Federal AE, good Surplus M193 and M855, and Black Hills works fine. Anything else, nothing but short stroking.

Winchester, UMC, PMP, Wolf, PMC, S&B, and SB all short stroke.

The rifle is a DPMS DCM with the Match SS Cryo-freeze barrel, and a titanium plated bolt assembly. Any ideas?

All Choke and no Stroke! Ladies aren't going to like that one!

Oh, and I have no idea

Is the Key loose on the carrier?

Do you have an extra tension Buffer Spring?

Does the gas tube seem to be lined up properly with the carrier?

How new is your rifle?  You may need to undergo a break-in period.

Lastly, you didn't gunk it up with CLP, did you?  I only ask because someone once showed me his rifle that he was having jam problems with, and that thing was oozing CLP out of every crack and crevice.

Check over your bolt and carrier, make sure the gas rings are in good shape.  I had a similar problem and it was a gas  leak between the carrier and the gas key.  

To check this, put a straw over the gas key, and blow on it with the bolt to the rear of the carrier, I used a little soapy water and had bubbles around the mating surface of the key and carrier.  To fix it I lapped the key to the carrier.  If you do take the gas key off, don't forget to re-stake the screws.

Another place to look is the gas tube, and finally check that the gas port is correctly sized.  

Mine was short stroking only with Wolf and I was starting to get pissed till I finally found the problem.

Hopefully this helps, good luck.

Short strokes are usually caused by a carrier key leak, broken gas rings or clogged gas port or gas tube...

i like short fast strokes, i whack it on a time limit

Check with Dano in the troubleshooting fourm.

How short a stroke?  failure to lock after last round in mag, or feed issues?  

Mine wouldn't lock the bolt after the last round with an H buffer being the culprit.  Runs fine with the stock buffer.

Well, this is an easy fix...just don't shoot the junk, underpowered stuff.

Sources of short stroking are not enough energy delivered to the carrier, too much energy sucked off by drag in the mechanism, too much energy taken up by extraction, too much energy taken up by the springs.

Not enough energy delivered to the carrier - Obstructed barrel port or front sight base, poor fit of the carrier key to the carrier, carrier key screws not tight, gas tube end or carrier key opening worn and leaky, carrier gas path obstructed, gas tube obstructed, gas rings gone, large clearance between tail of bolt and carrier;

Too much energy sucked off by drag in the mechanism - Binding or rubbing carrier, binding recoil spring, carrier and hammer binding on each other or inadequate lube on reciprocating parts. You can feel this during manual cycling, both with the trigger released and with the trigger pulled;

Too much energy taken up by extraction - Rough, sticky, or out-of-shape chamber, as evidenced by marks on cases and bent extraction rims. Ammo/chamber that make excess pressure, as evidenced by pierced, cratered, flattened, or lost primers, buttons of case metal extruded into the ejector plunger hole, case head growth in firing. Dirty chamber - clean with gun solvent, then lacquer thinner;

Too much energy taken up by the springs - Extra power recoil springs and hammer springs can be too much to allow full cycling. Start with GI, and if they work OK, then play with stronger ones.

Notice how many sources there are. Eliminate the gas path problems by checking them all, put in GI springs, clean and lube everything, and try it. Look over the case carefully in a good light for bent rims, trumpet or barrel shaped bodies, signs of rough chamber, excess pressure.

Quoted: How short a stroke?  failure to lock after last round in mag, or feed issues?   Mine wouldn't lock the bolt after the last round with an H buffer being the culprit.  Runs fine with the stock buffer.

Heres a breakdown of the problem with different ammo:

Federal AE - No problems, feeds and functions flawlessly.
Federal Match - Feeds and functions fine, never a problem
Black Hills Match - Same as federal, no problems
Good M193 - Works fine, no problems at all with Federal, LC, IMI, Guatemalan.
M855 - every M855 Ive tried works fine, LC, Winchester, and Talon

Now the bad:
PMC - Works fine for about 30 rounds, then wont kick the bolt back far enough to eject and feed.
PMP - Short strokes just like the PMC, but wont even go 1-2 rounds before short stroking.
Wolf - Actually went 20 rounds without a hitch, then one after the other jam ups. Now anytime I try it it usually goes 3-4 rounds before jamming up one after the other.
S&B- Just like the PMC and PMP, occasionally it will function and feed, but usually wont throw the bolt back far enough.
SB - Crap, every single round got stuck in the chamber, had to pop it out with a cleaning rod.
Remington UMC- Wouldnt even cycle at all, would fire and bolt wouldnt move.
Winchester white box (older around 99-02) - Just like remington, no feeding at all.

Quoted: Quoted: How short a stroke?  failure to lock after last round in mag, or feed issues?   Mine wouldn't lock the bolt after the last round with an H buffer being the culprit.  Runs fine with the stock buffer. Heres a breakdown of the problem with different ammo: Federal AE - No problems, feeds and functions flawlessly. Federal Match - Feeds and functions fine, never a problem Black Hills Match - Same as federal, no problems Good M193 - Works fine, no problems at all with Federal, LC, IMI, Guatemalan. M855 - every M855 Ive tried works fine, LC, Winchester, and Talon Now the bad: PMC - Works fine for about 30 rounds, then wont kick the bolt back far enough to eject and feed. PMP - Short strokes just like the PMC, but wont even go 1-2 rounds before short stroking. Wolf - Actually went 20 rounds without a hitch, then one after the other jam ups. Now anytime I try it it usually goes 3-4 rounds before jamming up one after the other. S&B- Just like the PMC and PMP, occasionally it will function and feed, but usually wont throw the bolt back far enough. SB - Crap, every single round got stuck in the chamber, had to pop it out with a cleaning rod. Remington UMC- Wouldnt even cycle at all, would fire and bolt wouldnt move. Winchester white box (older around 99-02) - Just like remington, no feeding at all.

