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Looking for a load for an ar-15 with a 24 inch barrel using H335

Looking for a starting load for an AR-15 with a 24 inch barrel using H335 using 55grain FMJ having problems with it short stroking. Thx T
 
http://accurateshooter.net/Downloads/sierra223ar.pdf

H335 is pretty easy to develop for the AR. It is best to use something like a Rem 7 1/2 in winter conditions.

Does your AR short stroke on factory ammo along the lines of XM-193?

If that type of load runs the rig okay, what type of ejection pattern do you see?

The AR platform is not too hard to debug if the problems are broken down methodically.
 
I have gone up to 24.5gr with h335 and 55gr fmj bullets. Start lower and work up. Has been fine in mune and friends rifles. I have not had any cycling issues.
 
What length is your gas tube. If your gas tube is rifle length, rifle +1 or rifle +2, consider going to a shorter gas tube (And gas port). The higher pressure will make for more energetic cycling.
 
If it has a 5.56 nato chamber I run 24.5gr to 24.9gr H335 with a 55FMJ, this is NOT a starting load.
Just keep in mind that if your rifle has a .223 chamber it will typically be tighter and this load
may be on the hot side for it.
 
What length is your gas tube. If your gas tube is rifle length, rifle +1 or rifle +2, consider going to a shorter gas tube (And gas port). The higher pressure will make for more energetic cycling.
Wouldn't that mean a whole new barrel?
An option would be to just ream the current gas port to the next size.

But, first, determine whether it's the gas system or something in the lower with this test.
As RegionRat mentioned, it's best to determine the root cause first.
 
I have used 25.0 grs. without any problems. However, I settled on 24.5 for better accuracy.
 
Thx for the info .T
If it has a 5.56 nato chamber I run 24.5gr to 24.9gr H335 with a 55FMJ, this is NOT a starting load.
Just keep in mind that if your rifle has a .223 chamber it will typically be tighter and this load
may be on the hot side for it.
 
Just keep in mind that if your rifle has a .223 chamber it will typically be tighter and this load
may be on the hot side for it.
High pressure loads in an AR can pop primers and beat up brass. Allowing a bullet to jump in the leade is a method for accommodating higher pressure in otherwise equal context.

The major difference between the 223 SAAMI standard and the 556 NATO Spec, is in the leade. The extended leade in the 556 was to allow for higher pressure loads in the NATO spec.

In reality, many modern 223 reamers do not stick with the traditional dimensions of the SAAMI standard with the trends to heavier longer bullets and faster twist. Many chambers marked 223 have modified leade dimensions to the point where the two designs largely overlap. That isn't advice to put high pressure ammo into a 223, just pointing out the differences in the two designs and the concept that gunsmiths get reamers to their own prescriptions so you have to be careful starting up any AR or bolt gun marked 223.

My advice is to always check your distance to lands and study your brass for signs of pressure regardless of the chamber markings, especially if the chamber is marked 223 to begin with. YMMV
 


and



 
having problems with it short stroking.
So many other potential causes:
  1. what buffer are you running?
  2. gas key tight?
  3. gas ring condition? (how many rounds since you changed them)
  4. gas block aligned with gas port?
  5. what bolt carrier weight (design) are you running?
  6. how often do your thoroughly clean your upper and BCG and properly lube them?
And the list goes on and on.
 
I just dealt with this on another rifle. Assuming you have a normal setup and not running with a suppressor, your short stroke is most likely the result of either (1) insufficient gas to properly cycle the BCG or (2) excessive buffer/spring setup. Excessive friction between parts (clean and lube your gun).

Inspect your spent cases to see if you are getting any form of a ridge/bulge just above the case web or does the surface of the cases look scuffed up (not shiny smooth)? These would be indications that your rifle is having extended lock-up time causing pressure to build inside the case. The case is staying in the chamber too long.

Confirm the alignment of the gas block and gas port. Check the size of the gas port in barrel and make sure it is clear of any obstruction. If the gas port and gas block are not perfectly aligned then this may result in insufficient amount of gas being captured/redirected to cycle the BCG. Chicken & Egg - If there isn't enough gas then it will create the issue of increased lock-up time (spent case stays longer in the chamber) causing increased pressure inside the case that results in the case sticking harder to chamber's walls further exacerbating the issue of reduced force moving the BCG rearward. If there is inadequate gas, the BCG doesn't get sent rearward with enough force to eject spent case and then to continue back beyond the rear of the magazine in order to either pick up the next round or lock open on empty magazine.

Also, you don't need an adjustable gas block on rifle length gas system. If you already have one installed then simply open it all the way.

I am assuming your AR15 has a Rifle Length Gas System (or something longer). For this setup you only need a normal buffer spring (not a super heavy) and a standard buffer (2.5oz-3oz). Make sure you have the correct length spring and buffer that match your buffer tube length.

Other potential culprit is mechanical interference between your parts, such as:
1) Upper and Lower Receivers are not aligned causing the BCG to hit or rub against a portion of the lower receiver (buffer tube connection area).
2) BCG is binding within Upper Receiver. Out of spec parts.
3) Make sure Gas Key on BCG is properly secured (screws tight and staked).
 
Last edited:
Is it short stroking with factory loads?
You are running a 24" barrel so your rifle has a longer dwell time than a standard 20"
rifle (longer gas pressure time)so either gas is being restricted or bleeding off somewhere in the gas system or there is some part mismatch.

Do you have the correct recoil spring and buffer and if you have an adjustable gas block
make sure it is correctly installed and properly adjusted ESPECIALLY if it is a bleed off gas block.
 
Your load should cycle . 24.5gr is not a hot load . 26.5gr get me to xm193 velocities. I run 25 & 25.5 grain with out issue , 25gr gets me right to 3000fps from a 16” barrel .

Your issue is the gas system somewhere as the last few post suggest .

Are you using an adjustable gas block ? Where is it set ? Start closed and open it in 1/2 or full turn increments while firing a few rounds in between. This allows you to keep track of where you are at from closed for later Reference.

Once it starts cycling correctly you are pretty much done . I usually do an extra 1/4 or 1/2 turn to be safe with any ammo . If it never cycle correctly all the way to full open . Then you have a leak of buffer/spring issue . .

If you have a long dwell time 10” + and don’t have an adjustable gas block you could be over gassed and the case is hanging up in the chamber do to the timing being off . The case may be staying under pressure and fully expanded/stuck to the chamber wall at the same time the bolt is trying to pull it out . As gass bleeds off the case may let go of the chamber but theres not enough gas left to cycle the BCG .
 
So many other potential causes:
  1. what buffer are you running?
  2. gas key tight?
  3. gas ring condition? (how many rounds since you changed them)
  4. gas block aligned with gas port?
  5. what bolt carrier weight (design) are you running?
  6. how often do your thoroughly clean your upper and BCG and properly lube them?
And the list goes on and on.
Thx so much for the reply most all have checked, cleaning was a factor. Another problem I found was powder, this rifle really finicky! What runs in most gun doesn’t in this one. T
 

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