New to Hide - LR-308

[Tiller1k]

Hello all!

I have lurked for a while on the Hide but recently built a new rifle to fit the longer range role in my safe. It is a DPMS "Semi-SASS". Basically a SASS type lower with an 18" free-floater upper (AP4 style BBL). It is an odd combo and I don't know exactly how it came to be but I purchased it new last month. I added a Harris bipod and Millett TRS-1 4.5-16X50 optics.

I have been shooting for 30 years but just recently started getting into longer ranges. I am a fair shot but am definitely needing some guidance with this rifle.

I have discovered that the rifle likes Federal 168BTHP GMM. I have tried many types of ammo and this works the best so far. I still haven't tried the Remington or PRVI loads but the Hornady works well too. I will post up some pics but at 100yds, it will shoot anywhere from .75" to 1.25" with regularity and the majority fall right at or just under 1 MOA (3 shot groups, I can post up some targets if it matters). I am quite happy with this but here is the problem...

I can shoot a group under 1 MOA and the next 3 might as well be done with my eyes closed. Same ammo, same rifle, 3" groups.

I won't proclaim to be an expert but my technique is fairly solid and consistent.

I am looking for any ideas why a reasonably capable rifle would be prone to inconsistency? I am not above accepting that I am doing something wrong but I think there is more to it than that. Upper/lower fit is fair but could be better which is one idea. Shots tend to be stringing a bit.

I like this rifle but I need to get some consistency before I can trust it.

I didn't mean to write a novel on this post but wanted to give the background. I am looking forward to your answers and spending some time on the Hide.

 

[JSTARSZ]

Re: New to Hide - LR-308

Just to weed out some errors of magazine feeding try loading the rounds singularly without the magazine. Then try before loading into the magazine get the Overall Length of the rounds and then feed them into the chamber; then pull them out of the chamber and recheck size. Have they changed? When dealing with an autoloader it is a violent action and can create numerous problems with consistency. Since it is FGGM I know it is not the round - 90% sure...You need to do little actions to find the issue. One step at a time to narrow out the issue. Change magazines, ammo. Could be your trigger control issues - little moves on an autoloder can make huge changes down range. Just try making small corrections to find the problem.

And, welcome to the Hide.

 

[Tiller1k]

Re: New to Hide - LR-308

Thanks for the welcome. I started thinking about it and you may be on to something here. That is not to say I won't be working on the trigger control but here is my thought.

Most of the time, I was loading three rounds at a time. Occasionally, I would load 6. The first three were good and they got progressively worse from there. I am going to take my caliper out there and measure before and after the cartridge sits in the mag for several recoil cycles. It could be making the OAL shorter even be distorting the tip of the projectile.

I will also take your recommendation on measuring a chambered cartridge.

Thanks for the suggestion. Someone recommended a receiver tensioner as well (JP or ??). Any feedback on these?

 

[JSTARSZ]

Re: New to Hide - LR-308

I have never used a receiver tensioner so no feedback on that. I tend to start with the easiest (cheapest) and work my way through until find the issue. Changing mags is easy as it could be pinching the rounds or the springs are too tight or loose. When it comes to autoloaders there are so many variables that taking it one step at a time to find the problem is the best. And when all else fails take it to a competent gunsmith and let them fix it. I am an amateur gunsmith ay best so there is a point when I can’t figure it out so I take to a professional.