see what happens.  I can't believe I paid $45 for something that doesnt even remotely begin to workTyrone

Quoted: It seems to be the same diameter as a 1911 spring, but longer. I've switched my pistol buffer out for a regular carbine buffer system in a RRA entry stock tube (with the rear threads removed so it won't mount a buttstock). This should help with reliability and also allows the upper to be removed like a regular AR without having to remove the buffer assembly first. The downfall is it's even longer now.

Ok, my 1911 springs are 6.5 inches long, and Commander length run about 5 inches.  They come in different weights.  Take YOUR spring down to a local gun shop that carries 1911 style 45's.  They probably will have replacement springs in the assorted weights.

Don't sweat it too much if the new one is slightly shorter, as long as it IS long enough to be under compression when assembled and will hold the carrier forward.  Maybe by feel you can guesstimate about how heavy to go, or try to get one or two each side of what Model 1 supplied.

The trouble with the Model 1 kit is that you are changing several operating parameters of the Arf system simultaneously.  The bolt carrier recoiling weight is lessened by deleting the normal buffer assembly.  The rubber end of the buffer also helps control rebound energy normally.  The forward acceleration after recoil is no longer the same as stock, and again, without the buffers weight once the carrier strikes the barrel face, energy rebound control is now different.  The strength and ability to strip rounds from the magazine will also be changed.  Good luck...

The Model 1 pistol buffer looks VERY SIMILAR to the one designed by Tom Provost and written of by D. Long.  Back when I built MINE using a home made carbine length buffer system , BUSHMASTER factory techs told me NONE of the pistol buffer kits worked reliably to their knowledge, and apparently they had been sent several to try to "make work".  They were surprised when I reported my carbine length buffer model functions 100%.

To my knowledge, I was the FIRST(1993) builder to do it my way, period.  There is absolutely NO mention in Long's book about my method.  And apparently no one else was willing to accept the longer length required...which was probably a good thing.

Paladin

Quoted: Quoted: It seems to be the same diameter as a 1911 spring, but longer. I've switched my pistol buffer out for a regular carbine buffer system in a RRA entry stock tube (with the rear threads removed so it won't mount a buttstock). This should help with reliability and also allows the upper to be removed like a regular AR without having to remove the buffer assembly first. The downfall is it's even longer now. Ok, my 1911 springs are 6.5 inches long, and Commander length run about 5 inches.  They come in different weights.  Take YOUR spring down to a local gun shop that carries 1911 style 45's.  They probably will have replacement springs in the assorted weights. Don't sweat it too much if the new one is slightly shorter, as long as it IS long enough to be under compression when assembled and will hold the carrier forward.  Maybe by feel you can guesstimate about how heavy to go, or try to get one or two each side of what Model 1 supplied. The trouble with the Model 1 kit is that you are changing several operating parameters of the Arf system simultaneously.  The bolt carrier recoiling weight is lessened by deleting the normal buffer assembly.  The rubber end of the buffer also helps control rebound energy normally.  The forward acceleration after recoil is no longer the same as stock, and again, without the buffers weight once the carrier strikes the barrel face, energy rebound control is now different.  The strength and ability to strip rounds from the magazine will also be changed.  Good luck... The Model 1 pistol buffer looks VERY SIMILAR to the one designed by Tom Provost and written of by D. Long.  Back when I built MINE using a home made carbine length buffer system , BUSHMASTER factory techs told me NONE of the pistol buffer kits worked reliably to their knowledge, and apparently they had been sent several to try to "make work".  They were surprised when I reported my carbine length buffer model functions 100%. To my knowledge, I was the FIRST(1993) builder to do it my way, period.  There is absolutely NO mention in Long's book about my method.  And apparently no one else was willing to accept the longer length required...which was probably a good thing. Paladin

I manged to look at the AR pistol spring vs a 1911 spring.  As stated, they are similar in diamter, 7/16".  The AR recoil is about 7 1/2" long (might have been longer), but it is deformed now- w/ less then 100 rounds .  Any how, I'm sure that the spring is the problem.  It is not strong enough to push the carrier "home" and the latch on the charging handle seemed to be the straw that broke the camel's back.  It seems to hold up the carrier at the last 1/4".  So, just maybe, when it's loading a round, the friction of loading is equal to the resistance of the charging handle latch holding it up.

