Range Report 6.5 American Gunner Not Feeding

[TFreeman]

I’m new to the precision rifle world. I took an introductory class two months ago where we were shooting out to 500 yards. I know it’s not far, but it felt like an accomplishment to me.

For the class I bought 400 rounds of 140 gr Hornady American Gunner. I noticed early on the first day I was having issues closing the bolt. The rounds would chamber but the bolt would not close. After forcefully pulling the bolt back and inspecting the round, I saw where the lands were making some distinct marks on the projectile. What I found was that anything 2.805” and over would not chamber in my rifle. I ended up taking a caliper and measuring 350 rounds (had already shot 50 rounds). When all the measuring was complete I had 195 rounds in the no go pile.

I called Hornady and they said “there’s nothing wrong with our ammo, the throat on your rifle is too short.” The SD on COAL for American Gunner is 2.800 +/- .006. I just measured 30 rounds from the no go box and 13 of them were 2.807 or greater.

My question is what can I do to get these rounds to feed through the rifle? ELD-M feeds just fine. I also bought a case of Prime a few days ago. I don’t reload yet. Once I do get some equipment would it be safe (or even possible) to seat the bullet deeper into the casing?

 

[Spblademaker]

Don’t seat them deeper

 

[b6graham]

what rifle? that's super short

 

[TFreeman]

It was built by Louisiana Precision Rifles.

I got it on here in 2014 and it has sat in the safe since then

 

[Codiekfx400]

If it is just the bullet hitting the lands I would have a friend that hand loads seat the bullet deeper in the case with a seating die. Or you can just force the bolt closed and shoot it. My guess is you have some other issue going on like too tight of neck or headspace issues.

 

[TFreeman]

You’re right, there are probably more issues than what I have been able to diagnose. I’m curios why the ELD-M chambers with no issue and the american gunner doesn’t.

 

[Rob01]

You’re right, there are probably more issues than what I have been able to diagnose. I’m curios why the ELD-M chambers with no issue and the american gunner doesn’t.

Different bullet and the ogive placement on the bullet so when they are both at the same OAL from the factory the ogive of the BTHP is a little farther forward than the ELD-M so it will touch the lands first.

You should check with the rifle maker about what chamber he used in that rifle and what free bore. It's definitely not the SAAMI ,199 freebore if the 140 BTHP won't seat.

 

[Praeger]

First, set aside the batch of American Gunner. You shouldn't force the bolt close, at the least it'll wipe the grease from the lugs, at worse it could result in galling between the bolt lugs and lug abutments.

The measurement you need to determine is not the cartridge overall length (COAL), it is the cartridge base to ogive (CBTO). The tip of the bullet doesn't touch the rifling, it is the bearing surface of the bullet, the leading edge of which is the ogive. Different bullets have different shapes and the point at which the ogive contacts the rifling lands will differ. Get a caliper micrometer and a comparator gauge to determine the CBTO.

Measure the CBTO of the American Gunner and you'll probably find a difference between those that chamber cleanly, and those that require force at the bolt. If there is a variance in CBTO of more than .005-.010" between the same batch of American Gunner, let Hornady know. That's an ammo problem. If you find that other factory ammo is also causing a heavy bolt, it may be that your chamber is so tight that the rounds that chamber are kissing the lands, and a normal variation in factory ammo CBTO results in some rounds jamming the lands. If that's the case, you can rent a reamer and finish reaming by hand an additional .005-.010" of freebore with a SAAMI spec reamer. If you go the hand reamer route, do your research, it is not difficult. Go slow - you can't but metal back. Always final check with a no-go gauge.

 

[Rob01]

First, set aside the batch of American Gunner. You shouldn't force the bolt close, at the least it'll wipe the grease from the lugs, at worse it could result in galling between the bolt lugs and lug abutments.

The measurement you need to determine is not the cartridge overall length (COAL), it is the cartridge base to ogive (CBTO). The tip of the bullet doesn't touch the rifling, it is the bearing surface of the bullet, the leading edge of which is the ogive. Different bullets have different shapes and the point at which the ogive contacts the rifling lands will differ. Get a caliper micrometer and a comparator gauge to determine the CBTO.

Measure the CBTO of the American Gunner and you'll probably find a difference between those that chamber cleanly, and those that require force at the bolt. If there is a variance in CBTO of more than .005-.010" between the same batch of American Gunner, let Hornady know. That's an ammo problem. If you find that other factory ammo is also causing a heavy bolt, it may be that your chamber is so tight that the rounds that chamber are kissing the lands, and a normal variation in factory ammo CBTO results in some rounds jamming the lands. If that's the case, you can rent a reamer and finish reaming by hand an additional .005-.010" of freebore with a SAAMI spec reamer. If you go the hand reamer route, do your research, it is not difficult. Go slow - you can't but metal back. Always final check with a no-go gauge.

Not necessarily as with that bullet you can go well past the factory 2.800" in a SAAMI spec .199 freebore chamber. If the rifle was built with a short freebore chamber then that is not an ammo issue. That's a shooter ammo choice issue for the rifle they have at hand. Hornady builds the ammo for the SAAMI spec chamber.

 

[Praeger]

Not necessarily as with that bullet you can go well past the factory 2.800" in a SAAMI spec .199 freebore chamber. If the rifle was built with a short freebore chamber then that is not an ammo issue. That's a shooter ammo choice issue for the rifle they have at hand. Hornady builds the ammo for the SAAMI spec chamber.

I don't think we're disagreeing. All mainstream factory is built for SAAMI spec chamber. I went on to say that if other factory ammo doesn't chamber it is probably a short freebore. Since the OP doesn't have the tools to measure, and check seating depth, all he can do is see if the problem exists with other factory ammo.

 

[Rob01]

But even if it doesn't with other factory ammo it doesn't mean it's a problem with the AG ammo as they are all loaded the same at around 2.800" but ogives are at different places on bullets. He really needs to get it measured to see for sure.

 

[TFreeman]

Thanks for all the feedback gentlemen. I definitely don’t want to risk damaging the rifle. I’m going to have to read through your posts a few times to make sure I completely understand everything. If I have any further questions you may be seeing a PM from me.

 

[Praeger]

I found these two articles helpful when I started reloading. The overall length of a cartridge is really only needed to determine if the round will fit in the magazine. After that, all seating depth measurements should be of the cartridge base to ogive.

http://www.bergerbullets.com/effect...coal-and-cartridge-base-to-ogive-cbto-part-1/

http://www.bergerbullets.com/effect...coal-and-cartridge-base-to-ogive-cbto-part-2/

 

[abentley324]

The real question is, where did you find a case of prime haha

 

[TFreeman]

I shot 80 rounds of 140 ELDM this past weekend and the rifle had no issues with it. No difficulty whatsoever closing the bolt. I am still going to get the equipment to get it measured and find out what the tolerances are.

Average on a 5 shot string was 2814 with an SD of 16.8 and an ES of 37. That doesn’t seem like great consistency. Is that normal for ELDM or does it vary from lot to lot? It did shoot a 5 shot group under 1/2” though.

 

[b6graham]

I shot 80 rounds of 140 ELDM this past weekend and the rifle had no issues with it. No difficulty whatsoever closing the bolt. I am still going to get the equipment to get it measured and find out what the tolerances are.

Average on a 5 shot string was 2814 with an SD of 16.8 and an ES of 37. That doesn’t seem like great consistency. Is that normal for ELDM or does it vary from lot to lot? It did shoot a 5 shot group under 1/2” though.

may be a little high but id say ES:30 and SD:10 are about normal

 

[TFreeman]

Thanks.