300BlkTalk

I have an IWI X95 recently bought that I'm using my old SBR ammo in, however my normal load using 208 Hornady ELD's with 9.7grn of 4227 (which have worked flawlessly in my AR short barrel) won't cycle fully in the X95, even with the gas system set to subsonic, and while firing suppressed.

That particular loading is already about as close to the speed of sound as I'm comfortable getting out of a 10.5" barrel. It's even closer now in the X95's much longer barrel (velocity didnt increase too much, but still a little)

Anyone else having this issue? FWIW some Lapua Scenar L's didn't have this issue with a hotter load (10.0gr 4227 with SRM) but LRBHO didn't work.

I don't have an X95, but I can say that in my experience 4227 is marginal for subs. I've done a lot of ladders with a lot of different heavy bullets. No matter what combo I always end up being right near supersonic to get reliable cycling in My ARs. Accuracy is decent, so I just use that powder for range plinking.

4227 is a bit sensitive to seated depth. If you seat the bullet too deep, it burns too efficient, and you lose gas volume needed to cycle. That ELD is pretty long.

As dumb as it sounds, either move the bullet out, decrease the charge, or a combination of both. It will slow down the burn rate and help with cycling. What happens is you will have less peak pressure, higher muzzle pressure, but most important, higher pressure at the port. Trade off is it runs dirtier.

I use something like 11.2 grains with a 125 SST and have full function as a sub in an 8" barrel. Manipulating the burn rate makes it possible.

Thanks for the suggestions. You've convinced me to abandon 4227 altogether now (a shame since I still have about 1/2 keg of it left). Couldn't increase OAL because I was already at max. Tried Lil Gun, and the two 4198's. Lil gun cycles well, but won't lock the bolt open. The 4198's would, but were wildly inconsistent in terms of velocity.

The X95 has an adjustable gas block ( to switch between sub and super) but as far as I can tell it's close to the same length as a carbine length has system on an AR, but it's a long stroke piston. I guess I got spoiled running pistol gas for so long.

Now that it seems to be working (I'll live without bolt hold open) it's remarkably quiet. Far more so than my AR. Not quite bolt gun quiet, but still good.

I personally use IMR4227 on 2 of my rifles and few others that I have helped people with. It definatley has worked great for me and is relatively clean and quiet.

Take Dellets advice and change seating depth and charge. I honesty havent had cycling issues and can get rounds to cycle with charges well under 1000fps. Out of the rifles and pistols I have tested, loads within 9.2-9.6gr using 190-220gr bullets is optimal velocity and accuracy.

I had been running 9.7 with the ELD in my short barrel. It worked great and was quiet, but the pistol length gas system was far more forgiving than the X95's long stroke piston. I don't have any more of the ELD's to experiment with, but they were already loaded to max length.

8.4 and 8.6 grn of Lil Gun worked well (although no bolt hold open) with 220grn Lapua Scenars. They're pretty quiet and cycle well when loaded to max length (as dellet mentioned about 4227, it appears to bear true with Lil Gun as well. Set just slightly deeper (by mistake) and I saw a nearly 10% increase in velocity and failure to cycle.)

Unfortunately, quick load has been useless in this endeavor. It doesn't seem to do well with subsonics, always overshooting the velocity by a wide margin. It's a problem I've noticed in both this cartridge and 458S. It's usually spot on for full power loads though.