As stated, I have another recoil tube on the way (CAR type), which I will modify.  But, looking on the wolfgun springs site, the extended 1911 recoil springs might be the solution.  Reading the descrption, the one as #1 is suppose to be the strongest.  They can't "rate" the springs since they have to be fitted (aka cut to fit).  It said that the 1911 long slide spring is required where there is a 3" space when the slide is locked back... what ever that infers.... They are listed as $9.00 each.

I know of a local store that carriers generic springs.  Granted, they are not "firearm" springs, but just for testing, I might go find one that fits and isn't so "strong".  Less then five bucks if I recall.....

lemme know how it works out

Alright...I finally got a reliable buffer system working in the pistol.  The best part is that the buffer tube is from a post-ban fixed tele so they should be cheap to purchase.  Its not the prettiest job, but it does function reliably so far.  It's basically a chopped buffer tube along with a chopped spring and buffer assembly plugged with a wooden dowel.  

These pictures are pretty big so I'm just going to post the links:

pic1
pic2
pic3
pic4


Tyrone

It works so farhe
Tyrone

Thats a good idea actually.  Wasn't a company selling M231 buffer assemblies a few years back?  Anyone know where I can get one?

Tyrone

I'm guessing it looks something like those semi-auto stengun setups where there are 2 guide rods with a spring on either one.  I would be an interesting project.  If I can find some springs, I'd like to try and make a 2 stage captive spring assembly like those found in subcompact glocks on a larger scale.  On that thought...what about an SKS recoil spring assembly?

Tyrone

i was thinking of shortening a car tube and buffer, but i was going to thread the tube on the threaded end a bit further and shorten from the threaded end, no plugs in the back for me dude

i am waiting on a kit with a 10.5 inch barrel, i will take spring measurements when it gets here

questions

Does it run right?

How long is the tube after your mod?

did you cut the car spring?

how many coils were cut from the spring?

did you shorten the buffer as well as the spring and tube, give me measurements

here is something like what i was thinking, i am nowhere near completed yet so i am open for suggestions

here is a pic, info below



standard car buffer spring, it will be shortened 1.5 inches to match the amt of length taken off of buffer
standard car tube, i took the lump off on a lathe really quick, this is a mock up part so do not be picky, it will be shortened 1.5 inches on the threaded end, the threaded part which goes into the reciever will be cut off during the chop, so it will be rethreaded

buffer was shortened 1.5 inches, this is long enough so the buffer does not cock in the bore, and operates smoothly


when the buffer is bottomed out the bolt carrier is still out far enough from the reciever extension so that the carrier key will not hit the lower reciever


i may have some weight issues with the buffer, this can be remedied a few ways

i could spin up a buffer body from steel, the current one is aluminum, this would add the needed weight, or i could fill the bffer with lead to add weight, it had 3 cylinder shaped metal parts, just steel bar stock, it now has one

who has measurements from the m231 reciever extension and parts

That looks remarkably similiar to what I did minus the nice lathe work.  I had to take off about 8-9 coils off the spring.  Basically I just kept checking to see if the carrier assembly would go back far enough each time until I had removed the correct but minimal number of coils. The buffer looks great on yoursh
Tyrone

Quoted: i may have some weight issues with the buffer, this can be remedied a few ways

How about using the 9mm carrier weight in the AR carrier?

i had no idea the 9mm had a carrier weight, do you have a pic, or link to a pic?

here is a pic of my 10.25 inch upper for my pistol, the spring measures 7 3/4 new

it will be a pita to get the buffer stuff assembled

i am not sure how much poundage the spring is rated at


i may order a heavy, like 26 or 28 pound unit for a 45 acp and see how it goes

Quoted: i had no idea the 9mm had a carrier weight, do you have a pic, or link to a pic?

