All I am new to the "tactical" game but working into shooting some matches and am about to work up loads for a GAP built rifle.

My load dilemma is this. On my Crusader with 168gn SMKs I get an ogive measurement of 2.145 with an OAL of 2.725. using the proper Hornady tools. Comparing that to SAAMI 2.8 OAL I have a .075 jam at SAAMI length and with factory Federal Gold Medal 168s.

Is this common in these type of rifles to chamber for that much jam? I am a hunting loader and this is my first time chasing uber precision at ranges beyond 600. I have never loaded jam as I never saw an improvement. Usually the contrary.

The factory stuff shoots as expected.

I planned to start with Varget at 2.8 and bring it in.

I would rethink the 168s if you are going out farther than 600. I started with them in factory GMM then switched to the 175s. Subsonic distance was 190 yards farther out of my 20" Tikka, obviously less drop also. I am in G'town, you shoot at MSSA?

Let me get this straight:

You seat the bullet to an OAL of 2.725"
The measurement at that OAL to the ogive is 2.145.
How did you arrive at the 2.725" OAL? How far from the lands is the ogive (2.145")?

Is what you are trying to say is that when the bullet touched the lands the OAL is 2.725" (ogive OAL 2.145")?

If this is true then what the measurements are trying to tell you is that you cannot load this bullet to SAAMI max length of 2.8" in your particular rifle with that particular throat.

The way to use the Hornady tool is to take the ogive measurement 2.145" (touching) and say, for example, subtract 0.01" = ogive OAL length of 2.135" and an OAL of 2.715" to yield a distance of 0.01" off the lands.

The SAAMI OAL is the maximum, not the minimum.

Overall, jamming is a bad idea, especially on a hunting rifle. Only way to clear the chamber is fire off a round or clean the powder out of your magazine and tap the bullet out of the chamber with a cleaning rod.

I would also add that to arrive at ogive OAL I would use a sample of 5-10 different bullets to arrive at an average ogive OAL as some bullets ogive can vary a small amount.

I know how to use the tools.

2.145 is max length at ogive touching the lands.
2.725 is the overall length with that bullet touching the lands.

Factory Federal Gold Medal is benchmark factory loaded ammunition recommended by GAP along with the Black Hills Gold.
The FGM 168s measure 2.8 OAL which has a .0725 jam. I have some 175s coming to measure and test also.
The FGM factory loads shoot VERY well in this rifle so I intended to replicate and improve its performance.
It is there .075 jam which threw me a little.

This is a GA Precision built rifle and they know how to build rifles.

I guess I will call GAP and ask them why the spec the rifle for jam with the recommended factory loads.

First, I don't think you can replicate the FGMM, because it's most likely a non-canister powder.

Second, if you want to improve it, start with an OAL that's appropriate for your percision build, short throated rifle, not the mass market.

As a handloader, if you can't come up with something that shoots better in your rifle than a factory load, you are not doing it right.

I suggest you start in the sticky thread named "Good .308 Loads", where members shared a couple hundred proven loads. See what powders people like with your chosen bullet, put 4 or 5 of those powders behind your bullet, Start low, and just OFF the rifling. and see what your rifle likes. Take the one's that look promising, then work up, and if necessary then work in.

I suspect you will have more success going then route then trying to replicate some factory load.

One experiment would be to seat some GM Match a little deeper, just off the lands and see how that shoots.

I agree with that for most factory ammo I've come across, but I did run across one I had trouble equaling let alone beating.

It was for 308 Winchester, some Norma military/police contract overrun stuff loaded with 168 Match Kings. It shot extremely well in my VTR, 5R, XCR CT, XCR LRT, and 40X.

This.......


Casey

Yep

I'm curious how you determined that FGM 168s are jammed .075"? Is that just from comparing OAL with your loads? Better measure that again; the ogives may be different between the 168 SMK you measured and the FGM ammo. Even different batches can vary some, although not generally that much.
I have a hard time believing they'd chamber without significant effort at .075" jam; you'd have to push on the bolt handle hard enough to seat the bullet deeper. Are you closing the bolt with a mallet? If not, that .075" number is probably not correct.

Avoid the 168 SMK for precision rifle competition. It'll almost always tumble, or at least dispersion will increase significantly, before 1,000 yards. It's not worth your time; it was designed as a 600-yard bullet, and that's what it's very good at.

Using Hornady OAL Guage, Hornady bullet .308 comparators, SMK 168gn bullet per usual and as instructed.

Bullet is lightly set on the lands. Average measure is 2.145 Ogive and/or 2.725" COAL.

Factory Gold Medal Match 168gn ammunition measures 2.8" COAL AND Factory chambered and ejected ammunition without firing shows consistent scuffs (not gouches) on bullet at ogive. Factory loaded ammo at 2.8 chambers just fine.

Factory FGMM 168gn measure 2.210 ogive.

I have some 175s on the way to play with. Local matches are 600 bench matches for score. With the exception of K&M Shooting Complex, PRS type matches are few and far between around here currently but that is the ultimate plan.

It is funny you mention the dispersion, the factory stuff shoots great to 500 and always opens up at 600.

If they chambered your barrel with a reamer that jams on factory ammo, they screwed up and need to throat it out for you or re chamber you a new barrel using a reamer with a longer freebore.

So for clarification, you haven't pulled a bullet from FGMM and determined max OAL with it?

The fact that you're able to chamber and eject that ammo suggests it's probably not jammed nearly as much as your numbers indicate. What is the ogive or OAL of ejected unfired rounds?

Any chance the barrel throat is not short, but instead maybe slightly tight for your bullets by a ten thousandth or two? That could possibly give false measurements to the lands, making it look like a short throat.

Unfired, ejected remains 2.8"

I assume the throat is tight too. It would make sense the more I think about it. I have a call in GAP to talk about it.