The NULA Model 20 has a 2.5” magazine box and the Howa Mini with Oregongunsmithing bottom metal (eliminates hinky mag and release) has a 2.54 magazine box. Would this extra length provide enough room for use of more copper bullets with the 300 Ham’r? Any ideas which bullets might work? These could be great ultralight, low recoil elk guns for those committed to copper bullets. I’m a meat hunter – mostly after cow elk 400-600#’s.

Ok guys has anybody saw groups like this on first time shoots? 18” barrel 125 TNT’s with 26grs CFEBLK and Hornady 110 V-Max with 27.5 grs CFEBLK New out of the box Burris 6.5 x20, new Monstrum mount

In my mind the two problems you'll run into are the distance to the lands and bullet construction. Most copper bullets are designed so that they expand properly at "typical" velocities for the rounds they'll most commonly be used for. Think .308 Winchester, .300 Winchester Mangum, etc. So very likely with the reduced velocities you'll encounter in the Ham'r, many of the longer .30 caliber copper bullets won't give great performance. Also the Ham'r (at least in the semi autos) have an appropriate distance to the lands for the bullets that perform the best in this chambering. Unless you run a custom reamer you'll likely run into the lands very quickly with the longer copper bullets.


Too many variables. It's this a factory build or home build? Is anything touching the barrel? Is EVERYTHING torqued to spec? Could your scope be bad? Maybe your rifle didn't like the loads? What kind of groups are you capable of? What distance were these shot at? Is the gas tube interfering with the bolt carrier? What kind of ejection pattern were you getting? What kind of brass are you using? And I'm sure there are 100 other questions to ask but these are a good start.

Home build but this is like number 15 or so that we have built. Scope was taken out of the box and installed. It was 100 yards. The gas block is the only thing touching the barrel.
What would the gas tube have to do with accuracy? Ejection pattern is fine. Brass is Lake City 1976. What you see are the groups. I hope it is as simple as it doesn’t like my reloads

Don't take my post as criticism but only as a sincere attempt to help. A dragging gas tube could cause inconsistent bolt lockup. Is it likely? Probably not. Is it possible? You bet. I can't tell you what to do but if I were going to try and diagnose it I'd take it apart one component at a time inspecting each piece as it came off and if I was satisfied each piece was as it should be, I'd put it back together triple checking my torque values. Then I'd try a different scope and mount that had been used and trusted. Get the barrel clean before heading back to the range. Try to up your charge weights to get close to factory velocities or get some factory ammo. If after all of that I was convinced the issue was with the barrel then I'd contact Wilson Combat.

I have plenty of parts to completely replace everything except the barrel. I don’t expect the barrel to be bad. Mostly I expect the barrel/chamber doesn’t like my reloads. I used the Wilson Combat recommendation less about 5% using the CFE BLK. I am now going to try different powders with the same bullets and maybe different primers. I can change the BCG and gas tube next if this doesn’t help.

I would be shocked if the problem was the powder selection.

Machinist - As suggested by others, check that your equipment is properly installed and tightened down. Based on your OP this is first time that rifle was fired. Did you clean the barrel before shooting it to ensure no metal shavings or grease/lubricant from factory? Immediately clean the rifle before you shoot it again.

Next, slam closed the bolt on a loaded magazine and then extract the cartridge from the chamber and inspect it to see if the bullet tip was deformed during feeding. Repeat several times and inspect bullet for damage. If bullet is striking the feed ramp then a minor dent to the bullet tip can cause inconsistent grouping.

After you have checked that the barrel is properly installed and tightened, scope mounts are tight, and that there is no issues during feeding ammo , you just need to blow through a couple of magazines worth of ammo. Clean the rifle after every 10-15 shots. These sacrifice rounds should help smooth any large burs and rough tool marks.

One last thing if the issue continues is to buy a couple of boxes of factory ammo to test how your rifle responds.

Good Luck!!!