Hot ammo works good and the normal doesn't... I would check for a gas leak, undersized gas port hole, clogged gas port or clogged gas tube...

Quoted: Check over your bolt and carrier, make sure the gas rings are in good shape.  I had a similar problem and it was a gas  leak between the carrier and the gas key.   To check this, put a straw over the gas key, and blow on it with the bolt to the rear of the carrier, I used a little soapy water and had bubbles around the mating surface of the key and carrier.  To fix it I lapped the key to the carrier.  If you do take the gas key off, don't forget to re-stake the screws. Another place to look is the gas tube, and finally check that the gas port is correctly sized.   Mine was short stroking only with Wolf and I was starting to get pissed till I finally found the problem. Hopefully this helps, good luck.

What is the "gas key" and what do you mean by "lapped" and "re-stake the screws"?

Wolf short stroked in mine.  I just lube a little more than usual and it is 100% fine.

Quoted: What is the "gas key" and what do you mean by "lapped" and "re-stake the screws"?

The gas key is the tube that is mounted on top of the bolt carrier. Sometimes you'll have a gas leak where it meets the bolt carrier. Lapping means to just smooth up the mating surfaces. Smooth them up, use some red Loc-Tite as a gasket, torque the screws to 35 inch pounds, and stake them to prevent them from loosening.

Staking Procedure

I only recommend removing the gas key if you are confident that it is leaking.

Lap it only if needed...

Lapping method:

Remove the 2 gas key screws and remove it from the carrier... Clean both mating surfaces with solvent and 0000 steel wool to remove any or all carbon and dirt buildup... Dry parts thoroughly... Put a drop of oil on the mating surfaces and then place them together and slide them back and forth while applying light pressure... The movement you would use is from front to back of the carrier... After it feels like there is no friction or grit between the two surfaces, your finished lapping... You may need to repeat the process a few times to get it right...

When reassembling, be sure to clean the mating surfaces, torque then stake the screws...

Quoted: Lap it only if needed... Lapping method: Remove the 2 gas key screws and remove it from the carrier... Clean both mating surfaces with solvent and 0000 steel wool to remove any or all carbon and dirt buildup... Dry parts thoroughly... Put a drop of oil on the mating surfaces and then place them together and slide them back and forth while applying light pressure... The movement you would use is from front to back of the carrier... After it feels like there is no friction or grit between the two surfaces, your finished lapping... You may need to repeat the process a few times to get it right... When reassembling, be sure to clean the mating surfaces, torque then stake the screws...

I checked the gas key, it definitely isnt leaking. As for the gas tube being too dirty, unlikely I clean it quite a bit with the pipe cleaners, squeaky clean. Not to mention I only have about 400-500 rounds through it, and the problems were there since the first day I fired it.

You might want to check the FLUX CAPACITOR  I heard they are real problems on dpms guns.

Quoted: Quoted: How short a stroke?  failure to lock after last round in mag, or feed issues?   Mine wouldn't lock the bolt after the last round with an H buffer being the culprit.  Runs fine with the stock buffer. Heres a breakdown of the problem with different ammo: Federal AE - No problems, feeds and functions flawlessly. Federal Match - Feeds and functions fine, never a problem Black Hills Match - Same as federal, no problems Good M193 - Works fine, no problems at all with Federal, LC, IMI, Guatemalan. M855 - every M855 Ive tried works fine, LC, Winchester, and Talon Now the bad: PMC - Works fine for about 30 rounds, then wont kick the bolt back far enough to eject and feed. PMP - Short strokes just like the PMC, but wont even go 1-2 rounds before short stroking. Wolf - Actually went 20 rounds without a hitch, then one after the other jam ups. Now anytime I try it it usually goes 3-4 rounds before jamming up one after the other. S&B- Just like the PMC and PMP, occasionally it will function and feed, but usually wont throw the bolt back far enough. SB - Crap, every single round got stuck in the chamber, had to pop it out with a cleaning rod. Remington UMC- Wouldnt even cycle at all, would fire and bolt wouldnt move. Winchester white box (older around 99-02) - Just like remington, no feeding at all.

I have a DPMS that is the same way, I guess I chose to just shoot the stuff that works in it.

Quoted: You might want to check the FLUX CAPACITOR  I heard they are real problems on dpms guns.

Can I have some of whatever you are smoking?

Quoted: Quoted: You might want to check the FLUX CAPACITOR  I heard they are real problems on dpms guns. hr Can I have some of whatever you are smoking?hock.gifhinking.gif

Forgot to add check sparkplug gap, could be severly worn
check tranny fluid hay you never know
also look for a build up of dylithium crystals

jaymeister99,
The gas port hole could be undersized... If you can absolutely rule out all other possibilities, then that's what I would be checking into...