Bwillis

Longer loads better, eg 115 jhp at 1.17

Jp spring carbine or rifle length?

I wasn’t answering your question (Look who I quoted). I covered ar9 ejection in my first sentence.

Ar9 blowback ejection doesn’t matter if it’s reliable. Ar15 ejection is dependent on the gas, before 3 oclock not enough gas after 4 o’clock to much gas. Not enough gas isn’t optimal because you can get a undercharge and stovepipe. Too much gas is reliable but batters the gun and internals.... allegedly

The 308 jp carbine is ar10 Yes it would be in the upper/barrel area and could potentially get in the lower/trigger parts. start with red sprinco. Shooting doubles or bills at 25 yds on a timer, fastest splits you can shoot and see which has fastest splits with best hits. another good spring is tubs flatwire @bwikel

Trial and error is the only way to tune your gun to you. I tried 3 buffers, 4 loads and yellow to orange sprinco, jp 308 carbine and rifle, weights in weights out. The setup I listed about is what I had the best accuracy on doubles and bills at 25 yards it felt the smoothest and had a fast predictable return. Also proper cheek weld (not chin) having gun near my centerline (buttstock mass below shoulder line)s!houlders squarish, while rolling or pressing my right shoulder into the buttstock and squeezing in with my left hand about mid way on the handguard. That said every gun is going to have a track, memorize the track and practice timing it. symptom of to light of a spring is a lot of unburnt powder , with direct blowback you want to keep the bolt in a lockup as long as possible just like a mechanical lock on ar15

Post a picture or video of you shooting. That setup should have very little to no dot movement. I use a 5150 with jp carbine and 2 oz spacer in front of dampener iron city bolt. Total weight is 26-28oz if I remember correctly.

12 yards

+1 to this, possibly include more info next time. That malfunction is typical of not having a ramp/decent feeding cone or handcycling and not actually shooting. Maybe ask taccom Tim what he suggests? Good luck

Round nose

Taccom ramp(if they still make them) file you’re own ramp shooting innovations barrel and bolt

https://bravocompanyusa.com/bcm-extractor-spring-upgrade-kit/

remove bolt weight first see how that shoots, then adjust buffer weight. Also try varying gn of powder, see what gives you the best feeling and dot track. At the end of the day everyone is different and perceives recoil differently.

What buffer? Does the bolt have a weight in it? With a fast powder like sp and using a rifle primer you should be able to take the weight out of the bolt. With slower powders removing the weight isn’t ideal because the bolt will open too fast and throw unburnt powder out.

Call and tell them you are a competitive shooter

What is your load data and bolt weight?

I have never broke a firing pin or changed the spring. I’ve shot over 40k rounds on my gen 2 iron city bolt, I’m fairly certain this is the pin they use. https://palmettostatearmory.com/psa-custom-ar-9-enhanced-firing-pin-116003.html

Smoke composite makes a LW stock for the mpx

Not sure how the “Manny” start is legal Always specify safety on and held in both hands, and any other positions you come up with should be fine. Remember, no uprange starts, and no start positions requiring starting in the weak hand. A competitor may start this way if he chooses, but the WSB cannot specify it. PCC Start Positions Troy McManus, DNROI Because course designers need to state a specific start position for all guns, including PCC, there is no default or “normal” start position for PCC. While the handgun rule book lists a default start position for handgun if it isn’t specified in the WSB, it really makes more sense to specify a start position, and one that’s easily understood and easy to enforce. The same goes for PCC. Terms like “port arms” and “low ready” are not defined in the USPSA Handgun rules—take the time to spell it out, as seen in our classifier WSB’s. Even though many of them use the “buttstock on belt, held in both hands, safety on, muzzle generally downrange” position, it’s not the default. An aiming point is a good idea if you want the PCC to start shouldered—a cheap cone, a mark on a wall, a prop—all will suffice. Always specify safety on and held in both hands, and any other positions you come up with should be fine. Remember, no uprange starts, and no start positions requiring starting in the weak hand. A competitor may start this way if he chooses, but the WSB cannot specify it. I’ve also had some questions about starting on the weak side for classifiers or other stages that will require weak side shooting. This is legal in our classifiers unless they specify starting on the strong side. It’s up to the competitor. Table or other placed starts, loaded or unloaded, are the same for both handgun and PCC. For unloaded starts, the bolt must be closed and the hammer down—yes, the competitor has to pull the trigger if he racked the bolt open to dry fire or to remove a flag. https://www.multibriefs.com/briefs/uspsa/pcc-start111617.pdf

I’ve shot stationary clays at 115yds with mbx and shooting innovations barrels. I’ve also hit 18” steel targets with both barrels (14.5”) at 300yds. My load was 115 gr eg jhp, 4.6gr wsf and app random brass. Oh and optic was 512t

No particular order mbx jp shooting innovations

Yes same issues, it will damage receiver and break the key on top of the bolt. You either need to use a spacer like Raylan posted above or shim it with weights.

Ive never had a mbx magazine with mbx guts cause a failure. Grams and mbx springs are both .052 wire cut by wolf. Only difference being the 4 coils on bottom.