The first two things I'd ck are to make sure the muzzle device is tight and the gas key slides once the end of the gas tube smooth so it doesn't flex the gas tube out of it's natural alignment. The only time I've seen huge groups like that were with a loose suppressor.

[quote=Wilson Combat]The first two things I'd ck are to make sure the muzzle device is tight and the gas key slides once the end of the gas tube smooth so it doesn't flex the gas tube out of it's natural alignment. The only time I've seen huge groups like that were with a loose suppressor.[/

I'm sorry for not being an AR expert but could you elaborate on what you mean by "the gas key slides once the end of the gas tube smooth"?

I couldn't even come close to the factory WC velocities or recommend powder charge with my LC brass until it was fireformed. If I remember correctly, I was a nearly a whole grain under max and still showing pressure signs that the factory WC 130 HHC didn't at a higher velo than I could achieve. After fireforming, I can easily duplicate recommend max loads without pressure signs.

Are you shooting with a suppressor? My only experience with large groups like that was caused by a suppressor that wasn't properly aligned causing the bullets to bounce off the exit hole.

I think he meant that the gas key slides OVER the end of the gas tube smooth. When I'm assembling an upper I spend quite a bit of time "tuning" the gas tube alignment until the tube does not move up, down, left, or right when the gas key meets the end of the gas tube. If it does I'll very gently bend the tube until the bolt carrier closes without disturbing its "natural" position as Bill said.

No suppressor. Just a regular muzzle flash device. I have another gas tube I think I will try it plus make sure that the gas key slides smoothly over the tube. I am sure the muzzle device is tight with a new crush washer and blue locative.

those 125s should be sitting on top of at least 27.5gr of cfeblk with any lot#... seriously.

pic for attn:

Sorry but I didn't read enough into your post before replying but how much load testing did you do to come up with these groups? My barrel likes loads about grain or so under the max with the best load for the TNT 125's being 26.5 gr of CFEBLK out of a 16" barrel. Could be you're only a few tenths of a grain from your best load.

"In my mind the two problems you'll run into are the distance to the lands and bullet construction. Most copper bullets are designed so that they expand properly at "typical" velocities for the rounds they'll most commonly be used for. Think .308 Winchester, .300 Winchester Mangum, etc. So very likely with the reduced velocities you'll encounter in the Ham'r, many of the longer .30 caliber copper bullets won't give great performance. Also the Ham'r (at least in the semi autos) have an appropriate distance to the lands for the bullets that perform the best in this chambering. Unless you run a custom reamer you'll likely run into the lands very quickly with the longer copper bullets"
Got it. I don't reload at this point so didn't get the problem with longer rounds. Kind of obvious now. I wonder about using copper 30-30 bullets. I think they are available from Lehigh, Barnes, Nosler, and Hornady. Would this deal with the OAL and velocity issues? I noticed some of the bullets recommended on the Wilson website are designed for 300 Black or 300 Savage.

Potentially yes. I think Hammer makes some copper .30-30 bullets also. Only way to tell if they'll load up properly is to seat some in dummy cartridges and check them in a bullet seat gauge. I've got one for the .300 Ham'r and it's handy.

ShadowFast1, Good Morning,

Is the bullet seat gauge you refer to the Wilson Combat TR-300HBSG?

The first thing I'd suspect is that brand new scope. Sometimes they come out of the box broken.

Yes sir. That's the one.

I would buy some factory 130 Hot Cor and try them. If it doesn't improve I would look at the scope or mount.

I ordered some factory brass from Wilson. I will see if that makes a difference with my reloads.

I doubt it, powder charge and OAL will make the most difference. Sometimes a change in charge weight of .2gr can mean the difference between a 1.75" group and a 3/4" group, especially with solid copper bullets.

Any Specials going on right now at Wilson Combat? Im thinking of pulling the trigger on a barrel and some brass/dies ect.. Thanks