Tikka Proof pre-fit question

Any of you using the Proof pre-fits have any issues with having to seat the longer, higher BC bullets too deep into the case with these?

It might help if we knew what cartridge and bullet you're thinking.

Sorry…it's gonna be in 7 PRC and using a 170 Gr hammer hunter

Korhil78 said:

Sorry…it's gonna be in 7 PRC and using a 170 Gr hammer hunter

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A 170 grain copper bullet is going to be REALLY long. Probably longer than a 180 eldm. So my guess is it's going to have to be seated pretty deep into the case

A Tikka Proof Pre-fit it will be chambered with a SAAMI reemer consequently the barrel chamber will not be the problem. You'll want to look at the data sheets on the CEB website. From that you can see how long the bullet is after the seal-tite band. Add that to the case length and get your COAL. Make sure it fits in the Tikka magazine. Tikka mags are short, the longest being 3.4". There are retrofit bottom metals and mags to expand that length a bit. Mountain Tactical and Unkown Munitions both have these.

I did run into this problem with a Proof Prefit barrel in 300 WSM for my Tikka. It wasn't so much a problem with the chamber as it was he bullet I wanted to use. It shot just fine, but the bullet was seated just a little too deep into the case (to get my best distance to the lands) for my liking. To be clear, the problem wasn't the chamber, but rather this particular bullet and how I wanted it positioned in the case. I rented a throat reamer and removed some additional material to move those lands further out. I still had plenty of room in the magazine as the WSM was built on a long action. It was an easy problem to fix.

azsugarbear said:

I did run into this problem with a Proof Prefit barrel in 300 WSM for my Tikka. It wasn't so much a problem with the chamber as it was he bullet I wanted to use. It shot just fine, but the bullet was seated just a little too deep into the case (to get my best distance to the lands) for my liking. To be clear, the problem wasn't the chamber, but rather this particular bullet and how I wanted it positioned in the case. I rented a throat reamer and removed some additional material to move those lands further out. I still had plenty of room in the magazine as the WSM was built on a long action. It was an easy problem to fix.

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Thanks. That's some of the information I was wanting to hear. Did you just hand turn the reamer? And how did you measure how much you took out?

Korhil78 said:

Any of you using the Proof pre-fits have any issues with having to seat the longer, higher BC bullets too deep into the case with these?

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No, I have used several, they all seemed to be spot on with SAAMI specs. I haven't used an all copper bullet though. You may, in fact, have to get a reamer and lengthen the throat.

Just turned by hand. There is a 'stop' built into the throater that will not allow you to go deeper than what was initially set by you. Go slow and be careful. I accidentally overshot the runway because a small shaving was holding the bullet back when testing to find my new lands. Once I realized the problem and removed the shaving, I found I had gone deeper than intended. I just used a longer bullet to make the adjustment I was looking for. The barrel now shoots the 190 gr. Hammer bullet into sub 0.5 MOA groups at 200 yds.

azsugarbear said:

I did run into this problem with a Proof Prefit barrel in 300 WSM for my Tikka. It wasn't so much a problem with the chamber as it was he bullet I wanted to use. It shot just fine, but the bullet was seated just a little too deep into the case (to get my best distance to the lands) for my liking. To be clear, the problem wasn't the chamber, but rather this particular bullet and how I wanted it positioned in the case. I rented a throat reamer and removed some additional material to move those lands further out. I still had plenty of room in the magazine as the WSM was built on a long action. It was an easy problem to fix.

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Do you think this was a quirk of Proof for Tikka or simply that you needed more throat than SAAMI specs to run the combination you wanted? I would think a SAAMI reemer is a SAAMI reemer regardless of who was doing the chambering.

As stated above, the chamber was cut to SAAMI specs. It was not the problem. I had chosen a bullet that was long-ish (it was a 190 gr. Berger) for the 300 WSM and I felt that seating the bullet off the lands to get optimal accuracy also required me to seat the bullet deeper into the case. This in turn robbed me of some powder capacity thereby hurting performance in terms of velocity. I could have gone with a shorter bullet, but then the BC was going to suffer. In the end, I chose to lengthen my throat. When I lengthened the throat a little too much, creating a larger-than-desired jump to the lands, I switched to a mono bullet which was an even longer bullet, but kept the weight the same.

We cannot naturally assume that the same 30 cal bullet will fit into every 30 calber case exactly the same. Some case designs come with extra long or generous case necks that can easily keep the bullet base above the powder charge when seated. Others - not so much. I have found that 'improving' a case by moving the shoulder forward robs you of some neck length. There are many 'work-around' solutions to deal with this issue, so it is not a big deal to me. The 300 WM has more than enough powder capacity to seat longer bullets further into the neck and still perform well. The 300 WSM can keep up with the 300 WM with lighter bullets, but begins to fall behind with the heavier bullets. Case capacity in the 300 WSM is less than the 300 WM, so any deeply seated long bullet begins to rob performance.

Many of the specs for certain cartridges came about years ago before long distance shooting became popular. Older calibers were never designed for the long modern bullets we shoot today. They simply didn't exist back then. These older specs/designs still work well today, provided the throat is lengthed. That is why many of us have gone to custom barrels. We get to tell the gunsmith how we want our barrel throated. SAAMI specs for newer calibers ( think 6.5 CM or any of the PRC's) don't have this problem as the cartridge design allows for throating deep enough to accomodate these longer bullets. Most of the pre-fit Proof Research barrels are chambered in calibers that have specs to accomadate the longer bullets we use today.

Thanks AZ…that's exactly what I was asking about. I usually go custom to but wanted to get into the DIY and see how it goes.

Most quality shops that do prefits can give you a little more freebore. I know PVA and unknown munitions will at least. Give them a call and tell them what you're trying to do. Could always buy a blank and give it to them, might save some headache and money in the long run.