I'll see if I can get a pic. It's pinned in so you'd have to drill but I doubt that would be a problem for you thus far.

definately, please post a pic, i will even make a weight if i have to

it will be a pita to get the buffer stuff assembled

Here is my method from having a fixed magazine AR pistol with this recoil system for a while.
(meaning I had to do this every time I loaded it)

assemble the recoil tube on the lower, locking plate, blah, blah (skip this if the tube is already installed) but remove the end cap from the recoil tube

drop in the bolt carrier, and attach the upper, close the action

draw the BC back with the charging handle, muzzle down, and depress the bolt catch

holding the bolt catch down press forward on the carrier until it touches it

still holding the bolt catch (this works best with an empty mag to hold it up), insert the guide in the back of the BC, and then insert the spring on the guiderod into the guide and compress.

this is the hard part, but the spring won't kink with the bolt carrier back and the guide rod compressing the spring into the guide.

Beware that the spring will kink if you don't compress it evenly

once the first few threads are started, use the charging handle to lower the BC and continue threading it on. Its easier to screw on the end cap with the bolt forward, but now the spring is correctly inserted into the guide at this point so the bolt doesn't need to be back.

A better method I have not found.

It takes a few times to get practiced and smooth.

Cheers, Otto

I bought a pistol buffer and tube last year.  I put it on one of my CARs and had the same problem with the 'bang, cycle, click'.  I have a new pistol receiver and was getting ready to order the upper kit.  Glad I saw this thread.

Have we figured out how to make the pistol buffer tube assembly work?  Reading through here, it looks like we are trying the M1911 springs.  Has that worked yet?  Did we give up and all decide to cut down other tubes?

I'd like to avoid mistakes others have already pioneered for me.

Thanks.

Dave.

i was thinking that the recoil spring from a fal would be about the right diameter and would be of good quality, already sagging as much as it would due to the many years of use, also they are really stiff, cut to length, anyone have a fal spring to get some measurements from

The below was posted on my thread on my AR pistol.

11:45am - I just installed the Wolff spring.......


The 1911 long slide Wolf spring arrived 11:20am.  Upon opening the package, I KNEW I had to cut it to fit.  The length of both springs (#1, #2) was over 12" long.  I would say 12 3/4" or 13" long.... I was in a hurry, so I didn't take pics or do a accurate measure.  THERE IS ENOUGH THERE FOR YOU TO PLAY WITH!!!!


Any how, the factory Model 1 spring is about 7.5" long.  Mine, used, is closer to 7".  With the original installed, no cap, it stuck out about 1.5-2" above the back of the buffer tube.  (The factory spring would not even send the cap flying if I unscrewed it.  It just sat there.)  I cut the new long slide spring at 8-8.5" long.  This gives about 3-3.5" sticking out of the back end.  Getting the unit together was "fun", but do-able.  The spring is now under compression all the time, like the rifle units.  The carrier, if I recall, could be pulled all the way back (I didn't try to lock it open).  The force to pull it was much greater then before, but not too excessive.

I guaged the force the spring had in a non scientific method.  With the hammer cocked, I took my thumb and pushed on the carrier through the ejection port to see how much force was required to move it.  I did the same on my full sized spring and buffered Cavalary Arms Cav 15.  The force was similar.  Got lucky I guess.  I didn't adjust the spring after install.

I will bring a set of cutters to trim the spring if needed, if it won't cycle.  I'm sure that it will be fine... (all based on the thumb test).....

I will go try this thing out this afternoon/evening.  Report on fuction to come this evening....



Here is a link of my pistol project: My Pistol project

I will post the update there, less duplication. (and typing).
edit- didn't copy all of my post... duh!!!!!

Click here for my update:

My pistol thread w/ update on recoil