LRB M25 build

[lennyo3034]

Re: LRB M25 build

So ten shot groups are hard. Not only was I feeling much less relaxed by the end, the barrel had gotten quite hot. Keep in mind this is a pencil thin barrel though.

First 5 shots were dead on. Shot 6 was lower so I decided to wait around 30 seconds between shots afterwards. Shot 7 was an epic pull on my part and I'm surprised it was as close as it is. Guy next to me shot his Nagant M44 and scared the Bejesus out of me. Shots 8-10 were right with 6 but the barrel was already heated up.

I also tried it without waiting between shots:

First 4 were right on. Then they just started stringing downwards. This is taking a shot every 8 seconds or so.

Next time I'll try shooting 5, going to the head then doing the rest.

Rifle is a SAI National Match model with Nightforce 2.5-10X32 shooting from sandbags.

 

[M21guy]

Re: LRB M25 build

When I said "hard" I meant keeping them tight. Though for a pencil thin barrel, not bad at all.

I'm going to get it. I'm not sure if I can keep all ten under a dime, but a quarter I should be able to in time. It's for kicks. I just get tired of the ridicule I shoot a M1a rifle and it isn't the all mighty AR. Shoot what you brung, but shoot it well is my thoughts on it.

 

[BCP]

Re: LRB M25 build

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lennyo3034</div><div class="ubbcode-body">
Rifle is a SAI National Match model with Nightforce 2.5-10X32 shooting from sandbags. </div></div>

Bedding maybe?

 

[NoExpert]

Re: LRB M25 build

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lennyo3034</div><div class="ubbcode-body">
Rifle is a SAI National Match model with Nightforce 2.5-10X32 shooting from sandbags. </div></div>

Bedding maybe? </div></div>

Yeah, I'd definitely question something with that kind of stringing. I've had two different medium weight barrels that didn't string at all.

 

[M21guy]

Re: LRB M25 build

The first group didn't string. It might just be shooter error. THough it does look to be something more.

 

[lennyo3034]

Re: LRB M25 build

The first group didn't string because I waited 30 seconds or more between shots. The second group was a shot taken as soon as I was comfortable.

I guess I should note the first group was with GMM and the second was with Nosler custom that has shot well through the rifle before, however is noticeably hotter (2740 vs 2660).

Although that group is particularly bad. I've seen strings, but not like that before. In fact, I've shot prone rapid fire stages with irons and no rest that were better than that. More dispersed, but smaller overall distance between shots.

The rifle is factory bedded and to my untrained eye, is very clean and an excellent job. The only modifications to the rifle is a Sadlak grooved gas piston.

There was certainly shooter error because by the end of the strings, I wasn't able to concentrate as well as the first few rounds.

 

[M21guy]

Re: LRB M25 build

Pistons can do that. While I to use the grooved piston, pistons can vary groupings. I seen this same sort of string before when a friends rifles piston had a small pitting on the tail end of his piston. Might be worth trying a different piston in your rifle.

 

[lennyo3034]

Re: LRB M25 build

This is my fourth piston I've tried. Not sure if its the best or not though. I have a match this weekend and will keep it until afterwards. None of the pistons are passing the tilt test though so it may be a gas cylinder issue. I have another one on the way.

I appear to have highjacked NoExpert's thread. We should get other people's attempts here. I doubt my ADD ass can hold 10 shots under a dime with any rifle. I couldn't do it with my bolt gun, in the past, which is an absolute tack driver.

 

[M21guy]

Re: LRB M25 build

Not passing the tilt test throws up flags. I'd sort that out. Both my action and piston moves clean and free. That is important stuff right there.

 

[NoExpert]

Re: LRB M25 build

This is all for fun and learning as far as I'm concerned, if you walk away with the stinging sorted out then hi-jack away.

Definitely sounds like a GC issue, that or the gas lock is too tight and warping the cylinder (I've seen this first hand).

 

[NoExpert]

Re: LRB M25 build

Finally got some range time, it shoots at least as well as the JAE setup did, but without five extra pounds. The last step will be changing to an SEI 18.5" standard contour barrel. Should happen in a few months. That's the last thing I can change to lose weight. That will cover the three heavy components; stock, optics package, and barrel.

 

[vereceleritas]

Re: LRB M25 build

About time you got some rounds through that thing. Looks great. How did she group? Do you think you're going to lose some accuracy going from a Krieger to a SEI?

 

[NoExpert]

Re: LRB M25 build

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vereceleritas</div><div class="ubbcode-body">About time you got some rounds through that thing. Looks great. How did she group? Do you think you're going to lose some accuracy going from a Krieger to a SEI? </div></div>

I was having a rough day shooting but managed 1" at 100 yards with some RG surplus ammo. Out at 600 yards I was able to hit the silhouettes I aimed at even with a little cross wind going on.

I may sacrifice a little accuracy, but I think SEI is using Criterion barrels and they have a 1:10 twist like my Krieger. I think the loss will be minimal and only appear with prolonged rapid fire. The barrel I'm getting will be CM, non chrome lined and melonite treated after being head spaced.

Losing a pound off the front end should make the rifle balance about perfect for me and make off hand easier. Right now it balances just ahead of the magazine; I put a one pound weight on the exposed extension tube and the rifle balanced on the magazine. The changes so far have been mobility inspired so I'm expecting some loss in accuracy at some point.