first shot low

So a little back ground to go along with my question. 300 rum, 200 AccuBond, twice fired brass, 94 grains ramshot magnum powder, dirty fouled barrel. Shooting at 200 yards to zero my rifle from a bench with shooting rests my first shot was 4 inches low then it grouped quite nice. Went home and loaded a few more to check my zero with my bipod this time and the first shot was once again 4 inches low. Everything after that shot where it should.

The rifle is bedded in a McMillan stock, night force base/rings, night force scope.

Has anyone else seen this? I never seen this with my retumbo load. I'm going to try it again in the next week but for now I'm puzzled.

I am curious about the effect of a warming barrel on POI. But is one shot enough.

Interesting what else might cause it, like some shift in the stock/action/scope that only occurs after transport, but resets after the first recoil???

I had an event where my first two shots from a cold barrel after a cease fire and shooting another gun changed the POI for two shots until the barrel was warm. Otherwise, nothing changed in MOA or less groups as I was shooting a series of loads for an OCW test.

And, one of the loads where it shifted a couple of inches from the cold barrel shot a .5 MOA group at 200 yards.

It was in a 7mm rem mag with a heavy sporter barrel.

You make me want to test my gun again, specifically for POI change and map my cold bore shots. I don't hunt with a warm barrel...

First shot from a cold barrel can be slower and shoot low but maybe not as low as what your seeing.

When I chrono the load today I got 3072, 3072, 3093, this was with a cold barrel so I don't think it's a low velocity that is the cause. This is a first for me with a fouled barrel.

I'm sure you've checked all the screws for tightness but what type of stock do you have it in, wood, custom or factory poly synthetic?

Bedded McMillan stock, night force rings/bases, night force scope.

There was a recall on a batch of Ram Shot powder but I'm not sure which one it was. Check the Western Powder site for the recall.

That's pretty interesting Bill. That truly makes it tough to get that cold core shot on the money.

Have you checked the bedding over? Could it be touching or close when the rifle is cold? My 338 would do the same thing till I re did the tang and recoil lug. Had a little bit of tension in the bedding.

OU812":2ha6zwxb said:

Bedded McMillan stock, night force rings/bases, night force scope.

Click to expand...

It's a poltergeist.

SJB358":2gilfux7 said:

That's pretty interesting Bill. That truly makes it tough to get that cold core shot on the money.

Have you checked the bedding over? Could it be touching or close when the rifle is cold? My 338 would do the same thing till I re did the tang and recoil lug. Had a little bit of tension in the bedding.

Click to expand...

Scotty your telling me. No I have not checked the bedding. Funny thing is my rifle has never done this with Retumbo, maybe it's just a coincidence. I'm going to recheck the load again later this week to be sure and maybe I'll start with Retumbo and see if it does it now. At 100 yards it shot a .319 3 shot group last week.

After the first low cold bore shot off the bench it shot sub 1/2 moa at 200 yards and after the second cold bore low shot it shot a 1.658, 1.571 and a 1.116 all 3 shot groups at 200 off the bi pod. I'll post pictures tomorrow.

Something to think about, try a different rest and see what happens. Could it possibly be the gun settles into the rest after the first shot?

That's a tough one Bill. Wished I had an answer for it. It sounds like it is wickedly accurate though. It's times like this I wished I had the ability to just take 1 shot and put it away until the next morning.

lefty315":2s72szum said:

Something to think about, try a different rest and see what happens. Could it possibly be the gun settles into the rest after the first shot?

Click to expand...

Good idea but I used a different rest each time.

pict 002 is from the bench, I had to pull the target from the cardboard backer because everything was soaked, I even tore the target doing so. 003 bi pod, 004, bi pod. shot 10 was supposed to be on 005 but I messed up after a cease fire. 005 bi pod 10 with black circle is where the shot would have landed. This is what the rifle shot after the 1 cold bore first shot each time 002 was first trip to the range, the rest were from my second trip to the range.

Bill, are you pre-loading the bipod with some tension while shooting it?

Looking at the 005 picture it looks like it would have been good to me. I need to keep looking at the pictures but it seems very consistent for the most part.

I would give a quick once over on the bedding and maybe see what happens when you load the legs a little.

Just for grins, maybe try 12 rounds at the same target, marking each one as you go? Might show the consistency of the rifle as an overall picture.

Again, it's a hair puller.

This is what my 338 would do Bill



Shot 1 would go high left, shot 2 would go in the bull... let the gun cool back to cold and it would do the same thing. Turns out it was a little bit of contact at the barrel boss on a P64 that was the culprit. It took me awhile to sort it out though.

I was once issued a Rem 700 for SWAT use, a .308 of course. It would consistently put the first shot about 1" lower at 100 yards than the rest of the group. The rest of the group would be very nice and tight, but that first one always shot low.

I put the rifle in a better stock with an aluminum bedding block, and the problem disappeared. No other changes.

McMillan makes a GREAT stock, but I suspect the bedding may be the problem. Maybe.

Guy

I'm going to look things over for sure as something has changed. I find it odd that it throws the first cold bore shot low with 2 different types of shooting rests.

Yes I put a little preload when using the bi pod.

For grins I may run my Retumbo load as a first shot and see what it does as it has always placed all 3 shots right together.

The rifle did none not do this when shooting at 100 yards with the first shot.

Being a Rifle Looney can be frustrating.

After all, we're only expecting perfection... :wink:

Guy